Peer Revenue Equity in science

Papers

Fresh from arXiv, typeset properly. Highlighted words trade on the market.

Physics Astrophysics

astro-ph Watch Astrophysics

Wednesday 20 May

Astrophysics of Galaxies

Euclid: Early Release Observations – The formation of peanutty dwarf galaxies in Perseus

A. U. Kapoor, R. Smith, A. J. Zuiderwijk et al. (+133 more)

Dwarf galaxies in dense cluster environments are susceptible to tidal interactions that can alter their morphology and kinematics. Boxy isophotes are well studied in massive galaxies but remain poorly understood in dwarfs. We aim to identify and characterise boxy/peanutty dwarf galaxies in the Perseus cluster and determine the origin of their isophotal shapes. Using Euclid Early Release Observations of the Perseus cluster, we present a cumulative light fraction method for robustly measuring the isophotal shape parameter $c_4$, particularly suited to low surface brightness regimes. From ~1100 cataloged dwarfs, we select a clean sample of ~190 early-type systems with reliable $c_4$ measurement. Observed trends are interpreted through comparison with mock Euclid observations of $N$-body simulations of tidally transformed dwarfs. We identify 13 dwarfs with significantly boxy isophotes ($c_4 < -0.0175$). These galaxies lack visible thin disks, lie on the cluster red sequence, and show no preferential spatial concentration within Perseus. We find a significant anticorrelation between $c_4$ and effective radius: larger galaxies exhibit more boxy isophotes. An analogous size-shape anticorrelation is recovered in the simulations, where inner regions are dominated by box orbits associated with a triaxial peanut structure and outer regions by short-axis tube orbits. The boxy dwarfs in Perseus are tidally transformed remnants of moderately rotating progenitors, with boxy isophotes tracing inner box-orbit-dominated peanut structures. The size-shape correlation arises from viewing geometry: face-on orientations reveal the rectangular profile of the elongated triaxial structure (large and boxy), while edge-on views yield rounder, compact morphologies. Our sample represents an orientation-selected subset of tidally transformed, peanutty dwarfs in the cluster.
Read the full abstract

All authors A. U. Kapoor, R. Smith, A. J. Zuiderwijk, S. De Rijcke, A. van der Wel, M. Baes, F. R. Marleau, P.-A. Duc, R. F. Peletier, B. Altieri, S. Andreon, N. Auricchio, C. Baccigalupi, M. Baldi, A. Balestra, S. Bardelli, P. Battaglia, A. Biviano, E. Branchini, M. Brescia, S. Camera, V. Capobianco, C. Carbone, J. Carretero, M. Castellano, G. Castignani, S. Cavuoti, K. C. Chambers, A. Cimatti, C. Colodro-Conde, G. Congedo, C. J. Conselice, L. Conversi, Y. Copin, F. Courbin, H. M. Courtois, M. Cropper, H. Degaudenzi, G. De Lucia, H. Dole, F. Dubath, X. Dupac, M. Fabricius, M. Farina, R. Farinelli, S. Ferriol, M. Frailis, S. Galeotta, K. George, B. Gillis, C. Giocoli, J. Gracia-Carpio, A. Grazian, F. Grupp, S. V. H. Haugan, J. Hoar, W. Holmes, I. M. Hook, F. Hormuth, A. Hornstrup, K. Jahnke, M. Jhabvala, S. Kermiche, A. Kiessling, B. Kubik, M. Kümmel, M. Kunz, H. Kurki-Suonio, A. M. C. Le Brun, S. Ligori, P. B. Lilje, V. Lindholm, I. Lloro, G. Mainetti, O. Mansutti, O. Marggraf, M. Martinelli, N. Martinet, F. Marulli, R. J. Massey, E. Medinaceli, S. Mei, M. Meneghetti, E. Merlin, G. Meylan, A. Mora, M. Moresco, L. Moscardini, R. Nakajima, C. Neissner, S.-M. Niemi, C. Padilla, S. Paltani, F. Pasian, K. Pedersen, W. J. Percival, V. Pettorino, G. Polenta, M. Poncet, L. A. Popa, F. Raison, A. Renzi, J. Rhodes, G. Riccio, E. Romelli, M. Roncarelli, R. Saglia, Z. Sakr, D. Sapone, P. Schneider, A. Secroun, E. Sihvola, P. Simon, C. Sirignano, G. Sirri, L. Stanco, P. Tallada-Crespí, A. N. Taylor, I. Tereno, S. Toft, R. Toledo-Moreo, F. Torradeflot, I. Tutusaus, J. Valiviita, T. Vassallo, A. Veropalumbo, Y. Wang, J. Weller, G. Zamorani, F. M. Zerbi, I. A. Zinchenko, E. Zucca, M. Magliocchetti, M. Sereno, F. Durret, D. Scott

High Energy Astrophysical Phenomena

Searching for links between energetic millisecond pulsars and repeating fast radio bursts

R. J. van Ruiten, J. W. T. Hessels, S. Bhandari et al. (+5 more)

The unexpected localization of the repeating FRB 20200120E to a globular cluster challenges conventional FRB models based on magnetars formed via core collapse. One alternative model suggests that FRB 20200120E is a millisecond pulsar (MSP) producing giant pulses (GPs). To test this hypothesis, we compared the characteristics of FRB 20200120E bursts with the GPs of the most energetic Galactic MSP known, M28A (PSR B1821$-$24A), using observations with the Parkes (Murriyang) telescope's Ultra Wideband Low-frequency (UWL) receiver. Our analysis provides insight into the spectral structure and frequency extent of M28A's GPs, revealing broad-band spectra spanning $700-4000$ MHz (in some cases) with complex spectral peaks. We find that known M28A GP characteristics persist at this bandwidth, such as durations, luminosities, periodicity, wait-time, and energy distribution. A sub-band search for narrow-band GPs yielded no detection of genuinely narrow-band GPs. However, we do find narrow-band spectral peaks of $\sim100$ MHz bandwidth, a similar scale observed for FRB 20200120E's bursts. Compared to FRB 20200120E's bursts, M28A's GPs have $50\times$ shorter durations, $10^5\times$ lower spectral luminosities, clear periodicity (vs. no periodicity), a purely Poissonian wait-time distribution (vs. quasi-Poissonian), and generally broad-band spectra with narrow-band peaks (vs. only narrow-band bursts). Both sources show a steep energy distribution and minor dispersion measure variability. Our study finds no strong links between M28A and FRB 20200120E. However, we cannot rule out the possibility that FRB 20200120E is a rare and unique type of MSP with no Galactic analogue. Furthermore, higher-cadence monitoring of M28A, for hundreds to thousands of hours, might reveal rare but extremely luminous pulses.
Read the full abstract

