Current date: 2026-05-15
Setting default datestamp limit: 0
Datestamp limit: 2026-05-15 (0 days ago)
Created/updated limit: 2026-05-08 (7 days ago)
Found keywords_cs.datFound keywords_cis.dat
Suggested sets: physics, physics:astro-ph, physics:gr-qc, physics:physics
Setting default set: physics
OAI-PMH request: http://export.arxiv.org/oai2?verb=ListRecords&from=2026-05-15&until=2026-05-15&set=physics&metadataPrefix=arXiv
Scoring abstracts
Number of records retrieved: 692
Keyword score statistics
score 8 -- 2 abstracts
score 6 -- 1 abstracts
score 5 -- 5 abstracts
score 4 -- 6 abstracts
score 3 -- 6 abstracts
score 2 -- 16 abstracts
in total -- 36 abstracts
Articles that appeared on 2026-05-15
-
[abstract 1 / 36] Wow! (score: 8)
- Title: GeV emission around SS 433 with 17 years FERMI-LAT observationAuthors: Qiwang Sun, Dmitry Khangulyan, Jiren Liu, Siming Liu,Comments: 9 pages, 5 figures submittedSubjects: astro-ph.HECreated: 2026-05-14; Updated: 2026-05-15; Datestamp: 2026-05-15
We present an analysis of 17 years of FERMI-LAT observations of the microQUASAR SS~433. We detect four GeV sources in the region: a newly identified source, PS J1910+0550, located outside W50; the previously reported source J1913+0512; and two features, denoted as the East and West excesses, apparently associated with the X-ray lobes. We focus on the three sources located within W50. We do not confirm the previously reported periodic modulation from J1913+0512, as no significant periodicity is found in the full 17-year dataset. The East and West excesses exhibit distinct morphological and spectral properties, suggesting different physical origins. The East excess shows a hard spectrum with photon index $\sim1.7$, consistent with inverse Compton emission from RELATIVISTIC electrons accelerated together with the particles responsible for the X-ray and TeV emission. In contrast, the West excess has a much softer spectrum with photon index $\sim2.6$ and is spatially offset from the known X-ray and TeV emission regions in the western lobe. The spectral shape and offset position of the West excess make it strikingly similar to J1913+0512. The emission from these two regions can be explained by GeV particles accelerated in SS~433, distributed throughout the source volume, and interacting with localized dense gas targets. Under reasonable assumptions regarding particle transport and energetics, both proton-proton and bremsstrahlung scenarios are viable, although the hadronic scenario is more naturally accommodated. These findings may therefore represent the first observational evidence for the acceleration of cosmic-ray protons in large-scale outflows from Galactic microQUASARs.
[abstract 2 / 36] Wow! (score: 8) - Title: Polarization Signatures from GRMHD Simulations of Black Hole AccretionAuthors: P. Chris Fragile, Maciek Wielgus, Cora Prather,Comments: Invited chapter for the edited book "X-ray Polarimetry: Detection, Observations, Modeling and the Future" (Eds. Honghui Liu and Adam Ingram), Springer Singapore, expected in 2026Subjects: astro-ph.HECreated: 2026-05-14; Updated: 2026-05-15; Datestamp: 2026-05-15
This chapter tells the still-unfolding story of extracting POLARIZATION signatures from general RELATIVISTIC MAGNETohydrodynamics simulations of accretion disks. In some sense, this effort is premature as there are still very few results of this kind. Much more abundant are phenomenological models. Nevertheless, we feel now is the time to rally the community to this cause. Since the focus of this book is on X-ray polarimetry, we focus exclusively on simulations of accretion onto compact objects. Most of the relevant work so far has been on BLACK HOLE accretion disks, though neutron stars are also viable targets for X-ray polarimetry. The focus of our chapter is on how X-ray polarimetry coupled with accretion simulations might help us better understand properties of the disks, coronae, and JETs that are the dominant components of accreting compact sources. We briefly illustrate the promise of this technique by demonstrating how it has already been used in the case of the Event Horizon Telescope (using radio polarimetry). We also speculate about where this field may be heading in the near future.
[abstract 3 / 36] Yes (score: 6) - Title: Search for SYNCHROTRON pair echo emission following KM3-230213AAuthors: Angelina Sherman, Nestor Mirabal, David Guevel, Ke Fang, Kohta Murase, Elizabeth Hays,Comments:Subjects: astro-ph.HECreated: 2026-05-13; Updated: 2026-05-15; Datestamp: 2026-05-15
The KM3NeT Collaboration has recently reported the detection of an extraordinary ultra-high-energy neutrino event with an energy of 220 PeV. Ultrahigh energy neutrinos and gamma-rays are co-produced in ultrahigh energy cosmic-ray interactions. If a UHE neutrino was produced within the large-scale structure around the source where it was accelerated, gamma-ray emission may be expected via the SYNCHROTRON pair echo mechanism. Here, we develop the SYNCHROTRON pair echo model in the specific context of the KM3NeT neutrino. Motivated by the fact that the SYNCHROTRON pair echo signal is expected to peak in the GeV - TeV band, and that the signal may appear as a dim, transient source, we investigate the data collected by the Large Area Telescope (LAT) on-board the \textit{FERMI} Gamma-ray Space Telescope for transient and sub-threshold gamma-ray sources in the vicinity of the KM3NeT neutrino. We find three sub-threshold sources with TS $\gtrsim 16$ within $3.5^{\circ}$ of the neutrino event not included in any existing \textit{FERMI}-LAT catalogs, but note that none of the identified sub-threshold sources seem to be compelling candidates for SYNCHROTRON pair echo emission.
[abstract 4 / 36] Yes (score: 5) - Title: Solving the cooling flow problem with combined JET-wind AGN feedbackAuthors: Aoyun He, Feng Yuan, Suoqing Ji, Minhang Guo, Yuan Li, Haiguang Xu, Ming Sun, Haojie Xia, Yuanyuan Zhao,Comments: 27 pages, 7 figures. Accepted for publication in Science AdvancesSubjects: astro-ph.GACreated: 2026-05-14; Updated: 2026-05-15; Datestamp: 2026-05-15
Active galactic nucleus (AGN) feedback is widely viewed as the most promising solution to the long-standing cooling flow problem in galaxy clusters, yet previous models prescribe JET properties inconsistent with accretion physics. We perform an idealized hydrodynamic simulation of a galaxy cluster with no merger history and a relaxed state, with its other properties similar to the Perseus cluster using the MACER framework, incorporating both JETs and winds whose properties are constrained by general RELATIVISTIC MAGNETohydrodynamic simulations of BLACK HOLE accretion and observations. The combined feedback reproduces key observables, including cold gas mass, STAR FORMATION rate, thermodynamic radial profiles, and BLACK HOLE growth, while JET-only or wind-only models fail. The success arises from turbulence driven by JET-wind shear that enhances kinetic-to-thermal energy conversion, boosting heating efficiency by factors of three and six relative to wind-only and JET-only cases, respectively.
[abstract 5 / 36] Yes (score: 5) - Title: Magnetar-powered long GAMMA-RAY BURSTs and connection to superluminous SUPERNOVAe and fast radio burstsAuthors: Yu-Qi Zhou, Shuang-Xi Yi, Yu-Peng Yang, Yan-Kun Qu, Ning Gai, Yan-Ke Tang, Fa-Yin Wang,Comments: Accepted for publication in ApJL; 28 pages, 5 figures and 2 tablesSubjects: astro-ph.HECreated: 2026-05-14; Updated: 2026-05-15; Datestamp: 2026-05-15
Based on X-ray afterglow observations from the SWIFT satellite, we construct a sample of 169 long GAMMA-RAY BURSTs (LGRBs) exhibiting the canonical MAGNETar plateau signature, i.e., a plateau followed by a $t^{-2}$ decay. We derive the plateau luminosity $L_0$ and break time $t_b$ for each burst by performing Markov Chain Monte Carlo (MCMC) fits to the light curves, and estimate pseudo-redshifts for bursts lacking known redshifts via the Amati relation. The fundamental MAGNETar parameters are subsequently inferred: the surface polar MAGNETic field strength $B_p \in [0.39,\ 23.08] \times 10^{15}$G and the initial spin period $P_0 \in [0.95,\ 13.79]$ms. Statistical analysis shows that both the known-redshift subsample and the full sample follow the Dainotti correlation between $L_0$ and $t_b$ with a slope close to $-1$, supporting a constant energy injection rate during the plateau phase. Furthermore, we identify a significant correlation between $B_p$ and $P_0$: $B_p \propto P_0^{0.83 \pm 0.09}$ for the full sample and $B_p \propto P_0^{0.80 \pm 0.16}$ for the known-redshift subsample, with both slopes consistent within uncertainties. Compared to MAGNETars powering superluminous SUPERNOVAe (SLSNe), GRB MAGNETars possess systematically stronger MAGNETic fields (by approximately one order of magnitude), suggesting fundamental differences in their progenitor systems or collapse conditions; while their MAGNETic field strengths show no significant difference from those powering fast radio bursts (FRBs), suggesting a possible common evolutionary pathway. This study provides a physics-motivated, model-consistent sample of MAGNETar-candidate GRBs, offering a robust foundation for statistical investigations within the MAGNETar central engine model and placing new observational constraints on the birth properties of these extreme compact objects.
