Cosmology and Nongalactic Astrophysics
The statistics of curvature-profile dispersion in primordial black hole formation
Albert Escrivà
In the standard
curvature-perturbation scenario, PBHs form from the collapse of superhorizon
curvature fluctuations after horizon re-entry. The predicted abundance is exponentially sensitive to the collapse threshold and hence to the shape of the
primordial curvature profile. In this work we develop a finite-action framework to describe
curvature-profile dispersion around representative peak profiles. Using a multipolar
Fourier-Bessel decomposition, we separate the local peak variables of the Gaussian field from residual radial and angular deformations, normalized by their Gaussian action. We apply the formalism to spherical numerical-collapse examples in order to isolate the effect of radial shape dispersion. For finite-width spectra, and in the presence of logarithmic local non-Gaussianity, we compute the collapse threshold as a function of a coherent shape variable and combine the result with peak statistics. We find that the dominant contribution to the PBH abundance is not necessarily the conditional-mean reference profile, nor simply the profile with the lowest threshold. Instead, it is selected by a competition between the Gaussian cost of realizing a coherent deformation and the exponential gain associated with lowering the collapse threshold. Broad spectra and negative non-Gaussianity can make rare shape deformations dominate the abundance. In the examples studied here, the dominant branches can correspond to several-sigma coherent shape fluctuations while enhancing the integrated abundance by orders of magnitude. Equivalently, including shape dispersion can reduce the power-spectrum amplitude required to obtain a fixed PBH abundance. Our results show that residual profile dispersion is a genuine statistical ingredient in PBH formation and can be quantitatively important for accurate abundance estimates.
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High Energy Astrophysical Phenomena
Tilted thin accretion disks in the full Kerr spacetime and their implications
K. S. Sruthy, Chandrachur Chakraborty and Sudip Bhattacharyya
We derive a steady-state warped-disk equation in the full Kerr spacetime to study the tilt dynamics of a thin, viscous
accretion disk around a spinning collapsed object. The formulation, based on Pringle's framework, remains valid for all values of the Kerr parameter $a$, thereby encompassing both Kerr black holes (BHs; $0 < a \le 1$) and Kerr naked singularities ($a > 1$). By incorporating the exact Keplerian and Lense-Thirring precession frequencies, we analytically obtain the radial tilt equations of the disk without invoking slow-
spin or weak-field approximations. Numerical solutions of the resulting equations, obtained under realistic boundary conditions, reveal significant deviations from slow-
spin approximations, particularly in the inner disk where the relativistic effects dominate. In the diffusive regime, we find that for Kerr naked singularities the tilt profile exhibits distinct inner hump(s) near the radius where the specific angular momentum vanishes – a feature absent for Kerr BHs. Consideration of a tilt in the inner disk could significantly influence the interpretations from observed X-ray spectral, timing, and polarization features, which are crucial to probe the strong
gravity regime and to infer the
spin of the central object. While such a distinct hump feature alone does not uniquely distinguish Kerr BHs from Kerr naked singularities, their interpretation in conjunction with constraints on the disk regime may provide a potential observational handle on the nature of the accreting collapsed object.
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Solar and Stellar Astrophysics
Cataclysmic Variables Photometric Periods from TESS
S. O. Kepler, Alejandra Daniela Romero, Larissa Luciano Amorim et al. (+1 more)
We present a sample of coherent and stable photometric period determinations for cataclysmic variables, based on TESS photometry through sector 102. We analyzed a total of 1554 cataclysmic variable
stars and detected periodic variations in 1362 objects, including 286 eclipsing or ellipsoidal-variation systems, 63 polars, and 135 intermediate polars. In particular, we present the first determination of the optical variability period for 564 cataclysmic variables. Due to the 21x21" pixel size of TESS, we tested whether the variability was coming from the cataclysmic variable and not from a nearby
star. For the intermediate polars, we detected
spin periods in addition to orbital periods for 83 systems. We detect a clear period gap between ~2 and ~3 h in the eclipsing sample, consistent with previous work. The gap remains for the complete sample of photometric variability periods. There is no apparent gap in the orbital period distribution for intermediate polars. Finally, the median of the photometric period distribution of our complete sample of cataclysmic variables is 3.681 h. Comparing this to the distribution of rotation periods for likely single white
dwarfs, we find a similar range, with a median photometric period of 6.803~h.
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All authors S. O. Kepler, Alejandra Daniela Romero, Larissa Luciano Amorim, Marcos Perez Diaz
Astrophysics of Galaxies
Force convergence in Monte Carlo Lyman-alpha radiative transfer
Joshua Kasiri, Aaron Smith, Kevin Lorinc et al. (+2 more)
Monte Carlo radiative transfer (MCRT) is widely used to model Lyman-alpha (Lya) resonant-line transport, but convergence is difficult to assess in optically thick media where
photons undergo many scatterings before escape. This is especially important for internal quantities such as radiative acceleration and the force multiplier, which depend on momentum deposition throughout the gas rather than only on emergent spectra. We study the convergence of Lya MCRT momentum-transfer
estimators in static spherical clouds. We first establish
diffusion-limit
benchmarks for radial acceleration profiles and integrated force multipliers, then develop a moment-based framework for diagnosing convergence from the
photon-packet contribution distribution. This framework separates three distinct questions: whether the
estimator converges to the correct mean, how large its finite-sampling uncertainty is, and whether the estimated uncertainty is itself stable. We apply this hierarchy to the direct event-based scattering
estimator, a gradient-of-energy-density
estimator, and a divergence-of-radiation-pressure
estimator. Zeroth-order convergence is assessed with profile comparisons, integrated force-multiplier bias, and finite-group relative error. First-order convergence is quantified with fractional error, the
photon number required to reach a target precision, and the corresponding runtime requirement. Second-order convergence is tested with the coefficient of variation of variance, which measures the reliability of the variance estimate used in the first-order diagnostics. Core-skipping prescriptions, source geometry,
estimator construction, and spatial resolution enter this hierarchy in different ways. Our results provide a practical convergence framework for internal Lya MCRT force calculations and show why statistical precision, computational cost, and physical accuracy must be evaluated separately.