All authors R. J. van Ruiten, J. W. T. Hessels, S. Bhandari, P. Chawla, A. Gopinath, D. M. Hewitt, K. Nimmo, M. P. Snelders

High Energy Astrophysical Phenomena

FR0 radio galaxy jets – I. linking jet dynamics and high-energy emission in LEDA 55267 and LEDA 58287

André F. S. Cardoso and Rita C. Anjos

Fanaroff-Riley type 0 (FR0) radio galaxies host anomalously compact jets whose disruption mechanism and high-energy emission remain poorly understood. We combine three-dimensional relativistic hydrodynamical (RHD) simulations with broadband spectral energy distribution (SED) modeling from radio to TeV energies, focusing on LEDA~55267 and LEDA~58287. Our simulations show that recollimation shocks trigger hydrodynamical instabilities that drive turbulence and rapid deceleration, preventing the jets from propagating beyond a few tens of parsecs and reproducing the observed compact radio morphology. Leptonic SED models adequately describe the observed emission up to GeV energies, but when simulated CTAO observations are included, statistical model comparison indicates strong evidence in favor of lepto-hadronic scenarios at TeV energies for both sources, a result that should be interpreted as a theoretical prediction to be tested by future observations. A leptonic analysis of the simulations reveals magnetized emitting regions with plasma beta parameters $\beta_{\rm p} \sim 10^{-5}$-$10^{-3}$, orders of magnitude below values reported for extended FRI jets, consistent with jets retaining the magnetization inherited from the launching region and providing a natural physical link between the compact jet dynamics and the lepto-hadronic emission.
Read the full abstract

Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc

Contrastive self-supervised convolutional autoencoder for core-collapse supernova gravitational-wave detection

Tian-Yang Sun, Yue Niu, Chun-Yan Jiang et al. (+3 more)

Gravitational-wave astronomy has opened a direct observational window onto compact-object dynamics, strong-field gravity, and cosmology. Among the transient sources accessible through this window, core-collapse supernovae (CCSNe) are uniquely valuable because their signals can probe the engine of stellar collapse, proto-neutron-star dynamics, and explosion asymmetries, yet their weak, stochastic, and model-dependent waveforms remain difficult to detect. In this work, we develop a contrastive self-supervised convolutional autoencoder (CS-CAE) for CCSNe gravitational-wave signal detection. The method combines a convolutional autoencoder (CAE), a noise-centered latent regularizer, and a projection head trained with a contrastive objective. This design encourages independent noisy realizations of the same CCSNe signal to be mapped to nearby latent representations, thereby reducing the influence of random noise fluctuations. CS-CAE achieves performance comparable to a supervised convolutional neural network while clearly outperforming a conventional CAE baseline, and generalizes better to unseen numerical CCSNe waveform families. Under the Einstein Telescope (ET) detector configuration, the method achieves an effective sensitive distance of approximately 120 kpc and shows improved separation of CCSNe signals from stationary noise and transient glitches in the low-false-alarm regime. These results highlight the potential of CS-CAE as a robust and less template-dependent framework for CCSNe gravitational-wave searches.
Read the full abstract

All authors Tian-Yang Sun, Yue Niu, Chun-Yan Jiang, Shang-Jie Jin, Yong Yuan, Xin Zhang

Solar and Stellar Astrophysics

HD 38973 b – a cold Saturn orbiting a Sun-like star

Adriana Errico, Robert A. Wittenmyer, Jonathan Horner et al. (+2 more)

We report the detection of a long-period companion to the nearby solar-type star HD\,38973 using precision radial-velocity measurements. The radial-velocity data reveal a coherent Keplerian signal with a period of $\sim$3000~days and moderate eccentricity, yielding a minimum mass in the sub-Jovian regime. We complement the radial-velocity analysis with astrometric constraints from the Hipparcos–Gaia Catalog of Accelerations (HGCA). Although no significant proper-motion anomaly is detected for HD\,38973, the absence of an astrometric signal provides an informative upper limit on the companion mass. By combining the radial-velocity posterior with the HGCA likelihood, we rule out high-mass solutions at low inclinations and derive a robust upper bound on the true companion mass. We find the best-fitting true mass to be $0.240_{-0.040}^{+0.102}\,M_{\rm Jup}$, on an orbit with period $2733^{+210}_{-190}$ days, making HD\,38973b a likely cold Saturn. This study highlights the diagnostic power of astrometric non-detections when combined with precision radial velocities, demonstrating that meaningful constraints on companion masses can be obtained even in the absence of a detected astrometric signal.
Read the full abstract

All authors Adriana Errico, Robert A. Wittenmyer, Jonathan Horner, Brad Carter, Alexander Wallace

High Energy Astrophysical Phenomena

Optical Super-orbital Modulation of SMC X-1: Disk Precession and a Revised Pulsar Mass

Masafumi Niwano, Nobuyuki Kawai and Michael Fausnaugh

The observational determination of the lower limit of neutron star masses is crucial for the physics of core-collapse supernovae. In this light, SMC X-1 is an important object because of its estimated pulsar mass lying near or potentially below the theoretical lower limit. SMC X-1 exhibits a double peaked optical orbital light curve due to the tidal distortion of the donor star, and analysis of this allows us to constrain the binary parameters. In this study, we analyzed optical and X-ray light curves of SMC X-1 obtained by Transiting Exoplanet Survey Satellite and Monitor of All-sky X-ray Image. We found the systematic variations in the optical orbital light curves synchronized with the X-ray super-orbital modulation, regarding the following two aspects: the minimum at inferior conjunction and the double-peak asymmetry. To explain this behavior, we developed a modified ellipsoidal modulation model in which the precessing accretion disk changes the geometry of X-ray irradiation on the donor and that of optical irradiation on the disk. As a result, this model succeeded in reproducing the observed optical and X-ray light curves. Furthermore, we discovered that intense X-ray irradiation could cause the optical emission center to shift away from the gravitational center, potentially leading to an underestimation of the radial velocity of the donor by approximately 20%. Correcting for this effect yields an updated pulsar mass estimation of about $1.35\>M_\odot$.
Read the full abstract