[abstract 6 / 36] Yes (score: 5) - Title: The Homogeneous MeerKAT and SWIFT/XRT X-ray Binary Radio:X-ray PlaneAuthors: Justine Crook-Mansour, Rob Fender, Andrew Hughes, Sara Motta, Patrick A. Woudt, Arash Bahramian, Melania Del Santo, Zuobin Zhang, Thomas D. Russell, Jakob van den Eijnden, Joe Bright, David Williams-Baldwin, Francesco Carotenuto, Stéphane Corbel, Fraser J. Cowie, Alex Andersson, Noa Grollimund, James Matthews, Kelebogile Gasealahwe, Itumeleng Monaleng, Lauren Rhodes, Payaswini Saikia, Katie Savard, Evangelia Tremou, Xian Zhang,Comments: Accepted for publication in MNRAS. The website accompanying this paper, including the full data release, can be found at: https://thunderkat.physics.ox.ac.uk/Subjects: astro-ph.HECreated: 2026-05-13; Updated: 2026-05-15; Datestamp: 2026-05-15
During the hard and quiescent spectral states in X-ray binaries, a non-linear correlation is observed between radio and X-ray luminosities, providing a valuable tool to probe the connection between accretion and JET production. This relation was originally thought to define a single 'standard' correlation spanning several orders of magnitude in X-ray luminosity, and was extended to ACTIVE GALACTIC NUCLEi by including a mass term. However, subsequent studies revealed a more complex picture, with some sources deviating from the standard correlation and instead populating distinct tracks. To date, all large studies of the radio:X-ray plane have combined data from multiple telescopes, introducing uncertainties due to differing instrument systematics and flux conversions between observing frequencies, thereby complicating comparisons and limiting constraints. ThunderKAT was a five-year programme on the MeerKAT radio telescope that monitored X-ray binaries in outburst, and ran alongside SWIFTKAT which provided quasi-simultaneous SWIFT/XRT X-ray coverage. We present the full set of light curves from these programmes, comprising 948 radio and 1029 X-ray data points. An important finding is the frequent detection of unresolved radio emission during the soft state, likely dominated by previously launched JET ejecta. Using these data, we construct the largest, observationally homogeneous X-ray binary radio:X-ray plane to date. We relate these results to the physical mechanisms proposed to drive inter-source diversity, and outline directions for future observational and theoretical work. This paper is accompanied by a public data release of the ThunderKAT and SWIFTKAT measurements and a compiled radio:X-ray plane, available through an interactive website.
[abstract 7 / 36] Yes (score: 5) - Title: The Role of Magnetic Reconnection in Energizing Protons and Heavier Ions at the Heliospheric Current SheetAuthors: Giulia Murtas, Xiaocan Li, Fan Guo, Giuseppe Arrò, Jeongbhin Seo, Colby Haggerty,Comments: 14 pages, 3 figures. Accepted in ApJ as of May 13, 2026Subjects: astro-ph.SR physics.plasm-phCreated: 2026-05-14; Updated: 2026-05-15; Datestamp: 2026-05-15
During near-Sun crossings of the heliospheric current sheet (HCS), Parker Solar Probe (PSP) observed populations of high-energy protons and heavier ions indicating possible energization by MAGNETic RECONNECTion up to 10s -- 100s keV nucleon$^{-1}$. Here we study ion acceleration by MAGNETic RECONNECTion at the HCS. To estimate ion energization, we solve the Parker transport equation coupled to a large-scale 2D MHD RECONNECTion simulation. We find that multiple ion species develop power-law distributions with both spectral index and high-energy cutoff $E_{\text{max}}$ consistent with in-situ data. By accounting for the injection physics determined by kinetic simulations, we confirm that the charge-to-mass ratio scales as $E_{\text{max}} \propto (Q/M)^α$ with $α\sim 0.8-1.1$, approximately consistent with PSP measurements in the broader range $α\sim 0.6-1.7$. In the limit where ions are injected at the same energy per nucleon, $α$ can be as low as $\sim 0.3$. These findings further support the role of MAGNETic RECONNECTion in producing high-energy heavy ions at the HCS.
[abstract 8 / 36] Yes (score: 5) - Title: Axion MAGNETohydrodynamics and RECONNECTion-driven axion burstsAuthors: H. Terças,Comments: Axion magnetohydrodynamics, magnetars, axion bursts, sensitivity projectionSubjects: physics.plasm-ph astro-ph.HECreated: 2026-05-14; Updated: 2026-05-15; Datestamp: 2026-05-15
We formulate axion MAGNETohydrodynamics beyond the ideal limit, retaining axion inertia and the essential physics of non-ideal plasmas from first principles. In this framework, regions where MAGNETic flux freezing breaks down acquire a new physical role: whenever $\mathbf{E} \cdot\ \mathbf{B} \neq 0$, MAGNETic dissipation acts as a localized source of axion radiation. We show that MAGNETic RECONNECTion naturally excites mixed Alfvén-axion modes, enabling coherent energy exchange between MAGNETic fields and axions in MAGNETically dominated environments. In neutron stars and MAGNETars, this mechanism leads generically to transient axion bursts powered by RECONNECTion--driven Alfvénic dissipation. We connect this production process to observational prospects and derive a characteristic sensitivity to the axion--photon coupling, complementary to searches based on static MAGNETic fields.
[abstract 9 / 36] Yes (score: 4) - Title: Primordial BLACK HOLEs and MAGNETic fields in conformal neutrino mass modelsAuthors: Shyam Balaji, João Gonçalves, Danny Marfatia, António P. Morais, Roman Pasechnik,Comments: 25 pages, 10 figures, 3 tables. Corrected bug in magnetic field code. Corresponding parameter space changedSubjects: hep-ph astro-ph.CO hep-exCreated: 2026-05-14; Updated: 2026-05-15; Datestamp: 2026-05-15
Sufficiently strong and long-lasting first-order phase transitions can produce primordial BLACK HOLEs (PBHs) that contribute substantially to the DARK MATTER abundance of the Universe, and can produce large-scale primordial MAGNETic fields. We study these mechanisms in a generic class of conformal $\mathrm{U(1)}^\prime$ models that also explain active neutrino oscillation data via the type-I seesaw mechanism. We find that phase transitions that occur at seesaw scales between $10^4$ GeV and $10^{11}$ GeV produce gravitational wave signals (from the dynamics of the phase transition and from the decay of cosmic string loops) at LISA/ET that can be correlated with microlensing signals of PBHs at the Roman Space Telescope, while scales near $10^{11}$ GeV can be correlated with Hawking evaporation signals at future gamma-ray telescopes. LISA can probe the entire range of PBH masses between $1\times 10^{-16}M_\odot$ and $8\times 10^{-11}M_\odot$ if PBHs fully account for the DARK MATTER abundance. For Z' masses between 5 TeV and 100 TeV, and $\sim 3$ TeV right-handed neutrinos, helical MAGNETic fields can be produced with magnitudes $\sim 10^{-16}$-$10^{-13}$ G and coherence lengths $\sim 10^{-4}$-$10^{-2}$ Mpc, above current BLAZAR lower bounds.
