Instrumentation and Methods for Astrophysics
MARVEL: A Multi Agent-based Research Validator and Enabler using Large Language Models
Nikhil Mukund, Yifang Luo, Fan Zhang et al. (+2 more)
We present MARVEL (https://ligogpt.mit.edu/marvel), a locally deployable, open-source framework for domain-aware question answering and assisted scientific research. It is designed to address the increasing demands of a digital assistant for scientific groups that can read highly technical data, cite precisely, and operate within authenticated networks. MARVEL combines a fast path for straightforward queries with a more deliberate DeepSearch mode that integrates
retrieval-augmented generation and Monte Carlo Tree Search. It explores complementary subqueries, allocates more compute to promising branches, and maintains a global evidence ledger that preserves sources during drafting. We applied this framework in the context of gravitational-wave research related to the
Laser Interferometer Gravitational-wave Observatory. Answers are grounded in a curated semantic index of research literature, doctoral theses, LIGO documents, and long-running detector electronic logbooks, with targeted web searches when appropriate. Because direct benchmarking against commercial LLMs cannot be performed on private data, we evaluated MARVEL on two publicly available surrogate
datasets that capture comparable semantic and technical characteristics. On these
benchmarks, MARVEL matches a GPT-4o mini baseline on literature-centric queries and substantially outperforms it on detector-operations content, where domain
retrieval and guided
reasoning are decisive. By making the complete framework and evaluation
datasets openly available, we aim to provide a reproducible foundation for developing domain-specific scientific assistants.
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All authors Nikhil Mukund, Yifang Luo, Fan Zhang, Lisa Barsotti, Erik Katsavounidis
Instrumentation and Methods for Astrophysics
Simulation-Based Inference for Probabilistic Galaxy Detection and Deblending
Ismael Mendoza, Derek Hansen, Runjing Liu et al. (+6 more)
Stage-IV dark energy wide-field surveys, such as the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST), will observe an unprecedented number density of
galaxies. As a result, the majority of imaged
galaxies will visually overlap, a phenomenon known as blending. Blending is expected to be a leading source of systematic error in astronomical measurements. To mitigate this systematic, we propose a new probabilistic method for detecting, deblending, and measuring the properties of
galaxies, called the
Bayesian Light Source Separator (BLISS). Given an astronomical survey image, BLISS uses convolutional neural networks to produce a probabilistic astronomical catalog by approximating the posterior distribution over the number of light sources, their centroids' locations, and their types (
galaxy vs.
star). BLISS additionally includes a denoising autoencoder to reconstruct unblended
galaxy profiles. As a first step towards demonstrating the feasibility of BLISS for cosmological applications, we apply our method to simulated single-band images whose properties are representative of year-10 LSST coadds. First, we study each BLISS component independently and examine its probabilistic output as a function of SNR and degree of blending. Then, by propagating the probabilistic detections from BLISS to its deblender, we produce per-object flux posteriors. Using these posteriors yields a substantial improvement in aperture flux residuals relative to deterministic detections alone, particularly for highly blended and faint objects. These results highlight the potential of BLISS as a scalable, uncertainty-aware tool for mitigating blending-induced systematics in next-generation cosmological surveys.
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All authors Ismael Mendoza, Derek Hansen, Runjing Liu, Zhe Zhao, Ziteng Pang, Axel Guinot, Camille Avestruz, Jeffrey Regier, the LSST Dark Energy Science Collaboration
Astrophysics of Galaxies
Integral field spectroscopy and numerical simulations of the NGC 2207/IC 2163 system
Camille Poitras, René Pierre Martin, Laurent Drissen et al. (+2 more)
We present integral field spectroscopy of the interacting
galaxy system NGC 2207/IC 2163 obtained with the imaging
Fourier Transform Spectrometer SITELLE. Approximately 1000 HII region complexes are detected in both
galaxies and analyzed using their strong optical emission lines. Their properties were studied via BPT diagrams and their luminosity function. We conducted a detailed study of the distribution of oxygen abundance across the system using a series of strong-line O/H indicators and calibrations. Both
galaxies exhibit negative galactocentric abundance gradients with a slope -0.015 dex kpc$^{-1}$. There are marginal signs of discontinuities in the O/H gradients with some indicators while no significant azimuthal variations are seen. A shallower slope in the HII region luminosity function between the arm and inter-arm regions in IC 2163 is observed, supporting previous conclusion that the
star formation process in this
galaxy eyelids has been altered during the interaction. The kinematics of the ionised gas reveal disturbed velocity fields, AGN-like features in the
nucleus of NGC 2207, and elevated velocity dispersion in turbulent or feedback-driven regions. To interpret these findings, we modeled the collision using the numerical
algorithm GCD+. The simulation reproduces key features of the system and demonstrates how close passages drive enhanced
star formation and localized chemical enrichment. Finally, two
dwarf galaxies in the field are found to have very similar systemic velocities as their larger counterparts, and could well play a minor role in the global interaction based on their morphology and position.
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All authors Camille Poitras, René Pierre Martin, Laurent Drissen, Hugo Martel, Carmelle Robert
Earth and Planetary Astrophysics
Estimation of the tidal heating in the TRAPPIST-1 planets. Influence of the internal structure
Emeline Bolmont, Mariana Sastre, Alexandre Revol et al. (+2 more)
With the arrival of JWST observations of the TRAPPIST-1
planets, it is timely to reassess the contribution of
tidal heating to their heat budget. JWST thermal phase curves could reveal endogenic heating through an anomalously high nightside temperature, providing an opportunity to estimate
tidal heating. In this study, we revisit the
tidal heating of these
planets and propose a simple method to compute the
tidal heating profile across a broad range of parameters. Our approach leverages a known formulation for synchronously rotating
planets on low-eccentricity orbits and the fact that the profile shape depends solely on internal structure. We calculate the
tidal heating contributions for all T-1
planets, with a particular focus on the impact of internal structure and eccentricity uncertainties on their total heat budget. Although the masses and radii of these
planets are well constrained, degeneracies remain in their internal structure and composition. For volatile-poor
planets of silicate-rock compositions, we investigate the role of core iron content by exploring a range of core sizes. For each structure, we compute the degree-two gravitational Love number, $k_2$, and the corresponding
tidal heating profiles. We assume sub-solidus temperatures profiles that are decoupled from interior heat production, which means our estimates are conservative and likely represent minimum values. We find that the
tidal heat flux for T-1b and c can exceed Io's heat flux, with uncertainties primarily driven by eccentricity. These high fluxes may be detectable with JWST. For T-1f to g, the
tidal flux remains below Earth's geothermal flux, suggesting that
tidal heating is unlikely to be the dominant energy source. For
planets d and e, however,
tidal heating likely dominates their heat budget, potentially driving intense volcanic and tectonic activity, which could enhance their habitability prospects.
