High Energy Astrophysical Phenomena
Degeneracy-Aware Pulsar Parameter Estimation from Light Curves via Deep Learning and Test-Time Optimization
Abu Bucker Siddik, Diane Oyen, Soumi De et al. (+2 more)
Probing properties of
neutron stars from photometric observations of these objects helps us answer crucial questions at the forefront of multi-messenger astronomy, such as, what is behavior of highest density matter in extreme environments and what is the procedure of generation and
evolution of
magnetic fields in these astrophysical environments? However, uncertainties and degeneracies-where different parameter sets produce similar light curves-make this task challenging. We propose a deep learning framework for inferring
pulsar parameters from observed light curves. Traditional deep learning models are not designed to produce multiple degenerate solutions for a given input. To address this, we introduce a custom loss function that incorporates a light curve emulator as a forward model, along with a dissimilarity loss that encourages the model to capture diverse, degenerate parameter sets for a given light curve. We further introduce a test-time optimization scheme that refines predicted parameters by minimizing the discrepancy between the observed light curve and those reconstructed by the forward model from predicted parameters during inference. The model is trained using a suite of state-of-the-art simulated
pulsar light curves. Finally, we demonstrate that the parameter sets predicted by our approach reproduce light curves that are consistent with the true observation.
Read the full abstract ▾
All authors Abu Bucker Siddik, Diane Oyen, Soumi De, Greg Olmschenk, Constantinos Kalapotharakos
High Energy Astrophysical Phenomena
The role of the secondary white dwarf in a double-degenerate double-detonation explosion, in the supernova remnant phase
Gilles Ferrand, Rüdiger Pakmor, Yusei Fujimaru et al. (+7 more)
Type Ia
supernovae (SNe) are believed to be thermonuclear explosions of white
dwarf (WD)
stars, but their progenitor systems and explosion mechanisms are still unclear. Here we focus on double degenerate systems, where two WDs are interacting, and on the double detonation mechanism, where a detonation of a helium shell triggers a detonation of the carbon-oxygen core of the primary WD. We take the results from three-dimensional SN simulations of Pakmor et al 2022 (arXiv:2203.14990) and carry them into the
supernova remnant (SNR) phase, until 1500 yr after the explosion. We reveal signatures of the SN imprinted in the SNR morphology. We confirm the impact of a companion on the SNR: its presence induces a conical shadow in the ejecta, that is long lived. Its intersection with the shocked shell is visible in projection as a ring, an ellipse, or a bar, depending on the orientation. New, we test the case of a nested explosion model, in which the explosion of the primary induces the secondary to also explode. As the explosion of the secondary WD is weaker only the primary outer ejecta interact with the ambient medium and form the main SNR shell. The secondary inner ejecta collide with the reverse shock, which enhances the density and thus the X-ray emissivity. The composition at the points of impact is peculiar, since what is revealed are the outer layers from the inner ejecta. This effect can be probed with spatially-resolved X-ray spectroscopy of young SNRs.
Read the full abstract ▾
All authors Gilles Ferrand, Rüdiger Pakmor, Yusei Fujimaru, Shiu-Hang Lee, Samar Safi-Harb, Shigehiro Nagataki, Friedrich K. Roepke, Anne Decourchelle, Ivo R. Seitenzahl, Daniel Patnaude
Cosmology and Nongalactic Astrophysics
N-body Simulations of cosmologies with Light Massive Relics
Vikhyat Sharma and Arka Banerjee
The presence of additional relativistic particles at the time of recombination can be inferred through their contribution to $\Delta N_{\rm eff}$. If these species have a finite but low mass (Light Massive Relics - LiMRs), they act as a hot subcomponent of dark matter and impact late-time structure formation. Understanding these effects will be crucial to pin down the underlying particle physics properties of any future $\Delta N_{\rm eff}$ detection. While their impact has been well-studied on linear scales, this work develops the framework for and presents results from the first set of cosmological N-body simulations that can track the effects of LiMRs, as a function of their mass and temperature, down to fully nonlinear scales. Importantly, our simulations model the impact of both the massive Standard Model
neutrinos and LiMRs, which will be crucial in disentangling possible degeneracies. We systematically explore the effects of LiMR properties such as mass, temperature, and initial distribution, on various cosmological observables, including the total matter power spectrum,
Halo Mass Functions (HMF), Mass-Concentration relation, radial
halo profiles, and weak
lensing signals around massive clusters. The framework and simulations developed here will enable detailed follow-up of the rich phenomenology of LiMR cosmologies.
Read the full abstract ▾
Cosmology and Nongalactic Astrophysics
Beware of the running $n_s$ when producing heavy primordial black holes
Sasha Allegrini, Antonio J. Iovino and Hardi Veermäe
We examine single-field inflationary models for the formation of
primordial black holes (PBHs). By analyzing the latest observations from the Atacama Cosmology
Telescope (ACT)~\cite{ACT:2025fju, ACT:2025tim}, we demonstrate that the observed preference for positive running ($\alpha_s$) of the scalar spectral index $n_s$ imposes significant restrictions on the parameter space for a large class of ultra-slow-roll (USR) models. This tension becomes progressively pronounced for more massive PBHs, posing substantial challenges for USR models to yield a detectable PBH abundance, especially in the mass range probed by ongoing and future gravitational-wave experiments such as LIGO-Virgo-KAGRA and the Einstein
Telescope. However, this discrepancy is minimal for asteroid-mass PBHs, which are still capable of feasibly constituting the entirety of dark matter. To numerically probe the six-dimensional parameter space of the models, we adapted a Markov Chain Monte Carlo approach to efficiently scan over the viable configurations. Our results further indicate that, in non-minimally coupled
polynomial inflation, a viable
cosmic microwave background (CMB) spectrum is best obtained at an inflection point for which second-order slow-roll approximation is necessary for precise CMB predictions.
Read the full abstract ▾
High Energy Astrophysical Phenomena
Multiple shells in supernova 2023ixf support the jittering jets explosion mechanism (JJEM)
Noam Soker and Kobi Shiran
Examining the photospheric time
evolution of the core-collapse
supernova (CCSN) SN 2023ixf from the literature, we identify two (possibly three) evolutionary time periods with constant expansion velocities, which we attribute to two (or three) ejecta shells. We find that several CCSN remnants have morphologies with two or more complete or partial shells, compatible with the presence of two (or three) photospheric shells during the photospheric phase of the explosion. Studies have attributed these CCSN remnants to the jittering-jet explosion mechanism (JJEM), which involves two or three energetic pairs of jets participating in the explosion. We, therefore, conclude that the structure of the photospheric shells of SN 2023ixf supports its explosion by the JJEM. This study adds to the accumulating evidence that the JJEM is the primary explosion mechanism of CCSNe.
