Current date: 2026-07-31
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Created/updated limit: 2026-07-24 (7 days ago)
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Number of records retrieved: 820
Keyword score statistics
score 10 -- 1 abstracts
score 9 -- 1 abstracts
score 8 -- 1 abstracts
score 7 -- 1 abstracts
score 6 -- 2 abstracts
score 5 -- 4 abstracts
score 4 -- 11 abstracts
score 3 -- 13 abstracts
score 2 -- 25 abstracts
in total -- 59 abstracts
Articles that appeared on 2026-07-31
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[abstract 1 / 59] Wow! (score: 10)
- Title: Tidal Disruption Events with the SKAAuthors: T. An, A. J. Goodwin, J. C. A. Miller-Jones, M. Pérez-Torres, L. Rhodes, X. Shu,Comments: Published in Advancing Astrophysics with the SKA II (AASKAII), 2026 (arXiv:2606.20366). Report-no:AASKAII/TaoAn03. Advancing Astrophysics with the SKA II (AASKAII) outlines the transformative scientific advances that will be enabled by the SKA telescopesSubjects: astro-ph.HECreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
Tidal disruption events (TDEs) and related nuclear transients probe JET launching, disk formation and circularization, particle acceleration, and the circumnuclear medium (CNM). However, the small fraction of events launching RELATIVISTIC JETs, the weak or delayed radio emission of many thermal TDEs, and the black-hole demographics of galactic nuclei remain poorly understood. SKA, with microJy sensitivity, wide bandwidth, long baselines, rapid response, and commensal surveys across 50-350 MHz (SKA-Low) and 0.35-15.4 GHz (SKA-Mid), will transform this field. Its sensitivity, frequency coverage, and very long baseline interferometry (VLBI) capability will extend radio calorimetry from a few well-studied nearby events to volume-limited samples of non-RELATIVISTIC outflows. The SKA will bring off-axis and mildly RELATIVISTIC JETs into routine reach, trace CNM density profiles through the evolution of the low-frequency SYNCHROTRON turnover, and localize faint off-nuclear transients with sub-arcsecond precision. These data will constrain JET incidence, energetics, geometry, and MAGNETization, map the CNM through shock interactions, test links to changing-look ACTIVE GALACTIC NUCLEi (AGN) and high-energy neutrinos, and identify off-nuclear events associated with recoiling supermassive or intermediate-mass BLACK HOLEs. We discuss the benefits of commensal surveys, rapid triggering, and SKA-VLBI, and provide predictions based on the projected performance of AA* and AA4. SKA will shift TDE radio studies from detailed case-by-case studies to population-scale inference, advancing studies of JET physics and black-hole demographics.
[abstract 2 / 59] Wow! (score: 9) - Title: An extra hard spectral component peaking at sub-GeV in the prompt emission of GRB 260226AAuthors: Yi-Yun Huang, Hai-Ming Zhang, Ruo-Yu Liu, Xiang-Yu Wang,Comments: Submitted to APJ on 15-July-2026Subjects: astro-ph.HECreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
The prompt emission spectra of GAMMA-RAY BURSTs (GRBs) have long been empirically described by the Band function over the keV--MeV range, whereas several \textit{FERMI}/LAT-detected GRBs show evidence for an extra hard component at higher energies. Here we present a joint GBM--LAT study of GRB~260226A, a rare LAT seeded onboard trigger GRB, and find that an extra sub-GeV component is present. In the time-resolved analysis, we find that a cutoff power-law model fits the spectral data of the extra component better than other models at earlier times, while at later times, the broken power-law model is preferred (or at least equally good). Interpreting the early cutoff as the $γγ$ absorption implies that the Lorentz factor at early time is lower and increases with time. The low ratio between the peak energy of the extra component and that of the Band component is difficult to explain with a one-zone SYNCHROTRON self-Compton (SSC) scenario. Two-zone emission models, such as external inverse Compton scattering of the photosphere emission by RELATIVISTIC electrons accelerated in internal shocks, could provide a possible explanation.
[abstract 3 / 59] Wow! (score: 8) - Title: Exploring cosmic MAGNETism with GAMMA-RAY BURST afterglow emissionAuthors: Paolo Da Vela, Davide Miceli, Lara Nava, Giancarlo Ghirlanda,Comments:Subjects: astro-ph.HECreated: 2026-07-29; Updated: 2026-07-31; Datestamp: 2026-07-31
The nature and origin of MAGNETic fields on cosmological scales are still unclear. Magnetic fields detected in galaxies and galaxy clusters are typically interpreted as the result of the amplification of weak seed fields, but their nature remains largely unknown with two scenarios considered: the cosmological and the astrophysical origin. Signatures of MAGNETization in cosmic voids from observations of very high energy (VHE, E > 100 GeV) photons from extragalactic sources can provide crucial results. Indeed, if a non-negligible intergalactic MAGNETic field (IGMF) is present in the voids, a time-delayed emission known as pair-echo is expected. The timing and intensity of this signal encode information on the IGMF strength B and properties. Given the recent detection of GRB afterglows at TeV energies, in this article we perform a detectability study of pair-echo signatures from GRBs. We simulate afterglow emission for different values of the JET kinetic energy (E$_{k,iso}$ = 10$^{49}$ - 10$^{55}$ erg), redshift (z = 0.03 - 1), and lightcurve break times, and estimate the expected pair-echo radiation for IGMF strengths in the range B = 10$^{-19}$ - 10$^{-16}$ G. We investigate the capability of CTAO to detect the resulting emission at tens of GeV. We find that a subsample of GRBs in the z - E$_{k,iso}$ parameter space can produce a detectable pair-echo component for CTAO for all the tested IGMF strengths. A steepening of the GRB afterglow light curve, caused e.g. by an early (0.1 - 1 days) JET break, is a key factor to increase the chances of detection. CTAO observations starting from 10 - 12 hrs up to a few days after the GRB trigger time can provide relevant results to probe IGMF.
[abstract 4 / 59] Wow! (score: 7) - Title: An extreme particle accelerator powered by pulsar PSR J1849-0001Authors: The LHAASO Collaboration,Comments: Published in Nature Astronomy. 41 pages including Methods, Extended Data and Supplementary InformationSubjects: astro-ph.HECreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
Pulsar wind nebulae (PWNe) are bubbles of RELATIVISTIC particles, powered by the rotational energy loss of the central pulsars. The Crab Nebula, powered by the Milky Way's most energetic pulsar, was discovered by the Large High Altitude Air Shower Observatory (LHAASO) as a PeV gamma-ray emitter, thereby establishing it as an extreme particle accelerator along with multiwavelength observations. Here we report LHAASO's detection of a point-like ultrahigh-energy (UHE, photon energy $E>100\,$TeV) gamma-ray source associated with the PWN powered by PSR J1849-0001, a pulsar of spindown power 50 times lower than the Crab pulsar. The measured gamma-ray spectrum extends to PeV energies following a power-law distribution, with the PeV luminosity a few times higher than that of the Crab Nebula. Combined X-ray observations constrain the average MAGNETic field within the source to about $3μ\,$G, and reveal an extreme particle acceleration efficiency approaching or even exceeding unity in the PWN, which we refer to as the "Aquila Booster". The result challenges the particle acceleration theory in PWN and implies non-ideal MAGNETohydrodynamics (MHD) conditions within the accelerator, potentially involving MAGNETic RECONNECTion upstream of the termination shock.
[abstract 5 / 59] Yes (score: 6) - Title: The eROSITA X-ray luminosity function of ACTIVE GALACTIC NUCLEiAuthors: W. Roster, J. Buchner, M. Salvato, R. Shirley, A. Merloni, T. Dwelly, J. Aird, A. Georgakakis, P. Boorman, M. Brusa, W. N. Brandt, B. Trakhtenbrot, B. Laloux, P. Baldini, C. Andonie, C. Aydar, C. Ricci, S. F. Anderson, P. Chakraborty, R. J. Assef, D. P. Schneider, E. Kyritsis, M. Kluge, E. Bulbul, K. Nandra, J. Weller,Comments: 25 pages, 15 figures. Catalogue including redshift information is released via the eROSITA web pages and CDS upon the journal's article acceptanceSubjects: astro-ph.GACreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
The X-ray luminosity function (XLF) of ACTIVE GALACTIC NUCLEi (AGN) provides an observational probe of the growth of supermassive BLACK HOLEs (SMBHs) across cosmic time. With its large survey grasp, Spectrum Roentgen Gamma (SRG)/eROSITA samples the luminosity--redshift plane with a depth--area balance complementary to pencil-beam surveys, providing the volume needed to detect rare luminous AGN, previously limited by small-number statistics. We measure the soft XLF, leveraging an eROSITA sample spanning approximately eight orders of magnitude in luminosity out to $z\simeq6$. This enables us to study luminosity-dependent evolution with improved constraints, and to infer both the SMBH accretion history and optical/UV missed AGN population. We introduce a new redshift-dependent smoothly broken power-law parameterisation in which all XLF model parameters are allowed to evolve continuously with redshift. We find lower space densities for moderately and very luminous AGN at low redshift, while the abundance is higher than previously found at the highest redshifts. Comparisons to optical/UV QUASAR LFs converted to rest-frame $2\!-\!10\,\mathrm{keV}$ show that the UV-missed fraction decreases with luminosity, and, in the most luminous bin, increases with redshift. Integrating the XLF yields a black-hole accretion-rate density peaking at $z \simeq 1.5$, with the corresponding cumulative black-hole mass density indicating $\sim80^{+11}_{-23}\%$ obscured growth relative to locally-inferred BH mass estimates derived from scaling relations and missed by the soft X-ray selection of our sample. With this work, we release the eROSITA DR2 AGN catalogue, including counterparts and their redshift information. We then discuss how these results can inform future spectroscopic, photometric, and X-ray survey strategies aimed at improving AGN demographic constraints.
[abstract 6 / 59] Yes (score: 6) - Title: X-ray Absorption Variability in NGC 1142: Another Constraint on the Nature of the Torus/Broad-Line Region in Active Galactic NucleiAuthors: Isaiah S. Cox, Núria Torres-Albà, Stefano Marchesi, Vittoria E. Gianolli, Xiurui Zhao, Marco Ajello, Indrani Pal, Andrealuna Pizzetti,Comments: 17 pages, 5 figures, 4 tables, submitted to ApJSubjects: astro-ph.GA astro-ph.HECreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
The physics, geometry, and kinematics of the gas and dust surrounding the central engine of ACTIVE GALACTIC NUCLEi (AGN) are not well understood. In some sources, this material obscures the coronal X-ray emission, allowing its line-of-sight column density ($N_H$) to be measured. Many sources display $N_H$ variability across multiple epochs. Studying this variability can provide information about the distribution and dynamics of the obscuring material. Particularly, previous works have shown that the probability of observing $N_H$ variability increases with the number of observations available. Additionally, the observed magnitudes of the $N_H$ variability depend on the timescale between observations. In this work, we present the $N_H$ variability analysis of NGC 1142, which has a total of nine X-ray observations over $\sim20$ years, including five from a NUSTAR+XMM-Newton monitoring campaign performed in 2024-2025 and reported here for the first time. We use the physically-motivated torus models UXCLUMPY, XSKIRTor, and RXTorusD to model the spectra. Our results confirm the previously observed trends, and we compare these trends to simulated obscuration curves assuming different locations and distributions of obscuring clouds.
[abstract 7 / 59] Yes (score: 5) - Title: Distinct Jet Properties in the X-Ray-Obscured State of GRS 1915+105Authors: Xi Yan, Lang Cui, Sergei Trushkin, Shuangjing Xu, Wu Jiang, Zhen Yan, Sándor Frey, Timur Mufakharov, Ruchika Dhaka,Comments: This is a revised manuscript submitted to ApJSubjects: astro-ph.HECreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
GRS 1915+105 has remained in an X-ray-obscured state since its transition from a long-lasting unobscured state in 2019. We report on 6.7-GHz East Asia VLBI Network observations of GRS 1915+105 obtained during strong radio flares detected at 2.3--11.2 GHz with the RATAN-600 radio telescope in 2025. Our images reveal two contrasting JET morphologies. The first epoch, associated with a flare evolving from an optically thick to an optically thin spectrum, shows a bright radio core accompanied by an extended JET structure. By contrast, the second epoch, observed near the peak of another flare displaying optically thin emission at lower frequencies, is dominated by two bright, symmetric, well-separated JET blobs and shows no detectable radio core. If these JETs exhibited the apparent superluminal motions commonly observed prior to 2019, measurable angular shifts would be expected over the five-hour observations. However, no significant JET motion is detected. Combined with our derived JET speed of $βΓ\lesssim 0.40$, these results suggest that the JETs launched during the current obscured state are slower than the RELATIVISTIC JETs ($βΓ\gtrsim 1$) observed earlier during the unobscured state. Together with the recently reported large variations in JET orientation, our findings in GRS 1915+105 provide robust support for the emerging paradigm that X-ray binary JETs launched in obscured and unobscured states likely exhibit distinct propagation properties.