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All authors Joshua Kasiri, Aaron Smith, Kevin Lorinc, Olof Nebrin, Kazutaka Kimura
Astrophysics of Galaxies
Thermal Sunyaev-Zel'dovich Measurements of Locally Bright Galaxies with ACT DR6: Radio Source Contamination and Excess Compton-y Signal
Nicholas Battaglia, Jean-Baptiste Melin, J. Colin Hill et al. (+1 more)
The Planck collaboration found a remarkable power-law relation between
stellar mass and the thermal Sunyaev-Zeldovich (tSZ) signal for the Locally Bright
Galaxy (LBG) sample, spanning over a decade in
stellar mass. We re-examine this measurement using the Atacama Cosmology
Telescope (ACT) DR6 component-separated Compton-$y$ maps, which provide lower noise and higher angular resolution than Planck, on a footprint spanning one-third of the sky. We recover a consistent power-law scaling between the cylindrical Compton-$y$ signal and
stellar mass. Additionally, we identify residual contamination in the tSZ signal from
radio sources at the few percent-level, which has not been considered previously. In parallel, we identify a factor-of-two excess in the Compton-$y$ signal in LBGs hosting co-spatial
radio sources relative to those without, at fixed
stellar mass. This excess persists to radii of at least 6 arcminutes, suggesting a
halo-scale effect, and is recovered in the original Planck results when the same
radio source subselection is applied. We consider two physical explanations: a systematic difference in
halo mass at fixed
stellar mass, or thermal energy injected into the circumgalactic medium by Active
Galactic Nuclei, although we cannot currently distinguish between the two. This result has direct implications for tSZ cross-correlation measurements more broadly, and necessitates careful characterization of the
radio source fraction in
galaxy samples in future analyses.
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All authors Nicholas Battaglia, Jean-Baptiste Melin, J. Colin Hill, James Bartlett
Earth and Planetary Astrophysics
The Impact of Planetary Phase Functions on Exo-Earth Detectability with EXOSIMS
Searra Foote, Tyler D. Robinson, Rhonda Morgan et al. (+3 more)
The under-development NASA Habitable Worlds Observatory (HWO) aims to provide breakthroughs in
exoplanet science, yet the most effective approaches to modeling the detection and characterization of potentially Earth-like worlds with HWO remain uncertain despite being essential considerations for mission design. In this work, we aim to better model and understand detection metrics through the use of EXOSIMS (
Exoplanet Open-Source Imaging Mission Simulator), an
exoplanet yield modeling tool. Yield modeling requires representing planetary brightness via a planetary phase curve. Earth's true visual phase curve is non-Lambertian, deviating from the idealized Lambertian model in EXOSIMS, particularly at phase angles beyond 90 degrees (i.e., quadrature). This leads to underestimating Earth's brightness. To address this, we incorporate phase-dependent reflectance from a high-fidelity Earth model into EXOSIMS for physically motivated simulations. We explore and quantify differences in phase-dependent detections, finding that the realistic Earth phase function produces modest changes in the median number of detected exo-Earths and systematically redistributes detections towards medium to high phase angles where Earth is intrinsically brighter than a Lambertian approximation. Additionally, we explore the role of coronagraph inner working angle (IWA) by running simulations across multiple IWA values with both phase functions, revealing that smaller IWAs expand access to a broader range of orbital phases, altering the resulting phase-angle distribution of detections. Together, these results demonstrate that realistic phase functions and IWA parameters both have measurable impacts on yield estimates for an HWO-like mission and highlight the need to more realistically represent Earth-like worlds in yield modeling.
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All authors Searra Foote, Tyler D. Robinson, Rhonda Morgan, Dmitry Savransky, Mario Damiano, Armen Tokadjian
Astrophysics of Galaxies
Detection of the Polycyclic Aromatic Hydrocarbon Phenalene (C$_{13}$H$_{10}$) in the Very Low Luminosity Object (VeLLO) MC27/L1521F
Gabi Wenzel, Thomas H. Speak, Ci Xue et al. (+12 more)
To date, 14 polycyclic aromatic hydrocarbons (PAHs) ranging in size from two to seven (including five- and six-membered) carbon rings have been detected in the starless dense core TMC-1 CP within the Taurus molecular cloud. Their detection raises questions about the distribution of PAHs in the cold interstellar medium (ISM) and their
evolution during
star formation. Here, we present the first interstellar detection of a three-ring PAH outside of TMC-1 CP. We detect phenalene (C$_{13}$H$_{10}$), a compact, peri-fused PAH, in the dense core MC27/L1521F, a molecular cloud in Taurus containing a very low-luminosity object (VeLLO). We compare the abundances of phenalene in the two sources with respect to the single-ring aromatic benzonitrile, and find that it is enhanced by a factor of four in MC27/L1521F. We discuss the implications for possible formation and destruction pathways in the two sources. These findings further support the widespread abundance of PAHs throughout the cold ISM and are consistent with survival, inheritance, or replenishment during the earliest stages of
star formation.