Read the full abstract ▾
Earth and Planetary Astrophysics
Pre-perihelion Development of Interstellar Comet 3I/ATLAS
David Jewitt and Jane Luu
We describe pre-perihelion optical observations of interstellar comet 3I/ATLAS taken during July - September 2025 using the Nordic Optical
Telescope. Fixed aperture photometry of the comet is well described by a power law function of heliocentric distance, rH, with the exponent (“index") n = 3.8+/-0.3 across the 4.6 au to 1.8 au distance range (phase function 0.04+/-0.02 magnitude/degree assumed). This indicates that the
dust production rates vary in proportion to rH**(-1.8+/-0.3). An rH**(-2) variation is expected of a strongly volatile material, and consistent with independent spectroscopic observations showing that carbon dioxide is the primary driver of activity. The measured heliocentric index is unremarkable in the context of
solar system comets, for which n is widely dispersed, and provides no basis on which to describe 3I as either dynamically old (thermally processed) or new (pristine). The morphology of the comet changes from a Sun-facing
dust fan in the early 2025 July observations, to one dominated by an antisolar
dust tail at later dates. We attribute the delayed emergence of the tail to the large size (effective radius 0.1 mm) and slow ejection (5 m/s) of the optically dominant
dust particles, and their consequently sluggish response to
solar radiation pressure. Small (micron-sized) particles may be present but not in numbers sufficient to dominate the scattering cross-section. Their relative depletion possibly reflects interparticle cohesion, which binds small particles more effectively than large ones. A similar preponderance of 0.1 mm grains was reported in 2I/Borisov. However, 2I differed from 3I in having a much smaller (asteroid-like) heliocentric index, n = 1.9+/-0.1.
Dust production rates in 3I are 180 kg/s at 2 au, compared with 70 kg/s in 2I/Borisov at the same distance.
Read the full abstract ▾
Astrophysics of Galaxies
Linking Electron Density with Elevated Star Formation Activity from $z=0$ to $z=10$
Sijia Li, Si-Yue Yu, Luis C. Ho et al. (+7 more)
The interstellar medium (ISM) in high-
redshift galaxies exhibits significantly higher electron densities ($n_{\rm e}$) than in the local universe. To investigate the origin of this trend, we analyze a sample of 9590 centrally
star-forming
galaxies with
stellar masses greater than $10^9\,M_\odot$ at
redshifts $0.01 < z < 0.04$, selected from the Dark Energy Spectroscopic Instrument (DESI) Data Release 1. We derive electron densities from the [S II] $\lambda\lambda6716,6731$ doublet, measuring values of $n_{\rm e} = 30$-$400~{\rm cm^{-3}}$ at $z \approx 0$. We find a tight correlation between $n_{\rm e}$ and the
star formation rate surface density ($\Sigma_{\rm SFR}$), which is well described by a broken power law. Above a threshold of $\log(\Sigma_{\rm SFR} / M_\odot\,{\rm yr^{-1}\,kpc^{-2}}) \ge -1.46$, the relation follows $n_{\rm e} = (233 \pm 13)\,\Sigma_{\rm SFR}^{0.49 \pm 0.02}$. Below this threshold, $n_{\rm e}$ remains approximately constant at $44 \pm 3~{\rm cm^{-3}}$. Remarkably, this relation remains consistent with measurements of
galaxies at $z = 0.9$-$10.2$. By converting the observed
redshift evolution of $\Sigma_{\rm SFR}$ into $n_{\rm e}$
evolution through our $n_{\rm e}$-$\Sigma_{\rm SFR}$ relation, we obtain $n_{\rm e} = 40(1+z)^{1.4}~{\rm cm^{-3}}$, consistent with previous direct observations. The $n_{\rm e}$-$\Sigma_{\rm SFR}$ relation likely arises because the high $\Sigma_{\rm SFR}$, fueled by dense cold gas or elevated efficiency, enhances radiative and mechanical feedback and produces dense ionized gas whose electron densities are further regulated by ambient pressure. We conclude that the
redshift evolution of $n_{\rm e}$ primarily reflects the
evolution of cold gas density and
star formation activity over
cosmic time.
Read the full abstract ▾
All authors Sijia Li, Si-Yue Yu, Luis C. Ho, John D. Silverman, Jing Wang, Amelie Saintonge, Niankun Yu, Qinyue Fei, Daichi Kashino, Hao-ran Yu
High Energy Astrophysical Phenomena
Particle acceleration at radiative supernova remnant shocks
Pierre Cristofari
Numerous astrophysical shock waves evolve in an environment where the radiative cooling behind the shock affects the hydrodynamical structure downstream, thereby influencing the potential for particle acceleration via diffusive shock acceleration (DSA). We study the possibility for DSA to energize particles from the thermal pool and from pre-existing
cosmic rays at radiative shocks, focusing on the case of
supernova remnants (SNRs). We rely on a semi-analytical description of particle acceleration at collisionless shocks in the test-particle limit, estimating the total
proton and electron content from SNRs throughout the radiative phase. Our results indicate that DSA can lead to significant particle acceleration during the first few tens of kyrs of the radiative phase. Although the associated multi-wavelength emission from SNRs in the radiative phase may not be detectable with current observatories in most cases, the radiative phase is found to lead to substantial deviations from the canonical p$^{-4}$ of the test-particle limit. The hardening/steepening is due to an interplay between a growing contribution of the reaccelerated term as the SNR volume expands and the effects of adiabatic and radiative losses on trapped particles as particles are confined for a longer time. The slope of the cumulative
proton and electron spectra over the SNR lifetime thus depends on the environment in which the SNR shock propagates, and on the duration of the radiative phase during which DSA can take place. Overall, DSA in the radiative phase can lead to a total electron spectrum steeper than the
proton spectrum, both at SNRs from thermonuclear and core-collapse SNe. Finally, we comment on the case of young radiative SNRs (in the first month to a few years after the explosion) for which the denser environments (with mass-loss rates of $\dot{M} \sim 10^{-1} - 1$ M$_{\odot}$/yr) tend to inhibit DSA.