High Energy Astrophysical Phenomena

On the Possibility of an Extragalactic Positron Annihilation Signal

Thomas Siegert and Hiroki Yoneda

With 20 years of INTEGRAL/SPI observations, Yoneda et al. (2025) created the most detailed map of the positron annihilation line at 511keV. While central bulge and extended disk are readily recognised in this map, several hotspots at high latitude regions may either be imaging artefacts or true signals. We discuss the possibility of extragalactic positron annihilation signals from hotspots in this map. We also calculate a cosmological positron annihilation signal as a contribution to the Cosmic Gamma-ray Background (CGB). For this investigation, we compare 511 keV emission hotspots away from the Galactic plane with a high velocity cloud column density map as well as with the catalogue of Local Volume Galaxies (LVGs) up to 25 Mpc. We find that in particular the Magellanic Stream in the southern and Complex C in the northern sky matches the brightest hotspots, which may indicate a higher positron production rate inside the Milky Way than measured from the Galactic interstellar medium alone, of $10^{44}\,\mathrm{s^{-1}}$. In addition, we can explain other hotspots by the cumulative effect of LVGs in the selected regions. The CGB contribution from positron annihilation might be sub-dominant on the per-cent level. However, depending on the true intrinsic annihilation spectrum, in particular depending on the positron injection energy for in-flight annihilation and the star formation rate per galaxy, a much higher imprint beyond 10% is possible above several MeV. If these findings turn out to be true, next generation MeV telescopes will, for the first time, identify individual extragalactic 511 keV sources. In particular, several dwarf spheroidal galaxies with fluxes of up to $(1$-$2) \times 10^{-5}\,\mathrm{ph\,cm^{-2}\,s^{-1}}$, the galaxies M31 and M33, as well as some of their satellites, with potentially several $10^{-6}\,\mathrm{ph\,cm^{-2}\,s^{-1}}$, each, may be detected.
Read the full abstract

Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

Self-Consistent Parker Bound on Magnetic Monopoles

Chen Zhang, Chun-Yan Jiang, Nayun Jia et al. (+1 more)

Magnetic monopoles arise generically in unified theories and offer a natural explanation of charge quantization. Beyond collider searches and cosmic-ray experiments, their flux is constrained by Parker-type bounds requiring galactic magnetic fields to survive monopole energy extraction. We formulate a self-consistent Parker bound anchored in the lowest eigenmode of the galactic mean-field dynamo and convert the resulting limit to the present-day flux. Small-scale turbulent fields both seed this eigenmode and set the monopole velocity via stochastic acceleration before energy extraction from the coherent field. These unavoidable effects substantially modify the standard extended Parker bound at low and intermediate masses, yielding flux limits robust to primordial magnetic fields (PMFs); PMFs strong enough to alter these limits lie in regimes constrained by Ly$\alpha$ data or testable by 21-cm observations and other cosmological probes.
Read the full abstract

All authors Chen Zhang, Chun-Yan Jiang, Nayun Jia, Xin Zhang

High Energy Astrophysical Phenomena

Chandra X-ray Observations of the Pulsar Wind Nebula within CTA 1

Seth Gagnon, Oleg Kargaltsev, Jason Alford et al. (+2 more)

We present deep Chandra observations of the pulsar wind nebula (PWN) powered by PSR J0007+7303 in the composite supernova remnant CTA 1. The merged ACIS image shows a $\sim20''$ jet extending south of the pulsar and bending toward the southwest, a faint counter-jet to the north, and a compact torus oriented approximately perpendicular to the jet axis. Using an archival observation from 2003 we perform relative astrometry over a $\sim20$ yr baseline and constrain the pulsar's transverse velocity to $\lesssim 200~\mathrm{km~s^{-1}}$ at the distance of 1.4 kpc at 95% confidence. Spatially resolved spectroscopy shows hard spectra for the jet and torus (photon indicies $\Gamma \approx 1.2-1.4$) and a softer spectrum for the extended nebula ($\Gamma = 1.85 \pm 0.11$), indicating minimal radiative cooling in the compact regions. Modeling of the torus, associated with the termination shock, as an inclined circle yields a viewing angle $\zeta \approx 50^\circ$. The outer gap and two-pole caustic pulsar emission models then imply a moderate magnetic inclination ($\alpha \sim 20^\circ$-$70^\circ$). Broadband spectral energy distribution (SED) modeling from radio to PeV $\gamma$-rays for a one-zone leptonic scenario yields a low magnetic field ($B \approx 1.4$-$3.2~\mu\mathrm{G}$) and a high electron cutoff energy ($E_{\rm cut} \sim 0.2$-$0.3~\mathrm{PeV}$), indicating that the magnetic field decreases rapidly outside of the compact nebula. These results establish CTA 1 as a young, low X-ray efficiency PWN with a hard injection spectrum capable of accelerating particles to PeV energies.
Read the full abstract

All authors Seth Gagnon, Oleg Kargaltsev, Jason Alford, Joseph Gelfand, Alexander Lange

Solar and Stellar Astrophysics

The Beauty of k2: Probing Stellar Interiors Using Apsidal Motion. I. The Benchmark Massive Binary HD 152248

Sophie Rosu, Luca Sciarini, Sylvia Ekström et al. (+4 more)

Over the last decades, several independent studies have shown the need for large convective boundary mixing (CBM) and convective core sizes in massive stars to reproduce a variety of their observed properties. Yet, stars more massive than 20Msun lack a quantitative prescription for CBM as well as an unequivocal constraint on the internal mixing mechanisms acting in them. We use the apsidal motion observed in the twin binary HD152248 - linked to the internal stellar structure constants k2 of the stars - to constrain massive stars' internal density stratification and CBM. We build GENEC stellar models assuming two different angular momentum transports: purely hydrodynamic (hydro) and magneto-diffusive (magnetic). We confront single- and binary-star models to assess the impact of tidal locking on the star's evolution. We investigate the impact of CBM (overshooting), metallicity, initial helium abundance and mass, mass-loss rate, and mixing length parameter on the evolution of stellar parameters. We highlight that k2 from the models are systematically larger than observed ones, the so-called k2-discrepancy. Models predict stars with too low a density contrast between their core and external layers. Both hydro and magnetic models require large step-overshoot of 1.2 to reproduce stellar parameters, including k2. Other parameters have almost no impact. Given the efficiency of tides to synchronise systems, the assumption of pseudo-synchronisation is sound for this system. It sets an upper limit on the misalignment angle of stellar rotation axes of ~50{\deg}. Even with such unexpected large angles, the k2-discrepancy is not solved. Even if the mass-loss rate was underestimated by a factor two, it would have no impact on stellar parameters evolution, including k2. It demonstrates that the apsidal motion is a powerful, robust means to probe stellar interiors.
Read the full abstract

All authors Sophie Rosu, Luca Sciarini, Sylvia Ekström, Patrick Eggenberger, Joris Josiek, Raphael Hirschi, Cyril Georgy