[abstract 8 / 59] Yes (score: 5) - Title: Comprehensive X-ray Study of Giant Radio Galaxies with XMM-Newton and ChandraAuthors: Niraj Maurya, Satish S. Sonkamble, Suraj Dhiwar, M. B. Pandge, S. Ilani Loubser, Avinash Kale,Comments: Accepted for publication in JHEAp , 21 pages, 7 figures, 12 tablesSubjects: astro-ph.HE astro-ph.GACreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
We present a systematic X-ray spectral analysis of 27 giant RADIO GALAXies (GRGs) using archival \textit{XMM-Newton} and \textit{Chandra} data. Roughly 44\% of the sample show intrinsic absorption ($N_{\mathrm{H,int}} \gtrsim 10^{21}\,\mathrm{cm}^{-2}$), while several exhibit narrow Fe K$α$ emission lines with equivalent widths up to $\sim$570 eV. Soft X-ray features are also common, including thermal plasma emission (kT$\sim 0.2$--0.8 keV) and ionized absorbers, in some cases consistent with high-velocity outflows. The photon indices are typically hard (median $ Γ\sim 1.6$), in line with radio-loud AGN. A comparison between nuclear X-ray luminosity and extended radio power shows that many sources host relatively strong X-ray cores compared to their lobes, pointing toward possible restarted nuclear activity. For 10 GRGs with published BLACK HOLE masses, we explore preliminary relations with X-ray luminosity, Eddington ratio, and photon index. We find a positive trend between $M_{\rm BH}$ and $L_{2-10\,{\rm keV}}$, while Eddington ratios show no clear dependence on mass. A tentative negative relation between $λ_{\rm Edd}$ and $Γ$ hints at inefficient accretion, although confirmation will require larger samples. Overall, GRGs display diverse nuclear conditions and accretion states, supporting scenarios where obscuration, episodic or restarted activity, and low-efficiency accretion shape their long-term evolution.
[abstract 9 / 59] Yes (score: 5) - Title: The First Measurement of Jet Collimation Profiles in an X-ray Binary: the Case of SS 433Authors: Xi Yan, Lang Cui, Zsolt Paragi, Sándor Frey,Comments: This is a revised manuscript submitted to ApJLSubjects: astro-ph.HECreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
While significant progress has been achieved in ACTIVE GALACTIC NUCLEi (AGN), JET collimation profiles in X-ray binaries (XRBs) have not been directly measured. Here we report the first measurement of JET collimation profiles in an XRB using very long baseline interferometry data from SS 433. The approaching JET exhibits a well-constrained quasi-parabolic profile in the 1995 and 1998 data, whereas the prominent local oscillations present in the 2000 JET-width measurements preclude a robust characterization of the JET collimation profile. Nevertheless, the 2000 data suggest that the intrinsic JET opening angle decreases gradually from $\sim 20^\circ$ at 8$\times 10^{14}$ cm to $\sim 3^\circ$ at $9\times 10^{15}$ cm (deprojected), providing evidence for progressive JET collimation. The width and opening angle of the receding JET are also presented, although their interpretation is limited by the free--free absorption effect. In addition, we measure the frequency-dependent core positions at four bands and derive a core-shift relation. These results establish SS 433 as the first XRB in which JET collimation, opening-angle evolution, and core-shift relation are constrained.
[abstract 10 / 59] Yes (score: 5) - Title: Magnetic Reconnection Process in Partially Ionized Fluids: Insights from the Solar ChromosphereAuthors: Adrian R. Montañez-Lobo, Fabio D. Lora-Clavijo,Comments: 34 pages, 14 figures. Accepted for publication in Solar PhysicsSubjects: astro-ph.SRCreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
Magnetic RECONNECTion converts stored MAGNETic energy into kinetic energy, heat, and radiation. While extensively studied in fully ionized plasmas, observations show that ionization and recombination also play a role by modifying the local plasma resistivity and enabling additional heating channels. This study examines MAGNETic RECONNECTion in the partially ionized solar chromosphere, analyzing its morphology and energy releases with attention to elastic collisions, ionization, and recombination. The MAGNUS code, originally built for ohmic resistivity and heat transfer, was modified to handle elastic and inelastic collisions. The simulations are 2.5D resistive MHD with two-fluid effects (charged + neutrals), adapted to handle interactions via these collision terms. A mixed explicit-implicit scheme was implemented to manage the stiffness of these terms. Simulations were carried out for three MAGNETic field strengths: 100~G, 110~G, and 120~G. These values correspond to the low- to mid-chromosphere under quiet-Sun conditions. We found that RECONNECTion heats the plasma components by 18\% to 110\%. Although plasma beta rises only slightly, the energy release grows far more, indicating that charged--neutral collisions, not just beta or available MAGNETic energy, drive the enhanced RECONNECTion. Furthermore, ionization and recombination become most significant in regions of peak temperature, particularly where particles are accelerated. Maximum RECONNECTion rates from temporal analysis are 0.226, 0.253, and 0.279, respectively. Finally, in terms of energy, our results show that in a chromospheric volume of $0.4 \times 0.01 \times 0.4$~Mm$^{3}$, the energy released ranges from $10^{22}$ to $10^{23}$.
[abstract 11 / 59] Yes (score: 4) - Title: Tests of scalar POLARIZATIONs with multi-messenger eventsAuthors: Sk Md Adil Imam, Macarena Lagos,Comments: 16 pages, 12 figuresSubjects: gr-qc astro-ph.HECreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
Gravitational wave (GW) observations provide a unique opportunity to test Einstein's General Relativity (GR) in the strong-field regime. While GR predicts only two tensor POLARIZATION modes, generic metric theories allow up to six independent modes. We perform a parameterized test of GR using the parameterized post-Einsteinian (PPE) framework applied to GW170817, incorporating for the first time the POLARIZATION angle constraints from the GAMMA-RAY BURST afterglow alongside other electroMAGNETic (EM) counterpart information. We extend the GR waveform by adding a scalar breathing mode and modifications to the tensor modes, introducing three non-GR parameters. We perform Bayesian inference for both quadrupole $\ell = |m|= 2$ and dipole $\ell = |m|= 1$ angular harmonics, with two frequency evolution models. For $\ell = |m| = 2$, we find that within the extended PPE framework the scalar amplitude deviates from zero at the $2$--$3σ$ level, leading to a modest preference for modified gravity. However, due to penalization of extra parameters, Bayesian model comparison still favors pure GR over the extended PPE waveform model, with a log Bayes factor of $Δ\log \mathcal{Z} = 4.67 \pm 0.32$. The EM constraint on the POLARIZATION angle places very tight bounds on non-GR parameters; for instance, in the case $\ell = |m| = 2$, the bound on the scalar (tensor) amplitude modification parameter improves by roughly $60\%$ $(30\%)$, highlighting the impact that long-term follow up of GW events can have on tests of gravity.
[abstract 12 / 59] Yes (score: 4) - Title: Bridging X-ray Polarization with Timing & Spectroscopic Parameters of a galactic BLACK HOLE: SWIFT J1727.8-1613Authors: Arka Chatterjee, Sujoy K. Nath, Kaushik Chatterjee, Samar Safi-Harb, Broja G. Dutta, Indranil Chattopadhyay, Sudip K. Garain, Hsiang-Kuang Chang,Comments: submitted to MNRAS, comments are welcomeSubjects: astro-ph.HECreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
We report the discovery of a correlated energy-dependent time lag and degree of POLARIZATION for SWIFT J1727.8-1613 during its 2023 outburst. The energy-dependent time lag is measured around the type-C quasi-periodic oscillations (QPO) observed by IXPE on 2023-09-07, while the degree of POLARIZATION is obtained from energy-resolved polarimetric measurements. The Spearman correlation coefficient was found to be 0.8, with a null hypothesis probability of 4.2\%. Furthermore, the correlation value drops as the quality factor, or Q value, of the observed QPO frequencies decreases. The spectral properties of SWIFT J1727.8-1613 are analyzed using simultaneous Insight/HXMT data. Thereafter, we present model-independent theoretical arguments to show that processes other than inverse Comptonization also contributes to both the observed POLARIZATION and time lags. This correlation may therefore point to additional mechanisms contributing to the connection between the spectral, temporal, and polarimetric properties of BLACK HOLE binaries in their hard state.
[abstract 13 / 59] Yes (score: 4) - Title: Photon Acceleration in Magnetized Plasma: A Mechanism for Fast Radio BurstsAuthors: Sergei V. Bulanov, Gabriele Maria Grittani, Marcel Lamac, Petr Valenta, Stepan S. Bulanov, Timur Zh. Esirkepov, Gianluca Gregori, Brandon K. Russell, Alexander G. R. Thomas, Arno Vanthieghem,Comments: 25 pages, 6 figuresSubjects: physics.space-ph astro-ph.HE physics.plasm-phCreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
We propose a mechanism for fast radio bursts based on photon acceleration by RELATIVISTIC shocks propagating through highly MAGNETized electron--positron plasmas, as expected in MAGNETar MAGNETospheres. Density modulations at the shock front create RELATIVISTICally moving refractive-index perturbations that transform low-frequency electroMAGNETic precursors into amplified high-frequency radiation. We show that the predicted frequencies, durations, and energetics of the resulting fast radio bursts are consistent with the MAGNETic-field strengths, shock Lorentz factors, and characteristic spatial scales expected in MAGNETar MAGNETospheres.
[abstract 14 / 59] Yes (score: 4) - Title: Effect of Multi-Species Plasma on Fanaroff-Riley Radio JetsAuthors: Priyesh Kumar Tripathi, Indranil Chattopadhyay, Raj Kishor Joshi, Ritaban Chatterjee, Sanjit Debnath, M. Saleem Khan,Comments: 11 pages, 5 figures. Accepted for publication in the Bulletin of the Liège Royal Society of Sciences as a part of 4th BINA workshop, November 2025Subjects: astro-ph.HECreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
The Fanaroff-Riley (FR) dichotomy observed in extragalactic radio JETs has been attributed to a range of possible mechanisms, including intrinsic JET properties such as the presence of different species in the plasma. Jet material may span from a pure electron-positron pair plasma to mixed plasmas containing electrons, positrons, and protons, or even to hadronic JETs made up of electrons and protons only. To investigate this aspect, we present results from three-dimensional simulations of low-power, supersonic, MAGNETized JETs at kiloparsec scales in a MAGNETohydrodynamic framework. By varying the plasma composition, we show its impact on JET stability and on the development of diffuse structures typical of core-brightened FR type I sources. Our results indicate that the growth of non-axisymmetric instabilities plays a key role in disrupting the JET head.
[abstract 15 / 59] Yes (score: 4) - Title: The influence of feedback on the baryonic content of haloes in the COLIBRE simulationsAuthors: Jonathan J. Davies, Joop Schaye, Filip Huško, Ruby J. Wright, Evgenii Chaikin, Matthieu Schaller, Robert J. McGibbon, Alejandro Benítez-Llambay, Sylvia Ploeckinger, Alexander J. Richings,Comments: 25 pages, 11 figures. Submitted to MNRAS, comments welcomeSubjects: astro-ph.GACreated: 2026-07-29; Updated: 2026-07-31; Datestamp: 2026-07-31
We present predictions for the relation between the halo gas mass fraction and halo mass, $f_{\rm gas}^{200}-M_{200}$, from the COLIBRE cosmological simulations of galaxy formation, and explore how the gas content of haloes is influenced by feedback from SUPERNOVAe and ACTIVE GALACTIC NUCLEi (AGN) over time. The $f_{\rm gas}^{200}-M_{200}$ relation in COLIBRE is non-monotonic, with a peak at $M_{200}\sim 10^{11.5-12}$~M$_\odot$. Below this mass, feedback from SUPERNOVAe efficiently expels gas from the haloes of dwarf galaxies, and above it, AGN feedback efficiently depletes the haloes of galaxy groups. The fiducial COLIBRE model yields gas fractions for galaxy groups and clusters that agree with constraints from Chandra and XMM-Newton X-ray data, but which are high relative to gas fractions inferred from eROSITA stacks and measurements of the kinetic Sunyaev-Zel-dovich (kSZ) effect. COLIBRE's hybrid AGN feedback model, which combines thermal and JET-driven feedback, produces lower gas fractions in better agreement with eROSITA and kSZ measurements. COLIBRE produces lower gas fractions for groups and clusters than EAGLE and other contemporary simulations, and better agreement with observational constraints. We investigate the origin of this improvement relative to EAGLE, and how the resolution of the simulation affects the impact of feedback. Our results demonstrate that halo gas fractions are a sensitive probe of feedback physics, and that they can differ significantly between simulations that otherwise produce very similar galaxy populations.
[abstract 16 / 59] Yes (score: 4) - Title: An Exploratory Analysis of New Large Gaia-informed Quasar Samples in SDSS-VAuthors: Shir Aviram, Benny Trakhtenbrot, Tom Dwelly, Scott F. Anderson, Sean Morrison, Michael Eracleous, Yue Shen, Mara Salvato, Donald P. Schneider, Roberto J. Assef, Catarina Aydar, Franz E. Bauer, W. N. Brandt, Joel R. Brownstein, Johannes Buchner, Jeremy Darling, Jose G. Fernandez-Trincado, Patrick B. Hall, Dong-Woo Kim, Anton M. Koekemoer, Stephanie LaMassa, Andrea Merloni, Claudio Ricci, Qian Yang, Grisha Zeltyn,Comments: Resubmitted to ApJ on 28 July 2026 after addressing the referee report. The data will be available in SDSS-V/DR20Subjects: astro-ph.GACreated: 2026-07-29; Updated: 2026-07-31; Datestamp: 2026-07-31
Quasars are luminous objects that provide insights into the physics and evolution of supermassive BLACK HOLEs (SMBHs) and their accretion flows, galaxy evolution, and even cosmology. In this study, we present an exploratory study based on the ongoing fifth generation of the Sloan Digital Sky Survey (SDSS-V) and its unique dual-hemisphere, wide-field, and multi-object spectroscopic capabilities, with the aim of creating a comprehensive, all-sky QUASAR sample. The targets were selected through two novel methods, GUA and Skewt-QSO, that rely primarily on data from WISE and Gaia, aiming to address gaps in previous large QUASAR samples. Our sample includes over 250,000 spectroscopically confirmed QUASARs reaching z~5, with tens of thousands of newly identified QUASARs in the southern hemisphere. The selection methods are highly pure, with well over 80% of the spectra collected being genuine QUASARs; the main contaminants are M-type stars. The detailed spectral decomposition procedure we employed shows that the QUASARs in the sample span a wide range of luminosities (Lbol~$10^{44}-10^{48} erg s^{-1}$), SMBH masses (MBH~$10^6-10^{10}$ Msun), and accretion rates (L/LEdd~0.01-1). The distributions of these properties are consistent with those of previous QUASAR catalogs, which are based on past generations of SDSS, once we account for potential selection biases related to the various survey depths. Our findings confirm that novel selection methods based on optical+IR colors and/or astrometry can yield a large, high-purity QUASAR sample over wide sky areas, including in cases where more nuanced multi-band photometry and/or multi-wavelength data in the X-ray or radio is not available. This SDSS-V sample, which will continue to grow, establishes a robust reference for future southern (time-domain) surveys, while enhancing and complementing our understanding of QUASAR demographics and SMBH evolution.