Read the full abstract ▾
Astrophysics of Galaxies
A Detailed Chemical Analysis of the Red Giant Orbiting the Black Hole $Gaia$ BH3: From Lithium to Thorium
Zoe Hackshaw, Keith Hawkins and Catherine Manea
Preliminary astrometric data from the fourth data release of the $Gaia$ mission revealed a 33 M$_{\odot}$ dark companion to a metal-poor red
giant star, deemed $Gaia$ BH3. This system hosts both the most massive known
stellar-origin black hole and the lowest-
metallicity star yet discovered in orbit around a black hole. The formation pathway for this peculiar
stellar-black hole binary system has yet to be determined, with possible production mechanisms that include isolated binary
evolution and dynamical capture. The chemical composition of the
stellar companion in $Gaia$ BH3 (hereafter \bhstar) can help constrain the potential formation mechanisms of this system. Here, we conduct the most comprehensive chemical analysis of \bhstar\ to date using high resolution spectra obtained by the Tull Coudé Spectrograph on the 2.7m Harlan J. Smith
Telescope at McDonald Observatory to constrain potential formation mechanisms. We derived 29 elemental abundances ranging from lithium to thorium and find that \bhstar\ is an $\alpha$-enriched ([$\alpha$/Fe] = 0.41), r-I
neutron-capture
star ([Eu/Fe] = 0.57). We conclude that \bhstar\ shows no chemical peculiarities (defined as deviations from the expected chemical pattern of an r-I
halo red
giant) in any elements, which is in
alignment with both the dynamical capture and isolated binary
evolution formation scenarios. With an upper limit detection on Th, we use the Th/Eu chronometer to place limits on the cosmochronometric age of this system. These observations lay the groundwork for heavy-element chemical analysis for subsequent black hole and low-
metallicity stellar binaries that will likely be found in $Gaia$ DR4.
Read the full abstract ▾
Cosmology and Nongalactic Astrophysics
Probing cosmology with bright sirens from the CosmoDC2_BCO LSST synthetic catalog
Ranier Menote and Valerio Marra
Bright sirens, i.e. gravitational-wave detections of compact binary mergers with electromagnetic counterparts, provide a self-calibrated distance-
redshift relation and are therefore powerful probes of
cosmic expansion. Using the CosmoDC2_BCO catalog, we forecast cosmological constraints from current (LVK) and next-generation (ET, CE) detector networks, in combination with a Roman-like Type Ia
supernova sample. We find that third-generation networks reach sub-percent precision on the Hubble constant within a few years, achieving 0.2% after a decade with CE+ET+LVK, while LVK remains limited to the 6% level. The LVK fifth observing run may shed light on the H_0 tension only if the inferred value falls outside the range spanned by the Planck and SH0ES determinations, which currently achieve far higher precisions.
Supernovae do not directly tighten H_0 but stabilize its inference through parameter correlations and enable an absolute calibration of the
supernova magnitude M_B. In dynamical dark-energy models, the joint analysis of Roman
supernovae and bright sirens yields a Figure of Merit of 25 for ET+LVK and 76 for CE+ET+LVK, to be compared with the state-of-the-art DESI DR2 BAO plus DESY5
supernovae value of 56. Sky-localization thresholds of DeltaOmega < 50 deg^2, or even DeltaOmega < 10 deg^2, entail only mild penalties, suggesting efficient follow-up strategies. These results establish third-generation GW+EM observations, especially when combined with Roman
supernovae, as a cornerstone for precision cosmology in the next decade.
Read the full abstract ▾
Cosmology and Nongalactic Astrophysics
Symbolic Emulators for Cosmology: Accelerating Cosmological Analyses Without Sacrificing Precision
Deaglan J. Bartlett and Shivam Pandey
In cosmology, emulators play a crucial role by providing fast and accurate predictions of complex physical models, enabling efficient exploration of high-dimensional parameter spaces that would be computationally prohibitive with direct numerical simulations. Symbolic emulators have emerged as promising alternatives to numerical approaches, delivering comparable accuracy with significantly faster evaluation times. While previous symbolic emulators were limited to relatively narrow prior ranges, we expand these to cover the parameter space relevant for current cosmological analyses. We introduce approximations to hypergeometric functions used for the $\Lambda$CDM comoving distance and linear growth factor which are accurate to better than 0.001% and 0.05%, respectively, for all
redshifts and for $\Omega_{\rm m} \in [0.1, 0.5]$. We show that integrating symbolic emulators into a Dark Energy Survey-like $3\times2$pt analysis produces cosmological constraints consistent with those obtained using standard numerical methods. Our symbolic emulators offer substantial improvements in speed and
memory usage, demonstrating their practical potential for scalable, likelihood-based inference.
Read the full abstract ▾
Solar and Stellar Astrophysics
Nonthermal electron acceleration in turbulent post-flare coronal loops
Clarissa Mora, Fabio Bacchini and Rony Keppens
The generation of nonthermal electrons during
solar flares plays a critical role in energy transport from the corona to the chromosphere, producing regions of observed intense X-ray emission.
Turbulence in post-
flare loops, particularly from Kelvin-Helmholtz instabilities (KHI), has been suggested and investigated as a mechanism for trapping and accelerating electrons in such scenarios. Starting from past results, we aim to characterize the energization process of electrons trapped in a turbulent post-
flare looptop, quantifying the contributions of different acceleration mechanisms, and establishing a coherent numerical framework for describing particle energetics. We perform test-particle simulations with the guiding-centre approximation on top of a 2.5D magnetohydrodynamic model of a time-evolving post-
flare coronal looptop. We implement an improved formulation of the guiding-centre equations that explicitly conserves energy, enabling a consistent analysis of electron acceleration in the turbulent
plasma. We find that, in the
plasma turbulence inside the looptop, electrons develop suprathermal energy distributions with tails compatible with hard X-ray emission. The dominant energization channel arises from perpendicular gradient effects in the form of second-order
Fermi-like
stochastic acceleration, while
curvature effects are dominant for particles on long trajectories. Statistical correlations with the measured particle pitch angle confirm that the strongest acceleration occurs for electrons trapped in bouncing motions within turbulent
magnetic structures. Our results provide an understanding of how KHI-induced
turbulence in coronal looptops produces and sustains populations of trapped nonthermal electrons. We dissect and clarify the relative roles of different
magnetic effects and the emergence of
stochastic Fermi-like energization.