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All authors Emeline Bolmont, Mariana Sastre, Alexandre Revol, Mathilde Kervazo, Gabriel Tobie
High Energy Astrophysical Phenomena
Late-Time Infrared Cooling in Magnetar-Driven Supernovae
Conor M. B. Omand
A central magnetar engine is commonly invoked to explain energetic
supernovae, which should have multiple signals in multiwavelength emission. Photoionization from the
pulsar wind nebula (PWN) can create distinct spectroscopic signals in the nebular phase. Recent models suggest infrared emission, particularly from Ne II, can be prominent at late times. This work examines the cooling power of optical and infrared transitions to determine which lines contribute strongly to cooling and on what timescale. The models show infrared cooling becomes strong at $\sim$ 3 years post-explosion and dominates by 6 years, with [Ne II] 12.8$\mu$m being the strongest coolant. The fraction of total cooling in the infrared increases sharply once the PWN luminosity decreases below 10$^{40}$ erg s$^{-1}$, and this fraction also increases with increasing ejecta mass and decreasing average PWN
photon energy. However, the emission from [Ne II] 12.8$\mu$m increases with increasing PWN luminosity and increasing ejecta mass. Cooling at 1 year is dominated by optical O and S lines, with infrared Ar, Ni, and Ne lines becoming strong at 3 years. Optical cooling is almost negligible at 6 years, with the
supernova cooling almost entirely through mid- and far-infrared transitions. JWST spectroscopy with MIRI should be able to detect these lines out to $z \sim 0.1$.
Supernovae with higher
magnetic fields transition to infrared cooling on earlier timescales, while infrared-dominated
supernovae should have strong emission from neutral atoms and emit strongly in
radio at sub-decade timescales.
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High Energy Astrophysical Phenomena
Multiwavelength Modeling of the Luminous Fast Blue Optical Transient AT2024wpp
Conor M. B. Omand, Nikhil Sarin, Gavin P. Lamb et al. (+14 more)
Luminous fast blue optical transients (LFBOTs) are a growing class of enigmatic energetic transients. They show fast rises and declines, high temperatures throughout their
evolution, and non-thermal emission in
radio and X-rays. Their power source is currently unknown, but proposed models include engine-driven
supernovae, interaction-powered
supernovae, shock cooling emission, intermediate mass black hole
tidal disruption events (IMBH TDEs), and Wolf-Rayet/black hole mergers, among others. AT2024wpp is the most optically luminous LFBOT to date and has been observed extensively at multiple wavelengths, including
radio, optical, UV, and X-rays. We take models from multiple scenarios and fit them to the AT2024wpp optical,
radio, and X-ray light curves to determine which of these scenarios can best describe all aspects of the data. We show that none of the multiwavelength light curve models can reasonably explain the data, and that other physical arguments disfavour models with homologously expanding ejecta. We discuss how a
stellar mass/IMBH TDE of a low mass
star can be tested with late-time observations, and what other scenarios could possibly explain the broadband data.
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All authors Conor M. B. Omand, Nikhil Sarin, Gavin P. Lamb, Daniel A. Perley, Andrew Mummery, Hamid Hamidani, Steve Schulze, Emma R. Beasor, Aleksandra Bochenek, Helena-Margaret S. Grabham, Sorcha R. Kennelly, Nguyen M. Khang, Shiho Kobayashi, Genevieve Schroeder, William N. Stone, Cairns Turnbull, Jacob Wise
Solar and Stellar Astrophysics
Extreme-ultraviolet synthesis of nanojet-like ejections due to coalescing flux ropes
Samrat Sen, A. Ramada C. Sukarmadji, D. Nóbrega-Siverio et al. (+3 more)
Detection and characterization of small-scale energetic events such as nanoflares and nanojets remain challenging owing to their short lifetimes, small spatial extent, and relatively low energy release, despite their potential role in coronal heating. Recent observations have identified nanojets as small-scale (length $\lesssim 6.6$~Mm, width $\lesssim 1$~Mm), fast ($\sim$~few 100 km s$^{-1}$), and short-lived ($\lesssim 30$~s) ejections associated with nanoflare-scale energies, providing evidence of
magnetic reconnection at small spatial scales. However, the lack of synthetic diagnostics has limited the connection between magnetohydrodynamic (MHD) models and observations. In this Letter, we present synthetic observations of the coalescence of two flux ropes, leading to nanojet-like signatures from a numerical model obtained with the MPI-AMRVAC code. We report synthetic observables in Extreme-ultraviolet lines compatible with existing instruments such as SDO/AIA, and upcoming MUSE mission, and compare the synthetic observables with an existing observation of nanojets. The synthetic diagnostics of the emissivity maps, Doppler velocity, thermal, and non-thermal line broadening produce key observational properties, suggesting a plausible 3D scenario for nanojet generation where tiny flux ropes reconnect within loops. Our results provide predictions for the detectability of nanojets with current and future spectroscopic facilities, and establish a bridge between MHD modeling and observations.