[abstract 10 / 36] Yes (score: 4) - Title: Impact of Resonant Compton Scattering on Magnetar X-Ray Polarization with QED Vacuum ResonanceAuthors: Tu Guo, Dong Lai,Comments: 13pages, 7 figures, submitted to ApJSubjects: astro-ph.HECreated: 2026-05-14; Updated: 2026-05-15; Datestamp: 2026-05-15
Recent obeservations have revealed significant soft X-ray POLARIZATIONs from several quiescent MAGNETars, including the intriguing $90^°$ POLARIZATION angle (PA) swing as a function of photon energy for some sources. We present a general semi-analytical framework for calculating energy-dependent soft X-ray POLARIZATION signatures from MAGNETars, consistently incorporating both QED vacuum resonance in the atmosphere and resonant Compton scattering (RCS) in the MAGNETosphere. Starting from the polarized radiative transfer equation for RCS and treating vacuum-resonance-induced mode conversion as an input, we employ a first-order approximation in RCS optical depth to evaluate the effect of different MAGNETospheric plasma density (which depends on MAGNETic twist), drift velocity and temperature, and viewing geometry on the observed radiation. Our analysis reveals that MAGNETic twist and plasma drift velocity are the critical parameters controlling the impact of RCS on both the absolute POLARIZATION degree and its variation across the soft X-ray spectrum. We find that sufficiently strong RCS can wash out the PA swing caused by vacuum resonance. Furthermore, in addition to the QED vacuum resonance effect, significant RELATIVISTIC signatures arising from plasma drift velocity ($β_0 \gtrsim 0.5$) may introduce an extra $90^\circ$ PA swing in the spectrum. Our calculation framework, based on single-scattering approximation, bypasses the need for complex, multi-dimensional Monte Carlo simulations, providing an analytical pathway for modeling full-surface emission and rotational-phase-resolved radiation from MAGNETic neutron stars, in support of current and future X-ray POLARIZATION missions.
[abstract 11 / 36] Yes (score: 4) - Title: Particle Acceleration, Coronal Neutrino Production, and the Diffuse Extragalactic Neutrino Background from Supermassive Black HolesAuthors: Rostom Mbarek,Comments: Submitted to PRDSubjects: astro-ph.HECreated: 2026-05-13; Updated: 2026-05-15; Datestamp: 2026-05-15
We present a generalized neutrino luminosity function for protons accelerated in the X-ray coronae of supermassive BLACK HOLEs in Seyfert-like galaxies. A major uncertainty in assessing the diffuse neutrino contribution of these systems is the underlying particle acceleration physics. We address this using a theoretical acceleration framework informed by plasma kinetic simulations, enabling a more self-consistent connection between coronal conditions, nonthermal proton populations, and neutrino production. In this picture, the neutrino luminosity depends primarily on the coronal X-ray luminosity and MAGNETization, and only weakly on BLACK HOLE mass. We find that the cosmologically integrated emission from these systems can account for the sub-PeV diffuse extragalactic neutrino flux observed by IceCube. We further argue that, although diffusive confinement is relatively well understood, the MAGNETic field topology near BLACK HOLEs naturally allows for COSMIC RAY-driven outflows near the X-ray corona. Such outflows may accompany additional efficient neutrino production at the PeV-level and influence the dynamics of the innermost galactic environment.
[abstract 12 / 36] Yes (score: 4) - Title: A new sample of Little Red Dots at $z<0.45$ in DESI DR1: Broad Balmer lines, low ionization spectrum and no variabilityAuthors: Kevin Park, Alberto Torralba, Jorryt Matthee, Sara Mascia, Zoltán Haiman, Rohan P. Naidu, Anna de Graaff,Comments: 21 pages, 17 figures, submitted to Astronomy & AstrophysicsSubjects: astro-ph.GACreated: 2026-05-14; Updated: 2026-05-15; Datestamp: 2026-05-15
JWST has unveiled an abundant population of compact broad-line emitters largely at $z\gtrsim4$, the Little Red Dots (LRDs), which might represent a previously unprobed supermassive BLACK HOLE evolution channel predominant at high redshift. However, the LRDs have remained mostly elusive at lower redshift ($z\lesssim2$) where detailed studies are possible from ground-based observatories. We searched for low-redshift LRDs in the Dark Energy Spectroscopic Instrument (DESI) survey. Our search is primarily based on emission line properties, as opposed to earlier approaches that searched for compact sources with specific photometric spectral energy distributions. We report the discovery of eight LRDs at $z=0.2-0.45$, which show spectral features akin to the high-redshift LRDs in the rest-frame optical. The sources are characterized by broad Balmer lines, steep Balmer decrements, compact morphologies, Balmer absorption features and/or strong He I emission, but weak or absent He II, [Ne V] or other high excitation lines typical of Type I AGN. For 7 out of 8 sources, we retrieve dense-cadence light curves from time-domain surveys and for most sources we find weak to no intrinsic variability ($0.0-0.1$ mag) over $4-17$ years in the rest-frame. We also highlight the identification of a QUASAR with similar Balmer line profiles as LRDs, but shows differences in Balmer decrement, significant variability, and high-ionisation lines. Given the effective volume $4.9{\rm Gpc^3}$ covered by DESI DR1 at $z<0.45$, our sample corresponds to a number density of $1.6\times10^{-9}$Mpc$^{-3}$, indicating a number density $\sim$10,000 times lower than in the first billion years of cosmic time. We find a dearth of luminous and red LRDs at $z<1$ compared to higher-redshift, which could suggest lower gas feeding rates of LRD activity due to higher metallicities at later cosmic epochs.
[abstract 13 / 36] Yes (score: 4) - Title: Self-confinement of ultra-high-energy nuclei in cosmic filaments: implications for the UHECR spectrum and compositionAuthors: Alessandro Cermenati, Roberto Aloisio, Carmelo Evoli,Comments: 13 pages (11 main text + 2 appendix), 7 figuresSubjects: astro-ph.HECreated: 2026-05-14; Updated: 2026-05-15; Datestamp: 2026-05-15
The spectrum and composition of ultra-high-energy COSMIC RAYs (UHECRs) suggest that the population dominating above the ankle releases particles with an unusual hard spectrum at low rigidity, below the EV scale. In self-confinement scenarios, such an apparent hardening arises from transport: escaping UHECRs generate MAGNETic turbulence that delays their own release from the MAGNETized environments surrounding their sources. We extend the self-confinement scenario based on the non-resonant streaming instability to a mixed nuclear composition. We describe the confinement region with an effective leaky-box model including escape, photodisintegration, and secondary production. We then compare the resulting spectrum and composition with Auger measurements and compute the associated cosmogenic neutrino and gamma-ray emission. We find that self-generated turbulence can suppress the escaping flux below the EV scale for source luminosities and MAGNETic-field coherence lengths compatible with UHECR sources hosted in galaxy clusters and propagating through cosmic filaments. During confinement, heavy nuclei efficiently photodisintegrate, producing secondary protons that contribute below the ankle and help account for the observed composition. The predicted neutrino flux remains compatible with current limits, while the diffuse gamma-ray background provides a potentially strong constraint on the most extreme configurations.
[abstract 14 / 36] Yes (score: 4) - Title: Eclipses of Nearby Radio-Loud Galactic Nuclei by Stars in Nuclear Star ClustersAuthors: Michal Zajaček,Comments: 13 pages, 9 figures, submitted to the AAS journals, comments welcomeSubjects: astro-ph.GA astro-ph.HECreated: 2026-05-14; Updated: 2026-05-15; Datestamp: 2026-05-15
It is of a general interest to look for signatures of stellar bodies orbiting supermassive BLACK HOLEs (SMBHs) in galactic nuclei other than the Galactic center. Previously stellar transits were analyzed in UV, optical, and X-ray domains as well as potential microlensing signatures due to more compact bodies orbiting SMBH accretion disks. Here we complement previous studies by considering nearby ($z=0.001$) radio-loud ACTIVE GALACTIC NUCLEi targeted by different facilities in the millimeter domain. At these wavelengths the radio core is sufficiently small so that it can be occulted by large evolved stars in dense nuclear star clusters. We find that in the millimeter domain evolved stars with stellar radii of $\gtrsim 500\,R_{\odot}$ can cause eclipses with the relative depth of $\sim 10\%$. Typical recurrence timescales are at least 10 years and the eclipse durations are $\sim 10$ days. Towards lower frequencies the eclipse temporal profiles become shallower and broader while towards higher frequencies they are deeper and narrower. Although expected to be rare due to selection effects and evolved stars being prone to tidal disruption, recurrent eclipses of mm radio cores can be applied to infer SMBH masses and constrain the composition of the Nuclear Star Cluster of the host nucleus.