[abstract 17 / 59] Yes (score: 4) - Title: Radio Follow-Up of Einstein Probe Fast X-Ray TransientsAuthors: Carmen Choza, Joe S. Bright, Francesco Carotenuto, Alex Pollak, Rob Fender, Andrew Siemion,Comments:Subjects: astro-ph.HE astro-ph.IMCreated: 2026-07-29; Updated: 2026-07-31; Datestamp: 2026-07-31
Fast X-ray transients (FXTs) are brief, luminous bursts of soft X-ray emission whose physical origins remain uncertain. The Einstein Probe (EP) mission has recently enabled prompt discovery of these events, providing opportunities for rapid multi-wavelength follow-up. We present a coordinated radio observing campaign targeting 20 FXTs detected by the EP in 2024. The core consists of 59 epochs with the Allen Telescope Array (ATA), sampling post-burst timescales from $\sim$1 to $\sim$65 days and reaching typical $3σ$ sensitivities of 0.6--1.5\,mJy across 1--8\,GHz. Two FXTs---EP240315a and EP241021a---have radio counterparts. For EP241021a, AMI-LA monitoring at 15.5\,GHz reveals a light curve peaking at $\sim$30 days with $F_ν\approx1.0$\,mJy; equipartition analysis implies a Newtonian equipartition energy of $\sim3\times10^{49}$\,erg and a mildly RELATIVISTIC on-axis solution with $Γ_{\rm on}\approx1.3$. Multi-frequency modelling of EP240315a, combining new VLA measurements with published MeerKAT, ATCA, and eMERLIN data, indicates highly RELATIVISTIC early emission ($Γ\gtrsim3$) that decelerates with time, consistent with JETted outflow. The detections and ATA non-detections span luminosities overlapping the brightest GRB and RELATIVISTIC tidal disruption event (TDE) afterglows, suggesting FXTs comprise a heterogeneous population including both RELATIVISTIC and non-RELATIVISTIC explosions. Under a GRB-like redshift prior, our $3σ$ ATA limits correspond to observer-frame specific-luminosity thresholds of $\sim10^{32}$--$10^{33}\,\mathrm{erg\ s^{-1}\ Hz^{-1}}$; for nearby events ($z\lesssim0.2$), $L_ν\lesssim10^{30\text{--}31}\,\mathrm{erg\ s^{-1}\ Hz^{-1}}$. Planned ATA upgrades and next-generation arrays (SKA, DSA, ngVLA) will enable sensitive, population-level radio studies of the FXT radio sky.
[abstract 18 / 59] Yes (score: 4) - Title: DePOLARIZATION Induced by Rapid Polarization Angle Swings: A Common Feature of Pulsars and Fast Radio Bursts?Authors: Yu-Chen Huang, Jie-Shuang Wang, Song-Bo Zhang, Zi-Gao Dai,Comments: 11 pages, 9 figures, accepted by MNRASSubjects: astro-ph.HECreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
The POLARIZATION angle (PA) of pulsars and fast radio bursts (FRBs) provides a useful diagnostic of the MAGNETic fields in their emission regions and is therefore crucial for understanding their radiation and origins. Within a general geometric framework for polarized emission from a rotating neutron star, we suggest a possible anti-correlation between the degree of linear POLARIZATION $Π_\text{L}$ and $d\text{PA}/dt$, the time derivative of the PA, as a common feature of pulsars and FRBs. The dePOLARIZATION arises from the incoherent superposition of radiation with different POLARIZATION directions within the observable part of the emission region, and is detectable only when the PA swing is steep enough. We test this conjecture using a sample of radio pulsars and find possible evidence for the expected anti-correlation in a subset of pulsars. Whether this relation holds in FRBs remains uncertain due to limited observational data. Identification of this feature would not only provide insights into the rotating MAGNETospheric origin of FRBs, but also place constraints on the spin periods and geometric parameters of the neutron stars that power these mysterious bursts.
[abstract 19 / 59] Yes (score: 4) - Title: On the Blueprint of Active Galaxies Producing NeutrinosAuthors: Chen Li, Francis Halzen,Comments: 16 pages, 8 figuresSubjects: astro-ph.HECreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
Based on the observation of the active galaxies NGC 1068 and TXS 0506+056, and on additional evidence for the sources NGC 4151, CGCG 420-015, NGC 7469, and the Circinus Galaxy emerging from IceCube data, we make the case for the production of high-energy neutrinos within a few gravitational radii of supermassive BLACK HOLEs surrounded by a dense plasma radiating X-rays. X-rays represents the target for the production of neutrinos by protons accelerated near the BLACK HOLE; they also absorb the gamma rays from the decay of neutral pions produced in the same interactions. Neutrinos with energies of tens of TeV and above originate in photoproduction interactions with X-rays of $0.1 \sim 1$\,keV energy on the $Δ$ resonance, $p + γ\rightarrow Δ\rightarrow n + π^+$. Our analysis of the multimessenger data points to gamma-ray-obscured sources with a characteristic neutrino flux linearly proportional to the X-ray flux originating within $\sim 10$ gravitational radii of the BLACK HOLEs, with lower values preferred. We speculate on such sources producing the diffuse flux of neutrinos and COSMIC RAYs of extragalactic origin.
[abstract 20 / 59] Yes (score: 4) - Title: Revealing the Physical Driver of the Baldwin Effect: Gas Density in the Broad-Line RegionAuthors: Wen-Qiang Liang, Zhi-Fu Chen, Rui-Jing Lu, Cheng-Feng Peng, Shao-Hua Zhang, Zhe-Geng Chen, Zhi-Qing Chen, Yi-Qi Chen, Dong-Li Jiang, Xi-Heng Shi, Zhi-Wen Wang,Comments: Comments: 11 pages, 7 figures, 4 appendix figures. Accepted for publication in ApJSubjects: astro-ph.GACreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
The Baldwin effect --- the inverse correlation between the equivalent width of emission lines and the continuum luminosity in ACTIVE GALACTIC NUCLEi (AGNs) --- has been known for nearly five decades, yet its physical origin remains poorly understood. Using a sample of 41,159 radio QUASARs constructed from the Sloan Digital Sky Survey and the Low-Frequency Array Two-metre Sky Survey, we investigate the origin and underlying physics of the Baldwin effect of MgII broad emission lines in both radio-quiet (RQ) and radio-loud (RL) QUASARs. We find that the slope $β$ of the Baldwin effect is positively correlated with the Eddington ratio $λ_{\rm Edd}$ in both populations, and RL QUASARs exhibit steeper $β$ than their RQ QUASARs at fixed $λ_{\rm Edd}$. Photoionization simulations reveal that the $β$ is primarily governed by the gas density in the broad-line region (BLR): lower gas densities yield steeper slopes. This density-driven mechanism naturally connects the Baldwin effect to the broader AGN evolutionary context. Specifically, higher $λ_{\rm Edd}$ drive stronger accretion disk winds, leading to denser BLRs and shallower $β$. Our findings indicate that BLR gas density serves as the primary physical driver underlying the "global" Baldwin effect, offering a physically grounded framework for interpreting AGN accretion states and their coupled evolution with host galaxies.
[abstract 21 / 59] Yes (score: 4) - Title: The Study of Quasi-Periodic Pulsations in Solar and Stellar Flares with SKAAuthors: Valery M. Nakariakov, Atul Mohan, Vishal Upendran, Teresa Monsue, Hamish A. S. Reid, Dmitrii Y. Kolotkov, Sergey A. Belov, Kyung-Suk Cho,Comments: Published in Advancing Astrophysics with the SKA II (AASKAII), 2026 (arXiv:2606.20366). Report-no:AASKAII/Nakariakov01. Advancing Astrophysics with SKA II (AASKAII) outlines the transformative scientific advances that will be enabled by the SKA telescopesSubjects: astro-ph.SRCreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
An intensively studied phenomenon which is not described by the standard flare model are quasi-periodic pulsations (QPP) of the flaring emission. As analysis of the QPP phenomenon intrinsically requires a combination of high time and spatial resolutions, especially in the radio band, the unprecedented capabilities of SKA offer us a unique opportunity to reach a breakthrough progress in the observational study of QPP. The SKA-Mid-frequency band falls in a unique window where both coherent emissions from particle acceleration sites and incoherent gyroSYNCHROTRON emissions from non-thermal particles in coronal loops can be studied. With an additional polarisation dimension and the capability to perform wideband spectroscopic imaging, the QPPs in gyroSYNCHROTRON emission ($\ge 1$~GHz) and plasma emission will help understand the local MAGNETic field modulation due to active phenomena and the response seen in the particle acceleration observable below ~600~MHz. An incomplete list of specific science questions to be addressed with SKA includes (a) the role of QPP in the energy partition in flares, (b) seismology of flaring sites by QPP of different classes, (c ) differences and similarities between QPP in solar and stellar flares, (d) advancing the standard flare model, (e) the physics of repetitive MAGNETic RECONNECTion: spontaneous vs induced, (f) ML techniques in the detection, classification and analysis of QPP, (g) QPP in weak flares. The latter topic could be especially advanced with SKA which will allow for high-cadence high fidelity radio imaging of weak energy release events.
[abstract 22 / 59] (score: 3) - Title: Lens Stochastic Diffraction: A Signature of Compact Objects in Gravitational-Wave DataAuthors: Miguel Zumalacárregui,Comments: 15 pages, 9 figures. Notebooks reproducing all results: https://github.com/miguelzuma/lsd-gw-notebooksSubjects: gr-qc astro-ph.CO astro-ph.HE hep-phCreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
Every signal propagating through the universe is diffracted by the gravitational field of intervening objects, known as gravitational lenses. Diffraction is most efficient when caused by compact objects, which form additional images of any source. Although secondary images are typically too weak to stand out in the noise, they can be detected collectively using gravitational waves (GWs) by leveraging 1) knowledge of the primary signal and 2) scaling of the signal's strength with the angular offset. The ensemble of secondary signals constitutes \textit{lens stochastic diffraction} (LSD): correlated Poisson-distributed fluctuations following a GW event due to intervening compact objects. The amplitude and temporal distribution of these signals encode the abundance of the lenses, their mass spectrum and their density profiles. By including all secondary signals over all resolved GW events, LSD offers an improvement of ${\sim}2.5$ orders of magnitude over the identification of individual lensed images, for objects with mass $M_l\gtrsim 10^3 M_\odot$ and size $\lesssim 1{\rm pc}(M_l/10^4M_\odot)^{1/2}$. The framework generalizes to wave optics, where halos too diffuse to form images imprint localized features on the waveform. Developing data-analysis techniques will allow LSD to probe compact dark-matter halos and allow next-generation instruments to detect supermassive BLACK HOLEs, given the abundance expected from QUASAR luminosity studies.
[abstract 23 / 59] (score: 3) - Title: A conserved thermo-mechanic invariant in extended fluid description of collisionless plasmasAuthors: E. S. Uchava, A. G. Tevzadze,Comments: Accepted for publication in Physical Review ESubjects: physics.plasm-ph astro-ph.SRCreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
We investigate linear perturbations of an incompressible, weakly collisional, anisotropic plasma in the low frequency limit using an extended 16-moment fluid description that retains parallel and perpendicular heat fluxes. We identify a new class of linear perturbations associated with a conserved thermo-mechanic invariant, a time independent, aperiodic structure involving coupled perturbations of heat fluxes, velocity, and MAGNETic field. In the standard CGL limit, where heat fluxes are neglected, no direct analogue of this invariant exists. Retaining heat flux dynamics alters the linear structure of the system promoting third order velocity moments to autonomous variables and gives rise to a thermo-mechanic mode with coupled thermal, kinetic, and MAGNETic components. The associated perturbations are inherently localized, favoring compact, filamentary aperiodic structures. The thermo-mechanic invariant reveals a previously unexplored stationary sector of collisionless anisotropic plasma dynamics, characterized by a fixed algebraic POLARIZATION that enforces time independent relations among the relevant perturbation fields.
[abstract 24 / 59] (score: 3) - Title: Doubling NIRSpec/IFS capability to calibrate the single-epoch BLACK HOLE mass relation at high redshiftsAuthors: Eleonora Parlanti, Bartolomeo Trefoloni, Stefano Carniani, Francesco D'Eugenio, Michele Perna, Giulia Tozzi, Hannah Übler, Giacomo Venturi, Sandra Zamora,Comments: 18 pages, 12 figures. Submitted to A&ASubjects: astro-ph.GACreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
The recent discovery of a large population of overmassive BLACK HOLEs (BHs) in the early Universe challenges the validity of the BH-host galaxy coevolution framework. However, the reliability of the estimated BH masses (M$_{BH}$) is being questioned, as these are typically derived using single-epoch (SE) relations calibrated locally. Calibrating SE relations at high redshift would therefore enable more accurate M$_{BH}$ estimates and help identify potential biases. In this work, we release a data-reduction technique for JWST/NIRSpec IFU observations that doubles the effective wavelength coverage, enabling detection of otherwise inaccessible emission. Whenever adjacent dispersers are required, observers should carefully evaluate the tradeoff between integrating longer in the bluer configuration alone versus distributing the exposure time across two dispersers. We apply this pipeline to a sample of 5 QUASARs at z~2 with M$_{BH}$ independently measured through reverberation mapping (RM). This enables a joint analysis of both H$β$ and H$α$; the latter lying beyond the nominal wavelength range. We assess the reliability of the most widely adopted SE calibrations, finding that H$β$ yields the closest agreement with RM-based M$_{BH}$ estimates, whereas H$α$-based estimators exhibit a larger scatter. For the least massive BH in our sample ($M_{BH,RM}$~$10^{7.5}M_\odot$), which is accreting at a rate close to the Eddington limit ($λ_{Edd}=0.8$), all SE calibrators overestimate M$_{\rm BH, RM}$ by one order of magnitude. This may indicate a systematic overestimation of M$_{BH}$ for highly accreting BHs at high redshift. Finally, we provide the first high-redshift SE calibration based on H$α$ and H$β$. Although a larger sample is needed to reduce the uncertainties, our calibration can already be applied to the newly discovered BH population in the early Universe.