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All authors Samrat Sen, A. Ramada C. Sukarmadji, D. Nóbrega-Siverio, F. Moreno-Insertis, J. Martínez-Sykora, Patrick Antolin
Solar and Stellar Astrophysics
The SOL $\textit{(Solar Origin and Life)}$ Project: Detailed characterization of candidates for the ZAMS and Subgiant stages
C. Eduardo-Oliveira S., L. Ghezzi, G. F. Porto de Mello et al. (+3 more)
The context of the Sun in the
galactic neighborhood is not well understood, especially when we compare its physical properties to those of nearby
stars. Thereby, we still cannot fully comprehend whether or not the Sun is a typical
star. This work aims to identify and characterize
stars aligned with the
solar evolutionary track that could represent it at the ZAMS and subgiant stages. We performed a spectroscopic analysis of 18 photometrically selected candidates using high-resolution and high-SNR spectra as well as the classical spectroscopic method, based on the excitation and ionization
equilibria of Fe I and Fe II lines. Additionally, we derived evolutionary parameters using isochrones, and kinematic parameters. We also estimated chromospheric activity levels and performed age estimates through 3 additional independent methods: activity-age relations using the Ca II H $\&$ K and H$\alpha$ lines, and rotation periods estimated from TESS light curves. We identified three candidates that provide a good match to the Sun at $\approx$ 0.5 Gyr (HD 13531 and HD 61033) and subgiant (HD 148577) stages. Moreover, HD 197210 could be of interest when studying the Sun at $\approx$ 2 Gyr, when the Earth's atmosphere started having a significant amount of oxygen. Our selection method was successful and we were able to identify
stars similar to the Sun at different evolutionary stages, which is essential for future research in the search of
exoplanets and understand habitability, especially with the advent of the next generation of
exoplanet-hunting instruments.
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All authors C. Eduardo-Oliveira S., L. Ghezzi, G. F. Porto de Mello, D. Lorenzo-Oliveira, P. V. Souza dos Santos, E. Costa-Almeida
High Energy Astrophysical Phenomena
Simulation-Based Prediction of Black Hole Spectra: From $10M_\odot$ to $10^8 M_\odot$
Chris Nagele, Julian H. Krolik, Rongrong Liu et al. (+2 more)
It has long been thought that black hole
accretion flows are driven by magnetohydrodynamic (MHD)
turbulence, and there are now many general relativistic global simulations illustrating the dynamics of this process. However, many challenges must be overcome in order to predict observed spectra from luminous systems. Ensuring energy conservation, local thermal balance, and local ionization
equilibrium, our post-processing method incorporates all the most relevant radiation mechanisms: relativistic Compton scattering, bremsstrahlung, and lines and edges for 30 elements and all their ions. Previous work with this method was restricted to black holes of $10 M_\odot$; here, for the first time, we extend it to $10^8 M_\odot$ and present results for two sub-Eddington
accretion rates and black hole
spin parameter 0.9. The spectral shape predicted for
stellar-mass black holes matches the low-hard state for the lower
accretion rate and the steep power law state for the higher
accretion rate. For high black hole mass, both
accretion rates yield power-law continua from $\sim 0.5 - 50$~keV whose X-ray slopes agree well with observations. For intermediate mass black holes, we find a soft X-ray excess created by inverse Compton scattering of low-energy
photons produced in the thermal part of the disk; this mechanism may be relevant to the soft X-ray excess commonly seen in massive black holes. Thus, our results show that standard radiation physics applied to GRMHD simulation data can yield spectra reproducing a number of the observed properties of accreting black holes across the mass spectrum.
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All authors Chris Nagele, Julian H. Krolik, Rongrong Liu, Brooks E. Kinch, Jeremy D. Schnittman
Cosmology and Nongalactic Astrophysics
Mind the peak: improving cosmological constraints from GWTC-4.0 spectral sirens using semiparametric mass models
Matteo Tagliazucchi, Michele Moresco, Nicola Borghi et al. (+1 more)
Gravitational wave spectral sirens can provide cosmological constraints by using the shape of the binary black hole (BBH) mass distribution (MD). However, the precision and accuracy of these constraints depends critically on the capturing all the MD features. In this work, we analyze 137 BBH events from the latest GWTC-4.0 with a novel data-driven semiparametric approach based on Bspline that adaptively places
knots around the most informative structures in the MD, while keeping the dimensionality of the parameter space moderate. Our flexible models resolve three distinct peaks at $\sim10$, $18$, and $33\,\mathrm{M}_\odot$ and are statistically preferred over standard parametric models, with Bayes factors up to 226. Because these features are correlated with $H_0$, the semiparametric model yields, under different prior assumptions, 12%-21% improvement in the precision of $H_0$ relative to parametric models, providing $H_0 = 57.8^{+21.9}_{-20.6}\,\mathrm{km/s/Mpc}$ in the best case. Our results demonstrate that capturing the full complexity of the BBH mass distribution is essential for realizing the cosmological potential of spectral sirens as gravitational wave catalogs continue to grow.
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All authors Matteo Tagliazucchi, Michele Moresco, Nicola Borghi, Chiara Ciapetti
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Sterile Neutrino Dark Matter as a Probe of Inflationary Reheating
James M. Cline and Yong Xu
Sterile
neutrinos offer a minimal and testable explanation for dark matter (DM), with their radiative decay actively searched for in X-ray observations. We show that cold sterile
neutrino DM can be efficiently produced during reheating from inflaton decays with a small branching ratio, ${\rm BR}\lesssim 10^{-4}$. This production mechanism opens regions of parameter space where the active-sterile mixing is small enough to evade current X-ray constraints while reproducing the observed DM abundance. We systematically map the viable parameter space in terms of the sterile
neutrino mass, mixing angle, inflaton mass, reheating temperature, and branching ratio. We further demonstrate that sterile
neutrino DM can serve as a probe of inflationary reheating, with future X-ray observations capable of yielding information on the inflaton mass and the reheating-temperature ratio $m_\phi/T_{\rm rh}$. For a given inflationary model in which the inflaton mass is known, this leads to a lower bound on the reheating temperature that is several orders of magnitude stronger than the existing bound from Big Bang Nucleosynthesis.