[abstract 15 / 36] (score: 3) - Title: Inferring neutron star properties through gravitational waves from r-modes and their RELATIVISTIC counterpartsAuthors: Dhanvarsh Annamalai, Rana Nandi,Comments: Version accepted by MNRASSubjects: astro-ph.HECreated: 2026-05-13; Updated: 2026-05-15; Datestamp: 2026-05-15
We present two frameworks to infer some of the properties of neutron stars from their electroMAGNETic radiation and the emission of continuous gravitational waves due to r-modes and their RELATIVISTIC counterparts, termed axial-led hybrid modes. In the first framework, assuming a distance measurement via electroMAGNETic observations, we infer three neutron star properties: the moment of inertia, a parameter related to the mode's saturation amplitude, and the component of MAGNETic dipole moment perpendicular to the rotation axis. Unlike signals from mountains, axial-led hybrid oscillations provide additional information through a parameter ($κ$) that satisfies a universal relation with the star's compactness. In the second framework, we utilize this and the relation between the moment of inertia and compactness, in addition to assuming an equation of state and utilizing pulsar frequency measurements, to directly measure the neutron star's distance, along with the parameters above. We employ a Fisher information matrix-based approach for quantitative error estimation in both frameworks. We find that the error in the distance measurement dominates the errors in the first framework for any reasonable observation time. In contrast, the second framework enables accurate parameter inference because it does not depend on electroMAGNETic distance measurements. Although its applicability is limited to a restricted parameter space and relies on assumptions about the equation of state, the simulated errors in this framework are found to be independent of the equation of state. Finally, we discuss the potential utility and critical limitations of our analyses, and propose possible solutions and directions for future research.
[abstract 16 / 36] (score: 3) - Title: Changing-Look Active Galactic Nuclei in SDSS-V: Host-Galaxy Properties and Black-Hole Scaling RelationsAuthors: Grisha Zeltyn, Benny Trakhtenbrot, Michael Eracleous, Scott F. Anderson, Claudio Ricci, Andrea Merloni, Jessie Runnoe, Mirko Krumpe, James Aird, Roberto J. Assef, Catarina Aydar, Franz E. Bauer, W. N. Brandt, Joel R. Brownstein, Johannes Buchner, Kaushik Chatterjee, Laura Duffy, Lorena Hernández-García, Héctor Hernández-Toledo, Anton M. Koekemoer, Sean Morrison, Castalia Alenka Negrete Peñaloza, Mara Salvato, Donald P. Schneider, Yue Shen, Marzena Śniegowska,Comments:Subjects: astro-ph.GACreated: 2026-05-14; Updated: 2026-05-15; Datestamp: 2026-05-15
Changing-look ACTIVE GALACTIC NUCLEi (CL-AGNs) exhibit dramatic spectral variability on unexpectedly short timescales, challenging standard accretion flow models. Despite growing samples, the physical drivers of this extreme variability, and the potential link to host-galaxy properties, remain unknown. Regardless of the underlying mechanism, the transition between AGN-dominated and host-dominated spectra offers a unique opportunity to study relations between AGNs and their hosts within the same objects. We present intermediate-resolution spectroscopy of 23 CL-AGNs identified by the Sloan Digital Sky Survey V (SDSS-V), obtained with the Very Large Telescope/X-shooter and Gemini-N/GMOS. An analysis of the Mgii emission line observed in the spectra demonstrates that the majority of these sources cannot be driven by variable obscuration. Our CL-AGNs roughly follow the M_BH-sigma_* and M_BH-M_* relations of inactive galaxies, with a median BLACK HOLE-to-stellar mass ratio of 0.38%. We find no evidence that the stellar population properties of our CL-AGNs, including stellar mass, age, young stellar fraction, and star-formation rate, differ from those of type 2 AGNs in SDSS. These results suggest that CL-AGNs reside in typical AGN host galaxies and that their extreme variability is likely unrelated to host-galaxy environment, supporting the idea that CL-AGNs are not a distinct population, but rather represent a phase of normal AGN activity. This result, in turn, implies that CL-AGNs can serve as useful probes of the AGN-host connection, providing access to both AGN-dominated and host-dominated spectra of the same systems.
[abstract 17 / 36] (score: 3) - Title: Matter- and MAGNETically-driven flavor conversion of neutrinos in MAGNETorotational collapsesAuthors: Marco Manno, Pablo Martínez-Miravé, Irene Tamborra,Comments: 18 pages, 8 figures, 2 tables. Accepted for publication in Classical and Quantum Gravity as an invited article for the Focus Issue "Core-Collapse Supernova Gravitational-Wave Theory and Detection: Past, Present and Future"Subjects: astro-ph.HE hep-phCreated: 2026-05-14; Updated: 2026-05-15; Datestamp: 2026-05-15
The MAGNETorotational collapse of massive stars copiously emits neutrinos of all flavors, with a prominent hierarchy between the non-electron and electron flavor average energies. Relying on a three-dimensional neutrino-MAGNETohydrodynamic simulation of a $13 M_\odot$ progenitor, we investigate flavor conversion in matter. We find that, in addition to resonant flavor conversion of neutrinos and antineutrinos in matter, (anti)neutrinos experience chirality-flipping interactions due to their non-zero MAGNETic moment ($μ\lesssim 10^{-12} μ_B$) and large MAGNETic field in the source ($B \simeq 10^{15}$ G). For Majorana neutrinos, this leads to resonant flavor-changing neutrino-antineutrino mixing. The event rate expected from a Galactic collapse at current and next-generation neutrino telescopes, such as IceCube and Hyper-Kamiokande, strongly depends on the orientation of the MAGNETorotational collapse with respect to the observer direction and flavor conversion scenario. The event rate is expected to be larger for an observer facing head on the JET launched during the stellar collapse and peaks around $400$-$600$ ms after bounce. Our work highlights that understanding the rich phenomenology of flavor conversion in MAGNETorotational collapses is essential to take full advantage of the joint detection of neutrinos and gravitational waves from these sources.
[abstract 18 / 36] (score: 3) - Title: Spin Demographics of Active Supermassive Black Holes: Updated Estimates from X-ray reflection and Future opportunitiesAuthors: Julia M. Sisk-Reynes, Christopher S. Reynolds, James H. Matthews, Dominic J. Walton, Joanna M. Piotrowska, James F. Steiner, Javier A. Garcia, Angelo Ricarte,Comments: 19 pages, 4 figures, 2 tables. Accepted for publication in Galaxies on 8 May 2026 as an invited review for the "X-Ray Probes of Black Hole Spin and Accretion Physics" Special Issue following the "Taking Spin Measurements for a Spin" workshop at Wake Forest University in September, 2025. Comments welcome!Subjects: astro-ph.HECreated: 2026-05-13; Updated: 2026-05-15; Datestamp: 2026-05-15
Understanding the growth of supermassive BLACK HOLEs (SMBHs) requires observational constraints on how their angular momentum (or spin) varies with mass, since the relative importance of coherent accretion, chaotic accretion, and mergers will be reflected in SMBH spin populations. Here we present an updated compilation of reflection-based SMBH spin measurements from the literature and assemble a set of ancillary quantities of interest for each SMBH (including redshift, Eddington ratio, and X-ray luminosity). No obvious apparent correlation between the Eddington-scaled accretion rate and the BLACK HOLE spin is seen, noting that formal statistical tests are beyond the scope of this review. We discuss the limitations of using this heterogeneous mass--spin sample to test predictions of SMBH growth from semi-analytic models and cosmological simulations, emphasizing the need for a more uniform sample. We then highlight the encouraging prospects enabled by the next-generation NewAthena X-ray flagship observatory. Finally, we summarize how hierarchical Bayesian population inference applied to observed SMBH mass--spin populations will constitute a powerful framework for confirming tentative mass--spin trends in future samples.