[abstract 25 / 59] (score: 3) - Title: Superdiffusion at the Galactic CentreAuthors: Pau Amaro Seoane, Kostas Tzanavaris, Reinhard Genzel, Frank Eisenhauer, Thomas Ott, Stefan Gillessen, Guillaume Bourdarot, Diogo C. Ribeiro, Matteo Sadun Bordoni, Simran Joharle, Felix Mang, Andreas Burkert, Jorge Cuadra, Diego Calderón, Hagai B. Perets, Tsvi Piran, Re'em Sari,Comments: SubmittedSubjects: astro-ph.GACreated: 2026-07-29; Updated: 2026-07-31; Datestamp: 2026-07-31
Tracking S-star cluster orbits around Sgr A* calibrates orbital transport models for space-borne gravitational wave detectors. Standard kinetic theories model this cluster via local Fokker-Planck equations, which predict that general RELATIVISTIC precession halts angular momentum diffusion at the Schwarzschild barrier. Because inverse-square gravitational encounters generate a Holtsmark torque distribution with infinite variance, resonant relaxation operates as a space-fractional process governed by non-local Lévy flights. We simulate this superdiffusive continuous-time random walk using a Markov chain initialized with empirical S-star orbits, including the recently observd S301. Integro-differential fractional operators allow trajectories to cross regions of quenched local diffusion without density buildup at the barrier. Non-equilibrium regimes yield immediate linear flux growth, while secular tidal heating at periastron inflates stellar radii to shift disruption boundaries. Regularized backward integration of the fractional transport equation traces current phase space configurations back to initial deposition states, matching the energy requirements of the \emph{FERMI} bubbles. Relativistic precession does not suppress mass-ratio inspiral rates, which provides a model for event topologies in target galactic nuclei.
[abstract 26 / 59] (score: 3) - Title: Relativistic effects of PSR~J1856--0039 double neutron star system in a 2.36-hour compact orbitAuthors: Z. L. Yang, J. L. Han, W. Q. Su, P. F. Wang, C. Wang, T. Wang, D. J. Zhou, Yi Yan, J. Xu, W. C. Jing, N. N. Cai, R. X. Xu, H. G. Wang, X. P. You,Comments: 9 pages, 4 figures, accepted by Phys. Rev. LettSubjects: astro-ph.HECreated: 2026-07-29; Updated: 2026-07-31; Datestamp: 2026-07-31
Compact double neutron star (DNS) systems are unique laboratories for testing gravitational theories and studying DNS mergers. Here we report the properties of a new DNS system, PSR J1856--0039, discovered in the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The pulsar is mildly recycled with a period of 23.4~ms in a compact eccentric orbit ($e=0.106$) with an orbital period of 2.36 hours. By following up FAST observations, we measured the RELATIVISTIC effects, including the orbital period derivative $\dot{P}_{\rm orb}=-1.284\pm0.019\times10^{-12}$ s s$^{-1}$, periastron advance $\dotω=17.5859\pm0.0007$ deg yr$^{-1}$, and Einstein delay $γ=0.445\pm0.011$ ms. This DNS system has a low orbital inclination of $i=133^\circ.2\pm1^\circ.1$ and the lowest total mass of any known DNS, $M_{\rm tot}=2.48841\pm0.00015 M\odot$, with a determined pulsar mass of $1.304\pm0.022 M_\odot$ and a companion mass of $1.185\pm0.022 M_\odot$, one of the lowest neutron-star masses. The observed orbital decay due to gravitational-wave emission $\dot{P}^{\rm GW}_{\rm orb,obs}$ and the orbital decay predicted by general relativity $\dot{P}^{\rm GW}_{\rm orb,pred}$ are consistent at a level of $\dot{P}^{\rm GW}_{\rm orb,obs}/\dot{P}^{\rm GW}_{\rm orb,pred}=$1.009(14) (68% confidence). This DNS will merge after 82 Myr and may form a stable neutron star or collapse into a BLACK HOLE after spin-down. Long-term monitoring could potentially probe the Lense-Thirring precession.
[abstract 27 / 59] (score: 3) - Title: Cosmic Pairs: A DESI Census of Dual and Offset AGN as Precursors to Massive Black Hole BinariesAuthors: Ekaterine Dadiani, Antonella Palmese, Yihao Zhou, Nianyi Chen, Tiziana Di Matteo, Alejandro Eróstegui, Mar Mezcua, Jessica Nicole Aguilar, Steven Ahlen, Stephen Bailey, Florian Beutler, Davide Bianchi, David Brooks, Todd Claybaugh, Axel de la Macorra, Arjun Dey, Biprateep Dey, Peter Doel, Victoria A. Fawcett, Benjamin Floyd, Andreu Font-Ribera, Jaime E. Forero-Romero, Enrique Gaztañaga, Satya Gontcho A Gontcho, Gaston Gutierrez, Mustapha Ishak, Robert Kehoe, Anthony Kremin, Ofer Lahav, Andrew Lambert, Martin Landriau, Laurent Le Guillou, Marc Manera, Aaron Meisner, Ramon Miquel, John Moustakas, Seshadri Nadathur, Enrique Paillas, Will J. Percival, Francisco Prada, Ignasi Pérez-Ràfols, Ragadeepika Pucha, Corentin Ravoux, Graziano Rossi, Rossana Ruggeri, Eusebio Sanchez, Christoph Saulder, David Schlegel, Michael Schubnell, Hee-Jong Seo, Joseph Harry Silber, Małgorzata Siudek, Gregory Tarlé, Benjamin Alan Weaver, DESI Collaboration,Comments: 38 pages, 18 figures, 1 table. To be submitted to ApJSubjects: astro-ph.GA astro-ph.HECreated: 2026-07-29; Updated: 2026-07-31; Datestamp: 2026-07-31
We present a systematic census of dual and offset ACTIVE GALACTIC NUCLEi (AGN) using spectroscopic data from the first data release (DR1) of the Dark Energy Spectroscopic Instrument (DESI). After correcting for observational systematics, our final sample contains $>7,000$ dual AGN and 27,000 galaxy pairs containing one AGN over the redshift range $0 \lesssim z \lesssim 3.6$. This sample expands the known dual AGN sample by $\sim 1-2$ orders of magnitude at $0.2 \lesssim z \lesssim 0.4$, includes $\sim 50$ dwarf dual AGN candidates in a regime where only a handful were previously known, and triples the census at $z>2$. Dual AGN are preferentially found at small separations, consistent with merger-driven triggering of AGN activity. The two members of a pair differ in their STAR FORMATION response: the more massive (primary) host changes little with separation, while the less massive (secondary) lies $\sim 0.3$ dex above matched inactive and one-AGN companions at the same projected separation in main-sequence offset. Using ASTRID simulations, we predict that the fraction of DESI dual AGN whose central BLACK HOLEs will merge by $z \sim 0$ increases with redshift, reaching $\sim 76\%$ by $z \sim 2$, while the fraction producing LISA-detectable mergers peaks at $\sim 37\%$ near $z \sim 0.9$. These results provide the largest uniformly selected spectroscopic sample of kpc-scale dual and offset AGN candidates from a single survey, connecting their host-galaxy and AGN demographics to the progenitor population of massive BLACK HOLE mergers detectable by LISA.
[abstract 28 / 59] (score: 3) - Title: Compton Polarimeter Prototype for the CUbesat Solar Polarimeter (CUSP) missionAuthors: Nicolas De Angelis, Andrea Alimenti, Riccardo Campana, Mauro Centrone, Giovanni De Cesare, Ettore Del Monte, Sergio Di Cosimo, Enrico Costa, Sergio Fabiani, Abhay Kumar, Pasqualino Loffredo, Giovanni Lombardi, Gabriele Minervini, Fabio Muleri, Paolo Romano, Alda Rubini, Enrico Silva, Paolo Soffitta, Giovanni Cucinella, Vito Di Bari, Simone Di Filippo, Andrea Negri, Massimo Perelli, Davide Albanesi, Valerio Campamaggiore, Giulia de Iulis, Andrea Del Re, Paolo Leonetti, Alessandro Zambardi, Ilaria Baffo, Pierluigi Fanelli, Costantino Zazza, Andrea Curatolo, Nicolas Gagliardi, Dario Modenini, Daniele Pecorella, Alice Ponti, Paolo Tortora, Valerio Vagelli, Daniele Brienza, Immacolata Donnarumma, Matteo Mergè, Emanuele Zaccagnino, Alessandro Turchi,Comments: 9 pages, 8 figures, SPIE Astronomical Telescopes + Instrumentation 2026 proceedingSubjects: astro-ph.IM astro-ph.SR physics.space-phCreated: 2026-07-29; Updated: 2026-07-31; Datestamp: 2026-07-31
The space-based CUbesat Solar Polarimeter (CUSP) mission aims to measure the linear POLARIZATION of solar flares in the hard X-ray band (25-100 keV) by means of a dual-phase Compton polarimeter. CUSP will allow to study the MAGNETic RECONNECTion and particle acceleration in the flaring MAGNETic structures of our star with its unprecedented sensitivity to solar flare POLARIZATION. CUSP is a project under development as part of the Alcor Program of the Italian Space Agency aimed at developing new CubeSat missions. In the frame of CUSP's Phase B, which started in December 2024, a flight-representative prototype of the Compton polarimeter has been developed and characterized with hard X-ray sources in the laboratory. This prototype consists of a 4$\times$4 central matrix of plastic scintillator bars surrounded by 4 strips of 8 elongated GAGG scintillators, respectively coupled to a multi-anode photomultiplier tube and arrays of avalanche photodiodes. These sensors are read out by custom front-end electronics based on MAROC-3A and SKIROC-2A ASICs with a Xilinx Artix 7 FPGA. The plastic scintillators act as scatterers, while the GAGG bars fully absorb the scattered photons. Coincident plastic-GAGG events allow for reconstructing the Compton scattering direction, whose distribution allows for inferring the POLARIZATION parameters of the source. We report here the measured performance of the polarimeter prototype using well-known radioactive isotopes and X-ray tubes, allowing us to assess the performance of our polarimeter prototype over the full 25-100 keV energy range.
[abstract 29 / 59] (score: 3) - Title: On the triple nature of the PSR J0435+3233 systemAuthors: Paulo C. C. Freire, Colin J. Clark, Cees G. Bassa, Guillaume Voisin, Rutger van Haasteren, Lars Nieder, Benjamin W. Stappers,Comments: Submitted to Astronomy and AstrophysicsSubjects: astro-ph.HE gr-qcCreated: 2026-07-29; Updated: 2026-07-31; Datestamp: 2026-07-31
Context. The recent pulsar timing ephemeris of PSR J0435+3233 indicates that this millisecond pulsar (MSP) has a spin-down rate that is much higher than observed in other MSPs and challenges our understanding of the formation and evolution of MSPs. Aims. We propose that this system is a hierarchical triple, and that the high spin-down rate is caused by varying acceleration due to a tertiary in a wide orbit. Methods. We use pulsar timing methods with radio and gamma-ray observations of PSR J0435+3233 to determine the system properties. Results. We find that a hierarchical triple timing model describes the timing observations of PSR J0435+3233 and that this results in the detection of gamma-ray pulsations back to the beginning of the FERMI Large Area Telescope (LAT) data in 2008. The intrinsic spin-down rate remains uncertain as it correlates with the parameters of the outer orbit, but large spin-down rates are excluded and the intrinsic rate is at least two orders of magnitude lower than the observed rate, in line with other Galactic MSPs. We identify a star located 11 mas from the pulsar position as the optical counterpart to the tertiary companion. From the 1.5-2.5 kpc distance and colours, we infer that the tertiary is a 1.2 solar mass F-type main-sequence star. Along with the pulsar binary, it orbits the common centre of mass with an eccentric (e ~ 0.6), wide (~ 70 yr) orbit that is likely seen at a low orbital inclination. Conclusions. We conclude that PSR J0435+3233 is a hierarchical triple system. We discuss the motivation and prospects for the continued study of this system. Spectral measurements of the outer star in addition to continued astrometric measurements will yield mass ratio and inclination estimates, while continued pulsar timing may yield a tighter constraint on violations of the Strong Equivalence Principle than are currently obtained from PSR J0337+1715.