Read the full abstract ▾
Cosmology and Nongalactic Astrophysics
Nonlinear Matter Power Spectrum from relativistic $N$-body Simulations: $\Lambda_{\rm s}$CDM versus $\Lambda$CDM
Özgür Akarsu, Eleonora Di Valentino, Jiří Vyskočil et al. (+3 more)
We present relativistic $N$-body simulations of a $\Lambda_{\rm s}$CDM - sign-switching cosmological constant (CC) - scenario under general relativity and compare its nonlinear matter power spectrum to $\Lambda$CDM at ${z = 15,\,2,\,1,\,0}$, using best-fit parameters from Planck-only and a combined ”full”
dataset. During the AdS-like CC ($\Lambda_{\rm s}<0$) phase, prior to the transition
redshift $z_\dagger$, reduced Hubble friction dynamically enhances the growth of perturbations; after the switch, with dS-like CC ($\Lambda_{\rm s}>0$), the larger late-time expansion rate partly suppresses, but does not erase, the earlier amplification. Consequently, the ratio $P_{\Lambda_{\rm s}\rm CDM}/P_{\Lambda\rm CDM}$ exhibits a pronounced,
redshift-dependent shape feature: a crest peaking at ${\sim 20-25\%}$ around ${k \simeq 1-3\,h\,\mathrm{Mpc}^{-1}}$ near the transition, which then migrates to larger physical scales and persists to ${z = 0}$ as a robust ${\sim 15-20\%}$ uplift at ${k \simeq 0.6-1.0\,h\,\mathrm{Mpc}^{-1}}$. These wavenumbers correspond to group or poor-cluster environments and lie within the sensitivity range of weak
lensing,
galaxy-
galaxy lensing, cluster counts, and tSZ power, providing a concrete, falsifiable target that cannot be mimicked by a scale-independent change in $\sigma_8$ or $S_8$. The timing (earlier for Planck-only, later for the full
dataset) and the amplitude of the crest align with the ”
cosmic noon” epoch (${z \simeq 1-2}$), offering a gravitational prior for the observed peak in the
cosmic star-formation rate.
Read the full abstract ▾
All authors Özgür Akarsu, Eleonora Di Valentino, Jiří Vyskočil, Ezgi Y{\i}lmaz, A. Emrah Yükselci, Alexander Zhuk
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-th
Ultraviolet Completion of the Big Bang in Quadratic Gravity
Ruolin Liu, Jerome Quintin and Niayesh Afshordi
We present a
quantum quadratic
gravity inflationary scenario that can accommodate the new cosmological constraints, which have disfavored Starobinsky inflation. The theory is asymptotically free in the ultraviolet, but 1-loop running is found to dynamically lead to slow-roll inflation toward the infrared. When a large number of matter fields contribute to the beta functions, the spectral index and the tensor-to-scalar ratio can be phenomenologically viable. We find that as inflation ends, the theory approaches its strong coupling regime and general relativity must emerge, as an effective field theory, as the universe must reheat and enter its standard radiation era. In order to avoid strong coupling, a minimum tensor-to-scalar ratio of 0.01 is predicted for this theory. Our framework offers a laboratory for connecting a concrete ultraviolet completion (
quantum quadratic
gravity) with inflationary dynamics, reheating, and precise cosmological observations.
Read the full abstract ▾
High Energy Astrophysical Phenomena
Gravitational-wave and electromagnetic detections in the context of the CosmoDC2 LSST synthetic catalog
Ranier Menote, Valerio Marra, Riccardo Sturani et al. (+3 more)
We release CosmoDC2_BCO, a synthetic catalog of gravitational-wave events and electromagnetic counterparts associated with
galaxies from CosmoDC2. The catalog provides intrinsic and extrinsic source parameters, signal-to-noise ratios, parameter uncertainties, sky localization areas, and kilonova apparent magnitudes in LSST filters. Our results show that third-generation detector networks substantially increase detection rates and improve parameter estimation. Second-generation detectors, when combined with third-generation ones, significantly enhance sky localization and distance precision, particularly for BNS mergers. Assuming a simplified Target of Opportunity strategy, we estimate that an LSST-like survey, partnered with the CE+ET+LVK network at 70% duty cycle, could detect about 5000 kilonovae with GW counterparts over a 10-year period on a 16000 deg^2 footprint, predominantly from low-mass BNS mergers that produce long-lived supermassive
neutron star remnants. While this is a substantial number, it represents only a small fraction of the total
neutron star mergers expected to be observed by third-generation networks. These projections rely on several simplifying assumptions-including the adopted merger rate, the kilonova luminosity distribution, and the configuration and scheduling of future surveys-which introduce notable uncertainties. Therefore, the estimated detection numbers should be interpreted with appropriate caution.
Read the full abstract ▾
All authors Ranier Menote, Valerio Marra, Riccardo Sturani, Felipe Andrade-Oliveira, Clécio R. Bom, The LSST Dark Energy Science Collaboration
High Energy Astrophysical Phenomena
Binding energy of compact stars and their non-radial oscillations
P. Laskos-Patkos, S. Papadopoulos and Ch. C. Moustakidis
In the past years, a significant effort has been made with the scope of determining correlations, involving compact
star properties, that are independent of the
nuclear equation of state. Such universal relations are of utmost importance as they allow for the imposition of constraints on
stellar properties without directly measuring them and they may also serve as a probe of General Relativity. In the present study, we investigated the possible existence of a universal relation between the binding energy of compact
stars and the frequency of their non-radial oscillations. The main motivation was related to the fact that both of the aforementioned quantities might be measured in the occurrence of a
supernova explosion. Interestingly, we found that there is a empirical relation between the oscillation frequency and the binding energy for both $f$ and $p_1$ modes, assuming hadronic
stellar matter. The inclusion of hybrid equations of state, incorporating sharp phase transitions, was shown to result into deviations from the aforementioned quasi-universal relation.