[abstract 19 / 36] (score: 3) - Title: Direct Evidence of Non-Ideal Dissipative Dynamics in Solar Wind Magnetic SwitchbacksAuthors: Forrest Mozer, Oleksiy Agapitov, Kyung-Eun Choi, Richard Sydora,Comments: 7 pages, 6 figuresSubjects: astro-ph.SRCreated: 2026-05-13; Updated: 2026-05-15; Datestamp: 2026-05-15
Magnetic switchbacks, large-amplitude, localized Alfvenic like rotations of the solar wind MAGNETic field, have been the subject of intensive investigation, with approximately 200 refereed papers published in the last decade. Yet, fundamental controversies persist regarding whether switchbacks can be described with Ideal MHD (MAGNETohydrodynamic) physics or Hall-MHD physics and whether their origin is at the solar surface or in the solar wind. To settle these controversies, we present Parker Solar Probe electric field measurements between 13 and 40 solar radii, which show that switchbacks have non-zero electric fields in the plasma frame, a finding that definitively settles the physics controversy by proving that switchbacks are Hall-MHD, not Ideal MHD, structures. Along with these electric fields, there are enhanced Poynting vectors having three components with similar magnitudes that exist only inside the switchbacks. These facts contradict the view of switchbacks as simple outward-propagating pulses. Together, they resolve one controversy by showing that switchbacks in the young solar wind are a non-MHD process. They contribute to the second (source) controversy by identifying switchbacks as sites of active, in-situ, evolution. These findings provide a new framework for understanding energy transport and dissipation in astrophysical plasmas.
[abstract 20 / 36] (score: 3) - Title: Significant or Not? The Impact of Randomisation During Data Reduction on Confirming a New Pulsating Ultraluminous X-ray Source Candidate in Centaurus AAuthors: Amy H. Knight, Timothy P. Roberts, Callum Potter, Alistair T. Pagan, Dominic J. Walton,Comments: 23 Pages, 13 Figures. Accepted for Publication in MNRAS. The supplementary material will be hosted on the MNRAS websiteSubjects: astro-ph.HECreated: 2026-05-14; Updated: 2026-05-15; Datestamp: 2026-05-15
We report the discovery of a new candidate pulsating ultraluminous X-ray source (PULX) in NGC 5128 (Centaurus A). The candidate, 4XMM J132542.2-425943, is a transient source, identifiable as a clear X-ray point source for $\sim 8$ months in 2014, during its only major recorded outburst. The source flux exceeded $10^{-12}$ erg cm$^{-2}$ s$^{-1}$ at the peak of the outburst. The long-term light curve of 4XMM J132542.2-425943 shows two further, less luminous detections in 2017 and 2024, but was otherwise in quiescence. This behaviour is similar to the class of pulsating transients with outbursts that reach the ultraluminous regime, which includes the well-studied Galactic PULX, SWIFT J0243.6+6124. However, 4XMM J132542.2-425943 displays a soft X-ray spectrum, making this source distinct from the existing population of PULXs, which typically show hard spectra below $10$ keV. We searched the 2014 XMM-Newton observations for X-ray pulsations, revealing coherent, sinusoidal X-ray pulsations at a frequency of $1.27$ Hz in one XMM-Newton observation (ObsID 0724060801), at a marginal significance. For this signal we measure a pulsed fraction, PF$\approx~15 - 17~\%$ and $\dot{f}~\sim~4~\times~10^{-9}$ Hz s$^{-1}$. However, we find that the intrinsic randomisation employed by XMM-Newton's Science Analysis Software, XMM-SAS, during the data reduction procedure introduces considerable uncertainty in the strength of our marginal pulsations, which varies significantly between consecutive data reduction iterations. We explore the impact of this randomisation and demonstrate that it can generate widespread false positives and false negatives, which, in the context of PULX searches, may cause viable candidates to be unnecessarily discarded or vice versa.
[abstract 21 / 36] (score: 2) - Title: A Robust and Efficient F-statistic-based Framework for Consistent Bayesian Inference of Compact Binary CoalescencesAuthors: Hai-Tian Wang,Comments: 23 pages, 10 figures, accepted by PRDSubjects: gr-qc astro-ph.HECreated: 2026-05-14; Updated: 2026-05-15; Datestamp: 2026-05-15
We present a comprehensive investigation of the F-statistic method for parameter estimation of gravitational wave (GW) signals from compact binary coalescences. By analytically maximizing the likelihood over the luminosity distance and POLARIZATION angle, this approach reduces the dimensionality of the parameter space to enhance computational efficiency. We also introduce a novel formulation for calculating the Bayesian evidence for the F-statistic, enabling a quantitative assessment of its performance against standard full frequency-domain (FFD) Bayesian inference. Applying these two methods to analyze several representative GW events (GW190412, GW190814, and GW170817), we find that the F-statistic consistently yields results in good agreement with the FFD approach, while offering a significant reduction in computational cost. We demonstrate that including calibration uncertainty generally improves the agreement between the two methods. Furthermore, under the assumption of physical priors, the F-statistic-based analyses consistently yield higher Bayesian evidence than the corresponding FFD analyses. While the F-statistic produces slightly broader constraints on some parameters, we argue this represents a more honest uncertainty quantification, particularly in high-dimensional parameter spaces with complex posterior structures. These results highlight the significant advantages of the F-statistic method for GW data analysis, positioning it as a powerful tool for the era of high-rate detections with future observatories.
[abstract 22 / 36] (score: 2) - Title: The mechanism for creating "dynamical gravastar" BLACK HOLE mimickers also explains formation of "little red dots"Authors: Stephen L. Adler,Comments: Latex, 9 pages, 2 figuresSubjects: gr-qcCreated: 2026-05-14; Updated: 2026-05-15; Datestamp: 2026-05-15
We argue that a high pressure phase transition of RELATIVISTIC matter to a state with negative energy density, which leads to the formation of horizonless, globally unitary BLACK HOLE mimickers, also gives rise to the appearance of ``little red dots''. The energy source for the dots is the release of latent energy from the phase transition, and their excess redness is a result of this release taking place in a central region of exponentially small positive $g_{00}$, and hence very high gravitational redshift.
[abstract 23 / 36] (score: 2) - Title: Constraining FRB Microstructure with Polarised Shot NoiseAuthors: J. C. F. Balzan, A. Bera, C. W. James, B. Meyers,Comments: 16 pages, 7 figures, 1 table. Submitted to PASASubjects: astro-ph.HECreated: 2026-05-14; Updated: 2026-05-15; Datestamp: 2026-05-15
We present FIRES, a polarised shot-noise (PSN) framework that models fast radio burst (FRB) dynamic spectra as the incoherent superposition of Gaussian microshots with varying polarisation angles (PAs). Applied to the CRAFT bursts FRB 20191001A and FRB 20240318A, FIRES can reproduce key spectro-polarimetric behaviours seen in these data: scattering suppresses PA variability on the trailing edge, while the leading edge preferentially retains intrinsic structure when sufficient signal-to-noise is present. We quantify this behaviour using the PA variance ratio $\mathcal{R}_ψ$ and explore the joint plane of measured linear polarisation fraction $Π_L$ versus PA variance to identify allowed regions of microshot number $N$, intrinsic PA dispersion $σ_ψ$, and intrinsic linear fraction $Π_{L,0}$ at fixed signal-to-noise. This restricts these combinations permitted within the adopted shot-noise framework. For FRB 20191001A, the data are consistent with an extended parameter space, reflecting degeneracies between intrinsic PA structure, microshot superposition, scattering, finite sampling, noise, and the assumed microshot-property distributions. FRB~20240318A occupies a more restricted region, favouring fewer microshots and larger intrinsic PA dispersion. By combining an emission-mechanism-independent forward-modeling framework with minimal assumptions and observational constraints, FIRES facilitates qualitative and quantitative exploration of how microshot superposition, scattering, finite sampling, and noise can shape observed FRB polarimetry under the PSN model.
[abstract 24 / 36] (score: 2) - Title: Population Properties of Binary Black Holes with EccentricityAuthors: Muhammad Zeeshan, Richard O'Shaughnessy, Natalie Malagon,Comments: Updated results based on revised datasetSubjects: astro-ph.HECreated: 2026-05-14; Updated: 2026-05-15; Datestamp: 2026-05-15
The development of eccentric waveform models enables us to explore the growing catalog of gravitational-wave events with measurable eccentricity. This opens new opportunities to gain insight into the formation channels and evolutionary pathways of compact binary systems using eccentricity. However, most recent population analyses have been limited to quasi-circular binaries, primarily due to constraints in waveform modeling and sensitivity estimates. We are now entering an era where both of these limitations are being addressed, allowing for a more comprehensive investigation of eccentric binary populations. In this work, we perform a very first population analysis that simultaneously fits the mass, spin, redshift, and eccentricity distribution. Specifically, we use source-parameter estimation on 153 binary BLACK HOLEs in GWTC-4 catalog provided by the Rapid Iterative FiTting (RIFT) framework using the SEOBNRv5EHM waveform model. We extend the default O4a population model to include orbital eccentricity. We find that inferred population properties are broadly consistent with conclusions obtained in previous analyses assuming quasi-circular binaries. To assess sensitivity of our results to the most eccentric sources, we repeat our analysis excluding GW200129_065458. Consistent with our conclusions about each event and using Nonoverlapping Mixture eccentricity model, we bound the branching ratio for eccentric events to be below $0.051890$ and $0.022011$ at $90\%$ confidence with and without GW200129_065458 respectively. Using four different parametric population models for eccentricity, we argue that the rate of eccentric events is weakly constrained by observations and highly model-dependent.