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Solar and Stellar Astrophysics
Non-thermal particle acceleration in multi-species kinetic plasmas: universal power-law distribution functions and temperature inversion in the solar corona
Uddipan Banik and Amitava Bhattacharjee
Non-thermal power-law distribution functions are ubiquitous in astrophysical, space, and laboratory kinetic
plasmas, but their origin remains unclear. A related puzzle is the temperature inversion of the
solar corona. We show that these phenomena are deeply connected by developing a self-consistent quasilinear theory for electromagnetically driven, unmagnetized kinetic
plasmas. The theory yields a multi-species Fokker-Planck equation with drive-induced
diffusion from direct acceleration by broad-band turbulent or narrow-band wave-like fields, indirect acceleration by excited waves, and Balescu-Lenard
diffusion/drag from Debye-scale fluctuations and Coulomb collisions. For a super-Debye turbulent electric-field spectrum, $|{\bf E}_{\bf k}|^2\propto k^{-\alpha}$, electrons and ions relax toward a universal $f(v)\propto v^{-5}$, or $N(E)\propto E^{-2}$, attractor, equivalent to the high-energy tail of a $\kappa=1.5$ distribution, when $\alpha\ge5$. This universality follows from Debye screening: large-scale fields accelerate unscreened fast particles but not screened slow ones. For shallower spectra, $\alpha<5$, the tail scales as $v^{-\alpha}$; incomplete relaxation and anisotropy also break universality. Anisotropic wave drives yield branch- and spectrum-dependent exponents. Because collisions cannot decelerate suprathermal particles, the tails resist Maxwellianization. In the
solar atmosphere, such tails may be generated by chromospheric convection or nanoflares despite collisional and radiative losses. Direct wave heating energizes electrons through Landau-resonant interactions with whistler and electron-cyclotron waves, while ions may be accelerated by turbulent ambipolar fields. Resulting $\kappa\simeq1.5$–$3$ distributions produce an abrupt upper-chromosphere/lower-corona transition and velocity-filtration-driven inverted profiles, yielding coronal temperatures $\sim10^6\,{\rm K}$.
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High Energy Astrophysical Phenomena · Cross-listed from hep-ph
Cavity Multimodes as an Array for High-Frequency Gravitational Waves
Yanfei Shang, Yuxin Liu, Diego Blas et al. (+2 more)
Microwave cavities operated in the presence of a background
magnetic field provide a promising avenue for detecting high-frequency gravitational waves (HFGWs). We demonstrate for the first time that the distinct
antenna patterns of multiple electromagnetic modes within a single cavity enable localization and reconstruction of key properties of an incoming HFGW signal, including its polarization ratio and frequency drift rate. Using a 9-
cell cavity commonly employed in particle accelerators as a representative example, we analyze the time-domain response of 18 nearly degenerate modes, which can be sequentially excited by a frequency-drifting signal. The sensitivity is further enhanced by the number of available modes, in close analogy to the scaling achieved by a network of independent detectors, enabling sensitivity to astrophysically plausible binary sources.
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All authors Yanfei Shang, Yuxin Liu, Diego Blas, Yifan Chen, Jing Shu
High Energy Astrophysical Phenomena · Cross-listed from gr-qc
Fast frequency-domain phenomenological modeling of eccentric aligned-spin binary black holes
Antoni Ramos-Buades, Quentin Henry and Maria Haney
We present the IMRPhenomXE frequency-domain phenomenological waveform model for the dominant mode of inspiral-merger-ringdown non-precessing binary black holes in elliptical orbits. IMRPhenomXE extends the quasi-circular IMRPhenomXAS waveform model for the dominant $(\ell, |m|) =$ (2,2) modes to eccentric binaries. For the inspiral part, orbit-averaged equations of motion within the quasi-Keplerian parametrization up to third post-Newtonian order, including
spin effects, are evolved, and the waveform modes are computed using the stationary phase approximation on eccentricity expanded expressions up to $\mathcal{O}(e^{12})$. The model assumes circularization at merger-ringdown, where it adopts the underlying quasicircular IMRPhenomXAS baseline. We show that IMRPhenomXE reduces to the accurate IMPhenomXAS model in the quasi-circular limit. Compared against 186 public numerical relativity waveforms from the Simulating eXtreme Spacetimes catalog with initial eccentricities up to $~0.8$, IMRPhenomXE provides values of unfaithfulness below $3\%$ for $72\%$ of simulations with initial eccentricities below 0.4. For larger eccentricities, the unfaithfulness degrades up to $\gtrsim 10\%$ due to the underlying small eccentricity expansions and additional modelling approximations. In terms of speed, IMRPhenomXE outperforms any of the existing inspiral-merger-ringdown eccentric waveform models. We demonstrate the efficiency, robustness, and modularity of IMRPhenomXE through injections into zero noise and parameter-estimation analyses of gravitational-wave events, showing that IMRPhenomXE is a ready-to-use waveform model for gravitational-wave astronomy in the era of rapidly growing event catalogs.
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Astrophysics of Galaxies
Early thin-disc assembly revealed by JWST edge-on galaxies
Marloes van Asselt, Francesca Rizzo and Luca Di Mascolo
The vertical structure of
stellar discs provides key constraints on their formation and
evolution. Nearby spirals, including the Milky Way, host thin and thick components that may arise either from an early turbulent phase or from the subsequent dynamical heating of an initially thin disc; measuring disc thickness across
cosmic time therefore offers a direct test of these scenarios. We present a new methodology to measure the thickness of edge-on
galaxies that explicitly accounts for departures from perfectly edge-on orientations by fitting a full three-dimensional model with forward modelling. This improves on traditional approaches that assume an inclination of $90^\circ$ and can bias thicknesses high. Applying the method to JWST imaging of
galaxies at $1<z<3$ with
stellar masses $\gtrsim 10^9~M_\odot$ from four major surveys, we measure a median scale height of $z_0 = 0.25\pm0.14$~kpc and a median ratio $h_r/z_0=8.4\pm3.7$. These values are consistent with the Milky Way and local thin discs, and indicate scale heights $\sim 1.6$ times smaller than those inferred for local
galaxies from single-disc fits. This result implies that thin discs are already present at $z\sim3$. We further show that a thick disc contributing 10% of the thin-disc luminosity would be detectable in the data considered in this work, implying that any thick disc present must be fainter and favouring a scenario in which thick discs build up progressively through dynamical heating at $z<1$.