[abstract 30 / 59] (score: 3) - Title: Thermal or Non-thermal? Diffuse emission in the infall region of stacked galaxy groupsAuthors: E. Bulbul, X. Zhang, Z. Ding, T. Mistele, M. Kluge, E. Artis, Y. E. Bahar, K. Dennerl, D. Eckert, L. Fiorino, P. F. Hopkins, N. Malavasi, A. Merloni, K. Nandra, E. Quataert, M. E. Ramos-Ceja, J. S. Sanders, J. Strunk, S. Zelmer,Comments: Submitted to A&A, 12 pages, 5 figures, 1 tableSubjects: astro-ph.HE astro-ph.COCreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
The faint infall regions surrounding the virial radius of galaxy groups remain largely unexplored due to their low X-ray surface brightness. Using the large statistical power of SRG/eROSITA survey observations, we present the first spectroscopic measurement of the intragroup medium (IGrM) in the infall regions of a large sample of low-mass galaxy groups ($M_{\rm tot}<1\times10^{14}\,M_{sun}$), extending to $\sim2\,R_{200m}$ (2.2 Mpc). Through spectral stacking of 827 nearby groups from the first eROSITA All-Sky Survey catalog, we detect diffuse emission and measure the thermodynamic properties of gas at densities previously inaccessible to X-ray observations. The stacked spectra are well described by a Gaussian differential emission measure model, yielding a temperature distribution with a mean temperature of $0.96_{-0.04}^{+0.05}$ keV and width of $0.28_{-0.10}^{+0.10}$ keV, and a metal abundance of $0.21_{-0.04}^{+0.06}$ A$_{sun}$, consistent with expectations for group outskirts. The inferred electron densities decrease from $(4.8\pm1.3)\times10^{-5}$cm$^{-3}$ at $(0.7-2)\,R_{500c}$ to $(5.5\pm2.0)\times10^{-6}$ cm$^{-3}$ at $(2-4)\,R_{500c}$, demonstrating eROSITA's ability to probe the low-density outskirts of galaxy groups. Residual emission in the spectra suggests the presence of an additional spectral component. While a secondary thermal interpretation requires an unexpectedly hot, metal-poor plasma, a non-thermal inverse Compton model provides an equally plausible explanation, contributing $\sim30\%$ of the thermal flux. Assuming that the additional component is produced by inverse Compton emission from a common population of RELATIVISTIC electrons, the inferred MAGNETic field strength would be in the sub-$μ$G regime.
[abstract 31 / 59] (score: 3) - Title: High-mass binary BLACK HOLE mergers from detailed binary evolution modelsAuthors: Max M. Briel, Olcay Bıyıklı, Tassos Fragos, Anarya Ray, Zepei Xing, Monica Gallegos-Garcia, Abhishek Chattaraj, Jeff J. Andrews, Michael Zevin, Vicky Kalogera, Seth Gossage, Philipp M. Srivastava, Elizabeth Teng,Comments: Submitted to ApJ. Comments welcomeSubjects: astro-ph.HE astro-ph.SRCreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
Gravitational-wave observations reveal a population of binary BLACK HOLE (BBH) mergers with primary masses above ${\sim}40\,\mathrm{M}_\odot$, extending into and potentially beyond the pair-instability mass gap, with a possibly flat mass-ratio and broader χ_\mathrm{eff} distribution. We investigate whether super-Eddington accretion during stable mass transfer in isolated binary evolution can produce BBH mergers consistent with these properties across primary BH mass, mass-ratio, and χ_\mathrm{eff} distributions. Using POSYDON, we simulate BBH merger populations with primary BH masses above ${\sim}40\,\mathrm{M}_\odot$, under three BH accretion efficiencies: Eddington-limited, GRRMHD-informed, and fully conservative. We additionally vary the natal kick strength, including strong kicks at high BH masses. We find that super-Eddington accretion does not suppress BBH mergers in the high-mass regime. Fully-conservative accretion leads to an increase of BBH mergers in POSYDON with a strong kick-independent peak at $χ_\mathrm{eff}=0.6$ and a sharp mass-ratio peak at $q\sim0.5$, whereas observations favor $χ_\mathrm{eff}=0.0$ and a flatter mass-ratio distribution. The GRRMHD-informed and Eddington-limited accretion are compatible with the observed primary BH mass and mass ratio distribution, but require natal kicks to populate negative χ_\mathrm{eff}. A joint analysis of the primary BH mass, mass ratio, and χ_\mathrm{eff} distributions provides strong constraints on binary evolution physics, and disfavor fully-conservative BH accretion as the dominant formation mechanism for high-mass BBH mergers. The Eddington-limited and GRRMHD-informed prescriptions with modest kicks can explain part of the high-mass population, but an additional formation channel is still needed to account for the high fraction of negative χ_\mathrm{eff} systems and high secondary BH spins.
[abstract 32 / 59] (score: 3) - Title: The Second Quadratic Invariant of Astrophysical GyrokineticsAuthors: Benjamin D. G. Chandran, Alfred Mallet, Romain Meyrand,Comments: 26 pages, 2 figuresSubjects: physics.plasm-ph astro-ph.SR physics.space-phCreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
We show that gyrokinetics in a spatially uniform equilibrium (or `astrophysical gyrokinetics') possesses a previously unknown quadratic invariant, which we call the gyrokinetic helicity. We derive the limiting forms of the gyrokinetic helicity in five subsidiary expansions of astrophysical gyrokinetics: the isothermal electron fluid (ITEF) approximation, kinetic reduced MAGNETohydrodynamics (KRMHD), electron reduced MAGNETohydrodynamics (ERMHD), finite-Larmor-radius MAGNETohydrodynamics (FLR-MHD), and the kinetic reduced electron heating model~(KREHM). We subdivide the real part of the gyrokinetic helicity into `MAGNETofluid' and `phase-space' components, which are separately conserved in KRMHD, ERMHD, and FLR-MHD (in which there is no phase-space helicity). The MAGNETofluid helicity is equivalent to the Alfvénic part of the cross helicity in KRMHD, the MAGNETic helicity in~ERMHD, and the generalized helicity in FLR-MHD and~KREHM. We derive an analytic expression for the rate at which MAGNETofluid helicity is converted into phase-space helicity at length scales comparable to the proton gyroradius in the ITEF approximation. We also explain how this conversion circumvents the helicity barrier and enhances turbulent heating in coronal holes and the near-Sun solar wind.
[abstract 33 / 59] (score: 3) - Title: Back Reaction of the Untwisting Solar Corona Scars SunspotsAuthors: Chen Xing, Xin Cheng, Guillaume Aulanier, Mingde Ding,Comments: 37 pages, 9 figures; published in Science AdvancesSubjects: astro-ph.SRCreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
The evolution of MAGNETic fields in the tenuous solar corona is predominantly governed by the motions of the underlying dense photosphere. Despite, coronal MAGNETic restructuring driven by MAGNETic RECONNECTion between interacting coronal fields can sometimes react backwards to change photospheric MAGNETic fields. However, the mechanism of reactions remains undetermined. Here, we report the discovery of a back-reaction phenomenon: the untwisting of coronal loops that become twisted during RECONNECTion in an eruption results in enhanced currents at the boundary of their footpoint away from the eruption, manifesting as the growth of a sunspot scar. It is revealed to arise from the Alfvenic reverse transfer of MAGNETic twist from the corona to the lower atmosphere, thanks to joint space observations and a MAGNETohydrodynamics simulation. These findings provide a viable and quantitative interpretation for the majority of puzzling photospheric changes associated with coronal mass ejections and/or flares and warn for unexpected MAGNETic field evolutions in sunspots and starspots.
[abstract 34 / 59] (score: 3) - Title: Spinning down neutron-star merger remnants with the Tayler-Spruit dynamo: Global simulations reveal the formation of massive disks and neutron-rich ejectaAuthors: Harry Ho-Yin Ng, Elias R. Most,Comments:Subjects: astro-ph.HECreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
Magnetic-field amplification and angular momentum (AM) transport critically shape the secular evolution, lifetime, and electroMAGNETic signatures of binary neutron-star merger remnants. While the MAGNETorotational instability can operate in the outer negative-shear regions of the neutron-star remnant and accretion disk, the positive-shear, stably stratified core may instead be susceptible to the Tayler-Spruit dynamo. We present the first global, long-term general-RELATIVISTIC neutrino-radiation MAGNETohydrodynamics simulations of a neutron-star merger remnant incorporating the unresolved Tayler-Spruit dynamo through a new mean-field dynamo subgrid prescription. Our axisymmetric simulations starting from a realistic merger remnant show that the Tayler-Spruit dynamo is primarily active in high-latitude regions of the remnant core. The resulting Maxwell stresses redistribute AM on a spin-down timescale of a few hundred milliseconds, substantially flattening the core rotation profile and transferring mass and AM from the outer remnant into the disk. This produces a more massive, extended, and strongly MAGNETized disk with a low electron fraction, leading to substantially more neutron-rich ejecta. Our results demonstrate that currently unmodelled Tayler-Spruit dynamo action can qualitatively alter the rotational evolution, collapse prospects, disk formation, and multi-messenger signatures of long-lived neutron-star merger remnants.
[abstract 35 / 59] (score: 2) - Title: Continuous gravitational waves from Galactic neutron stars: demography, detectability and prospectsAuthors: Gianluca Pagliaro, Maria Alessandra Papa, Jing Ming, Jianhui Lian, Daichi Tsuna, Claudia Maraston, Daniel Thomas,Comments:Subjects: gr-qc astro-ph.HECreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
We study the prospects for detection of continuous gravitational signals from "normal" Galactic neutron stars, i.e. non-recycled ones. We use a synthetic population generated by evolving stellar remnants in time, according to several models. We consider the most recent constraints set by all-sky searches for continuous gravitational waves and use them for our detectability criteria. We discuss detection prospects for the current and the next generation of gravitational wave detectors. We find that neutron stars whose ellipticity is solely caused by MAGNETic deformations cannot produce any detectable signal, not even by 3rd-generation detectors. Currently detectable sources all have $B\lesssim10^{12}$ G and deformations not solely due to the MAGNETic field. For these in fact we find that the larger the MAGNETic field is, the larger is the ellipticity required for the signal to be detectable and this ellipticity is well above the value induced by the MAGNETic field. Third-generation detectors as the Einstein Telescope and Cosmic Explorer will be able to detect up to $\approx 250$ more sources than current detectors. We briefly treat the case of recycled neutron stars, with a simplified model. We find that continuous gravitational waves from these objects will likely remain elusive to detection by current detectors but should be detectable with the next generation of detectors.
[abstract 36 / 59] (score: 2) - Title: MALLORN: Many Artificial LSST Lightcurves based on Observations of Real Nuclear transientsAuthors: Dylan Magill, Matt Nicholl, Vysakh Anilkumar, Sjoert van Velzen, Xinyue Sheng, Thai Son Mai, Hung Viet Tran, Ngoc Phu Doan, Thomas Moore, Shubham Srivastav, David R. Young, Charlotte R. Angus, Joshua Weston,Comments:Subjects: astro-ph.HECreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
The Vera C. Rubin Observatory's 10-Year Legacy Survey of Space and Time (LSST) is expected to produce a hundredfold increase in the number of transients we observe. However, there are insufficient spectroscopic resources to follow up on all of the wealth of targets that LSST will provide. As such it is necessary to be able to prioritise objects for followup observations or inclusion in sample studies based purely on their LSST photometry. We are particularly keen to identify tidal disruption events (TDEs) with LSST. TDEs are immensely useful for determining BLACK HOLE parameters and probing our understanding of accretion physics. To assist in these efforts, we present the Many Artificial LSST Lightcurves based on the Observations of Real Nuclear transients (MALLORN) data set and the corresponding classifier challenge for identifying TDEs. MALLORN comprises 10178 simulated LSST light curves, constructed from real Zwicky Transient Facility (ZTF) observations of 64 TDEs, 727 nuclear SUPERNOVAe and 1407 AGN with spectroscopic labels using Gaussian process fitting, empirically-motivated spectral energy distributions from SNCosmo and the baseline from the Rubin Survey Simulator. Our novel approach can be easily adapted to simulate transients for any photometric survey using observations from another, requiring only the limiting magnitudes and an estimate of the cadence of observations. The MALLORN Astronomical Classification Challenge, launched on Kaggle on 15/10/2025, will allow competitors to test their photometric classifiers on simulated LSST data to find TDEs and improve upon their capabilities prior to the start of LSST.
[abstract 37 / 59] (score: 2) - Title: Interpreting map-based $E$/$B$ spectral properties of CMB foregroundsAuthors: Gilles Weymann-Despres, Léo Vacher, Michael E. Jones, Angela C. Taylor, Carlo Baccigalupi, A. J. Banday, Richard D. P. Grumitt, Nicoletta Krachmalnicoff,Comments: 29 pages, 20 figures. Accepted for publication in MNRASSubjects: astro-ph.CO astro-ph.GACreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
Map-space $E$/$B$ decompositions of linear POLARIZATION are attractive for foreground and CMB analyses because they separate parity families: $B$-family patterns directly contaminate primordial tensor searches, while $E$-family patterns trace coherent Galactic structures. However, the $E$/$B$ transform is not fully local and can induce apparent spectral complexity even when the underlying sky is spectrally simple in $\underline{P}=Q+iU$. We quantify this effect for SYNCHROTRON emission using complex log--Taylor and moment expansions for $\underline{P}$, its spin-preserving projections $\underline{P}_E$ and $\underline{P}_B$, and its more standard scalar projections $E$ and $B$. We relate the coefficients of these expansions to physical mechanisms such as line-of-sight mixing, SYNCHROTRON ageing, and Faraday effects. Using simple sky models, we show how $\underline{P}_E$ and $\underline{P}_B$ reorganize the spectral behaviour of $\underline{P}$ into parity families with a clear geometric meaning. They retain interpretable amplitudes and angles and satisfy the closure relation $\underline{P}=\underline{P}_E+\underline{P}_B$, which extends to all moment orders. By contrast, scalar quantities such as $|E|$ and $|B|$ show larger induced variability of effective spectral parameters and enhanced spectral complexity, while $E+iB$ lacks interpretable POLARIZATION amplitude and angle. Finally, we present simple CMB-oriented applications: three-frequency diagnostics to test whether the sky is better described by a power law in $P$ or by separate effective laws in $(P_E,P_B)$, and idealized ILC and masking examples showing that the preferred map-space field depends on where foreground simplicity and residual contamination reside. This framework provides practical diagnostics for choosing foreground modelling, cleaning, and masking strategies in Galactic and CMB $B$-mode analyses.