[abstract 25 / 36] (score: 2) - Title: A XRISM view of the iron line complex in NGC 1068: Rethinking the prototypical Compton-thick AGNAuthors: S. Bianchi, B. Vander Meulen, E. Bertola, V. Braito, A. Comastri, P. Condò, M. Dadina, R. Della Ceca, A. De Rosa, V. E. Gianolli, M. Guainazzi, K. Iwasawa, E. Kammoun, M. Laurenti, A. Luminari, A. Marinucci, G. Matt, G. Matzeu, R. Middei, G. Miniutti, E. Nardini, F. Nicastro, F. Panessa, P. -O. Petrucci, E. Piconcelli, C. Pinto, G. Ponti, R. Serafinelli, P. Severgnini, D. Tagliacozzo, F. Tombesi, A. Tortosa, F. Ursini, C. Vignali, L. Zappacosta,Comments: Accepted for publication in A&A. Replaced with final versionSubjects: astro-ph.HE astro-ph.GACreated: 2026-05-14; Updated: 2026-05-15; Datestamp: 2026-05-15
We analyze a XRISM/Resolve observation of NGC1068, focusing on the Fe K$α$ and Fe K$β$ fluorescent lines and on the Fe XXV and Fe XXVI emission complexes. Line centroid energies, intrinsic widths, flux ratios, and constraints on the Compton shoulder are derived through local spectral fitting, and compared with atomic calculations and theoretical predictions. The centroid energies of the Fe K$α$ and Fe K$β$ lines tightly constrain the emitting material to be neutral or near-neutral. The observed Fe K$β$/K$α$ ratio, together with the stringent upper limit on the Compton shoulder ($\lesssim$8--11% of the core flux), disfavour reflection dominated by a homogeneous, classical Compton-thick medium, indicating that most of the neutral Fe K$α$ emission arises in optically thin or moderately Compton-thick gas. The Fe XXV and Fe XXVI emission lines exhibit remarkably large velocity widths, of several thousand km~s$^{-1}$. These broad profiles closely resemble the integrated optical and infrared [O III] and [O IV] lines associated with the large-scale biconical outflow, and are naturally interpreted as the X-ray signature of a more highly ionized, faster, and more spatially confined phase of the same outflow. The iron-K emission of NGC1068 reveals a stratified circumnuclear environment in which neutral and highly ionized components arise in physically distinct regions. The neutral Fe K fluorescence originates predominantly in optically thin or mildly Compton-thick material, despite the persistently Compton-thick line-of-sight obscuration, indicating a geometrically complex cold reprocessor. The highly ionized iron emission lines trace a fast component consistent with a warm bipolar outflow on parsec scales, whose large velocities and inferred energetics suggest that it may represent an efficient channel for feedback in a heavily obscured Seyfert galaxy.
[abstract 26 / 36] (score: 2) - Title: Ellipsoidal modulation and multi-wavelength activity in the pre-cataclysmic binary RX J1553.0+4457Authors: S. -Y. Wu, M. Gritsevich, Q. -H. Lao, A. J. Castro-Tirado, Y. -D. Hu, I. Perez-Garcia, R. Sanchez-Ramirez, N. Castro-Segura, E. J. Fernandez-Garcia, M. D. Caballero-Garcia, S. Guziy, I. Olivares, J. D. Sakowska, G. Garcia-Segura, D. Hiriart, W. H. Lee, P. J. Meintjes, H. J. van Heerden, A. Martin-Carrillo, L. Hanlon, A. Maury, L. Hernandez-Garcia, I. M. Carrasco-Garcia, S. Castillo-Carrion, A. Castellon, S. B. Pandey, C. J. Perez del Pulgar, A. J. Reina, Y. -F. Fan, C. -J. Wang, Y. -X. Xin, D. -R. Xiong, X. -H. Zhao, J. Mao, B. -L. Lun, K. Ye, C. -Z. Cui, A. F. Valeev, B. -B. Zhang, T. -R. Sun, Z. Li,Comments: 16 pages, 10 figures, 6 tables. Updated title and author list; minor textual revisionsSubjects: astro-ph.SR astro-ph.HECreated: 2026-05-14; Updated: 2026-05-15; Datestamp: 2026-05-15
RX J1553.0+4457 (TMTS J15530469+4457458) is a detached post-common-envelope binary containing a cool white dwarf and an active late-type companion. We present a multi-wavelength study combining BOOTES multi-band photometry, six sectors of public TESS full-frame imaging, Einstein Probe/FXT X-ray observations, CAFOS optical spectroscopy, and archival ultraviolet-to-mid-infrared photometry. The BOOTES data reveal two short optical flares separated by about 3 h, with amplitudes of roughly 1--1.5 mag and faster decay at shorter wavelengths. The combined TESS light curve shows a stable signal at P = 0.083782 d, consistent with the first harmonic of the known spectroscopic orbital period, and the folded morphology indicates ellipsoidal modulation from a tidally distorted late-type companion rather than an irradiation-dominated waveform. The TESS flare energetics lie in the active M-dwarf regime. The Einstein Probe/FXT spectra show a factor of about 4 decline in the 0.3--10 keV flux, mainly associated with decreasing emission measures. The broadband SED is reproduced by a cool white dwarf plus a late-type M dwarf, with no clear mid-infrared excess. RX J1553.0+4457 is therefore best interpreted as a detached post-common-envelope binary whose rapid optical variability is dominated by MAGNETic activity and whose orbital modulation is ellipsoidal, although a weak wind-fed or intermittent accretion contribution remains possible.
[abstract 27 / 36] (score: 2) - Title: On the impossibility of observational confirmation of BLACK HOLEsAuthors: Thiago T. Bergamaschi,Comments: 10 pages. Essay written for the Gravity Research Foundation 2026 Awards for Essays on GravitationSubjects: gr-qc astro-ph.HECreated: 2026-05-12; Updated: 2026-05-15; Datestamp: 2026-05-15
General relativity has achieved remarkable experimental and observational success. Critically, recent data from the LIGO-Virgo-KAGRA, Event Horizon Telescope, and GRAVITY collaborations are often credited with \textit{demonstrating} the existence of BLACK HOLEs, but in fact they only provide evidence for objects that should be regarded as BLACK HOLE candidates. While current data are in striking agreement with the predictions for Kerr BLACK HOLEs, they can only rule out specific alternative models of compact objects rather than provide conclusive proof of BLACK HOLEs. More fundamentally, and independent of whether or not BLACK HOLEs exist, general relativity itself imposes limits on what can be observationally established. Essentially, no observational data is sufficient to confirm the existence of BLACK HOLEs.