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Astrophysics of Galaxies
Fast rotations in galaxies at cosmic noon indicate central concentration of stars, dark matter or massive black holes
Fernanda Roman-Oliveira, Francesca Rizzo and Filippo Fraternali
The rotation curves of regularly rotating disc
galaxies are a unique probe of the gravitational potential and dark matter distribution. Until recently, matter decomposition of rotation curves at $z>0.5$ was challenging, not only due to the lack of high resolution kinematic data but also of both suitable photometry to accurately trace the
stellar surface density and spatially-resolved sub-mm observations to trace the cold gas distribution. In this paper, we analyse three
galaxies from the Archival Large Program to Advance Kinematic Analysis (ALPAKA) sample, combining highly resolved cold gas observations from ALMA with rest-frame near-infrared imaging from JWST to investigate their dynamical properties and constrain their dark matter
halos. The
galaxies, initially classified as regularly rotating discs based on ALMA observations alone, appear in JWST as extended and symmetric
stellar discs with spiral arms. Our dynamical models reproduce the rotation of the discs in the outer parts well, but they systematically underpredict the inner rotation velocities, revealing a deficit of central mass relative to the data. This discrepancy indicates either an underestimation of the bulge masses due to variations in the
stellar mass-to-light ratio or
dust attenuation or the presence of overmassive black holes. Alternatively, it may suggest departures from standard dark-matter
halo profiles, including enhanced central concentrations.
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High Energy Astrophysical Phenomena
AT2024wpp: An Extremely Luminous Fast Ultraviolet Transient Powered by Accretion onto a Black Hole
Daniel A. Perley, Anna Y. Q. Ho, Zoë McGrath et al. (+69 more)
We present the discovery of AT 2024wpp ("Whippet"), a fast and luminous 18cow-like transient. At a
redshift of z=0.0868, revealed by Keck
Cosmic Web Imager spectroscopy of its faint
star-forming host, it is the fourth-nearest example of its class to date. Rapid identification of the source in the Zwicky Transient Facility data stream permitted ultraviolet-through-optical observations to be obtained prior to peak, allowing the first determination of the peak bolometric luminosity (2x10^45 erg/s), maximum photospheric radius (10^15 cm), and total radiated energy (10^51 erg) of an 18cow-like object. We present results from a comprehensive multiwavelength observing campaign, including a far-UV spectrum from the
Cosmic Origins Spectrograph on the Hubble Space
Telescope and deep imaging extending >100 days post-explosion from the Very Large
Telescope, Hubble Space
Telescope, Very Large Array, and Atacama Large Millimetre Array. We interpret the observations under a model in which a rapidly-accreting central engine blows a fast (~0.2c) wind into the surrounding medium and irradiates it with X-rays. The high Doppler velocities and intense ionization within this wind prevent identifiable spectroscopic features from appearing in the ejecta or in the surrounding circumstellar material. Weak H and He signatures do emerge in the spectra after 35 days in the form of double-peaked narrow lines. Each peak is individually narrow (full width ~3000 km/s) but the two components are separated by ~6600 km/s, indicating stable structures of denser material, possibly representing streams of
tidal ejecta or an ablated companion
star.
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All authors Daniel A. Perley, Anna Y. Q. Ho, Zoë McGrath, Michael Camilo, Cassie Sevilla, Ping Chen, Genevieve Schroeder, Taya Govreen-Segal, Aleksandra Bochenek, Yu-Jing Qin, James H. Gillanders, Benjamin Amend, Joseph P. Anderson, Igor Andreoni, Amar Aryan, Eric C. Bellm, Joshua S. Bloom, Thomas de Boer, Jonathan Carney, Ilaria Caiazzo, Ken C. Chambers, Panos Charalampopoulos, Ting-Wan Chen, Tracy X. Chen, Eric R. Coughlin, Michael Coughlin, Michel Dennefeld, Georgios Dimitriadis, Christoffer Fremling, Danielle Frostig, Avishay Gal-Yam, Lluís Galbany, Anjashay Gangopadhyay, Melzie Ghendrih, Matthew J. Graham, Mariusz Gromadzki, Steven L. Groom, Claudia P. Gutiérrez, K.-Ryan Hinds, Mark E. Huber, Cosimo Inserra, Benjamin C. Kaiser, Mansi M. Kasliwal, Niilo E. Koivisto, Chien-Cheng Lin, Chang Liu, Thomas B. Lowe, Eugene Magnier, Ashish A. Mahabal, Andrew Milligan, Paloma Minguez, Geoffrey Mo, Tomás E. Müller-Bravo, Matt Nicholl, Priscila J. Pessi, Giuliano Pignata, Josiah Purdum, Nabeel Rehemtulla, R. Michael Rich, Anwesha Sahu, Avinash Singh, Stephen J. Smartt, Jesper Sollerman, Gokul Srinivasaragavan, Shubham Srivastav, Robert D. Stein, Steve Schulze, Jack W. Tweddle, Richard Wainscoat, Jacob L. Wise, Lin Yan, David R. Young
Cosmology and Nongalactic Astrophysics
Heavy Black-Holes Also Matter in Standard Siren Cosmology
Grégoire Pierra and Alexander Papadopoulos
With the release of the Gravitational-Wave Transient Catalog GWTC-4.0 by the LIGO-Virgo-KAGRA (LVK) collaboration, 218 candidate detections of gravitational waves (GWs) from compact binary coalescences (CBCs) have been reported. This milestone represents a major advancement for GW cosmology, as many methods, particularly those employing the spectral siren approach, critically depend on the number of available sources. We investigate the impact of a novel parametric model describing the full population mass spectrum of CBCs on the estimation of the Hubble constant. This model is designed to test the impact of heavy black holes in GW cosmology. We perform a joint inference of cosmological and population parameters using 142 CBCs from GWTC-4.0 with a false alarm rate smaller than 0.25 per year, using both spectral and dark siren approaches. With spectral sirens, we estimate the Hubble constant to be $H_0 = 78.8^{+19.0}_{-15.3}\,{\rm km s^{-1} Mpc^{-1}}$ (68% CL), while the dark siren method yields $H_0 = 82.5^{+16.8}_{-14.3}\,{\rm km s^{-1} Mpc^{-1}}$ (68% CL). These results improve the uncertainty by approximately 30.4% and 36.2%, respectively. We show that this improvement is linked to the presence of a new mass scale in the binary black hole mass spectrum at $63.3^{+4.8}_{-4.8}\,M_{\odot}$, which provides additional constraints on the Hubble constant. Besides providing the tightest standard-siren constraints on $H_0$, this highlights the importance of a heavy-mass feature in the black hole spectrum.