[abstract 38 / 59] (score: 2) - Title: Wave interactions in a screeching JETAuthors: Ali Farghadan, Jayson Beekman, Petronio Nogueira, Daniel Edgington-Mitchell, Aaron Towne,Comments:Subjects: physics.flu-dynCreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
We use a series of global models to investigate the linear and nonlinear interactions between shock cells, Kelvin-Helmholtz waves, guided JET modes, and other fluctuations in a screeching JET. First, we identify a set of lightly damped global eigenmodes of the Navier-Stokes operator linearized about the mean flow and show that they result from interactions with different shock-cell wavenumbers. Second, we use resolvent analysis to study the linear input-output behavior of the JET and obtain a time-periodic representation of the screech mode, which compares favorably with experimental data. Third, we use harmonic resolvent analysis to study triadic interactions, including inter-frequency energy transfer, between the screech mode determined from resolvent analysis and other fluctuations in the JET. The components of the optimal harmonic resolvent mode at harmonics of the screech frequency are consistent with experimental observations that have not been previously predicted by global models. Fourth, we leverage a novel bilinear formulation of harmonic resolvent analysis to study the impact of the screech mode's nonlinear self-interaction on other fluctuations in the JET. We show that the forcing provided by this nonlinear self-interaction of the screech mode, along with its triadic interactions with other frequencies embedded within the harmonic resolvent operator, is sufficient to explain the redistribution of energy to other frequencies and the associated experimental observations. In aggregate, these findings underscore the critical role of triadic and nonlinear interactions in shaping screech dynamics and offer a promising workflow for studying similar interactions in other flows dominated by periodic motions.
[abstract 39 / 59] (score: 2) - Title: The first decade of gravitational-wave measurements of BLACK HOLE spinsAuthors: Sylvia Biscoveanu,Comments: Prepared for the Galaxies special issue on "Gravitational-Wave Probes of Black Hole Spin and Binary Dynamics", v2 matches accepted versionSubjects: gr-qcCreated: 2026-07-29; Updated: 2026-07-31; Datestamp: 2026-07-31
A decade after the first direct detection of gravitational waves, the growing catalog of hundreds of confirmed events is revealing new insights into the spins of stellar-mass BLACK HOLEs. Spin measurements have long been heralded as a promising tracer of compact-object binary formation and evolution, as different formation channels predict distinct spin signatures on a population level. In this review, we summarize the astrophysics, phenomenology, and current measurements of BLACK HOLE spins. We begin with an overview of the predictions for BLACK HOLE spin magnitudes and orientations from leading formation channels--isolated binary evolution, dynamical formation in clusters, formation in AGN disks, and hierarchical triples. We then describe the imprint of spin effects on the gravitational waveform and the measurability of spin in individual events. Finally, we review current population-level constraints on spin magnitudes, orientations, and effective spin parameters, including correlations with mass and redshift, and discuss their astrophysical implications. We conclude by highlighting open questions and future prospects, emphasizing how improved detector sensitivity will enable increasingly precise spin measurements for both individual events and the binary BLACK HOLE population as a whole.
[abstract 40 / 59] (score: 2) - Title: The toroidal flux and separatrix effects in tokamaksAuthors: Allen H Boozer,Comments:Subjects: physics.plasm-phCreated: 2026-07-29; Updated: 2026-07-31; Datestamp: 2026-07-31
An implication of Faraday's Law is thst the rate of change of the poloidal flux relative to the toroidal flux associated with a MAGNETic surface is given by the loop voltage. The emphasis in the tokamak literature on the poloidal almost to the exclusion of the toroidal MAGNETic flux has led to fundamental mistakes in understanding MAGNETic field evolution, especially as it affects plasma disuptivity. Designs of tokamak power plants include a divertor that is defined by a separatrix at the plasma edge. The use of the toroidal flux clarifies the descriptions of such plasmas. This paper explores the effects of a separatrix on plasma parameters that are used for assessing disruptivity: the edge safety factor and the internal inductance. The exploration of these effects includes an analytic model, which illustrates why the use of the poloidal instead of the toroidal flux introduces a significant definitional uncertainty in what is meant by the edge safety factor and the internal inductance.
[abstract 41 / 59] (score: 2) - Title: On the braking index evolution of PSR B0540-69: wind braking of pulsarsAuthors: H. Tong,Comments: 6 pages, accepted in RAASubjects: astro-ph.HECreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
The pulsar PSR B0540-69 has both a braking index measurement and spin-down state change. After its spin-down state change, it shows an increasing braking index with time. Previously, it is pointed out that the spin-down state change may be caused by an enhanced particle wind. The prediction is that its braking index will be smaller in the high spin-down state. The current measured braking index is approaching the previous prediction. The transient variation of braking index may be due to a small varying part of the particle density. The braking index evolution of PSR B0540-69 is found to be in an exponential form. Its braking index is expected to approach some steady value. Future braking index measurement may make clear the physics for the braking index evolution. It may also help to make test the particle acceleration mechanism in the pulsar MAGNETosphere. Finally, a phenomenological treatment of the wind braking model is presented in the appendix. It can simplify the applications of wind braking model to pulsar braking index, intermittent pulsars and PSR B0540-69.
[abstract 42 / 59] (score: 2) - Title: Outflow Behavior from the Transonic Advective Disks: A Hydrodynamical Simulation StudyAuthors: Sanjit Debnath, Indranil Chattopadhyay, Raj Kishor Joshi, Philippe Laurent, Priyesh Kumar Tripathi, M. Saleem Khan,Comments: 12 pages, 4 figures, Proceedings of BINA conference held on November 2025Subjects: astro-ph.HECreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
We investigate the properties of outflows from the transonic advective accretion disk using hydrodynamical numerical simulations. We consider two different disk temperatures with an order-of-magnitude difference. For the hotter disk, we adopt initial conditions for velocity, specific angular momentum, and temperature from analytical solutions. In the colder disk case, the velocity and angular momentum profiles are kept identical, while an order of magnitude reduction in the temperature. The simulations are performed in the presence of viscosity and radiative cooling, considering bremsstrahlung and SYNCHROTRON processes. In both disk models, the outflow rate increases with viscosity. We also examine the poloidal velocity structures for both cases. We analyze the influence of viscosity on the mass flux-weighted energy and momentum fluxes of the outflows. Our results show that both energy and momentum fluxes increase with higher viscosity and may play a significant role in accretion feedback mechanisms.
[abstract 43 / 59] (score: 2) - Title: Semi-analytic Inference of Satellite Densities in the Cold Dark Matter Model Part II. Implications for Dark Matter Indirect Detection ConstraintsAuthors: Kailash Raman, Dylan Folsom, Manoj Kaplinghat, Mariangela Lisanti, Benjamin R. Safdi,Comments: 16+9 pages, 4+6 figures, video abstract at https://youtu.be/x9zNkN6XyAASubjects: astro-ph.HE astro-ph.CO hep-phCreated: 2026-07-29; Updated: 2026-07-31; Datestamp: 2026-07-31
Dwarf galaxies provide excellent targets to search for signals of DARK MATTER annihilation or decay. Using a calibrated semi-analytic model and the latest stellar kinematic data (presented in Part I), this paper updates the astrophysical J-factors for the Milky Way's dwarf spheroidal galaxies. We infer the probability distributions for the J-factors of 39 dwarfs by conditioning a population of subhalos, generated with the SatGen semi-analytic satellite model, on either a dwarf's kinematically determined dynamical mass or its stellar mass. We also compute the J-factors using the Jeans equation with updated stellar kinematics and priors that incorporate varying degrees of SatGen information. We use the computed J-factors to recast existing limits from FERMI-LAT data on the annihilation cross section. Our main result is that variations in the J-factors computed using the Jeans analysis introduce a factor of 2-4 uncertainty into the inferred limits on the cross section. We argue that a cosmologically informed prior is a motivated choice that excludes thermal relic annihilation cross sections to $b\bar{b}$ below about 70 GeV. For comparison, the more commonly used priors, which can lead to unphysical halo parameters, exclude masses below 130 GeV at 95% confidence level. We also show that the highest-J-factor dwarfs are spatially extended, approximately one degree on the sky, which challenges the validity of the point-source approximation adopted in many analyses of FERMI data. Finally, based on the semi-analytic model and the kinematic data, the highest J-factor halos have already been discovered, suggesting future ultra-faint discoveries are unlikely to substantially strengthen limits on annihilating DARK MATTER.
[abstract 44 / 59] (score: 2) - Title: Validation of the DESI DR2 Ly$α$ forest full-shape analysisAuthors: M. Herbold, A. Cuceu, P. Martini, H. K. Herrera-Alcantar, J. Guy, C. Gordon, O. Manasoiu, J. Aguilar, S. Ahlen, O. Alves, U. Andrade, E. Armengaud, S. Avila, A. Aviles, A. Bault, F. Beutler, D. Bianchi, M. Bonici, A. Brodzeller, D. Brooks, A. Carnero Rosell, E. Chaussidon, J. Chaves-Montero, Z. Chen, T. Claybaugh, K. S. Dawson, A. de la Macorra, A. Dey, W. Elbers, V. A. Fawcett, S. Ferraro, A. Font-Ribera, J. E. Forero-Romero, G. Gambardella, S. Gontcho A Gontcho, D. Gonzalez, A. X. Gonzalez-Morales, R. Gsponer, G. Gutierrez, B. Hadzhiyska, C. Hahn, K. Honscheid, D. Huterer, M. Ishak, S. Jos, S. Juneau, N. V. Kamble, N. G. Karaçaylı, T. Karim, R. Kehoe, D. Kirkby, F. -S. Kitaura, A. Kremin, O. Lahav, M. Landriau, J. Lasker, L. Le Guillou, A. Leauthaud, M. E. Levi, Q. Li, W. Liu, K. Lodha, M. Manera, A. Meisner, R. Miquel, J. Morawetz, J. Moustakas, P. Mukherjee, A. Muñoz-Gutiérrez, S. Nadathur, G. Niz, H. E. Noriega, E. Paillas, N. Palanque-Delabrouille, J. Pan, M. P. Ibanez, W. J. Percival, F. Prada, H. Pulido-Hernández, A. Pérez-Fernández, I. Pérez-Ràfols, C. Ravoux, J. Rohlf, G. Rossi, R. Ruggeri, M. F. Ruiz-Herrera Bernal, L. Samushia, E. Sanchez, C. Saulder, D. Schlegel, H. Seo, J. Silber, F. Sinigaglia, M. Siudek, G. Tarlé, W. Turner, R. Vaisakh, M. Vargas-Magaña, B. A. Weaver, M. Wolfson, H. Yang, H. Zhang,Comments:Subjects: astro-ph.COCreated: 2026-07-29; Updated: 2026-07-31; Datestamp: 2026-07-31
We present the validation of the Dark Energy Spectroscopic Instrument (DESI) Data Release 2 (DR2) Lyman-$α$ (Ly$α$) forest full-shape analysis. This analysis combines three-dimensional Ly$α$ forest auto-correlations and cross-correlations with QUASARs to extract information from both the baryon acoustic oscillation (BAO) feature and the broadband clustering signal, with primary emphasis on the Alcock-Paczynski (AP) measurement. Compared to the DESI DR1 analysis, the DR2 validation uses substantially larger and more realistic mock datasets, including CoLoRe 2LPT and AbacusSummit Ly$α$ forest simulations. The modeling framework is also improved through analytic marginalization over small scales ($<10$ $h^{-1}$Mpc) and the impact of ultraviolet background fluctuations. The validation program was completed prior to unblinding and defines quantitative requirements for the cosmological parameters of interest, which are evaluated using hundreds of mock realizations. We further test the analysis through independent fits to the auto- and cross-correlations, multiple catalog splits, and a broad suite of analysis and modeling variations applied to both mocks and blinded observational data. We find that the BAO and AP parameters satisfy all validation requirements and remain stable across all tests. In contrast, mock studies reveal a significant bias in the inferred growth-rate parameter $fσ_8$, leading us to exclude this measurement from the final analysis. The consistency across mocks, data splits, and robustness tests demonstrates that the DR2 Ly$α$ full-shape analysis provides a reliable and substantially improved broadband AP measurement over previous Ly$α$ forest studies.