[abstract 28 / 36] (score: 2) - Title: The Hunt for Red Dual AGNs I: Spatially-Resolved Mid-IR Dual AGNs in the DeCam Legacy SurveyAuthors: Ryan W. Pfeifle, Kimberly A. Weaver, Barry Rothberg, Miranda McCarthy, Emma Schwartzman, Nathan J. Secrest, Peter G. Boorman, Daniel Stern, Joanna Piotrowska, Kevin McCarthy, Emily Moravec, Jenna M. Cann, Kimberly Engle, Kyla Mullaney, Ryan Tanner, Kelly Whalen,Comments: 35 pages, including 5 tables, 10 figures, and 4 appendix sections. Submitted to ApJ; feedback welcome!Subjects: astro-ph.GACreated: 2026-05-13; Updated: 2026-05-15; Datestamp: 2026-05-15
Theoretical studies predict that dual AGNs are a critical stage of galaxy merger-driven supermassive BLACK HOLE growth. Systematic searches for dual AGNs typically target late-stage mergers ($\leq10$ kpc nuclear separations) and select AGNs based on optical diagnostics. Yet, simulations predict that obscuration can occur early in the merger sequence, and that a significant fraction of dual AGNs can be found beyond $10$ kpc. Here, we report on a new sample of 157 spatially resolved mid-IR dual AGNs candidates selected based upon their mid-IR $W1-W2$ colors from the Wide-Field Infrared Survey Explorer and optically classified as galaxy merger candidates using imaging from the Dark Energy Camera Legacy Survey. Spectroscopic results are presented for approximately 2/3 of the sample. 76 candidates have been confirmed to reside in galaxy mergers; among these, 13 have been confirmed as bona fide mid-IR dual AGNs, while 63 represent strong dual AGN candidates that require further examination. 46 candidates have been rejected as non-merger contaminants (foreground-background AGNs, separations inconsistent with interacting galaxies, etc.). 35 candidates still await spectroscopic coverage. The confirmed and high confidence dual AGN candidates exhibit separations of 14.5-129 kpc; $>50$% reside at separations $>50$ kpc. Confirmed and high confidence candidates also exhibit a diversity of nuclear optical BPT classes. Seyfert-Seyferts and Seyfert-HIIs dominate the overall BPT pairs sample. 31% of confirmed mid-IR dual AGNs reside in multi-mergers involving three or more galaxies. The diversity in AGN properties and environments identified in this work highlights the importance of multiwavelength selection strategies and analyses in the quest to holistically understand dual AGNs as a population.
[abstract 29 / 36] (score: 2) - Title: Infrared Line Diagnostics Fail to Constrain Sgr A*'s UV OutputAuthors: Mayura Balakrishnan, Sebastiano D. von Fellenberg, Daryl Haggard, Joseph M. Michail, Nicole M. Ford, Joseph L. Hora, Laurent Loinard, Sera Markoff, Joey Neilsen, Giacomo Principe, Nadeen B. Sabha, Howard A. Smith, Zach Sumners, Shuo Zhang,Comments: 12 pages, 5 figures, 1 table. Submitted to ApJSubjects: astro-ph.HE astro-ph.GACreated: 2026-05-13; Updated: 2026-05-15; Datestamp: 2026-05-15
Sgr A*, the 4 x 10^6 solar-mass supermassive BLACK HOLE at the Galactic Center, exhibits frequent flaring with X-ray luminosities of L_X ~ 10^35--10^36 erg s^-1, while its ultraviolet (UV) emission remains unconstrained due to extreme extinction (A_V ~ 30 mag). We use JWST/MIRI time-resolved spectroscopy of the central Galactic Center's 0.3 arcsec region to search for mid-infrared emission-line variability driven by Sgr A* flares, comparing the results to CLOUDY photoionization models spanning flare luminosities of L_UV = 10^32--10^39 erg s^-1 in a dense medium. We detect no statistically significant variability in any mid-infrared line, including [Fe II] 5.34 micron, [Ne II] 12.813 micron, [Fe II] 17.936 micron, and [S III] 18.713 micron. Despite expectations of a flare-driven response, we show that the lack of variability is consistent with the physical conditions in the spatially extended line-emitting gas, where light-crossing timescales of ~0.1--10 days and recombination and cooling timescales much longer than the flare timescale suppress any observable response to individual flares. We further find that the predicted emission is continuum dominated and that even the brightest lines are intrinsically weak and broadened by velocities of order 10^3 km s^-1, reducing their contrast against the continuum and limiting their detectability. Extending the analysis to higher-ionization mid-infrared and near-infrared lines does not improve sensitivity. These results demonstrate that infrared emission lines trace a steady-state radiation field rather than individual flaring events, and therefore infrared line diagnostics cannot be used to constrain the instantaneous UV flux of Sgr A*.
[abstract 30 / 36] (score: 2) - Title: Constraining the Galactic Center Dark Cluster with ELT/MICADO ObservationsAuthors: Sebastiano D. von Fellenberg, Matúš Labaj, Sean M. Ressler,Comments: Accepted for publication in A&A (aa59043-26)Subjects: astro-ph.GA astro-ph.HECreated: 2026-05-13; Updated: 2026-05-15; Datestamp: 2026-05-15
The Galactic Center hosts the densest known stellar environment in the Milky Way, dominated by the massive BLACK HOLE Sgr A* and the surrounding nuclear star cluster. Theory predicts that this region should also contain a large population of stellar compact objects (SCOs) - BLACK HOLEs, neutron stars, and white dwarfs - forming a "dark cluster" whose distribution and properties remain observationally unconstrained. These unseen stellar remnants are central to questions of mass segregation, cluster dynamics, and the expected rate of extreme mass ratio inspirals (EMRIs) detectable by future gravitational-wave observatories including LISA. Current evidence for SCOs in the Galactic Center is indirect, relying on dynamical mass measurements, X-ray surveys, and a small number of transient sources. Direct detections remain elusive due to crowding, extinction, and the sensitivity limits of existing instruments. We explore how upcoming facilities, in particular the Extremely Large Telescope (ELT) with its first-light imager MICADO, can fundamentally transform this field. MICADO's combination of deep photometry, high spatial resolution, and precise astrometry will enable systematic searches for SCO-star binaries via photometric variability and orbital astrometric signatures, as well as direct detection of isolated accreting BLACK HOLEs interacting with the gas-rich Galactic Center environment. We outline the observational pathways, technical challenges, and expected sensitivities, showing that ELT/MICADO observations can provide the first quantitative constraints on the dark cluster population. Establishing these constraints will be pivotal for understanding the dynamical evolution of the Galactic Center, the role of compact remnants in nuclear star clusters, and the astrophysical context of gravitational-wave sources in galactic nuclei.
[abstract 31 / 36] (score: 2) - Title: Boris and Exponential Integrators in the Theory of Particles Interacting with Magnetic TurbulenceAuthors: Andreas Shalchi,Comments:Subjects: physics.plasm-ph astro-ph.SRCreated: 2026-05-13; Updated: 2026-05-15; Datestamp: 2026-05-15
The interaction of electrically charged particles with MAGNETic fields is a fundamental problem in several areas of physics. An example is the motion of energetic particles through a MAGNETized plasma. The most accurate and reliable way to explore theoretically the interactions between particles and fields is via test-particle simulations. In such simulations one creates the turbulent MAGNETic field and solves the Newton-Lorentz equation numerically by employing an integration scheme. In the current article we discuss exponential integrators and derive systematically from this the Rodrigues scheme as well as the famous Boris integrator. For an approach where one creates the MAGNETic field anew at each time step, both integrators are overall comparable. In theory the Rodrigues approach should be more accurate due to the fact that the occurring matrix exponential is evaluated without further approximations. Practically, both methods provide very similar results. It is argued in the current article that a Rodrigues based integrator is a very strong alternative because for the specific problem discussed here, it does not require longer computing times.
[abstract 32 / 36] (score: 2) - Title: Planets in Pulsar WindsAuthors: T. Kaister, S. Andrés Joya Méndez, P. Marmat, M. Čemeljić, M. Velli, J. Varela, M. Falanga,Comments: 9 pages, 6 figures, submitted to ApJSubjects: astro-ph.HE astro-ph.EP astro-ph.SRCreated: 2026-05-13; Updated: 2026-05-15; Datestamp: 2026-05-15
Planets around pulsars were the first discovered exoplanets, found thanks to the extremely precise pulsar timing. Here we suggest that they could also be found through the radio emission generated by the pulsar-planet MAGNETospheric interaction. We present the results of special RELATIVISTIC numerical simulations of planets in a pulsar wind of velocity $v=0.985~c$, corresponding to a Lorentz factor $γ=5.795$. Planets, modeled as a perfectly conducting solid surface in an external MAGNETic field originating from the pulsar, produce radio emission in the extended MAGNETic structure on the planet's nightside. We find that the planet around a known pulsar, PSR J0636+5129 b, could be detected via its radio emission. We outline the observational prospects for such objects.
[abstract 33 / 36] (score: 2) - Title: Determination of Poynting Vector CharacteristicsAuthors: I. Mokhun, V. Danko, A. Kovalenko,Comments:Subjects: physics.opticsCreated: 2026-05-14; Updated: 2026-05-15; Datestamp: 2026-05-15
This paper presents a novel method for measuring the Poynting vector characteristics of monochromatic electroMAGNETic waves. We outline a specific design for such a meter and provide experimental data to validate the approach. For testing purposes, we utilized vortex beams with both linear and circular POLARIZATION.