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All authors Gabi Wenzel, Thomas H. Speak, Ci Xue, Edwin A. Bergin, Andrew M. Burkhardt, Martin A. Cordiner, Miya Duffy, Zachary T. P. Fried, Andrew Lipnicky, Christopher N. Shingledecker, Reace H. J. Willis, Anthony J. Remijan, Michael C. McCarthy, Brett A. McGuire, Ilsa R. Cooke
High Energy Astrophysical Phenomena
H\alpha\ clarifies picture of IIn supernova SN 2015da
Nikolai Chugai
Observational data on type IIn
supernova SN 2015da are revisited to clarify some ambiguous issues of this phenomenon. The H alpha–emitting site is found to switch around day 90 from the circumstellar matter to the unshocked ejecta. This picture makes it possible to recover the expansion velocity of late time ejecta and to locate the
dust formation in the inner zone of unshocked ejecta.The bolometric light curve and expansion velocities combined with modelling the circumstellar interaction imply that the
supernova exploded with an energy of $\gtrsim 4\times10^{51}$ erg inside the circumstellar envelope with the mass of $\approx 14$ Msun. The recovered density of the circumstellar matter is consistent with the Thomson optical depth inferred from H alpha modelling on day 46.The observed circumstellar envelope is produced by an average mass loss rate of 0.035 Msun/yr during 400 yr before the
supernova explosion.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Leptogenesis and Low Reheating Temperatures
Marcos A. G. Garcia, Stephen E. Henrich, Wenqi Ke et al. (+1 more)
We study leptogenesis during non-instantaneous reheating in the canonical type-I seesaw framework, with the dominant source of right-handed
neutrino (RHN) production being non-thermal from inflaton decays ($\phi \rightarrow NN$). While matter-like reheating ($w_\phi=0$) fails to be compatible with standard leptogenesis for very low reheating temperatures, the situation is strikingly different for generalized Starobinsky potentials approximated by $V(\phi)\propto\phi^k$ with $k\geq4$ about the minimum. In the latter cases, the observed
baryon asymmetry can readily be obtained for arbitrarily low reheating temperatures above the BBN bound of $\sim4$ MeV. We study radiation-like reheating ($w_\phi=1/3$, $k=4$) in detail, showing that the evolving effective mass of the inflaton condensate leads to kinematic shutoff of the $\phi\rightarrow NN$ channel, which qualitatively changes the leptogenesis dynamics. We include a detailed treatment of the effects of fragmentation of the inflaton condensate. The final
baryon asymmetry depends primarily on only two parameters: the inflaton-RHN coupling, $y_{\phi NN}$, and the CP-violating parameter $|\epsilon|$. Interestingly, the final asymmetry is largely insensitive to the RHN mass, the reheating temperature, and the RHN decay rate. While we focus on fermionic reheating, we show that the general features of these results also hold for bosonic reheating to scalars.
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All authors Marcos A. G. Garcia, Stephen E. Henrich, Wenqi Ke, Keith A. Olive
Astrophysics of Galaxies
VAPOLA – A multi-year, multi-band polarization survey of AGN and Sgr A* at mm wavelengths with ALMA I. Survey Overview and Science-Ready Archival Products
Alejandro Mus, Ciriaco Goddi, Douglas Carlos et al. (+13 more)
The Atacama Large Millimeter/submillimeter Array (ALMA) is the most sensitive interferometric array at millimeter and submillimeter wavelengths. Through the ALMA Phasing System (APS), it can participate in global Very Long Baseline Interferometry (VLBI) arrays, enhancing their sensitivity and resolution. However, processing and analzing the ALMA data obtained in APS mode during VLBI observations remains a complex task, requiring specialized expertise and time-consuming calibration and imaging procedures. In this paper, we present VAPOLA-the first online, multi-epoch, multi-band repository of high-level data products from ALMA observations of active
galactic nuclei (AGN) and Sgr A* during global VLBI campaigns. Built on an automated pipeline that processes fully calibrated ALMA (QA2) data, generates science-ready products with minimal user intervention. The repository includes fully calibrated interferometric visibilities, full-Stokes images across individual and combined spectral windows, polarimetric and spectral index maps, as well as tabulated polarimetric parameters from visibility-domain polarization fitting. By offering ready-to-use data through a user-friendly web portal, VAPOLA enables non-expert users to perform advanced science analyses without needing in-depth knowledge of ALMA procedures. This resource will facilitate a broad range of scientific investigations, including the characterization of
magnetic field properties in
accretion flows and relativistic jets, the structure and kinematics of dusty and molecular
tori in AGN, and absorption studies of the interstellar medium toward the
Galactic Center. In addition, the
dataset provides source-integrated parameters and calibration metadata essential for refining VLBI calibration and imaging workflows as well as for placing robust observational constraints on theoretical models of supermassive black holes and their environments.
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All authors Alejandro Mus, Ciriaco Goddi, Douglas Carlos, Vincenzo Galluzzi, Ezequiel Albentosa-Ruiz, Ivan Martí-Vidal, Hugo Messias, Kazi L. J. Rygl, Geoffrey B. Crew, Lynn D. Matthews, Elisabetta Liuzzo, Nicola Marchili, Raphael P. Rolim, Mariafelicia De Laurentis, Rocco Lico, Cristiano Urban
Cosmology and Nongalactic Astrophysics
Can Distance Duality Violation Save Late-time Solutions to the Hubble Tension?
Yashi Tiwari, Ujjwal Upadhyay, Shao-Jiang Wang et al. (+1 more)
The discrepancy between early- and late-Universe determinations of the Hubble constant may point to physics beyond $\Lambda$CDM or to unaccounted-for systematics. Numerous late-time modifications to the expansion history have been proposed to alleviate this discrepancy, with limited success. Recent works have shown that, when the sound-horizon and
supernova calibrations are held fixed, any purely late-time resolution requires a violation of the
cosmic distance duality relation (CDDR). Recasting the tension in the $r_d$-$M_B$ plane, we show explicitly that distance duality, together with BAO and uncalibrated
supernova data and a fixed sound-horizon calibration, determines $H_0$ independently of the late-time expansion history. We then test the viability of the required CDDR violation by separately constraining reciprocity violation and
photon number non-conservation, deriving a new constraint on reciprocity-violating distortions of angular-diameter distances from BAO and
cosmic-chronometer data. Combining this result with existing
photon-number-conservation constraints, we find that the level of distance-duality violation needed to resolve the tension is strongly disfavoured by current data. We therefore conclude that, for fixed sound-horizon and
supernova calibrations, no modification confined to the late-time expansion history – even one violating distance duality – can resolve the Hubble tension, pointing instead toward early-Universe physics or unresolved local systematics.