Solar and Stellar Astrophysics

Solar Vortices: Catalysts of Magnetoacoustic Wave Dissipation and Atmospheric Heating

Nitin Yadav and Apanba Khuman

The propagation and dissipation of magnetohydrodynamic waves play a key role in transporting energy from the solar photosphere to the chromosphere. Using high-resolution three-dimensional radiative MHD simulations, we investigate the evolution of slow magnetoacoustic waves along magnetic field lines and examine the influence of photospheric vortex flows on wave dynamics and heating. Field-line tracking reveals upward-propagating slow-mode waves that amplify in the stratified atmosphere and steepen into shocks in the chromosphere, producing recurrent plasma surges with characteristic chromospheric shock signatures. Vortex regions are identified using the swirling strength diagnostic with height-dependent Gaussian smoothing to capture expanding vortex structures. A comparison between vortex and non-vortex field lines shows systematically enhanced temperature in vortex regions.Furthermore, a comparison of shock formation height between vortex and non-vortex regions reveals no systematic difference, indicating that rotational flows do not significantly alter the height at which shocks form. However, supersonic upflows at vortex locations exhibit somewhat higher parallel velocities compared to non-vortex regions, suggesting that vortex-driven motions may amplify the velocity of propagating shocks. These results indicate that vortex-driven motions contribute to increased shock dissipation and modify the thermal structure of the lower solar atmosphere, highlighting the coupled role of slow-mode shocks and vortex flows in chromospheric energy transport.
Read the full abstract

Astrophysics of Galaxies

Detection of a dark matter subhalo in the strongly lensed system PJ011646

Aristeidis Amvrosiadis, James W. Nightingale, Qiuhan He et al. (+12 more)

We present a strong lensing analysis of the system PJ011646 using high-resolution ($\sim$0.1 arcsec) Atacama Large Millimeter/submillimeter Array (ALMA) dust-continuum observations to test for the presence of dark matter substructures. The lens mass distribution is modelled with an elliptical power law and third- and fourth-order multipoles (PL+MP; $m=3,4$), plus external shear. The multipoles have amplitudes of $\simeq$1.5 per cent of the convergence, consistent with nearby early-type galaxies, and improve the fit by $\Delta\ln Z = 52.1$ relative to a pure PL model. Using this best-fitting macromodel, we perform a grid-based subhalo search in the image plane, parametrising the perturber as a spherical NFW. A subhalo in two locations in the image plane improves the fit by $\Delta\ln Z>10$. Both correspond to the same location in the source plane, so they are partially degenerate; follow-up analysis suggests that only one is physically real. This is a subhalo of mass $M_{200} = {2.78}_{-0.66}^{+0.43} \times 10^{10} \, M_\odot$ and concentration $c_{200} = 30_{-7}^{+5}$, detected at $\sim$5.8$\sigma$ significance (relative to the PL+MP). This concentration is consistent with that expected for a typical tidally stripped Navarro-Frenk-White subhalo. The enclosed projected mass is most tightly constrained within a radius of 2 kpc, where we infer $M_{\rm sub} = {3.57}_{-0.14}^{+0.16}\times 10^9 \, M_\odot$. From grid cells consistent with no detection ($\Delta \ln Z < 10$), we derive limits on the minimum subhalo mass that could have been detected at $3\sigma$ significance, finding $M_{200} \approx 8 \times 10^{8} \, M_\odot$ in the most sensitive regions of the lensed arcs. This demonstrates that ALMA continuum imaging at sub-arcsecond resolution can probe dark matter substructure in a mass regime where cold and warm dark matter models predict different abundances of subhalos.
Read the full abstract

All authors Aristeidis Amvrosiadis, James W. Nightingale, Qiuhan He, Andrew Robertson, Shaun Cole, Carlos S. Frenk, Samuel Lange, Richard Massey, Maximilian von Wietersheim-Kramsta, Xiaoyue Cao, Ran Li, Shubo Li, Kaihao Wang, Xianghao Ma, Leo W. H. Fung

Solar and Stellar Astrophysics

The benefit of a multi-band high resolution spectroscopic monitoring for studying stellar transients: the NGC 300 OT2008-1 UVES spectrum as a test case

Elena Mason, Steven N. Shore, Andrea Pastorello et al. (+1 more)

This work advocates the benefit of high resolution spectroscopic monitoring in the study of transients (local group transients given the available collecting power). As an exemplary analysis, we focus on the optical transient NGC300OT2008-1. Searching the ESO archives, we found a low resolution (LR, FORS) and a high resolution (HR, UVES) spectrum that were separated by only one day with no changes between them. The independent analysis of the FORS and UVES spectra show that in the LR spectrum we can securely identify only a small sample of lines and miss the correct characterization of the ejecta energetics which remain at the level of speculation. In the HR data, we identify a larger sample of emission lines and analyze their profiles suggestive of a complex geometry and ejecta dynamics whose inferences are simply impossible in LR spectra. Line profile studies are not possible with LR spectra, and may lead to potentially misleading measures. The limited information available from LR data compromises the interpretation and prevents formulating realistic physical scenarios, favoring parameter fitting to oversimplified, biased, standard models. In this occasion only one epoch was available, but monitoring is fundamental to characterize the transient evolution. The new scenario derived from the analysis of the HR spectrum cannot be confirmed or dismissed lacking a HR spectroscopic monitoring. LR and HR spectra serve different but complementary purposes. With LR one does bolometric-like studies (SED, strengthening or weakening of the major transitions), while with HR one does dynamics and precise physical characterization. HR spectroscopic monitoring on different types of transient has already shown how it serves to disentangle the various components, constrain their physical parameters, the involved energy source, and derive the ejecta dynamics.
Read the full abstract

All authors Elena Mason, Steven N. Shore, Andrea Pastorello, Paolo Di Marcantonio

Cosmology and Nongalactic Astrophysics

CosmoForge I: A unified framework for QML power spectrum estimation and pixel-based likelihood analysis