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Cosmology and Nongalactic Astrophysics
The Squeezed Bispectrum from CHIME HI Emission and Planck CMB Lensing: Current Sensitivity and Forecasts
CHIME Collaboration, Arnab Chakraborty, Matt Dobbs et al. (+18 more)
Line intensity mapping using atomic hydrogen (HI) has the potential to efficiently map large volumes of the universe if the signal can be successfully separated from overwhelmingly bright
radio foreground emission. This motivates cross-correlations, to ascertain the cosmological nature of measured HI fluctuations, and to study their connections with
galaxies and the underlying matter density field. However, these same foregrounds render the cross-correlation with projected fields such as the
lensing of the
cosmic microwave background (CMB) difficult. Indeed, the correlated
Fourier modes vary slowly along the line of sight, and are thus most contaminated by the smooth-spectrum
radio continuum foregrounds. In this paper, we implement a method that avoids this issue by attempting to measure the non-linear gravitational coupling of the small-scale 21cm power from the Canadian Hydrogen Intensity Mapping Experiment (CHIME) with large-scale Planck CMB
lensing. This measurement is a position-dependent power spectrum, i.e. a squeezed integrated bispectrum. Using 94 nights of CHIME data between $1.0 < z < 1.3$ and aggressive foreground filtering, we find that the expected signal is five times smaller than the current noise. We forecast that incorporating the additional nights of CHIME data already collected would enable a signal-to-noise ratio of 3, without any further improvements in filtering for foreground cleaning.
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All authors CHIME Collaboration, Arnab Chakraborty, Matt Dobbs, Simon Foreman, Liam Gray, Mark Halpern, Gary Hinshaw, Albin Joseph, Joshua MacEachern, Kiyoshi W. Masui, Juan Mena-Parra, Laura Newburgh, Tristan Pinsonneault-Marotte, Alex Reda, Shabbir Shaikh, Seth Siegel, Haochen Wang, Dallas Wulf, Zeeshan Ahmed, Nickolas Kokron, Emmanuel Schaan
Solar and Stellar Astrophysics
Helioseismic Evidence That the Solar Dynamo Originates near the Tachocline
Krishnendu Mandal and Alexander G. Kosovichev
The exact location of the
solar dynamo remains uncertain–whether it operates primarily in the near-surface shear layer, throughout the entire convection zone, or near the tachocline, a region of sharp transition in the
solar rotation, located at the base of the convection zone, approximately 200,000 km beneath the surface. Various studies have supported each of these possibilities. Notably, the
solar magnetic "butterfly" diagram and the pattern of zonal flows ("torsional oscillations") exhibit strikingly similar characteristics, suggesting a link between
magnetic field
evolution and
solar flows. Since
magnetic fields cannot be measured directly in the deep
solar interior, torsional oscillations and rotation gradients are employed as diagnostic proxies. Our analysis reveals that the gradient of rotation displays "butterfly"-like behavior near the tachocline, which is similar to the
magnetic butterfly diagram at the surface. This result supports the idea that the
solar dynamo has a deep-seated origin, likely operating either near the tachocline or throughout the convection zone, thereby disfavoring the recent scenario of a shallow, near-surface dynamo. This finding may also have important implications for understanding how
stellar dynamos operate in general.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Standard Model Higgs Peaks: a Note on the Vacuum Instability during Inflation
G. Franciolini, A. Kehagias and A. Riotto
In the Standard Model, the
Higgs potential develops an instability at high field values when the quartic self-coupling runs negative. Large
quantum fluctuations during
cosmic inflation could drive the
Higgs field beyond the potential barrier, creating regions that would be catastrophic for our observable universe. We point out that the extreme-value statistics describing the peaks (maxima) of the
Higgs values is the correct statistics to infer the condition to avoid
vacuum instability. Even if this statistics delivers a bound on the Hubble rate during inflation which is only a factor $\sqrt{2}$ stronger than the one commonly adopted in the literature, it is qualitatively distinct and we believe worthwhile communicating it.
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High Energy Astrophysical Phenomena
Large-scale radio bubbles around the black hole transient V4641 Sgr
Noa Grollimund, Stéphane Corbel, Rob Fender et al. (+7 more)
Black holes (BHs) in microquasars can launch powerful relativistic jets that have the capacity to travel up to several parsecs from the compact object and interact with the interstellar medium. Recently, the detection of large-scale very-high-energy (VHE) gamma-ray emission around the black hole transient V4641 Sgr and other BH-jet systems suggested that jets from microquasars may play an important role in the production of
galactic cosmic rays. V4641 Sgr is known for its superluminal
radio jet discovered in 1999, but no
radio counterpart of a large-scale jet has been observed. The goal of this work is to search for a
radio counterpart of the extended VHE source. We observed V4641 Sgr with the MeerKAT
radio telescope at the L and UHF bands and produced deep maps of the field using high dynamic range techniques. We report the discovery of a large-scale (35 pc), bow-tie-shaped, diffuse,
radio structure around V4641 Sgr, with similar angular size to the extended X-ray emission discovered by XRISM. However, it is not spatially coincident with the extended VHE emission. After discussing the association of the structure with V4641 Sgr, we investigate the nature of the emission mechanism. We suggest that the bow-tie structure arose from the long-term action of large-scale jets or disk winds from V4641 Sgr. If the emission mechanism is of synchrotron origin, the
radio/X-ray extended structure implies acceleration of electrons up to more than 100 TeV as far as tens of parsecs from the black hole.