Read the full abstract ▾
Earth and Planetary Astrophysics
Chemistry, Climate, and Transmission Spectra of TRAPPIST-1 e Explored with a Multimodel Sparse Sampled Ensemble
Eric T. Wolf, Edward W. Schwieterman, Jacob Haqq-Misra et al. (+6 more)
TRAPPIST-1 e is one of a few habitable zone
exoplanets that is amenable to characterization in the near term. In this study our motivations are both scientific and technical. Our technical goal is to establish a multimodel sparse sampled ensemble approach for coherently exploring large unconstrained parameter spaces typical in
exoplanet science. Our science goal is to determine relationships that connect observations to the underlying
climate across a large parameter space of atmospheric compositions for TRAPPIST-1 e. We consider atmospheric compositions of N2, CO2, CH4, and H2O, with water clouds and photochemical hazes. We use a 1D photochemical model, a 3D
climate model, and a transmission spectral model, filtered through a quasi-Monte Carlo sparse sampling approach applied across atmospheric compositions. While clouds and hazes have significant effects on the transmission spectra, CO2 and CH4 can be potentially detected in <10 transits for certain compositional and
climate states. Colder climates have better prospects for characterization, due to being relatively dry and having fewer clouds, permitting transmission observations to probe more deeply into their atmospheres. CH4 volume mixing ratios of >$10^{-3}$ trigger strong antigreenhouse cooling, where near-IR absorption simultaneously creates an inversion in the stratosphere and reduces the
stellar radiation reaching the
planet surface. In such cases, interpreting the disk-averaged emission and albedo at face value can yield misleading conclusions, as here low albedo and high thermal emission are associated with cold
planets. Future work will use our sparse sampling approach to explore broader parameter spaces and other observationally amenable
exoplanets.
Read the full abstract ▾
All authors Eric T. Wolf, Edward W. Schwieterman, Jacob Haqq-Misra, Thomas J. Fauchez, Sandra T. Bastelberger, Michaela Leung, Sarah Peacock, Geronimo L. Villanueva, Ravi K. Kopparapu
Earth and Planetary Astrophysics
Diurnal temperature variations and migrating thermal tides in the Martian lower atmosphere observed by the Emirates Mars InfraRed Spectrometer
Siteng Fan, François Forget, Michael D. Smith et al. (+12 more)
The Martian atmosphere experiences large diurnal variations due to the ~24.6 h planetary rotation and its low heat capacity. Understanding such variations on a planetary scale is limited due to the lack of observations, which are greatly addressed with the recent advent of the Emirates Mars Mission (EMM). As a result of its unique high-altitude orbit, instruments onboard are capable of obtaining a full geographic and local time coverage of the Martian atmosphere every 9-10 Martian days, approximately ~5{\deg} in
solar longitude (LS). This enables investigations of the diurnal variation of the current
climate on Mars on a planetary scale without significant local time (LT) gaps or confusions from correlated seasonal variations. Here, we present the results of diurnal temperature variations and thermal tides in the Martian atmosphere using temperature profiles retrieved from the Emirates Mars InfraRed Spectrometer (EMIRS) observations. The data during the primary mission is included, covering an entire Martian Year (MY) starting from MY 36 LS = 49{\deg}. The diurnal temperature patterns suggest a dominant diurnal tide in most seasons, while the semi-diurnal tide presents a similar amplitude near perihelion. The seasonal variation of the diurnal tide latitudinal distribution is well explained by the total vorticity due to zonal wind, while that of the semi-diurnal tide following both
dust and water ice clouds, and the ter-diurnal tide following the
dust only. Comparison with the updated Mars Planetary
Climate Model (PCM, version 6) suggest improvements in simulating the
dust and water cycles, as well as their radiative processes.
Read the full abstract ▾
All authors Siteng Fan, François Forget, Michael D. Smith, R. John Wilson, Sandrine Guerlet, Khalid M. Badri, Samuel A. Atwood, Roland M. B. Young, Christopher S. Edwards, Philip R. Christensen, Justin Deighan, Hessa R. Al Matroushi, Antoine Bierjon, Jiandong Liu, Ehouarn Millour
High Energy Astrophysical Phenomena
Assessing the performance of future space-based detectors: Astrophysical foregrounds and individual sources
Alice Perego, Matteo Bonetti, Alberto Sesana et al. (+2 more)
The space mission LISA, scheduled for launch in 2035, aims to detect gravitational wave (GW) signals in the milli-Hz band. In the context of the ESA Voyage 2050 Call for new mission concepts, other frequency ranges are explored by the Gravitational-Wave Space 2050 Working Group to conceive new proposals for a post-LISA space-based detector. In this work, we give a preliminary estimate of the observational potential of three mission designs proposed in the literature, namely $\mu$Ares, AMIGO and the Decihertz Observatory. The analysis framework includes astrophysical GW sources, such as massive black hole binaries and extreme mass-ratio inspirals, and compact binaries, such as
stellar black holes and white
dwarfs. For each detector, we first present a consistent computation of the unresolved gravitational wave background (GWB) produced by the sum of all anticipated astrophysical populations using an iterative subtraction
algorithm. We then investigate which types of systems are the most appealing by measuring the number of GW signals detected and exploring the source properties.
Read the full abstract ▾
All authors Alice Perego, Matteo Bonetti, Alberto Sesana, Silvia Toonen, Valeriya Korol
Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Comprehensive analysis of dissipative effects in the induced gravitational waves
Yan-Heng Yu, Zhe Chang and Sai Wang
Dissipation is an intrinsic property of the
cosmic fluid, leading to the damping of
curvature perturbations at small scales. In this paper, we comprehensively study dissipative effects in gravitational waves induced by
curvature perturbations, known as induced gravitational waves (IGWs). We find dissipative effects become especially significant at wavenumber $k \sim k_{\mathcal{H},\mathrm{dec}}$, where $k_{\mathcal{H},\mathrm{dec}}$ corresponds to the horizon scale at the decoupling of weakly-interacting particles. They can leave characteristic features on the IGW spectrum, including a notable suppression with a “double-valley” structure at $k \sim k_{\mathcal{H},\mathrm{dec}}$ and a modified infrared behavior without logarithmic running at $k \lesssim k_{\mathcal{H},\mathrm{dec}}$. Within the Standard Model of particle physics, dissipative effects caused by
neutrinos at the nanohertz frequencies can be important in the analysis of
pulsar timing array data. Furthermore, dissipation-induced features associated with possible new weakly-interacting particles can be detectable by a wide range of gravitational-wave experiments, serving as a promising probe of new physics at extremely high energy scales. As an extension, we also discuss dissipative effects in the presence of
primordial non-Gaussianity and their impacts on the anisotropies of IGWs and the poltergeist mechanism. These dissipative effects not only provide a more realistic description of IGWs but also exhibit rich phenomenology and profound physical implications, opening a new window into understanding the early Universe and fundamental physics.