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All authors Yashi Tiwari, Ujjwal Upadhyay, Shao-Jiang Wang, Vivian Poulin
High Energy Astrophysical Phenomena · Cross-listed from gr-qc
Beyond black hole spectroscopy: Quasinormal mode contamination by massless scalars
Miguel Yulo Asuncion, Giovanni D'Addario and Thomas P. Sotiriou
Testing General Relativity (GR) with black hole ringdowns has conventionally focused on attempting to detect shifts away from the quasinormal mode (QNM) frequencies of the Kerr metric. It has recently been argued, however, that the ringdown signal will also be contaminated with the QNM frequencies of any new fields that are present in a beyond-GR scenario, provided that they couple nonminimally to
gravity. We study black hole perturbations for the shift-symmetric Horndeski action, which includes all interactions between a massless scalar and
gravity that lead to second order equations upon variation. We perturb linearly in the field and also employ a perturbative expansion in the scalar charge per unit black hole mass, $q$. Assuming that the scalar amplitude is suppressed by $q$, we demonstrate that, to order $q^2$, the coupling between the scalar and the Gauss-Bonnet invariant is the only term that contributes to both frequency shifts and contamination, and that the two effects appear at the same perturbative order. If the assumption about the suppression of the scalar amplitude is relaxed, contamination can appear at leading order in $q$, and hence dominate over frequency shifts. In this case, contamination also receives subleading corrections from an additional coupling
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Cosmology and Nongalactic Astrophysics
The Three Hundred Project: Validating $H_0$ inference from mock X-ray and millimetre analyses of galaxy clusters
F. De Luca, H. Bourdin, P. Mazzotta et al. (+6 more)
Measurements of thermodynamical quantities in
galaxy clusters are differently affected by simplified modelling of radially averaged observables in the X-ray and millimetre bands. This includes assumptions about the cosmological model and the morphology of the cluster intracluster medium (ICM). Within a large sample of clusters extracted from The Three Hundred hydrodynamical simulations, we assess the systematic differences expected from the morphological assumptions between ICM temperatures as inferred from X-ray spectroscopy or joint X-ray and millimetre imaging. We find that these differences show a well-defined statistical behaviour that correlates with the cluster dynamical and morphological indicators. We then investigate how joint inferences of cluster temperature profiles, a priori informed by this statistical behaviour, allow us to constrain cosmological parameters inferred from the apparent cluster sizes. Assuming a flat $\Lambda$ cold dark matter ($\Lambda$CDM) cosmology and priors on $\Omega_\mathrm{m}$ and the helium abundance, this method provides us with unbiased estimates of the Hubble constant, $H_0$, characterised with a precision of about $4\%$ and $1.5\%$ for samples of 100 and 1000 clusters, respectively, and ultimately limited by systematic uncertainties of about $0.6$–$0.8\, {\rm km\, s^{-1} Mpc^{-1}}$. This work highlights the potential of joint X-ray and millimetre observations of
galaxy cluster samples to place tight constraints on $H_0$.
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All authors F. De Luca, H. Bourdin, P. Mazzotta, E. Rasia, A. Kozmanyan, W. Cui, M. De Petris, D. de Andres, G. Yepes
High Energy Astrophysical Phenomena
Active galactic nuclei are not responsible for systematics in the empirical properties of type Ia supernovae
Peter Clark
Despite being key cosmological anchors, the empirical properties of Type Ia
supernovae (SNe Ia) remain subject to significant systematic uncertainties, the largest of which being their astrophysics and how this is linked to their environment. The relative importance of these uncertainties will grow as larger observational samples reduce statistical uncertainties. Here I explore if the presence of an active
galactic nucleus (AGN) within a portion of SN Ia host
galaxies could be one such systematic uncertainty. With the ZTF SNe Ia DR2 sample I find that, in the low
redshift regime (z < 0.15), the presence of AGNs in some SN Ia hosts does not produce a significant systematic effect on their measured Hubble residuals.
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Earth and Planetary Astrophysics
Near-perihelion activity and composition of 3I/ATLAS from JUICE/MAJIS observations
D. Bockelee-Morvan, F. Poulet, Y. Langevin et al. (+16 more)
We present visible-to-infrared (0.5-5.56 microns) observations of the interstellar comet 3I/ATLAS obtained with the Moons and Jupiter Imaging Spectrometer (MAJIS) aboard the Jupiter Icy Moons Explorer (JUICE) spacecraft between 2025 November 2 and 25, shortly after perihelion. The fluorescence emission from H2O at 2.7 microns and CO2 at 4.3 microns is detected at heliocentric distances of 1.36-1.68 au. A weak
dust-scattered continuum is identified from which we determine the spectral slope, with values ranging from ~15% per 100 nm in the 0.65-0.9 microns region to 1-3% per 100 nm from 0.9 to 2.6 microns. Spatially resolved measurements show that the radial distributions of H2O and CO2 species are consistent with release in the near-
nucleus environment. We derive H2O production rates that decreased from 8 x 1028 s-1 to 4 x 1028 s-1 over the period November 2-25, while the CO2/H2O ratio remained nearly constant at ~10%. The heliocentric
evolution of the CO2 production rate indicates activity controlled by
solar heating. Combined with published CO measurements and the low gas expansion velocities, our analyses support a scenario in which CO2 plays a major role in driving the activity of 3I/ATLAS near perihelion. In addition, broad emission features are identified in the 3.2-3.6 microns region that cannot be explained by the fluorescence of common cometary CH-bearing volatiles. Their spectral characteristics are consistent with aliphatic C-H functional groups and provide tentative evidence for the release of complex organic material from
dust grains in the coma.