Giacomo Galloni and Luca Pagano

Optimal power spectrum estimation on the largest angular scales of the cosmic microwave background relies on the Quadratic Maximum Likelihood (QML) estimator. Existing public implementations, however, each address only a subset of the problem and none combine power spectrum estimation with a self-consistent pixel-space likelihood within a single framework. We present CosmoForge, a public Python framework that unifies QML power spectrum estimation and pixel-based Gaussian likelihood evaluation for spin-0 and spin-2 fields on the sphere, with general (non-diagonal) noise covariances. The framework is split into three installable packages: CosmoCore (infrastructure), QUBE (Fisher and QML estimation), and PICSLike (pixel-space likelihood). A common interface exposes two interchangeable computation bases $-$ a harmonic basis built on the Sherman-Morrison-Woodbury identity and a direct pixel-space basis $-$ selecting whichever is cheaper for the configuration at hand. Exact algorithmic optimisations reduce the Fisher cost to $\mathcal{O}(\ell_{\rm max}^4)$ for arbitrary noise covariances, with Numba JIT compilation of the hot kernels and MPI parallelisation of the likelihood scan. CosmoForge reproduces the Planck low-$\ell$ Fortran reference implementation across both the QML and pixel-space likelihood pipelines, consistently with double-precision arithmetic. Native multipole binning and three output normalisations (deconvolved, decorrelated, window-convolved) are exposed through a single code path, and the same covariance infrastructure powers both QML estimation and likelihood evaluation. CosmoForge offers a general-purpose, modular, and validated tool for the optimal analysis of large-scale data on the sphere. It is publicly available, pip-installable, and extensible to non-CMB observables.
Read the full abstract

Solar and Stellar Astrophysics

Multi-diagnostic convergence: a single measurement in weakly collisional plasmas

Victor Edmonds

When multiple electron temperature diagnostics converge on the same value, the standard inference is that the measurement is robust. We show that this convergence is a structural consequence of the shared ionization bottleneck in any plasma where the electron Knudsen number exceeds $\sim 0.01$: all diagnostics downstream of collisional ionization report the effective temperature $T_{\rm eff}$, not the core temperature $T_{\rm core}$. Their agreement is a single measurement reported $N$ times. We introduce a taxonomy: Type A (ionization-gated, $T_{\rm eff}$), Type B (bulk-sampling, $T_{\rm core}$), Type C (distribution-resolving). The ratio $R = T_A/T_B$ yields $\kappa = 3R/[2(R-1)]$ directly. Applied to the solar corona ($R = 2.4$, $\kappa \approx 2.5$) and the tokamak scrape-off layer, single kappa distributions ($\kappa \approx 2$–$10$) reproduce published bi-Maxwellian EEDF decompositions to 3–8% RMS with one fewer parameter, and Thomson scattering confirms the predicted Type B temperature. We test applicability in planetary nebulae (the 80-year CEL–ORL abundance discrepancy). Knudsen calculations with the Shoub $v^4$ mean-free-path scaling show ionizing electrons are collisionless in the corona even when the bulk is fluid; in PNe, both ionizing ($\sim 55$ eV) and excitation ($\sim 5$ eV) electrons are collisional over nebular scales, identifying PNe as the falsification boundary; in the SOL, non-local parallel transport maintains tails even where local collisionality is high. For $\kappa \approx 3$–$5$, the raw Spitzer–Härm formula with spectroscopic $T_e$ overestimates parallel heat flux by factors of 3–25$\times$; flux-limited models inherit the bias through their boundary conditions, relevant to ITER divertor predictions. Every diagnostic campaign on a weakly collisional plasma should include at least one Type B measurement.
Read the full abstract

Astrophysics of Galaxies

B-Fields and Star Formation across Scales with TRAO (B-FROST): CO Abundances, Dynamics and Relative Orientations in the Translucent High Latitude Cloud MBM12

J.M. Vorster, J. Montillaud, M. Juvela et al. (+14 more)

In our Galaxy, the average star formation efficiency is of the order of a few percent. We investigated the high-latitude molecular cloud MBM12 as part of the B-fields and star formation across scales (B-FROST) survey with the Taeduk Radio Astronomical Observatory (TRAO) to assess why star formation activity in MBM12 is low. We combine Herschel-based, locally $\kappa_\nu$-calibrated $N$(H$_2$) estimates with $^{12}$CO and $^{13}$CO ($J=1-0$) observations (2.5$^\circ \times$3$^\circ$ at 48$''$) to map $N$(CO), $X$(CO), and [CO/H$_2$], compute multi-scale $\alpha_{\rm vir}$ and mass-size scaling laws from dendrograms, and derive the histogram of relative orientations from Planck dust polarisation. We identify four main regions based on velocities that have H$_2$ column densities ranging from $2\times10^{20}$ cm$^{-2} - 1.3\times10^{22}$ cm$^{-2}$. The average $X$(CO) is close to the galactic average, with variations below $X_{\rm Gal}$ from collisional de-excitation in low-density gas, and above $X_{\rm Gal}$ from CO photodissociation at cloud edges. The hierarchical structures follow a broken power law mass-size relation $M=AR^\alpha$. The values of $\alpha_{\rm vir}$ ranged from $3-60$, with the smallest values at 0.1 pc scales. The mass-size relations for the structures with the lowest $\alpha_{\rm vir}$ have scaling factors $A$ three times larger than those of high $\alpha_{\rm vir}$ structures, indicating external pressure one order of magnitude larger. We found a transition of parallel to perpendicular between column density structures and magnetic field orientations at $N$(H$_2$) $= 4.5 \times 10^{21}$ cm$^{-2}$. We provide the first integrated chemical, dynamical, and magnetic field analysis of MBM12. Scale-dependent mass-size and virial analysis can further constrain the role of external pressure in regulating the star formation efficiency.
Read the full abstract

All authors J.M. Vorster, J. Montillaud, M. Juvela, E. Falgarone, J. Oers, E. Mannfors, D. Alina, Q. Gu, H. Kang, C.W. Lee, S. Li, T. Liu, K. Pattle, V.-M. Pelkonen, I. Ristorcelli, A. Zavagno, L. V. Tóth

Earth and Planetary Astrophysics

The Search for Technosignatures: a Review of Possibilities

Clément Vidal, Benji L. Fields, Damian R. Sowinski et al. (+16 more)

This paper reviews the diverse range of technosignatures that have been proposed in the literature. We organize the review by spatial scales from the Earth and the solar system to the edge of the Universe, not tied to a specific observatory or technical capability. This provides a more comprehensive view of technosignature science beyond the search for radio signals that has dominated SETI since its inception. We introduce the Kardashev and Barrow scales before exploring exoplanetary technosignatures, from surface, atmospheric to orbital sources. Next, we consider stellar technosignatures that may involve massive energy utilization, stellar modification or stellar pollution, and end with a section about compact objects. We then review attempts to detect interstellar communication, and discuss many dimensions of the search space from first principles. We also consider interstellar travel technosignatures, and end with galactic, extragalactic and universal signatures. The paper argues for stronger synergies between biosignature and technosignature searches, and the importance of multimodal and multimessenger strategies. Central to this is the importance of anomaly detection as a fundamental and agnostic search strategy. We highlight instruments for detecting technosignatures, as well as a science traceability matrix template.
Read the full abstract