Read the full abstract ▾
High Energy Astrophysical Phenomena
Line-force driven wind from a thin disk in tidal disruption event
De-Fu Bu, Xiao-Hong Yang, Liang Chen et al. (+2 more)
Winds from the
accretion disk in
tidal disruption events (TDEs) play a key role in determining the radiation of TDEs. The winds from the super-Eddington
accretion phase in TDEs have recently been studied. However, properties of the winds from the sub-Eddington
accretion disk in TDEs are not clear. We aim to investigate properties of winds from the circularized sub-Eddington
accretion disk in TDEs. We study the line force driven
accretion disk wind. We perform two-dimensional hydrodynamic simulations using the PLUTO code to study the line force driven wind from the circularized
accretion disk around a $10^6$
solar mass black hole in TDEs. We find that although the disk has a very small size in TDEs, strong wind can be driven by line force when the disk have luminosity higher than $20\%$ of the Eddington luminosity. The maximum velocity of wind can be as high as $0.3$ times the speed of light. The kinematic power of wind is in the range of $1\%-6\%$ times the Eddington luminosity. Strong wind can be driven by line force from the thin disk around a $10^6$
solar mass black hole in TDEs. We briefly discuss the possible
radio emission from the shock when the wind collides with the surrounding medium.
Read the full abstract ▾
All authors De-Fu Bu, Xiao-Hong Yang, Liang Chen, Chenwei Yang, Guobin Mou
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Constraints on Attractor Models of Inflation and Reheating from Planck, BICEP/Keck, ACT DR6, and SPT-3G Data
John Ellis, Marcos A. G. Garcia, Keith A. Olive et al. (+1 more)
We analyze the latest
cosmic microwave background (CMB) constraints on the scalar spectral index $n_s$ and tensor-to-scalar ratio $r$ from Planck 2018, BICEP/Keck 2018, the Atacama Cosmology
Telescope Data Release 6 (ACT DR6), and the South Pole
Telescope (SPT-3G) data, focusing on their implications for attractor models of inflation. We compare systematically observational bounds with theoretical predictions for both E-model ($\alpha$-Starobinsky) and T-model potentials. The observational constraints accommodate E-models with $\alpha \lesssim 25$, with the canonical Starobinsky model ($\alpha = 1$) predicting $n_s = 0.958-0.963$ for reheating temperatures between $100 - 10^{10}$ GeV, in good agreement with Planck 2018 data and within the 95% CL region determined by the Planck-ACT-SPT combination, but below the 95% confidence region of the Planck-ACT-DESI combination. Higher reheating temperatures from near-instantaneous reheating improve the compatibility. T-models predict slightly lower $n_s$ values (0.956-0.961), in some tension with Planck 2018 data, and we find an upper limit of $\alpha \lesssim 11$ in these models. We extend our analysis to generalized $\alpha$-attractors with monomial potentials $V(\varphi) \propto \varphi^k$ near the minimum, demonstrating that models with $k \geq 6$ naturally predict $n_s \simeq 0.965 - 0.968$ for typical number of $e$-folds, in better agreement with the ACT DR6 data. We also consider deformed E- and T-models, which allow significantly higher values of $n_s$ for low values of $\alpha \simeq 1$.
Read the full abstract ▾
All authors John Ellis, Marcos A. G. Garcia, Keith A. Olive, Sarunas Verner
High Energy Astrophysical Phenomena
Transitional Spectral Behavior in Blazar OJ 287: A Comprehensive Multi-Epoch SED Study
Navaneeth P K, Gopal Bhatta and Sangeetha Kizhakkekalam
We present a comprehensive multi-wavelength investigation of BL Lac object OJ 287 using Swift and
Fermi observatories spanning 2008-2025. The source exhibits significant flux variability across optical-UV, X-ray, and $\gamma$-ray regimes, with outbursts observed in optical, UV and X-ray frequencies. Variability and correlation analyses of the long-term lightcurves reveal strong correlations among optical, UV, and X-ray bands, whereas there is no significant correlation between $\gamma$-ray and other bands. Using a decade-long
dataset (MJD 57382-60448), we analysed X-ray spectral variability across different flux states (
flare, intermediate, and quiescent). Multi-wavelength spectral energy distributions (SEDs) were constructed using a one-zone leptonic model to investigate the transitional nature of the X-ray spectral position in the broadband. The analysis reveals OJ 287's consistent flux-dependent transitional spectral behavior: quiescent states show hard X-ray spectra dominated by inverse Compton emission; intermediate states exhibit contributions from both inverse Compton and synchrotron components with moderately hard spectra; flaring events are characterized by predominantly synchrotron emission, resulting in soft X-ray spectra. Broadband SED modelling captures the systematic
evolution of model parameters across different activity states, with correlation analysis revealing strong positive correlations between synchrotron peak frequency, Synchrotron-Self Compton peak frequency, and X-ray flux, providing quantitative evidence for the changing dominance of emission components within the blazar's relativistic jet.
Read the full abstract ▾
Cosmology and Nongalactic Astrophysics
J-PAS: forecast on the primordial power spectrum reconstruction
Guillermo Martínez-Somonte, Airam Marcos-Caballero, Enrique Martínez-González et al. (+27 more)
We investigate the capability of the J-PAS survey to constrain the
primordial power spectrum using a non-parametric
Bayesian method. Specifically, we analyze simulated power spectra generated by a local oscillatory
primordial feature template motivated by non-standard inflation. The feature is placed within the range of scales where the signal-to-noise ratio is maximized, and we restrict the analysis to $k \in [0.02,0.2] \text{ h} \text{ Mpc}^{-1}$, set by the expected J-PAS coverage and the onset of non-linear effects. Each
primordial power spectrum is reconstructed by linearly interpolating $N$
knots in the $\{\log k, \log P_{\mathcal{R}}(k)\}$ plane, which are sampled jointly with the cosmological parameters $\{H_0,\Omega_b h^2, \Omega_c h^2\}$ using PolyChord. To test the
primordial features, we apply two statistical tools: the Bayes factor and a hypothesis test that localizes the scales where features are detected. We assess the recovery under different J-PAS specifications, including
redshift binning, tracer type, survey area, and filter strategy. Our results show that combining
redshift bins and tracers allows the detection of oscillatory features as small as 2%.