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All authors D. Bockelee-Morvan, F. Poulet, Y. Langevin, B. Seignovert, C. Leyrat, G. Piccioni, C. Royer, S. Rodriguez, E. d'Aversa, R. Brunetto, J. Carter, T. Cavalie, M. De Sanctis, E. Lellouch, A. Migliorini, C. Pilorget, E. Quirico, S. Robert, F. Tosi
High Energy Astrophysical Phenomena
FAST Discovery of $\mu$Jy Radio Pulsations from PSR J2238+5903, Providing a DM Distance Anchor for the Candidate TeV Halo 1LHAASO J2238+5900
Jianli Zhang, Hui Zhu, Guanhong Lin et al. (+10 more)
We report the first detection of
radio pulsations from PSR J2238+5903, a gamma-ray
pulsar spatially coincident with the extended TeV source 1LHAASO J2238+5900. Our 3000 s FAST L-band observation reveals a weak periodic signal at the known
Fermi-LAT
spin period, with $P=162.76568$ ms and $\mathrm{DM}=247.5\pm3.0~\mathrm{pc~cm^{-3}}$. The signal is independently confirmed by both FFT-based and Fast Folding
Algorithm searches. The radiometer equation gives a flux density of $S_{1250}\simeq3\,\mu$Jy, placing PSR J2238+5903 among the faintest
radio-detected
Fermi pulsars. Interpreting the DM with
Galactic electron-density models gives $d_{\rm DM}=7.4\pm3.9$ kpc. At this distance, the LHAASO WCDA 39% containment radius corresponds to a characteristic diameter of $\sim132$ pc, and the $>1$ TeV luminosity is $L_{\rm TeV}\simeq7.1\times10^{34}$ erg s$^{-1}$, about 8% of the
pulsar's
spin-down power. The
radio DM thus provides the first
pulsar-specific distance constraint for assessing whether 1LHAASO J2238+5900 is a young relic-PWN / TeV-
halo transition system.
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All authors Jianli Zhang, Hui Zhu, Guanhong Lin, Dejia Zhou, Yuting Chu, Songzhan Chen, Min Zha, WenJun Huang, ZiWei Ou, P. H. Thomas Tam, Sha Wu, Qiang Yuan, Yi Zhang
Astrophysics of Galaxies
Classification of blazars based on data-driven approaches
Simone Vaccaro, Maria Isabel Carnerero, Claudia M. Raiteri et al. (+5 more)
Active
galactic nuclei (AGNs), including blazars, exhibit distinctive variability in their optical light curves, making them ideal for classification studies. This work uses data from the latest
GAIA and Pan-STARRS data releases to analyze these patterns. The goal of this work is to classify AGNs into two categories: "blazars" and "non-blazars” using only optical light curves. This strategy differs from most existing works, as it relies exclusively on optical variability without employing any other multiwavelength information. We processed optical light curves from
GAIA and Pan-STARRS using the FATS library to extract standard time-series features. We computed additional features with custom
algorithms based on literature methods. A Light Gradient-Boosting Machine (LightGBM) model was trained to classify AGNs into blazars and non-blazars based on these features. We then used this knowledge base to carry out a self-learning experiment with AGN candidates of an unknown nature. The LightGBM model achieved an accuracy of $86\%$, with precision, recall, and F1 score above $80-85\%$ for classifying blazars and non-blazar AGNs using optical data. The application of a BoostBoruta
algorithm for feature selection reduced the feature space from 70 to 13. while maintaining comparable performance. A self-training classifier yielded similar results $85\%$, confirming the robustness of the model and the reliability of pseudo-labeling for unknown objects.
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All authors Simone Vaccaro, Maria Isabel Carnerero, Claudia M. Raiteri, Massimo Brescia, Ylenia Maruccia, Natale De Bonis, Giuseppe Riccio, Stefano Cavuoti
Cosmology and Nongalactic Astrophysics
Beyond {\Lambda}CDM with the SKA Observatory – II: Unveiling the Secrets of the Early Universe
José Fonseca, Benedict Bahr-Kalus, Mario Ballardini et al. (+12 more)
The origins of the universe remain one of the biggest mysteries in modern cosmology. While the Planck satellite has provided a wealth of information about the early universe, there is still much to be discovered. The Square Kilometre Array Observatory (SKAO) offers a unique opportunity to probe the universe's infancy, going beyond the current limitations of our knowledge. By measuring the power spectrum of biased tracers of the dark matter distribution on the largest cosmological scales and exploring beyond 2-point statistics, SKAO will enable us to refine our understanding of the
primordial universe, including the shape of the inflationary power spectrum and the presence of
primordial non-Gaussianity. In this chapter we will review recent works looking at the potential of SKAO's surveys, and how synergies with other surveys can revolutionize our understanding of the origins of the cosmos.
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All authors José Fonseca, Benedict Bahr-Kalus, Mario Ballardini, Matilde Barberi-Squarotti, Steven Cunnington, Sêcloka L. Guedezounme, Dionysios Karagiannis, Samantha J. Rossiter, Ziad Sakr, Cora Uhlemann, Stefano Camera, Bikash R. Dinda, Cláudio Gomes, Roy Maartens, Mário G. Santos
Astrophysics of Galaxies
Disentangling the dark and stellar mass through precise lens modelling of the JWST observation of lensed quasar WFI2033–4723
Tian Li, Thomas E. Collett, Coleman M. Krawczyk et al. (+2 more)
We use high-resolution JWST/NIRCam imaging and measured time delays to model the quadruply imaged
quasar WFI2033–4723 with a composite
stellar plus dark-matter mass model. We first construct an elliptical power-law baseline model and recover Fermat-potential differences (fpd) consistent with previous HST-based and JWST-based analyses, providing a reference scale for composite modelling. We then replace the total mass profile with a physically motivated decomposition in which the
stellar mass follows a multi-Gaussian expansion of the lens light, with a free radial mass-to-light gradient, and the dark matter is described by a generalized Navarro–Frenk–White (gNFW)
halo. Using two external cosmological priors, Planck+DESI and Pantheon+SH0ES, the measured time delays constrain the mass-sheet-transformation freedom that would otherwise damage the
stellar–dark-matter decomposition. In both cosmological cases, the
stellar normalization lies between the expectations for Chabrier and Salpeter initial mass functions, while the radial mass-to-light gradient is not strongly required by the data (mildly positive). The dark matter
halo has an inner slope $\gamma_{\rm in}\simeq1.3$, steeper than a standard NFW cusp, and the main astrophysical conclusions are insensitive to the adopted cosmological prior. This work shows that composite time-delay lens modelling can effectively separate
baryons from dark matter. As a qualitative check, we reverse the logic and use our composite lens model without kinematic information to infer the cosmology instead. However, the strong degeneracy between $H_0$ and the
halo scale radius $R_s$ prevents a robust standalone constraint.