All authors Clément Vidal, Benji L. Fields, Damian R. Sowinski, Stuart Bartlett, Richard J. Terrile, Alex Ellery, Daliah Bibas, Armando M. Mastrogiovanni, Niklas Döbler, Manika Singla, Julia DeMarines, Theresa Fisher, Yuri Uno, Jake D. Turner, Evan L. Sneed, Advait Huggahalli, Megan Grace Li, Zhuofu Li, Ramiro Saide

Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

Audible Axion Magnetogenesis: Linking Intergalactic Magnetic Fields and Gravitational Waves

Christopher Gerlach, Daniel Schmitt and Pedro Schwaller

Identifying dark matter candidates that simultaneously generate multiple observable cosmological signatures is a key goal in connecting particle physics with upcoming observations. Axion-like particles coupled to the Standard Model photon offer a promising framework. In the trapped misalignment mechanism, the onset of axion oscillations is delayed, inducing a period of supercooling in the early Universe. This can lead to exponential production of photon quanta via a tachyonic instability, generating observable gravitational wave signatures. Simultaneously, reheating of the Standard Model plasma produces strong, helical magnetic fields on intergalactic scales. The parameter space most promising for gravitational wave detection yields magnetic field strengths that exceed lower bounds from blazar observations.
Read the full abstract

High Energy Astrophysical Phenomena

The radio emission from radiative filaments of Cygnus Loop

D. Urošević, M. Andjelić, M. D. Filipović et al. (+4 more)

The Galactic supernova remnant (SNR) Cygnus Loop emerges as an ideal laboratory for analyzing the different radiation mechanisms, as well as the particle acceleration mechanisms at different types of shocks. In order to determine radio spectral indices of non-radiative and radiative filaments in Cygnus Loop, we observed previously optically analyzed filaments with the Karl G. Jansky Very Large Array (VLA). At 1 and 5 GHz, we detected only radiative filaments in the field of view. Non-radiative optical filaments are also present, but were not detected in radio. Contrary to the expected non-thermal spectral slopes characteristic of SNRs, we instead observed spectral slopes characteristic of the thermal radiation mechanism from the radiative filaments in Cygnus Loop. These evolutionary older parts of Cygnus Loop radiate at radio frequencies predominantly via the thermal bremsstrahlung mechanism, and in that sense their emission more closely resembles the radio emission of HII regions rather than the radio emission of SNRs.
Read the full abstract

All authors D. Urošević, M. Andjelić, M. D. Filipović, Z. J. Smeaton, E. Crawford, J. Raymond, D. Onić

Solar and Stellar Astrophysics

Neutron star-companion interaction in core collapse supernovae. Population synthesis based on detailed binary evolution models

Andrea Ercolino, Norbert Langer, Avishay Gal-Yam et al. (+6 more)

Most massive stars live in binary systems. When the first supernova (SN) in a binary occurs, the ejecta hit the companion, which may inflate as a consequence, and then interact with the newly formed compact object. The recent Type Ic SN2022jli shows a periodic modulation in its emission, which is interpreted as evidence for such interaction. We derive predictions for the occurrence rate and observables of SNe exhibiting these companion - compact-object interactions (CCIs). We analyze a comprehensive, state-of-the-art grid of detailed binary stellar evolution models, and implement analytic prescriptions for the expansion of the companion star following its interaction with the SN ejecta. We employ the newly developed population synthesis code SN-ORACLE to derive the distribution functions of the properties of the SNe affected by CCI and their companions, where we use different explodability and neutron star birth kick distributions. We find that periodic CCI is expected to occur in more than half of the binary systems that produce a hydrogen-poor core-collapse SN and are not disrupted, while the occurrence rate in systems producing hydrogen-rich SNe is small. We find broad period ranges, peaking around 20-50 days, with the interaction lasting for 0.5-10 years. We identify specific binary evolution models that reproduce the observed period of the light curve undulations of SN2022jli, SN2015ap, and SN2022esa. The inflation of the companion also increases its luminosity and brightness, increasing its detectability with current instruments. For SN2022jli, our best-fit models predict a J-band magnitude of 21-23 for up to 10 years. We find that up to 27% of H-poor SNe could show periodicity in their light curves, while only a few such events have been identified so far. Our results may help find periodic CCI features in future and archival SN observations.
Read the full abstract

All authors Andrea Ercolino, Norbert Langer, Avishay Gal-Yam, Abel Schootemeijer, Caroline Mannes, Harim Jin, Ruggero Valli, Selma de Mink, Luc Dessart

Cosmology and Nongalactic Astrophysics

Reconstruction of Reionization Histories from 21 cm Power-Spectrum Evolution with Artificial Neural Networks

Yu-Le Wang and Hayato Shimabukuro

We investigate whether the redshift evolution of the fixed-$k$ dimensionless 21 cm power spectrum, $\Delta^2_{21}(k, z)$, contains sufficient information to reconstruct reionization histories $x_{\rm HI}(z)$ with artificial neural networks. Using semi-numerical realizations generated within a restricted three-parameter 21cmFAST model family, we train a compact feed-forward network to learn the inverse mapping from power-spectrum trajectories to the neutral-fraction history on a 97-point redshift grid spanning $6 \le z \le 15$. For $k = 0.1$, $0.5$, and $1.0\ h\ \mathrm{Mpc}^{-1}$, representative tests on an independent test set show that the midpoint redshift $z_{50}$ is recovered more accurately than the duration $\Delta z = z_{75} - z_{25}$ in terms of dimensionless relative errors: $z_{50}$ is reconstructed with $\mathrm{MAE} = 0.0046$ and $\mathrm{RMSE} = 0.0100$, whereas $\Delta z$ yields $\mathrm{MAE} = 0.0302$ and $\mathrm{RMSE} = 0.0378$. This result indicates that fixed-$k$ power-spectrum evolution carries stronger information about the timing of reionization than about the detailed width of the transition within the adopted prior. We further test an idealized foreground-free SKA1-Low-like thermal-plus-sample-variance noise model and find that the reconstruction remains stable in the favorable signal-to-noise regime considered here. These results demonstrate that neural networks can serve as prior-dependent inverse mapping for reconstructing reionization histories from 21 cm power-spectrum evolution.
Read the full abstract

High Energy Astrophysical Phenomena

Lack of Significant Orbital-Phase Locking in the Active Phases of the Recurrent Nova T CrB

Songpeng Pei, Xiaowan Zhang, Renzhi Su et al. (+6 more)