Read the full abstract ▾
All authors Guillermo Martínez-Somonte, Airam Marcos-Caballero, Enrique Martínez-González, Antonio L. Maroto, Miguel Quartin, Raul Abramo, Jailson Alcaniz, Narciso Benítez, Silvia Bonoli, Saulo Carneiro, Javier Cenarro, David Cristóbal-Hornillos, Simone Daflon, Renato Dupke, Alessandro Ederoclite, Rosa María González Delgado, Antonio Hernán-Caballero, Carlos Hernández-Monteagudo, Jifeng Liu, Carlos López-Sanjuán, Antonio Marín-Franch, Claudia Mendes de Oliveira, Mariano Moles, Fernando Roig, Laerte Sodré Jr., Keith Taylor, Jesús Varela, Héctor Vázquez Ramió, José M. Vilchez, Javier Zaragoza-Cardiel
Earth and Planetary Astrophysics
Locked In Ice: how Pebble Drift and Volatile Entrapment can Significantly Impact Carbon and Oxygen Ratios in Evolving Protoplanetary Discs
Joe Williams, Sebastiaan Krijt, Bertram Bitsch et al. (+2 more)
The complex interplay between the growth, drift, and sublimation of ice-covered pebbles can strongly influence the volatile distribution and
evolution of disc composition, and therefore impact the composition of forming
planets. Classic pebble drift models treat volatile species individually as sublimating at their respective snowlines, although observations from the James Webb Space
Telescope (JWST) suggest that ices are likely mixed; laboratory studies suggest ice mixtures can exhibit more complex sublimation behaviours, remaining trapped beyond their nominal sublimation temperatures. We present the first model that couples pebble growth and drift with CO entrapment inside water ice - preventing a fraction (up to ~60%) of the CO from sublimating at its snowline, instead desorbing via volcanic desorption at the water crystallisation front, at 130K. Our models show that CO entrapment will significantly impact the carbon and oxygen distributions, enhancing the gas-phase C/O and C/H inside the water snowline by up to a factor of 10 over 1 Myr and a factor of a few around the CO2 snowline; O/H is also increased around the CO2 snowline, but is water-dominated in the inner disc. Entrapment therefore provides a means of introducing more carbon to the inner disc whilst retaining a large amount of water. We discuss connections to
planet formation, noting that CO entrapment can increase the gas-phase heavy element content around the water snowline by up to 150%. We also consider links to JWST observations and highlight the importance of entrapment for pebble drift models to accurately model disc composition.
Read the full abstract ▾
All authors Joe Williams, Sebastiaan Krijt, Bertram Bitsch, Adrien Houge, Jennifer Bergner
Cosmology and Nongalactic Astrophysics
CHEX-MATE: towards a consistent universal pressure profile and cluster mass reconstruction
M. Muñoz-Echeverría, E. Pointecouteau, G. W. Pratt et al. (+31 more)
In a self-similar paradigm of structure formation, the thermal pressure of the hot intra-cluster gas follows a universal distribution once the profile of each cluster is normalised based on the proper mass and
redshift dependencies. The reconstruction of such a universal pressure profile requires an individual estimate of the mass of each cluster. In this context, we present a method to jointly fit, for the first time, the universal pressure profile and individual cluster $M_{500}$ masses over a sample of
galaxy clusters, properly accounting for correlations between the profile shape and amplitude, and masses scaling the individual profiles. We demonstrate the power of the method and show that a consistent exploitation of the universal pressure profile and cluster mass estimates when modelling the thermal pressure in clusters is necessary to avoid biases. In particular, the method, informed by a cluster mass scale, outputs individual cluster masses with same accuracy and better precision than input masses. Using data from the {\guillemotleft}Cluster HEritage project with XMM-Newton: Mass Assembly and Thermodynamics at the Endpoint of structure formation{\guillemotright}, we investigate a sample of $\sim 25$
galaxy clusters spanning mass and
redshift ranges of $2 \lesssim M_{500}/10^{14} \; \mathrm{M}_{\odot} \lesssim 14$ and $0.07 < z < 0.6$.
Read the full abstract ▾
All authors M. Muñoz-Echeverría, E. Pointecouteau, G. W. Pratt, J.-F. Macías-Pérez, M. Douspis, L. Salvati, I. Bartalucci, H. Bourdin, N. Clerc, F. De Luca, M. De Petris, M. Donahue, S. Dupourqué, D. Eckert, S. Ettori, M. Gaspari, F. Gastaldello, M. Gitti, A. Gorce, S. Ilić, S. T. Kay, J. Kim, L. Lovisari, B. J. Maughan, P. Mazzotta, L. McBride, J.-B. Melin, F. Oppizzi, E. Rasia, M. Rossetti, H. Saxena, J. Sayers, M. Sereno, M. Tristram
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
The Muonic Portal to Vector Dark Matter:connecting precision muon physics, cosmology, and colliders
Alexander Belyaev, Luca Panizzi, Nakorn Thongyoi et al. (+1 more)
We present a comprehensive study of the Muonic Portal to Vector Dark Matter (MPVDM), a minimal extension of the Standard Model featuring a new $SU(2)_D$ gauge
symmetry and vector-like
muons that mediate interactions between the dark sector and the
muon sector. We show that the MPVDM can simultaneously reproduce the observed dark matter relic abundance and accommodate scenarios consistent with the current experimental determination of the
muon anomalous
magnetic moment, $(g-2)_\mu$, as well as scenarios allowing for a non-zero new physics contribution to $(g-2)_\mu$. One of the key results of this work is the identification of a generic off-resonance velocity-suppression mechanism that allows light ($\lesssim 1$ GeV) vector dark matter to evade stringent CMB constraints near $2m_{\mathrm{DM}}\simeq m_{H_D}$. A five-dimensional parameter scan combining cosmological,
collider, and precision constraints shows that scenarios admitting a non-zero contribution to $(g-2)_\mu$ favour sub-GeV dark matter realised near the scalar resonance with a dark gauge coupling $g_D\!\sim\!10^{-3}$ and TeV-scale vector-like
muons, while scenarios consistent with a Standard-Model-like $(g-2)_\mu$ allow a broad viable dark matter mass range from sub-GeV to multi-TeV. By recasting ATLAS and CMS searches for $\mu^+\mu^-$ final states with missing transverse energy, we derive a lower bound of approximately 850~GeV on the vector-like
muon masses. We further identify distinctive multi-
lepton collider signatures, including six-, eight-, and ten-
muon final states as well as mixed
muon–electron
topologies with displaced electron pairs, providing striking and well-motivated targets for searches at the LHC and future
colliders.