[abstract 34 / 36] (score: 2) - Title: Numerical simulations of waves and turbulence in coronal loops: observables and spectraAuthors: Fabio Feraco, Francesco Pucci, Claudio Meringolo, Giuseppe Nisticò, Fabio Reale, Paolo Pagano, Gabriele Cozzo, Tom Van Doorsselaere, Bart De Pontieu, Paola Testa, Sergio Servidio, Oreste Pezzi, Francesco Valentini, Francesco Malara,Comments:Subjects: physics.plasm-phCreated: 2026-05-14; Updated: 2026-05-15; Datestamp: 2026-05-15
We investigate numerically the time evolution of velocity and MAGNETic field fluctuations in a coronal loop, focusing on the dynamics due to both phase mixing and turbulent cascade. The intensity, doppler velocity and non-thermal broadening are synthesized from numerical results in order to establish if the upcoming Multi-slit Solar Explorer (MUSE) mission could reveal the presence of those phenomena in the solar corona through its unprecedented high-resolution spectroscopic observations. The loop is represented by a cylindrical pressure-balanced MAGNETic structure with a transverse density and MAGNETic field inhomogeneity. The initial perturbation is a superposition of a torsional Alfvén wave and a transverse turbulent component with different tunable weights. In order to reconstruct plasma emission features we calculate moments of the Fe IX 171 Å spectral line. 2D maps obtained by integrating the emission along the assumed line of sight are calculated for the emission intensity $I_0$, the Doppler shift $I_1$ and the non-thermal broadening $I_2$, for several values of the model parameters. Finally, we simulate MUSE spectrograph by considering a resolution of $312$ km $\times$ $312$ km. We observe how intensity maps show the formation of longitudinal threads. The generation of small-scale fluctuations mainly takes place in the inhomogeneity region at the loop boundary, where the effects of phase mixing and non-thermal broadening are stronger. 1D power spectra of intensity and Doppler shift maps are calculated and compared with the corresponding spectra of density and line-of-sight velocity component. The agreement observed between the spectral indexes of the intensity power spectra at MUSE resolution and the one computed from the full 3D density field indicates that spectra of $I_0$ can be used to infer information on the spectrum of density inside a loop.
[abstract 35 / 36] (score: 2) - Title: Analysing the highly irregular boundaries of solar poresAuthors: T. J. Duckenfield, D. B. Jess, S. Jafarzadeh, L. A. C. A. Schiavo, S. S. A. Silva, S. D. T. Grant,Comments: Submitted to A&ASubjects: astro-ph.SRCreated: 2026-05-14; Updated: 2026-05-15; Datestamp: 2026-05-15
Solar pores possess irregular and evolving boundaries that are often far from the ideal circular flux tubes assumed in many MAGNETohydrodynamic (MHD) oscillation models. To tackle this irregularity in a consistent way for wave analysis, we introduce a framework that employs the convex hull of the pore boundary - derived from intensity minimum error thresholding - as the domain to perform further analysis. Using the modal assurance criterion, we find the range of pore shapes for which this approximation is valid. We demonstrate the usefulness of this framework by applying it to multi-height, high-cadence observations (4170 angstrom continuum, G-band, Na~\textsc{i}, and Ca~\textsc{ii}~K) of a solar pore, and apply Proper Orthogonal Decomposition of the convex hull to determine wave modes. The fundamental sausage ($m=1$) and kink ($m=2$) mode is found to remain reliable, while higher-order fluting modes ($m\ge3$) are strongly degraded by small-scale boundary irregularity. As expected, sausage-like modes dominate the variance at all heights and exhibit a systematic upward shift in frequency, consistent with freely propagating compressive waves. In contrast, the kink-like motions appear weak, confined to a persistent low-frequency peak, and most plausibly interpreted as a forced response to granular buffeting rather than a propagating mode. Together, these results establish a practical methodology for boundary-mode analysis in real, highly structured pores and provide new constraints on the nature and height evolution of MHD waves in the lower solar atmosphere.
[abstract 36 / 36] (score: 2) - Title: Primordial Black Hole from Tensor-induced Density Fluctuation: First-order Phase Transitions and Domain WallsAuthors: Utkarsh Kumar, Anish Ghoshal,Comments: 24 pages, 12 figures, 3 tables+ appendicesSubjects: astro-ph.COCreated: 2026-05-14; Updated: 2026-05-15; Datestamp: 2026-05-15
We present a novel \textit{gauge-invariant and minimal} formation mechanism of primordial BLACK HOLEs (PBHs) in first-order phase transition (FOPT) and domain walls (DW) separately. This is based on the first-order tensor perturbations, generated during FOPT from bubble collisions \& sound waves, and from DW annihilation, sourcing curvature, at second-order in perturbation theory. We show that the PBH formation implies \textit{model-independent constraints} on FOPT parameters ($β/H, α, T_{\star}$ ) and on DW parameters, ($α_{\rm ann}, V_{\rm bias}, σ$), from existing PBH constraints. We find that asteroid mass PBHs can become the entire DARK MATTER (DM) of the Universe, for $T_{\star} \in (4 \times 10^{2}, 10^{4})$ GeV, for $β/H \simeq 6$, involving $α>\mathcal{O}(1)$ values. The corresponding FOPT Gravitational Waves (GW) amplitude will have its characteristic peak at $Ω_{\rm GW}^{\rm p} h^2$ $\sim \mathcal{O}(10^{-8})$ between frequencies $f_{\rm p} \in ({10^{-5},10^{-2}})$ Hz which is within the reach in LISA and SKA detectors. PBH as entire DM is possible for $σ^{1/3} \in [10^{6}, 10^{8}]$ TeV, for $V_{\rm bias}^{1/4} \in [10^7, 10^{10}]$ MeV with the corresponding GW amplitude peak from DW annihilation $Ω_{\rm GW}^{\rm p} h^2$ $\sim \mathcal{O}(10^{-9})$ (for $α_{\rm ann} \sim 10^{-2}$) and peak frequencies between $f_{\rm p} \in (4 \times {10^{-4},10^{-1}})$ Hz with ($T_{\rm ann} \in 4.5 \times [10^3, 10^6] $) GeV within the reach in LISA and ET detectors. We also provide semi-analytical formulae for the tensor-induced density spectrum, $P_{δ^{(2)}}$, $M_{\rm PBH}$ and $f_{\rm PBH}$, relating them in terms of FOPT and DW parameters which in turn, are related to viable particle physics origin of such FOPT and DW, and therefore, constrain such microphysics, either in the visible, or in dark sector models.
arXiv:2605.14623 [pdf, ps, other]
arXiv:2605.15166 [pdf, ps, other]
arXiv:2510.09101 [pdf, ps, other]
arXiv:2511.02796 [pdf, ps, other]
arXiv:2605.13440 [pdf, ps, other]
arXiv:2605.14003 [pdf, ps, other]
arXiv:2605.15068 [pdf, ps, other]
arXiv:2605.15162 [pdf, ps, other]
arXiv:2505.08011 [pdf, ps, other]
arXiv:2603.08119 [pdf, ps, other]
arXiv:2605.13968 [pdf, ps, other]
arXiv:2605.14233 [pdf, ps, other]
arXiv:2605.14869 [pdf, ps, other]
arXiv:2605.15145 [pdf, ps, other]
arXiv:2406.13043 [pdf, ps, other]
arXiv:2511.07532 [pdf, ps, other]
arXiv:2603.08843 [pdf, ps, other]
arXiv:2605.13949 [pdf, ps, other]
arXiv:2605.14114 [pdf, ps, other]
arXiv:2605.15137 [pdf, ps, other]
arXiv:2509.14849 [pdf, ps, other]
arXiv:2509.23490 [pdf, ps, other]
arXiv:2601.19254 [pdf, ps, other]
arXiv:2602.11030 [pdf, ps, other]
arXiv:2602.16252 [pdf, ps, other]
arXiv:2605.02796 [pdf, ps, other]
arXiv:2605.13901 [pdf, ps, other]
arXiv:2605.13946 [pdf, ps, other]
arXiv:2605.13990 [pdf, ps, other]
arXiv:2605.14017 [pdf, ps, other]
arXiv:2605.14065 [pdf, ps, other]
arXiv:2605.14077 [pdf, ps, other]
arXiv:2605.14466 [pdf, ps, other]
arXiv:2605.15057 [pdf, ps, other]
arXiv:2605.15112 [pdf, ps, other]
arXiv:2605.15197 [pdf, ps, other]