T Coronae Borealis (T CrB) is a symbiotic recurrent nova (RN) that exhibits both nova eruptions and long-term active phases resembling superoutbursts and normal outbursts. Motivated by proposed connections between these events and the binary orbit, we test whether the onset, maximum, or termination of the active phases is locked to orbital phase. We use long-term optical $B$- and $V$-band light curves from the American Association of Variable Stars Observers (AAVSO) International Database and historical photometry from the literature. We measure the onset, maximum, and termination times of superoutbursts and normal outbursts and convert these times to orbital phase. We test the resulting circular distributions with Kuiper and Watson statistics. We find no statistically significant orbital-phase locking. The onset phases and maxima are consistent with a uniform phase distribution. The smallest probabilities occur for the 13 measurable termination phases ($p_{\rm MC}=0.043$ for the Kuiper statistic and $p_{\rm MC}=0.048$ for the Watson statistic), but this result is only marginal in an uncorrected $p<0.05$ sense, far from a $3\sigma$ detection, and insufficient to establish robust phase locking. The four historical nova eruptions likewise do not provide robust evidence for a unique ignition phase once the small sample size, historical date uncertainties, and long-term period changes are considered. The two known secondary eruptions occurred at similar phases, but two events are insufficient to establish an orbital-geometry connection. Overall, the active phases of T CrB appear to be governed primarily by accretion-disk physics rather than by a fixed binary phase.
Read the full abstract

All authors Songpeng Pei, Xiaowan Zhang, Renzhi Su, Yongzhi Cai, Ziwei Ou, Qiang Li, Xiaoqin Ren, Yu Liu, Taozhi Yang

Astrophysics of Galaxies

Dawn of the Milky Way disk: Determination of when a rotationally supported disk appears and dating the spin-up of the disk

Sofia Feltzing, Diane Feuillet and Thomas Bensby

Spiral galaxies, like the Milky Way, transform at some point in time into a rotationally supported system. Using an extant data-set consisting of 319 835 sub-giants from LAMOST with precise ages from the literature, we determine, for the first time the age when the Milky Way disk spins up, i.e. when the mean circular velocity changes from halo-like to disk-like. We find in concordance previous studies that the spin-up takes place for -1.25 < [Fe/H] <- 0.9 and we can date this transition to a mean age of 12.1 +/- 2.8 Gyr (median age 12.4 Gyr). We further study when the disk became rotationally supported, i.e. when the ordered, disky motion dominates over the random motions. We find that this happens for $-1.25<$[Fe/H]$<-1$. The transition is very rapid in age. This gives support to that the spin-up seen in this and other works genuinely traces the motion to a rotationally supported disk, which has not previously been shown. These transitions are traced by the high-alpha stars. while the low-alpha stars do not spin-up but start directly at approximately the circular velocity seen for the Sun today. The low-alpha disk is rotationally supported with no transition period in [Fe/H] or in age.
Read the full abstract

Solar and Stellar Astrophysics

Type-III solar radio bursts with spike-like toppings

Shuwang Chang, Chuanyang, Bing Wang et al. (+5 more)

Spike-type III burst pairs represent a distinct class of solar radio emissions in which clusters of spike-like bursts appear atop the highfrequency onset of type III bursts. Using high time-frequency resolution data from the Chashan Broadband Solar radio spectrometer at meter wavelengths (CBSm), we present the largest statistical study to date of such events, comprising 502 spike-type III pairs from 35 events recorded between November 2023 and October 2025. We find that spike-like clusters systematically precede their associated type III bursts by 0.5-3 s in time (~87% of pairs) and by 3-30 MHz in frequency (~80%), a temporal and spectral offset that differs from earlier reports. The spike-like clusters exhibit diverse morphologies, including point-like, blob-like, drifting, and diffuse structures, with durations of ~0.5-5 s and bandwidths of 15-150 MHz. Bi-directional drifting structures with rates of ~20-100 MHz s-1 are observed, consistent with source motion both toward and away from the Sun. Furthermore, spike emission is predominantly strongly circularly polarized, with more than 64% of clusters showing maximum polarization exceeding 0.6, in stark contrast to the generally weak polarization of type III bursts. These findings point to an origin of the spike radiation in a multiscale, inhomogeneous, and highly dynamic electron-acceleration region, providing novel observational constraints on the mechanisms underlying coherent solar radio bursts.
Read the full abstract

All authors Shuwang Chang, Chuanyang, Bing Wang, Guang Lu, Zhao Wu, Fabao Yan, Hao Ning, Yao Chen

High Energy Astrophysical Phenomena

Superfluid fraction in the crystalline crust of a neutron star: role of quantum zero-point motion of ions

Nicolas Chamel

The suppression of the neutron superfluid fraction in the inner crust of a cold neutron star is mitigated by the quantum zero-point motion of ions about their equilibrium position. In turn, the crustal dynamics is altered by the presence of the neutron superfluid. These effects are studied self-consistently to assess the validity of the usual assumption of a perfect rigid lattice. To this end, fully three-dimensional band-structure calculations of the superfluid fraction are carried out in the weak-coupling approximation, considering body- and face-centered cubic lattices. In both cases, the superfluid fraction is still found to be strongly suppressed in the intermediate region of the inner crust. In turn, the effective mass of the ions is dramatically increased, thus further damping the ion fluctuations. These results are of relevance for the rotational and thermal evolutions of neutron stars.
Read the full abstract

Astrophysics of Galaxies

Interpretations of galaxy spectra at high redshift. \ The H_gamma/H_beta excess

M. Contini

Spectra from the cosmic dawn obtained with JWST/NIRSpec (James Webb Space Telescope near-infrared spectroscopy) in the SMACS0723 Early Release Observations are now available. Analyses carried out by different teams indicate poor to extremely low oxygen metallicities (log(O/H)+12<8.0), a characteristic feature of pristine galaxies. In this work, we present new modelling of spectra emitted by objects in the redshift range 2.16<=z<= 8.68, including their recently corrected spectra in the z = 2-9 range. The models account for both photoionisation and shock processes. Our aim is to identify similarities and differences with respect to local galaxies by searching for possible remnants of pristine galaxies among low-z objects. We analyse selected emission-line ratios in relation to elemental abundances and physical parameters. We find that the gaseous clouds within galaxies at cosmic dawn have preshock densities at least a factor of 100 higher than those in local galaxies, but comparable to those calculated for local metal-poor galaxies at 0.005<z<0.05. The metallicities log(O/H)+12 and log(Ne/H)+12 range between 7.9 and 8.55, and between 7.0 and 7.48, respectively. Uncorrected observed Hg/Hb line ratios are mostly >0.5, indicating high temperatures (>10^5K) in the emitting gas. Clear affinities are evident between the high-z galaxy spectra and those of local metal-poor galaxies at 0.005<z<0.05. However, in order to reproduce all the observed line ratios for each spectrum - including Hg/Hb values as high as ~0.8 - emission from cloud fragments was added to that from the main clouds in the pluri-cloud models. We suggest that fragments close to pristine galaxies were destroyed by events that occurred between z>6 and z<0.05, whereas some cloud remnants of pristine galaxies survived and are now found embedded, for example, at 0.005<z<0.05.
Read the full abstract