Read the full abstract ▾
All authors Alexander Belyaev, Luca Panizzi, Nakorn Thongyoi, Franz Wilhelm
Solar and Stellar Astrophysics
Improved thermonuclear rate of $^{42}$Ti($p$,$\gamma$)$^{43}$V and its astrophysical implication in rp-process
S. Q. Hou, C. Iliadis, M. Pignatari et al. (+4 more)
Accurate $^{42}$Ti($p$,$\gamma$)$^{43}$V reaction rates are crucial for understanding the nucleosynthesis path of the rapid capture process (rp-process) that occurs in X-ray bursts. We aim to improve the thermonuclear rates of $^{42}$Ti($p$,$\gamma$)$^{43}$V based on more complete resonance information and accurate direct component, together with the recently released
nuclear masses data. We reevaluated the $^{42}$Ti($p$,$\gamma$)$^{43}$V rate by the sum of the isolated resonance contribution instead of the Hauser-Feshbach statistical model. A Monte Carlo method is used to derive the uncertainties of new rates. The nucleosynthesis simulations are performed via the NuGrid post-processing code ppn. The new rates differ from previous estimations because of using a series of updated resonance parameters and direct S-factor. Compared with the previous results from Hauser-Feshbach statistical model, which assumes compound
nucleus $^{43}$V with a sufficiently high-level density in the energy region of astrophysical interest, differences exist over the entire temperature region of rp-process interest, even up to 4 orders of magnitude. Using a trajectory with a peak temperature of 1.95$\times$10$^9$ K, we perform the rp-process nucleosynthesis simulations to investigate the impact of the new rates. Our calculations show that the adoption of the new forward and reverse rates result in abundance variations for Sc and Ca by 128% and 49% respectively compared to the case using statistical model rates. On the other hand, the overall abundance pattern is not significantly affected. The results of using new rates also confirm that the rp-process path does not bypass the isotope $^{43}$V. It is found that the Hauser-Feshbach statistical model is inappropriate to the reaction rate evaluation for $^{42}$Ti($p$,$\gamma$)$^{43}$V.
Read the full abstract ▾
All authors S. Q. Hou, C. Iliadis, M. Pignatari, J. B. Liu, T. C. L. Trueman, J.G. Li, X. X. Xu
High Energy Astrophysical Phenomena
The Optical Study of the Eclipsing Polar SDSS J002637.06+242915.6
V.Yu. Kochkina, A.I. Kolbin, T.A. Fatkhullin et al. (+2 more)
We have analyzed phase-resolved photometric and spectroscopic observations of the eclipsing polar SDSS J002637.06+242915.6. The light curve has a M-shaped bright phase that was reproduced using a simple model of an accreting
magnetic white
dwarf. The hydrogen emission lines exhibit a narrow component formed on the irradiated hemispere of the donor. The Doppler
tomography revealed differences in the positions of emission regions of hydrogen and HeII $\lambda$4686 lines. The spectra exhibit a Zeeman absorption triplet of the H$\alpha$ line, formed in the cold
halo around the
accretion spot at a
magnetic field strength of $B = 15.1 \pm 1.3$ MG. The spectra of the bright phase have a red cyclotron continuum, whose orbital variability has been interpreted within a simple model of an
accretion spot. The modeling of the cyclotron continuum constrains the white
dwarf's
magnetic field to $B_{cyc} \lesssim 45$ MG. The analysis of the eclipse light curve and the radial velocities of the irradiated hemisphere yielded estimates for the orbital inclination $77.2^\circ \le i \le 80.6^\circ$, the mass ratio $0.23 \le q \le 0.43$, and the white
dwarf mass $0.72 \ge M_1/M_\odot \ge 0.42$.
Read the full abstract ▾
All authors V.Yu. Kochkina, A.I. Kolbin, T.A. Fatkhullin, A.S. Vinokurov, N.V. Borisov
Astrophysics of Galaxies
GLEAM-300: The GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey at 300 MHz
S. W. Duchesne, J. H. Cook, N. Hurley-Walker et al. (+11 more)
In this paper we present a wide-field
radio survey at 300 MHz covering the sky from $-90^\circ \leq \delta_\text{J2000} \lesssim +40^\circ$ using the Murchison Widefield Array (MWA). This 300-MHz survey follows the
Galactic and Extragalactic All-sky MWA (GLEAM) survey, and provides an additional comparatively high-frequency data point to existing multi-frequency (72-231 MHz) data. With this data release we provide mosaic images and a catalogue of compact source components. We use two-minute snapshot observations covering 2015-2016, combining overlapping two-minute snapshot images to provide full-sensitivity mosaic images with a median root-mean-square noise of $9.1_{-2.8}^{+5.5}$ mJy beam$^{-1}$ and median angular resolution of $128.8^{\prime\prime} \times 112.5^{\prime\prime}$, with some position-dependent variation. We find a total of 338 080 unique Gaussian components across the mosaic images. The survey is the first at 300 MHz from the MWA covering the whole Southern Hemisphere. It provides a unique spectral data point that complements the existing GLEAM survey and the ongoing GLEAM-eXtended survey, and points toward results from the upcoming SKA-Low surveys.
Read the full abstract ▾
All authors S. W. Duchesne, J. H. Cook, N. Hurley-Walker, A. J. M. Thomson, S. Paterson, C. J. Riseley, S. J. McSweeney, S. Mantovanini, G. Heald, T. M. O. Franzen, K. Ross, N. Seymour, R. B. Wayth, T. J. Galvin