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All authors Tian Li, Thomas E. Collett, Coleman M. Krawczyk, Wolfgang J. R. Enzi, Aymeric Galan
Cosmology and Nongalactic Astrophysics
XShooter DESI Lens Program: Sample characterization
Eric Jullo, Christophe Boghossian, Luderic Chapel et al. (+6 more)
Large imaging surveys in cosmology are detecting orders of magnitude more lens systems than known so far. This unprecedented
dataset will lead to robust constraints on cosmology and
galaxy evolution models. However, a preliminary careful characterization of the lens and source samples are mandatory. In this work, we report on a VLT/XShooter observation program of 67 lens systems to characterize their spectroscopic
redshift distribution. These systems were previously detected on the Dark Energy Spectroscopic Instrument Legacy Imaging Surveys by Huang et al. 2021 and Storfer et al. 2022 with deep residual neural network. We manage to measure
redshifts for 58 lenses and 57 sources. We also identify 2 sources with indication of
outflow in the shape of the emission lines and 7 sources with rotating disks in $[OII]$ or $H\alpha$. We find no particular bias associated to the
redshift measurement operation, meaning that our measured source
redshift distribution is likely representative of the true one and can be used to calibrate analyses in large imaging surveys.
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All authors Eric Jullo, Christophe Boghossian, Luderic Chapel, Felipe Urcelay, Christopher Storfer, Xiaosheng Huang, Raphael Gavazzi, Jens-Kristian Krogager, Aleksandar Cikota
High Energy Astrophysical Phenomena
The 20 GeV Galactic Halo Excess: Pixel-Level Confirmation and Consistency with Sub-TeV WIMP Annihilation
Trinity Rosebud Stenhouse, Chamkaur Ghag and Frank F. Deppisch
A recent analysis of 15 years of
Fermi-LAT data reported a spherically symmetric,
halo-like component of the
Galactic diffuse emission that peaks near 20GeV. We independently reproduce this
cell-aggregated analysis, then extend it to a pixel-level likelihood on the native $0.125^\circ$ maps, adding energy-dependent point-spread-function forward folding and masking bright sources. Both methods replicate the 20GeV
halo spectrum, with the pixel-level normalisation ${\sim}20\%$ above the cellwise fit across NFW emissivity scalings $\rho^p$, $p \in 1,2,2.5$. This 20GeV
halo is a high-latitude feature, distinct from the inner-
Galaxy excess, and consistent with sub-TeV dark matter (WIMP) annihilation. It is centrally concentrated, strongly disfavouring extragalactic emission. Fitting
prompt $s$-wave annihilation spectra, best-fit masses are $m_\chi \simeq 0.55$TeV ($W^+W^-$) and $0.72$TeV ($b\bar{b}$) with $\langle\sigma v\rangle \simeq 1\times10^{-24}~\mathrm{cm^3\,s^{-1}}$, in $\sim\!4$-$5\times$ tension with
dwarf spheroidal
galaxy limits. However, accounting for foreground modelling and $J$-factor systematic uncertainties widens the tension window to $R\simeq1.6$-$9.3$, leaving the $s$-wave interpretation viable. To close the tension, we consider alternative particle dark matter models. $p$-wave annihilation misses relic abundance constraints by $\sim\!7$ orders of magnitude. A decay interpretation evades
dwarf limits but is disfavoured by the isotropic gamma-ray background. The only viable velocity structure consistent with
dwarf limits, present-day
halo rates, and relic density is low-velocity-enhanced annihilation (resonant Sommerfeld or Breit-Wigner). This supplies the required $\approx\!45\times$ boost from a thermal relic. Fully resolving the
dwarf tension requires a fine-tuned resonance peaking at the
halo velocity and falling for colder systems.
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Earth and Planetary Astrophysics
How to measure tidal dissipation in long resonant chains
Matías Cerioni and Cristian Beaugé
Context. Resonant chains are systems with three or more
planets caught in a succession of two- and three-
planet mean-motion resonances (2P-MMRs and 3P-MMRs). Most of the observed chains show significant amounts of separation from the nominal commensurabilities. These are lower energy states and therefore suggestive of a process of long-scale dissipation. The most frequently invoked mechanism is active tides affecting the innermost
planets, produced by the
star. Aims. Simulations of
tidal separation are expensive and generally impractical for extensive parameter explorations. Therefore, it is essential to have access to analytical tools that would allow us to inspect tidally separated chains, as probing these systems can give valuable insight into the physical parameters involved in dissipation. Methods. We extended an existing analytical model of the
tidal separation of resonant chains with adjacent first-order 2P-MMRs that is meant to be applicable to longer N-
planet chains. We have demonstrated how this approach can be used to constrain those parameters involved in the
tidal evolution, such as the frequently unresolved Q' factors. Results. We show how this tool can be used to place meaningful bounds over the effective planetary Q' value of long resonant chains, even in the realistic case where the system is poorly characterized, lacking measurements of parameters such as the
stellar age or one of the planetary masses. We also show how the magnitude of separation in a resonant chain is specially sensitive to the mass of certain
planets. In particular, a more massive second
planet will boost
tidal separation, while a more massive last
planet will inhibit it.