Astrophysics of Galaxies

Difference Between Half-mass Radius and Half-light Radius of Galaxies at 0.2 $< z <$ 2.5 Revealed by JWST/NIRCam Data

Mingen Xin, Guanwen Fang, Jie Song et al. (+3 more)

Using JWST observations in CANDELS fields, we measure the half-light radius ($r_{\rm e,light}$) and half-mass radius ($r_{\rm e,mass}$) for 14,333 galaxies with stellar masses $M_* > 10^9 M_\odot$ at redshifts $0.2 < z < 2.5$. To investigate the difference between $r_{\rm e,light}$ and $r_{\rm e,mass}$, we find that $r_{\rm e,light}$ is larger than $r_{\rm e,mass}$ for both quiescent galaxies (QGs) and star-forming galaxies (SFGs). Moreover, the difference between these two radii is clearly correlated with galaxy stellar mass, $r_{\rm e,light}$, and the rest-frame $U - V$ color. When examining the evolution of the $r_{\rm e,mass}/r_{\rm e,light}$ ratio, we observe a significant increase for SFGs at $z > 1.7$. In contrast, no clear increase is observed for QGs at $z > 1$, though a slight decreasing trend is seen between $0.2 < z < 1.0$. By fitting a linear relationship between galaxy size and stellar mass, we find that the slope for $r_{\rm e,light}$ is $\sim$ 0.1 to 0.3 dex larger than that for $r_{\rm e,mass}$. In terms of galaxy size evolution at a fixed stellar mass, the $r_{\rm e,mass}$ of QGs increases by a factor of $\sim$ 3 to 5 from $z \sim 2.5$ to $z \sim 0.2$. In contrast, the $r_{\rm e,mass}$ of SFGs increases by a factor of approximately 2 over the same redshift range, with this growth trend closely following that of their $r_{\rm e,light}$. These results indicate that previous insights into galaxy evolution based on $r_{\rm e,light}$ remain valid when considering $r_{\rm e,mass}$, although the specific slopes show some variations.
Read the full abstract

All authors Mingen Xin, Guanwen Fang, Jie Song, Shiying Lu, Zesen Lin, Xu Kong

Astrophysics of Galaxies

The TNG50-SKIRT Atlas: Multi-wavelength nonparametric galaxy morphology

Sena Bokona Tulu, Maarten Baes, Angelos Nersesian et al. (+5 more)

Context: Galaxy morphology is a fundamental property to describe galaxy evolution. However, the observed morphology of a particular galaxy may depend on the observed wavelength. Aims: Our aim is to investigate the wavelength dependence and the effect of dust attenuation on nonparametric morphology indicators. Methods: We use the TNG50-SKIRT Atlas, an atlas of synthetic UV to near-infrared (NIR) broadband images for a complete stellar-mass-selected sample of 1154 galaxies extracted from the TNG50 cosmological simulation at $z = 0$. For each image, we calculate four nonparametric morphology indicators using the StatMorph code. Results: We find that the known correlations between the stellar mass and the morphological parameters measured in the optical, together with the Gini-$M_{20}$, concentration-Gini, and concentration-$M_{20}$ planes, are fully consistent with observational data. However, nonparametric morphological indicators change significantly with wavelength and that this wavelength dependence is stronger for disc-dominated than for bulge-dominated galaxies. The wavelength dependence of the morphology of our simulated TNG50 galaxies is consistent with measurements of local galaxies from the SINGS survey. We demonstrate that the effect of dust attenuation on nonparametric morphology indicators is modest across the full galaxy population but can be significant for individual galaxies.
Read the full abstract

All authors Sena Bokona Tulu, Maarten Baes, Angelos Nersesian, Tolu Biressa, Vicente Rodriguez-Gomez, Andrea Gebek, Marco Martorano, Abdissa Tassama Emana

High Energy Astrophysical Phenomena

Relativistic Scattering in the Funnel of Cygnus X-3

Suraj K. Chaurasia, Ranjeev Misra and Amit Pathak

Cygnus X-3 presents significant challenges to standard accretion models. Recent polarimetric observations by IXPE reveal high polarization degrees (PD) in the hard state ($\sim 23\%$) and unexpectedly significant polarization in the soft state ($\sim 12\%$), which are difficult to reconcile with static scattering models at low inclination ($i \approx 30^\circ$). We present a relativistic scattering model within a funnel-shaped geometry that resolves this discrepancy. We show that a single funnel-outflow configuration with variable bulk velocity $\beta$ can reproduce both polarization states, with lower velocities ($\beta \approx 0$) yielding $\sim 12\%$ polarization (soft state) and mildly relativistic velocities ($\beta \lesssim 0.4$) producing $\sim 23\%$ polarization (hard state) at $i \approx 30^\circ$ for half funnel opening angles of $\sim 13^\circ$-$16^\circ$. Relativistic aberration modifies the effective scattering angle in the comoving frame, enhancing polarization in the hard state while recovering the static limit in the soft state. The model also yields a consistent estimate of the intrinsic luminosity, of order $\sim 10^{40}$ erg s$^{-1}$, supporting a super-Eddington interpretation. This framework provides a unified explanation of the observed polarization properties of Cygnus X-3.
Read the full abstract

Instrumentation and Methods for Astrophysics

Down going muon rate monitoring in the ANTARES detector

K. Gracheva, M. Anghinolfi, V. Kulikovskiy et al. (+2 more)

Large underwater telescopes have been proposed as a challenging method to measure high energy neutrinos from astrophysical objects. In recent years, The Antares collaboration has designed and realized the first detector of this type in the Mediterranean Sea. Muon tracks produced by the neutrino interaction in the surrounding medium are reconstructed from the arrival time and the number of photo-electrons of the Cherenkov light measured by the Photomultiplier tubes (PMT) array of the detector. In order to provide sufficient statistics, the events from various periods in the year must be summed together taking care of the various environmental conditions and detector configurations. In this note we describe effective criteria to group compatible runs based on the effective number of active PMTs in each run.
Read the full abstract

All authors K. Gracheva, M. Anghinolfi, V. Kulikovskiy, E. Shirokov, Y. Yakovenko