[abstract 45 / 59] (score: 2) - Title: CoLoRe-2LPT: Lyman-$α$ mock catalogues for the validation of DESI cosmological analysesAuthors: M. F. Ruiz-Herrera Bernal, S. Avila, A. Font-Ribera, H. K. Herrera-Alcantar, D. Alonso, A. Cuceu, L. Casas, F. Sinigaglia, J. Aguilar, S. Ahlen, O. Alves, U. Andrade, E. Armengaud, A. Bault, F. Beutler, D. Bianchi, M. Bonici, A. Brodzeller, D. Brooks, A. Carnero Rosell, J. Chaves-Montero, Z. Chen, Y. Cho, T. Claybaugh, K. S. Dawson, A. de la Macorra, A. Dey, W. Elbers, S. Ferraro, J. E. Forero-Romero, G. Gambardella, S. Gontcho A Gontcho, D. Gonzalez, A. X. Gonzalez-Morales, C. Gordon, R. Gsponer, G. Gutierrez, J. Guy, C. Hahn, M. Herbold, K. Honscheid, M. Ishak, S. Jos, S. Juneau, N. V. Kamble, T. Karim, D. Kirkby, A. Kremin, M. Landriau, A. Leauthaud, Q. Li, W. Liu, K. Lodha, O. Manasoiu, M. Manera, P. Martini, A. Meisner, R. Miquel, J. Morawetz, P. Mukherjee, A. Muñoz-Gutiérrez, S. Nadathur, G. Niz, H. E. Noriega, E. Paillas, N. Palanque-Delabrouille, J. Pan, M. Pellejero Ibanez, W. J. Percival, C. Poppett, F. Prada, H. Pulido-Hernández, A. Pérez-Fernández, I. Pérez-Ràfols, C. Ravoux, J. Rohlf, G. Rossi, R. Ruggeri, L. Samushia, E. Sanchez, C. Saulder, D. Schlegel, H. Seo, J. Silber, M. Siudek, G. Tarlé, W. Turner, R. Vaisakh, M. Vargas-Magaña, B. A. Weaver, H. Yang, H. Zhang,Comments: 17 pages, 11 figures, 2 tables. Plan to submit to A&ASubjects: astro-ph.COCreated: 2026-07-29; Updated: 2026-07-31; Datestamp: 2026-07-31
The Lyman-$α$ (Ly$α$) forest has become a crucial probe for studying the large-scale structure of the universe at high redshift ($z > 2$), providing powerful constraints on Baryon Acoustic Oscillations (BAO) and the full-shape (FS) clustering of matter. As a key ingredient for upcoming BAO and FS analyses, we present a new generation of fast cosmological Ly$α$ mocks based on second-order Lagrangian perturbation theory (2LPT). These new mocks significantly improve upon previous log-normal approaches, both at accurately capturing small scale clustering and at recovering the non-linear broadening of the BAO peak. They are able to reproduce Ly$α$ statistics within $10\%$ of the latest DESI measurement; including the Ly$α$ bias and the redshift-space distortion $β$ parameter, mean transmitted flux, and 1D power spectrum. The corresponding QUASAR (QSO) clustering is also improved with respect to previous approaches, calibrated against high-resolution Abacus simulations, recovering the observational QSO linear bias to less than $5\%$ and improving redshift-space distortions via 2LPT velocities and the addition of Fingers-of-God effects. Furthermore, these mocks incorporate high column density systems and metal lines, allowing us to explore the effects and systematics induced by these astrophysical contaminants. This new set of mocks has been key for enhancing the modeling and validation of the DESI DR2 Ly$α$ full shape cosmological analysis. This work provides a physically motivated and computationally efficient tool for simulating current and next-generation Ly$α$ surveys and validating FS and BAO analysis.
[abstract 46 / 59] (score: 2) - Title: Coaxial GyroMAGNETic Nonlinear Transmission Line with a Slow-Wave Structure: 2D/3D FDTD ModelingAuthors: Serhii Karelin, Ivan Onishchenko,Comments: Submitted to IEEE Transactions on Plasma Science (Manuscript ID: TPS18901). Materials of this paper were presented as a poster report "2D/3D FDTD Modeling of Coaxial Waveguide with Magnetized Nonlinear Ferrite and Slow-Wave Structure" at the XXXII International Workshop on Optical Wave & Waveguide Theory and Numerical Modelling, 8-10 April 2026, Lausanne, Switzerland (https://owtnm26.epfl.ch/)Subjects: physics.plasm-phCreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
A coaxial gyroMAGNETic nonlinear transmission line (GNLTL) enables pulse-front compression and oscillation packet generation in the 0.3-10 GHz range. Numerical modeling of such systems typically employs a 2D axially symmetric FDTD scheme coupled with the parallel solution of full non-linearized Landau-Lifshitz-Gilbert equations. Previous studies have shown that using an insulating dielectric with a permittivity $ε$>60 enables the generation of long-lasting oscillations via a Cherenkov-like effect. However, practical implementation is limited due to the severe high-frequency losses inherent in materials with such extreme permittivity, like water. To overcome this limitation and enhance performance, we propose a novel design utilizing a spiral central conductor to mimic a high-permittivity environment, with the ferrite placed inside the spiral. Due to the loss of axial symmetry, the FDTD model was extended to 3D coordinates. Simulations confirm that the spiral conductor configuration generates a prolonged oscillation packet similar to that of a high-permittivity dielectric waveguide, but with significantly reduced losses and improved energy transfer efficiency.
[abstract 47 / 59] (score: 2) - Title: The X-ray-Weak Tail of the Quasar Population: Physical Properties and Redshift Evolution of Variability-Selected AGN in eFEDSAuthors: P. Arévalo, J. Buchner, M. Salvato, P. Sánchez-Sáez, F. Bauer, M. L. Martínez-Aldama, D. Tubín-Arenas, J. Cerón-Meneses, R. Pucha, P. Lira, A. Merloni, M. Mezcua, M. Krumpe,Comments: Submitted to A&ASubjects: astro-ph.GACreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
(abridged) Aims: To characterize variability-selected AGN candidates within the eROSITA Final Equatorial-Depth Survey (eFEDS), leveraging the synergy between optical variability and deep X-ray observations by SRG (Spectrum Roentgen Gamma)/eROSITA, to compare the physical properties of AGN populations selected through complementary methods. Methods: We used a sample of AGN candidates selected via optical variability by Arévalo et al. and cross-match it to the X-ray selected eFEDS AGN sample. Spectroscopic characterizations are obtained for the matched samples from the Dark Energy Spectroscopic Instrument public data products. Results: We find a high classification purity with 98% candidates confirmed as broad-line AGN/QSOs. We identify a significant population (25%) that lack X-ray counterparts (X-U) in the eFEDS survey. We find that the X-D and X-U samples exhibit distinct physical properties and redshift distributions. The X-U sample peaks at $z = 2$ while the X-D sample at $z =1$, with nearly half of the variability-selected AGN at $z > 2.5$ remaining undetected in X-rays. This missing fraction can be attributed to K-correction effects and SED evolution with luminosity, mainly resulting in high accretion rate objects falling out of the X-D sample at higher redshifts. X-ray variability accounts for a part of the missing fraction but its dependence with redshift is less clear. Ensemble spectral analysis reveals that X-D sources have steeper optical continua and stronger broad emission lines than their X-U counterparts, while the forbidden and semi-forbidden lines have equal EWs in both samples. Finally, broad absorption line (BAL) features are found almost exclusively in the X-U population. This "missing" X-ray population must be accounted for when extrapolating X-ray-selected AGN to the broader Type I population and could impact cosmic estimates of massive BLACK HOLE growth.
[abstract 48 / 59] (score: 2) - Title: eRASSU J043115.8-711730: The first pulsating symbiotic super-soft X-ray source in the Magellanic BridgeAuthors: Tathagata Saha, Chandreyee Maitra, Philip Charles, Frank Haberl, David Kaltenbrunner, Andrej Udalski, David Buckley, Itumenleng Monageng, Lee Townsend, Manami Sasaki, Sara Saeedi, Mara Salvato,Comments: Submitted to MNRASSubjects: astro-ph.HECreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
The Magellanic Bridge stellar population is a relic of the tidal interaction between the Large and Small Magellanic Clouds. A comprehensive view of the evolution of the Bridge stellar population requires probing the compact remnants of stellar evolution, otherwise hidden at optical wavelengths. The all-sky survey conducted by the eROSITA instrument on-board the Spectrum Roentgen Gamma observatory has discovered a significant population of compact-object-powered systems in the Bridge using X-ray. The candidate super-soft source eRASSU J043115.8-711730 (hereafter J0431-71) was discovered as a part of this campaign, and we present here a deeper study of this source using XMM-Newton and SALT spectroscopy, long-term optical-infrared photometry using OGLE, ATLAS, ASAS-SN, WISE, and GAIA data. J0431-71 is a highly variable super-soft X-ray source, classified as a red giant with the GAIA color-magnitude diagram. The source exhibits: (a) a thermal X-ray spectrum with a temperature of kT$\sim$30 eV and a bright state luminosity of $3.2\times10^37$~erg~s$^{-1}$ in the 0.15-1 keV band, (b) Balmer emission lines, [Fe X] coronal line, HeII emission, and the Bowen fluorescence blend, (c) an optical and infrared periodicity of $\sim$500-560 days in phase with the X-ray-UV emission, (d) a 'redder-when-brighter' trend in the stellar emission with a $\sim$520 day period indicating a pulsating donor star. We argue that the observed spectral and temporal properties in J0431-71 are consistent with a high-accretion rate onto a white-dwarf via Roche-lobe overflow, making J0431-71 the first symbiotic source discovered in the Bridge.
[abstract 49 / 59] (score: 2) - Title: Accretion Burst Crystallizes Silicates in a Planet-Forming DiskAuthors: Jeong-Eun Lee, Chul-Hwan Kim, Jaeyeong Kim, Seokho Lee, Young-Jun Kim, Seonjae Lee, Giseon Baek, Joel D. Green, Gregory J. Herczeg, Doug Johnstone, Klaus M. Pontoppidan, Yuri Aikawa, Yao-Lun Yang, Logan Francis, Mihwa Jin, Hyerin Jang,Comments: 33 pages, 12 figures, 1 table, This is the author accepted manuscript of an article published in Nature. The final published version is available at this https URL (https://www.nature.com/articles/s41586-025-09939-3)Subjects: astro-ph.EP astro-ph.SRCreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
Crystalline silicates form at high temperatures (> 900 K; Fabian et al. 2000; Hallenbeck et al. 1998). Their presence in comets (Hanner et al. 1994; Hayward et al. 2000; Wooden et al. 2002; Shinnaka et al. 2018) suggests that high-temperature dust processing occurred in the early Solar System and was subsequently transported outward to comet-forming regions. However, direct evidence for this crystallization and redistribution in Sun-like protostars has remained elusive. By comparing James Webb Space Telescope (JWST) mid-infrared spectra of the periodically bursting protostar EC 53 (Lee et al. 2020), we detect crystalline silicate (forsterite and enstatite) emission features that appear only during the burst. The emergence of these features indicates active crystal formation via thermal annealing in the hot inner disk during the accretion burst. We also detect a nested outflow-a collimated atomic JET enclosed by slower molecular outflows, consistent with MAGNETohydrodynamic (MHD) wind models (Pascucci et al. 2025). This configuration provides a mechanism for outward transport of freshly crystallized silicates (Giacalone et al. 2019). Our results provide the first direct observational evidence of in-situ silicate crystallization during episodic accretion bursts in a very young star still embedded in its dense envelope. Although we do not directly detect grains transported to the outer disk, the observed trends are consistent with outward redistribution, indicating that both dust processing and transport occur during the earliest and most dynamic stages of STAR FORMATION.
[abstract 50 / 59] (score: 2) - Title: The Volans-Carina association An X-ray Bridge Between Younger and Older Stellar PopulationsAuthors: Daniela Muñoz-Giraldo, Beate Stelzer, Alex Binks, Enza Magaudda, Stefanie Raetz, Christian Schneider,Comments: 12 pages, 14 figures. Submitted to A&ASubjects: astro-ph.SR astro-ph.GACreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
Nearby young moving groups (NYMGs) provide benchmarks for studying the evolution of MAGNETic activity and planetary environments at early ages. The Volans-Carina association (VCA), as a pre-main sequence association at a distance of ~90 pc, occupies a sparsely sampled region of parameter space between younger nearby associations and older distant open clusters. We have re-evaluated the membership probabilities of the VCA catalog presented in Gagne et al. (2018a) with BANYAN as well as updated kinematics from Gaia DR3. Stellar parameters were derived from multi-wavelength spectral energy distributions, with the obtained bolometric luminosity and effective temperature being used in combination with pre-main sequence evolutionary models to obtain an isochronal age of the association. We joined data from the SRG (Spectrum Roentgen Gamma)/eROSITA and ROSAT all-sky surveys with a dedicated XMM-Newton Large Programme to construct a comprehensive X-ray catalog. Our updated census of the VCA comprises 29 highly probable members, 30 candidate members, and four uncertain objects. Isochronal analysis of the association yields an age of 80+-20 Myr, consistent with previous estimates. We detect X-ray emission from 56 objects, reaching ~90% completeness, one of the most complete X-ray censuses achieved for a NYMG. Low-mass members and candidates (<0.6 Msolar) have X-ray to bolometric luminosity ratios around the canonical saturation limit (Lx/Lbol~10^-3). X-ray luminosity functions show the VCA to be consistent with the similarly aged Pleiades (in the F5 to M3 range) and significantly more active than the older Hyades (in the F5 to K4 range). The combination of an updated membership census and a nearly complete X-ray census establishes the VCA as a particularly robust calibration point for studies of the early evolution of coronal X-ray activity.
[abstract 51 / 59] (score: 2) - Title: The X-ray catalogue of FGK stars within 10 pc: The coronal temperature-brightness relation explained with the RTV scaling lawAuthors: M. M. Bennedik, B. Stelzer, M. Caramazza, S. Orlando, A. Binks, J. Robrade,Comments: 17 pages, 15 pages, Submitted to A&ASubjects: astro-ph.SRCreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
A comprehensive measurement of stellar X-ray emission has important implications for our understanding of stellar dynamos, exoplanet atmosphere loss, and evaporation of protoplanetary disks. We present a catalogue of X-ray detections of the FGK-type main-sequence stars within 10 pc, which accounts for stellar multiplicity and optical loading of the detectors. To build the X-ray catalogue, we analysed all observations from SRG (Spectrum Roentgen Gamma)/eROSITA and XMM-Newton for stars in the FGK 10pc sample, and we cross-matched the sample with ROSAT catalogues. We fit thermal plasma models to the X-ray spectra to derive X-ray fluxes and coronal temperatures. We investigate the relation between coronal temperature and X-ray surface flux and find the result to be consistent with the ranges covered by different types of solar coronal MAGNETic structures. The lower end of the temperature-brightness relation is defined by the Maunder minimum star HD 166620 and three other stars whose positions identify them as possible Maunder minimum candidates. We identify systematic differences between the temperature-brightness law derived from XMM-Newton and eROSITA data that we attribute to their different instrumental response functions. We study the impact of both short-term flaring and long-term activity cycles on the evolution of coronal temperature along with X-ray brightness. With the exception of three stars, a remarkably small scatter is observed in the temperature-brightness relation across the whole sample. A natural explanation of the empirical kT-FX relation is provided by the RTV scaling law defined for solar MAGNETic loops. The small spread of the observed relation indicates a universal scaling between the length and the filling factor of coronal loops. The three observed outliers deviate from this invariance of the ratio of loop length to filling factor for an as of yet unknown reason.