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Earth and Planetary Astrophysics
A circumbinary approach to the study of spin-orbit resonances around irregular shaped bodies. Application to the Quaoar system
Fernando Roig
We propose to model
spin-orbit resonances that appear in ring systems around minor bodies of the
Solar System using a circumbinary approximation. In our model, the ellipsoidal/irregular shape of the minor body is replaced by a binary dumbbell, i.e., two equal masses evolving in circular orbits around their center of mass. This allows us to apply the equations of motion of the restricted circumbinary N-body problem, duly adjusted to mimic the rotation of the central body and its quadruple momentum. The equations also allow for the simple inclusion of other perturbing bodies, like small satellites, enabling the analysis of the simultaneous effect of
spin-orbit resonances and mean motion resonances on the ring dynamics. The goal of the circumbinary model is to substitute the study of a given
spin-orbit resonance by a surrogate mean motion resonance, allowing for the application of well established numerical and semianalytical models to map the
topology and stability of these resonances. We discuss the differences between the circumbinary model and a triaxial ellipsoid. The model is also extended to study the problem of a mass anomaly. We present some applications to the dynamics of Quaoar's ring system, indicating that
spin-orbit resonances do not seem to play any relevant role in the present dynamics of the ring particles.
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Astrophysics of Galaxies
Constraints on the properties of warm ionized gas from low-frequency hydrogen radio recombination lines
Pedro Salas, Kimberly L. Emig, Matteo Luisi et al. (+2 more)
The ionized gas in the Milky Way is a major component of the interstellar medium. Observations of extinction free tracers, such as hydrogen
radio recombination lines (HRRLs), have revealed the presence of a dense (electron density 1 to 100 cm$^{-3}$) warm ionized medium. Motivated by advances in
radio instrumentation, the existence of fully sampled HRRL maps, and a better knowledge about the population of discrete HII regions in our
Galaxy, we have acquired new low-frequency ($\nu\lesssim1$ GHz) observations of HRRLs to characterize the properties of this gas. We target three positions in the
Galactic plane, with few or no known HII regions, using the 342 MHz and 800 MHz feeds of the Green Bank
Telescope. We detect HRRL emission from all three positions. We combine these with the fully sampled HRRL 5.8 GHz cubes from the GBT Diffuse Ionized Gas Survey (GDIGS) to determine the gas properties using a forward modeling approach. From our analysis we find electron densities between 6 and 15 cm$^{-3}$, and that to determine the gas temperature and emission measure we require informative priors or higher signal-to-noise observations.
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All authors Pedro Salas, Kimberly L. Emig, Matteo Luisi, D. Anish Roshi, Loren Anderson
Solar and Stellar Astrophysics · Cross-listed from nucl-th
Microscopic description of $^{12}$C+$^{12,13}$C fusion reactions at nuclear astrophysical energies
K. Nagao, K. Hagino and K. Uzawa
The $^{12}$C + $^{12}$C fusion reaction plays a key role in several astrophysical phenomena. However, it is difficult to determine its cross sections in the relevant energy region because of both low cross sections and strong resonant structures. On the other hand, the $^{12}$C + $^{13}$C system shows a much smoother energy dependence of fusion cross sections. To simultaneously analyze the $^{12}$C + $^{12,13}$C systems, we here develop a reaction model that explicitly treats the entrance channel and the compound
nucleus states. For this purpose, we combine the discrete basis model for the entrance channel and the shell model for the compound
nuclei. The coupling strengths between the entrance channel and the compound
nucleus states are determined so that the fusion cross sections for these systems match with each other at the resonance energies for the $^{12}$C + $^{12}$C system, as has been observed experimentally. The model successfully reproduces the significantly different behaviors of fusion cross sections in these systems.
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Solar and Stellar Astrophysics
Multi-Path Quasi-Periodic Fast-mode Propagating Magnetoacoustic Waves to Diagnose Coronal Magnetic Field and Flaring Core
Yuhu Miao
Quasi-periodic fast-mode magnetoacoustic waves are often detected during
solar flare events, although they are not observed in every
flare, due to observational signal-to-noise limits and differences in
flare magnetic topology and energy release strength. These structures propagate along
magnetic configurations and supply effective diagnostics for coronal
magnetic environments and flaring regions. Periodic signatures seen in fast-mode QFP wave trains carry physical information about excitation processes and propagation conditions. These signatures support quantitative studies of
flare cores and
magnetic channel properties. This work focuses on a well-documented event involving two oppositely oriented QFP waves simultaneously excited by a GOES-class M6.0
solar flare that occurred in active region NOAA 11261 on August 3, 2011. These QFP waves can be categorized into broad and narrow wave trains, with the narrow one propagating along funnel-like loops and the broad one moving through the low corona. Observational results suggest that both broad-wave and narrow-wave QFP phenomena can be simultaneously triggered by a single
flare eruption. This study also indicates that such multi-path QFP wave events can be utilized to diagnose the
magnetic field and the
flare's core, and demonstrates the capability of multi-path QFP waves for robust coronal
magnetic field and
flare core diagnostics.
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Earth and Planetary Astrophysics
Phase-dependent chemistry of WASP-43 b revealed with a suite of one-, two-, and three-dimensional models
Robin Baeyens, Julianne I. Moses, Jasmina Blecic et al. (+17 more)
Our goal is to investigate the chemistry of the hot Jupiter WASP-43 b in detail using theoretical models, considering the constraints of the James Webb Space
Telescope MIRI phase curve. With a suite of pseudo-two-dimensional and three-dimensional photochemical models, we simulate the composition of WASP-43 b in various configurations, and compare them with atmospheric
retrieval models. We confirm that disequilibrium chemistry in our theoretical models reduces the methane concentration on the
planet night side for wind jet speeds > 500 m/s. Varying the
metallicity in the models induces large changes in the CO$_2$ and SO$_2$ concentrations, with SO$_2$ producing mid-infrared absorption features in synthetic emission spectra of the night side at atmospheric
metallicities > 10x
solar. Our models provide evidence for pole-to-equator circulation enhancing the CH$_4$, NH$_3$, and HCN abundances, which is nonetheless insufficient for detectable spectral features. Finally, we show that H$_2$O, CO, and CO$_2$ are robustly modeled, but species affected by photochemistry are more sensitive to model-specific assumptions and pathways. We conclude that horizontal quenching is the
prime mechanism that explains the non-detection of methane in the MIRI phase-curve of WASP-43 b. This mechanism requires only moderate wind speeds and is operative at various thermal structures and atmospheric
metallicities. Furthermore, coupled carbon-sulfur chemistry leads to an additional decrease in methane compared to previous models in the literature that did not contain sulfur chemistry. We do not favor a high
metallicity as it would have led to observable SO$_2$ features in the MIRI spectra. Our study shows that phase-dependent photochemistry models are essential tools in the interpretation of hot-Jupiter phase curves, but benchmarking is needed to improve the accuracy of photochemical models in the future.