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All authors Noa Grollimund, Stéphane Corbel, Rob Fender, James H. Matthews, Ian Heywood, Fraser J. Cowie, Andrew K. Hughes, Francesco Carotenuto, Sara E. Motta, Patrick Woudt
Cosmology and Nongalactic Astrophysics
Late-time Background Constraints on Linear and Non-linear Interacting Dark Energy after DESI DR2
David Figueruelo, Marcel van der Westhuizen, Amare Abebe et al. (+1 more)
In this study, we present observational constraints on a class of phenomenological interacting dark energy (IDE) models that admit analytical solutions for the Hubble parameter $H(z)$. We consider a set of five linear and three non-linear IDE scenarios, encompassing both interactions proportional to the dark matter and/or dark energy densities, as well as non-linear combinations of the two. For all eight IDE models, we find a better fit than $\Lambda$CDM from a $\Delta\chi^2$ analysis for both combinations of
datasets considered. When using the Akaike Information Criterion ($\Delta$AIC), we find a similarly improved fit in all cases, except for one
dataset combination in $Q=3H\delta\rho_{\rm de}$. Our analysis also shows a preference for sign-switching interactions, with energy transfer from dark energy to dark matter at low
redshift, reversing direction at higher
redshift. These results should be interpreted with caution, as the latter direction of energy transfer is accompanied by negative dark energy densities in the past, which may be unphysical. Models that do not allow sign-changing behaviour instead show a preference for energy flow from dark matter to dark energy, and hence negative dark energy densities. The only exceptions are $Q=3H\delta\rho_{\rm de}$ and $Q=3H\delta\left(\tfrac{\rho_{\rm de}^2}{\rho_{\rm dm}+\rho_{\rm de}}\right)$, which exhibit energy flow in the opposite direction. Furthermore, for all interactions considered, we find a phantom-divide crossing in the effective dark energy equation of state $w^{\rm eff}_{\rm de}$, with the dark energy density decreasing ($w^{\rm eff}_{\rm de}>-1$) at present and at low
redshift, while increasing ($w^{\rm eff}_{\rm de}<-1$) in the past at high
redshift. These results highlight the promising, but problematic, nature of dark sector interactions, as well as the need to extend the analysis using early-time physics and
datasets.
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All authors David Figueruelo, Marcel van der Westhuizen, Amare Abebe, Eleonora Di Valentino
Astrophysics of Galaxies
A Long Tidal Feature Extending from a Low-Redshift Galaxy Revealed in Rubin Data Preview 1 Imaging
Virginia Johnson and Aaron J. Romanowsky
Using the Vera C. Rubin Observatory Data Preview 1 (DP1), we present the detection and photometric analysis of a
stellar stream extending along the minor axis of a massive disk-
galaxy, LEDA 751050, at a
redshift of z = 0.1 in the Extended Chandra Deep Field-South (ECDFS). This feature appears to be an analog of the M31
Giant Stellar Stream, spanning around 130 kpc by 15 kpc, with an estimated
stellar mass of M_* = 6x10^8 M_Sun, and a mean g-band surface brightness (SB) of mu_g = 28.6 mag/arcsec^2. This discovery demonstrates Rubin's ability to reveal low-SB substructures and foreshadows the future capabilities when the full Legacy Survey of Space and Time (LSST) data set is actualized.
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Solar and Stellar Astrophysics
The winds of OBA hypergiants and luminous blue variables: Dynamically-consistent atmosphere models reveal multiple wind regimes
Matheus Bernini-Peron, Andreas A. C. Sander, Gautham N. Sabhahit et al. (+3 more)
OBA hypergiants (OBAHGs) are evolved massive
stars with notable wind features in their optical spectrum. Located at the cool edge of the line-driven wind regime, many are candidate luminous blue variables (LBVs) likely near the Eddington limit. Although brief, this evolutionary stage deeply affects their surroundings and subsequent
evolution. We study the mechanisms behind OBAHG winds and spectra, covering the temperature range of non-eruptive LBVs. Using the PoWR atmosphere code, we compute models with an Eddington parameter Gamma_e ~ 0.4 and moderate turbulent pressure, typical for cool hypergiants, varying the effective temperature from ~12.5 to ~38.0 kK at
solar metallicity. Our models show a complex temperature-dependent mass-loss pattern, with regions of higher/lower rates linked to two wind solutions: "dense" and "rarefied." Spectra of known OBAHGs and LBVs match models from all solution regions. We find bi-stability jumps – with sharp mass-loss increases – at temperatures where Fe IV recombines to Fe III (and Fe III to Fe II). "Drops" in mass loss also occur when the leading Fe ion changes at wind onset, signaling a switch to rarefied solutions under insufficient driving opacity. The resulting velocity fields also reflect these different regimes: rarefied solutions match the empirical terminal velocity vs temperature relation, while dense ones deviate. Turbulent pressure is crucial for wind acceleration at cooler temperatures. We demonstrate that the bi-stability jumps exist in OBAHGs but are part of a broader complex behavior not replicated by current mass-loss recipes. Combining our and other recent results, we suggest that the switch between rarefied and dense solutions only occurs within a certain proximity to the Eddington Limit. Testing this requires future models with broader parameters and advanced treatments of radiatively-driven
turbulence.
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All authors Matheus Bernini-Peron, Andreas A. C. Sander, Gautham N. Sabhahit, Francisco Najarro, Varsha Ramachandran, Jorick S. Vink
Cosmology and Nongalactic Astrophysics
Bounce Inflation with Dynamical Dark Energy in Light of DESI DR2
Xin-zhe Zhang, Hao-Hao Li and Taotao Qiu
Recently, the Dark Energy Spectroscopic Instrument Data Release 2 (DESI DR2) suggests that the dark energy in our universe might be evolving, favoring the Chevallier-Polarski-Linder (CPL) parameterization and a lower Hubble constant. In our previous work, it has been reported that cosmological model with the non-singular bounce inflation (BI) scenario and $\Lambda$CDM might alleviate the Hubble tension into 3$\sigma$ confidence. In this paper, we study the cosmological model of BI with a dynamical dark energy. We find that individual consideration of the CPL parameterization and the data DESI DR2 tend to larger Hubble constants for both BI and power law (PL) case with
cosmic microwave background (CMB) data. Employing BI with combined CPL parameterization and DESI DR2, we obtain the Hubble constant $H_ 0 = 65.2^{ + 1.8}_{ - 2.2} \ \mathrm{km} \cdot \mathrm{s}^{ -1 } \cdot \mathrm{Mpc}^{ -1 }$, which is larger than $H_ 0 = 64.0 \pm 2.1 \ \mathrm{km} \cdot \mathrm{s}^{ -1 } \cdot \mathrm{Mpc}^{ -1 }$ for the PL case. After considering nontrivial weak
lensing effect and spatial
curvature as well as adding Pantheon+, BI fits 3.1$\sigma$ confidence of $\Lambda$CDM with $w_ 0 = -0.919 \pm 0.038$ and $w_{ \mathrm{a}} = -0.37 \pm 0.12$, and it prefers evolving dark energy than the PL case with $w_ 0 = -0.960 \pm 0.074$ and $w_{ \mathrm{a}} = -0.15^{ +0.28}_{ -0.25}$.