[abstract 52 / 59] (score: 2) - Title: Configuration crossing, shape evolution, and odd-proton POLARIZATION in yttrium isotopesAuthors: Noam Gavrielov,Comments: 8 pages, 5 figures, 1 tableSubjects: nucl-thCreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
The odd-mass $^\text{91-101}$Y isotopes provide a testing ground for how an unpaired proton modifies an abrupt collective structural evolution. A configuration-mixing Bose-FERMI description shows that the lowest negative- and positive-parity states undergo a crossing of normal and intruder configurations near neutron number $N = 60$, intertwined with an evolution from weak coupling of a quasiparticle to a near-spherical core toward strong coupling to a deformed core. To isolate the role of the odd proton, a differential charge-radius POLARIZATION observable is introduced as the difference between the isotope shifts of the odd-mass chain with those of the corresponding even-even cores. Its pronounced peak at $N = 58$ and sign reversal at $N = 60$ reveal a localized modification of the core evolution in the critical region. Energy levels, wave-function content, electroMAGNETic moments, two-neutron separation energies, and coherent-state energy surfaces support this interpretation.
[abstract 53 / 59] (score: 2) - Title: Angular Momentum Evolution from Core to Disk Scales in the Early Phase of Star Formation: Constraints from HH 212, HH 211, and B335Authors: Chin-Fei Lee,Comments: 16 pages, 2 figuresSubjects: astro-ph.GACreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
I investigate the angular momentum evolution from core to disk scales in the early phase of STAR FORMATION using three protostellar systems: HH 212, HH 211, and B335. Observations show that the specific angular momentum follows a power-law dependence at core scales and transitions to an approximately constant value at smaller radii, indicating dynamical collapse in the inner envelope. I model this behavior using the inside-out collapse solution of Shu (1977) and its rotating extension, the Terebey-Shu-Cassen model, including modest MAGNETic effects through a flattened, MAGNETized core. I find that the observed angular momentum profiles in all three sources are broadly consistent with an inside-out collapse scenario with approximate conservation of specific angular momentum in the collapsing region. The inferred collapse ages and mass infall rates yield total masses accreted onto the center that are broadly consistent with the central masses derived from kinematics, allowing for a fraction of the material to be ejected by JETs and winds. The predicted midplane densities at typical radii, including the effect of MAGNETic flattening, are also consistent with observational estimates. The three systems exhibit a similar pattern of angular momentum evolution despite large differences in the magnitude of their specific angular momentum. In particular, the small disk in B335 can be naturally explained by its lower initial specific angular momentum, although alternative explanations, such as MAGNETic braking or different initial conditions, cannot be excluded. These results suggest that inside-out collapse, with modest MAGNETic modification, provides a plausible first-order description of angular momentum evolution from core to disk scales in the early phase of STAR FORMATION.
[abstract 54 / 59] (score: 2) - Title: Magnetic Field Stratification in Active-Region Plage from Ca II K and Ca II 8542 Å SpectropolarimetryAuthors: Iñigo Juanikorena Berasategi, Ernest Alsina Ballester, Javier Trujillo Bueno, Francisco A. Iglesias, Yusuke Kawabata, Juan Sebastián Castellanos Durán, Masahito Kubo, Alex Feller, Yukio Katsukawa, Sami K. Solanki, Jose Carlos del Toro Iniesta, Andreas Lagg, Achim Gandorfer, Pietro Bernasconni, Thomas Kerkefeld, Tino L. Riethmüller, Yoshihiro Naito, Alberto Álvarez-Herrero, H. N. Smitha, David Orozco Suárez, Bianca Grauf, Michael Carpenter, Alexander Bell, Valentín Martínez Pillet, Francisco Javier Bailén, Julian Blanco Rodríguez, Edvarda Harnes, Johannes Hölken, Ryohtaroh T. Ishikawa, Takuma Matsumoto, Takayoshi Oba, Azaymi L. Siu-Tapia, Hanna Strecker, Dušan Vukadinović,Comments: 9 pages, 4 figures, 4 appendices. Accepted for publication in The Astrophysical Journal Letters; Sunrise III focus issueSubjects: astro-ph.SRCreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
We investigate the height variation of the line-of-sight (LOS) MAGNETic field in solar active-region (AR) plage from the upper photosphere to the upper chromosphere using co-spatial ultraviolet (UV) and infrared (IR) spectropolarimetric observations from the Sunrise III stratospheric balloon flight. The Ca II K and Ca II 8542 Å lines provide complementary chromospheric diagnostics, while nearby Fe I lines sample photospheric layers. The LOS MAGNETic field is inferred from the intensity and circular POLARIZATION profiles, applying the weak field approximation for the Ca II lines and the center-of-gravity method for the Fe I lines. The photospheric Fe I lines reveal strong, finely structured MAGNETic fields of the order of a kG. In contrast, the chromospheric Ca II diagnostics yield systematically weaker fields, typically in the $\sim$ 100-400 G range, with a more diffuse spatial distribution. Magnetic field maps inferred from the Ca II K line, formed higher in the chromosphere, are smoother and more extended than those derived from the Ca II 8542 Å line, which samples lower heights. We find that the MAGNETized area increases by a factor of $\sim$ 2 from the photosphere to the chromosphere. These results provide direct quantitative evidence that MAGNETic fields in AR plage weaken and expand with height, evolving from compact kG photospheric concentrations into weaker and more spatially extended structures in the upper chromosphere.
[abstract 55 / 59] (score: 2) - Title: ElectroMAGNETically Driven Thermal Dissipation Scaling in Plasma Centrifuges for Mass SeparationAuthors: Drue P. Hood-McFadden, Shreyas Kotla, Thomas C. Underwood,Comments:Subjects: physics.plasm-phCreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
ElectroMAGNETically driven centrifuges (EMDCs) rotate fluids using the Lorentz force, but their separative performance is limited by thermal dissipation that is coupled to electroMAGNETic forcing. This follows because local centrifugal strength is proportional to λ=mV_θ^2/2k_B T, which compares directed kinetic energy that drives species separation to thermal energy that smooths concentration gradients and counteracts separation. In this work, we develop a reduced two-temperature MAGNETohydrodynamic model to determine how radial geometry, current density, and MAGNETic field strength control the coupled evolution of rotation and heating that dictates λ. The model is benchmarked against Ar and Ar/Kr experiments spanning current density up to 15 kA/m^2, MAGNETic field up to 0.57 T, feed pressures of 0.5-3 Torr, and annulus sizes of 1-5 cm. The results show that volumetric Lorentz forcing sustains higher λ and therefore greater local compositional shifts throughout a larger radial portion of the fluid volume than wall-bounded shear centrifuges, despite lower peak λ. Simulations of a 40Ar/36Ar isotopic mixture demonstrate that, when electroMAGNETic force and geometry are jointly optimized, EMDCs can exceed the separative performance of shear-driven centrifuges operating near material speed limits, for lower area-averaged values of λ. These results challenge assertions that viscous dissipation constrains weakly ionized plasma centrifuges to λ<1, and indicate that enhanced radial mass separation can be achieved by increasing the radial distribution of λ rather than maximizing its peak or area-averaged value.
[abstract 56 / 59] (score: 2) - Title: Variational Formulation of a Hybrid Kinetic and Gyrokinetic Model for Astrophysical and Laboratory PlasmasAuthors: F. N. deOliveira-Lopes, S. C. Thatikonda, D. Told, A. Mustonen, K. Pommois, K. Hagiwara, F. Jenko, R. Grauer,Comments: 17 pages, 10 figuresSubjects: physics.plasm-phCreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
We present a Lagrangian model that encapsulates fully kinetic ions and gyrokinetic electrons for solar wind electroMAGNETic turbulence. Using a consistent method, where both electrons and protons are treated with the same mathematical formalism, we derive and implement a model in which high-frequency waves and kinetic electron effects are described in a computationally cost-efficient way. Higher-order Lie-transform perturbation methods applied to Hamiltonian formulation of guiding center motion are used to describe the dynamics of particles and fields. We use a variational approach to derive field equations for closure of the system.
[abstract 57 / 59] (score: 2) - Title: Multi-branch classification of diffuse cluster radio emissionAuthors: Markus Bredberg, Emma Tolley,Comments: 16 pages, 12 figures, Accepted in A&ASubjects: astro-ph.COCreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
Context. Galaxy clusters sometimes host SYNCHROTRON radiation on scales of ~100 kpc to ~1 Mpc, with surface brightness only a few times the image noise. This diffuse cluster radio emission is a sensitive probe of MAGNETic fields and intracluster medium dynamics, but disentangling the underlying physical processes requires statistically large samples spanning a wide range of cluster masses, dynamical states, and redshifts, together with sufficient sensitivity to low-surface-brightness emission. Aims. We explore two techniques for improving detection of diffuse emission in galaxy cluster images, relative to a baseline classifier: the scattering transform (ST) and squeeze-excitation (SE) attention. Methods. We integrate an ST encoder into a dual-branch classifier (DualSSN) and a scattering network (ScatterNet). We incorporate SE attention into the DualSSN and dual-branch convolutional neural network (DualCSN). These classifiers are then benchmarked against a simple CNN, across ten image preprocessing configurations and three cropping strategies. Performance is evaluated on small labelled datasets from the second data release of the LOFAR two-metre sky survey overlapping with the second Planck catalogue of Sunyaev-Zel'dovich sources (LoTSS-DR2/PSZ2). Results. Alongside the multi-branch approach with SE and ST, cropping the image to a fixed number of telescope beams and uv- tapering (smoothing to a coarser angular resolution) improve classification performance, while stacking multiple preprocessed ver- sions of an image does not. Conclusions. Scattering-transform-based multi-branch architectures with beam-normalised cropping are a promising direction for diffuse emission classification in the SKA era.
[abstract 58 / 59] (score: 2) - Title: Binary neutron stars in the next-generation era: Multi-messenger detection prospects and constraints on the equation of state, mass distribution, and cosmologyAuthors: Hauke Koehn, Thibeau Wouters, Gilad Sadeh, Peter T. H. Pang, Mattia Bulla, Chris Van Den Broeck, Michael W. Coughlin, Tim Dietrich,Comments: 30 pages, 14 figures, comments welcomeSubjects: astro-ph.HE astro-ph.CO nucl-thCreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
Next-generation gravitational-wave (GW) observatories will provide crucial insights into the nature of neutron star (NS) matter and the cosmological expansion history. We estimate the number of multi-messenger detections from binary neutron stars (BNS) with the Einstein Telescope (ET) and Cosmic Explorer (CE), and project the resulting constraints on the equation of state (EOS), BNS mass distribution, and cosmology via joint hierarchical Bayesian inference. Assuming a local merger rate of 106.6 Gpc$^{-3}$ yr$^{-1}$ and considering two different mass functions, a narrow one centred around 1.4 $M_\odot$ and a wide one ranging between 1.1--2 $M_\odot$, we find that for ET, our mock follow-up algorithm results in at least $\sim40$ and up to $\sim100$ successfully identified electroMAGNETic counterparts per year, depending on the detector layout and mass distribution. In a joint network with CE, the number of multi-messenger detections can range from $\sim 200$ to $\sim500$. Additionally, several more afterglows from GAMMA-RAY BURSTs or KNe could be found with dedicated late-time observations. Based on the identified multi-messenger events, we perform an injection campaign to hierarchically constrain the EOS, mass distribution, and cosmology in a fully Bayesian framework. Focussing on ET alone, we show how in an ideal scenario, GW signals, KNe, and host galaxy redshifts can constrain the canonical NS radius $R_{1.4}$ within $\sim 0.2$ km and the Hubble constant $H_0$ within $\sim 1$ km s$^{-1}$ Mpc$^{-1}$, while recovering the essential features of the mass distribution. By comparing inference results that rely solely on GW data and those that incorporate light curve information, we find that while KN light-curve posteriors have a negligible impact on the EOS constraints, they can benefit the inference of cosmological parameters.
[abstract 59 / 59] (score: 2) - Title: A Four-dimensional Model-agnostic Probe into the Astrophysical Origins of Binary Black Hole SubpopulationsAuthors: Anarya Ray, Vicky Kalogera,Comments:Subjects: astro-ph.HE gr-qcCreated: 2026-07-30; Updated: 2026-07-31; Datestamp: 2026-07-31
There is strong evidence of multiple binary BLACK HOLE~(BBH) subpopulations in the cumulative gravitational wave catalog by the LIGO-Virgo-KAGRA collaboration that likely originate through distinct evolutionary channels. The astrophysical interpretation of this complex underlying population is subject to theoretical uncertainties in treatments of binary stellar evolution, core collapse, and host environments. Due to a lack of robust predictions and the sheer diversity of plausible features, strongly modelled population analyses often lead to prior-driven conclusions. On the other hand, flexible alternatives are often difficult to scale in higher dimensions, which can lead to a loss of critical information on astrophysically meaningful correlations. In this \textit{Letter}, we present the first data-driven reconstruction of the joint four-dimensional distribution of BBH primary masses, mass ratios, effective inspiral and effective precessing spin parameters, which yields novel model-agnostic constraints on the astrophysical origins of BBH subpopulations. We characterize four distinct subpopulations spanning different ranges of BBH masses and report new correlations in these specific mass ranges that are beyond the reach of strongly modeled parametrizations and lower-dimensional data-driven frameworks. Our results unveil novel insights into the abundances of specific subchannels of isolated binary evolution, dynamical assembly, and hierarchical mergers across various mass ranges in the astrophysical BBH population.
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