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Earth and Planetary Astrophysics
Mean opacity tables for probing the interior and atmosphere of giant planets
Louis Siebenaler and Yamila Miguel
We present new Rosseland and Planck mean opacity tables relevant to the shallow interiors and atmospheres of
giant planets. The tables span
metallicities from 0.31 to 50 times
solar, temperatures from 100 - 6000 K, and pressures from 1e-6 - 1e5 bar, thereby covering a wider parameter space than previous data sets. Our calculations employ the latest molecular and atomic line lists and pressure-broadening treatments, and include contributions from collision-induced absorption, free electrons, and scattering processes. We further provide cloudy mean opacity tables that account for cloud particle extinction across a range of particle sizes and capture the sequential removal of condensates as the gas cools. We
benchmark our cloud-free tables against widely used opacity tables and find significant relative differences, exceeding 100% in Rosseland mean opacities at T \gtrsim 3000 K due to the inclusion of additional short-wavelength absorbers. Differences in Planck mean opacities at high temperatures are even larger, in some cases exceeding two orders of magnitude, which is most likely driven by the inclusion of Ca, Mg, and Fe cross-sections and updated Na D and K I resonance line treatments. Cloud opacities substantially increase Rosseland mean opacities for T \lesssim 2800 K, while their effect on Planck mean opacities is weaker. We also discuss limitations of our mean opacities at high pressures, where non-ideal effects become important. This work provides improved cloud-free mean opacity tables for
giant planets, as well as the first publicly available cloudy mean opacity tables, which will enable more realistic modeling of their atmospheres and interiors.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Inflation in Extra-Dimensions with one or two branes
Nicolás Bernal, Catarina Cosme, Andrea Donini et al. (+1 more)
In this paper, we study two inflationary models, namely, monomial inflation and the simplest $\alpha$-attractor inflation, within extra-dimensional frameworks. We consider three extra-dimensional setups: Dark Dimension, which embeds one flat extra-dimension to explain the observed smallness of the 4D cosmological constant $\Lambda_4$; and the two Randall-Sundrum scenarios with one warped extra-dimension, namely RS1 with two branes and RS2 with one brane. We derive the corresponding Friedmann equations, compute the slow-roll parameters in each case, and we fit the experimental data for ($n_s - 1$, $\alpha$, $\Delta_s^2$, $r$), using Planck, BICEP, and ACT data. We find that monomial inflation is strongly disfavored in all scenarios, while $\alpha$-attractor inflation provides an excellent fit to current observations, with extra-dimensional setups offering additional flexibility compared to the standard 4D case.
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All authors Nicolás Bernal, Catarina Cosme, Andrea Donini, Nuria Rius
High Energy Astrophysical Phenomena · Cross-listed from nucl-th
An Effective Upper Bound on the Pressure-to-Energy Density Ratio in Neutron Stars
Bao-Jun Cai, Bao-An Li and Yu-Gang Ma
The equation-of-state (EOS) parameter $\phi \equiv P/\varepsilon$, defined as the ratio of pressure to energy density, encapsulates the fundamental response of matter under extreme compression. Its value at the center of the most massive
neutron star (NS), $\x \equiv P_{\rm c}/\varepsilon_{\rm c}$, provides an upper bound on the maximum attainable central EOS parameter of cold visible matter. Remarkably, owing to the intrinsically nonlinear structure of the EOS in General Relativity (GR), this bound lies far below the naive Special Relativity (SR) limit of unity. In this work, we refine the theoretical upper bound on $\x$ in a self-consistent manner by incorporating, in addition to the causality constraint from SR, the mass-sphere stability condition associated with the mass
evolution pattern in the vicinity of the NS center. This condition is formulated within the intrinsic and perturbative analysis of the dimensionless Tolman–Oppenheimer–Volkoff equations (IPAD-TOV) framework. The combined constraints yield an improved bound, $\x \lesssim 0.385$, which is slightly above but fully consistent with the previously derived causal-only limit, $\x \lesssim 0.374$. We further derive an improved scaling relation for NS compactness and demonstrate its robustness across a broad set of 284 realistic EOSs, including models with first-order phase transitions, exotic degrees of freedom, continuous crossover behavior, and deconfined
quark cores. Within the IPAD-TOV framework, the resulting bound on $\x$ provides a new EOS-insensitive probe of the microphysics of cold superdense matter compressed by strong-field
gravity in GR.
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Cosmology and Nongalactic Astrophysics
Polarization of the CMB in the Standard Model Extension
Iman Motie, Jafar Khodagholizadeh, S. Mahmoudi et al. (+2 more)
In standard cosmology,
Cosmic Microwave Background
photons near the last scattering surface exhibit only linear polarization due to Compton scattering, leading to the assumption that
primordial circular polarization is negligible. However, the physics of Lorentz violation (LV), associated with specific operators, can influence these polarization characteristics. This study employs the Boltzmann equation within the framework of the Standard Model Extension (SME) to explore how the background LV tensor $ K_{AF} $ can induce circular polarization in CMB radiation. By computing the transformation of linear polarization into circular polarization and utilizing the Faraday conversion angle, we derive a bound for $ K_{AF} $ on the order of $ 10^{-41} \, \text{GeV} $, aligning with recent findings. Additionally, we consider the total pure
photon terms within the SME, demonstrating that LV in the presence of scalar perturbations can also generate
cosmic birefringence (CB) in the CMB radiation. Through analysis of best-fitting CB angles, we establish a more stringent bound of approximately $ 10^{-32} \, \text{GeV} $ for $ K_{F} $.
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All authors Iman Motie, Jafar Khodagholizadeh, S. Mahmoudi, Brahim Lamine, Alain Blanchard