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All authors Robin Baeyens, Julianne I. Moses, Jasmina Blecic, Elspeth K. H. Lee, Lucas Teinturier, Shang-Min Tsai, Jeehyun Yang, Jingxuan Yang, Ludmila Carone, Renyu Hu, Sven Kiefer, Anjali A. A. Piette, Taylor J. Bell, Nicolas Crouzet, Ian Dobbs-Dixon, Christiane Helling, Nicolas Iro, Dominic Samra, Olivia Venot, Jean-Michel Désert
Solar and Stellar Astrophysics
Long-term speckle interferometric monitoring of binary systems II: 2007-2025 positional measurements and improvement of orbits
Arina Mitrofanova, Vladimir Dyachenko, Anatoly Beskakotov et al. (+4 more)
This article is focused on the analysis of observational data and improvement of orbital solutions of 8 objects. The listed objects are members of a sample of approximately 300 nearby (d < 100 pc) multiple systems compiled for long-term monitoring at the 6-meter
telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. Speckle interferometric observations were carried out from 2007 to the present, which corresponds to 19 years of monitoring of the systems. Therefore, the new measurements are more numerous than or comparable to those in the literature, which makes it possible to make the observation series more complete. A long observation series made it possible to cover from 20% to 70% of the phases of the orbital periods of the objects under study. In combination with previously published data, the percentage of orbital coverage by measurements ranged from 45% to 85%. As a result, 4 orbits were classified as "definitive", one as "good", 2 as "reliable", and one as "preliminary" according to a grading scheme suggested by W.I. Hartkopf et al. Despite the high grades of the orbital solutions, it is recommended to continue monitoring (in particular, to obtain periastron observations) for HIP 1055, HIP 2532, HIP 15633, HIP 19472 and HIP 20751 in order to derive the final orbital parameters. It is not possible to obtain an accurate orbital solution for HIP 20227 due to measurements whose assigned weight strongly influences the period value, and for HIP 21710(Aa,Ab) due to the long orbital period (Porb > 200 yr) and, consequently, the lack of observational data. An analysis and comparison of the mass sums and masses of components obtained by two independent methods and based on several parallax values were also carried out. In most cases, the best agreement is found between fundamental parameters calculated using
Gaia parallaxes, if available.
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All authors Arina Mitrofanova, Vladimir Dyachenko, Anatoly Beskakotov, Alexander Maksimov, Margarita Butorina, Yuri Balega, Denis Rastegaev
High Energy Astrophysical Phenomena · Cross-listed from physics.space-ph
Photon Acceleration in Magnetized Plasma: A Mechanism for Fast Radio Bursts
Sergei V. Bulanov, Gabriele Maria Grittani, Marcel Lamac et al. (+7 more)
We propose a mechanism for fast
radio bursts based on
photon acceleration by relativistic shocks propagating through highly magnetized electron–positron
plasmas, as expected in magnetar magnetospheres. Density modulations at the shock front create relativistically moving refractive-index perturbations that transform low-frequency electromagnetic precursors into amplified high-frequency radiation. We show that the predicted frequencies, durations, and energetics of the resulting fast
radio bursts are consistent with the
magnetic-field strengths, shock Lorentz factors, and characteristic spatial scales expected in magnetar magnetospheres.
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All authors Sergei V. Bulanov, Gabriele Maria Grittani, Marcel Lamac, Petr Valenta, Stepan S. Bulanov, Timur Zh. Esirkepov, Gianluca Gregori, Brandon K. Russell, Alexander G. R. Thomas, Arno Vanthieghem
Cosmology and Nongalactic Astrophysics
HETDEX [OII] galaxies at $z \le 0.48$: Volume-limited samples and their power spectra
Jeongin Moon, Eiichiro Komatsu, Robin Ciardullo et al. (+15 more)
The catalog from the Hobby-Eberly
Telescope Dark Energy Experiment (HETDEX) Public Data Release 1 (PDR1) contains half a million emission-line-selected [OII]
galaxies spread across $540~\mathrm{deg}^2$ at $z \le 0.48$ from HETDEX's unprecedented untargeted spectroscopic survey. In this paper, we construct volume-limited samples from PDR1 in three luminosity bins across the two main fields: "Spring” and "Fall”. The numbers of
galaxies in the bins range from 11,354 to 64,794 and number densities, $\bar{n}\simeq (2-5)\times10^{-3}~h^3~\mathrm{Mpc}^{-3}$, are higher than those of typical cosmological spectroscopic surveys of emission-line
galaxies by a factor of five to ten. The monopole and quadrupole power spectra derived from these samples are in excellent agreement with the mock power spectra from the Uchuu simulation based on a flat $\Lambda$CDM model and the cosmological parameters from the Planck
cosmic microwave background data, at all wavenumbers used for the measurement ($0.01<k<0.7~h~\mathrm{Mpc}^{-1}$). We find that the power spectrum amplitudes are consistent with a characteristic dark matter
halo mass of $\log(M_0~[h^{-1}M_{\odot}])\simeq 11.9$-$12.3$, with the
halo mass showing a weak dependence on [OII] luminosity, $M_0\propto L^a$, increasing with a slope of $a = 0.37\pm0.10$. The best-fit mock suggests that approximately 13 percent of the [OII]
galaxies in our sample reside in subhalos. The new, high-density tracers of the underlying matter distribution presented in this paper provide precise measurements of clustering in a low-
redshift regime sensitive to the late-time growth of structures. These samples will form the basis for forthcoming analyses of the
redshift-space distortion effect,
galaxy-
halo connection, and cross-correlations with external low-
redshift probes.
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All authors Jeongin Moon, Eiichiro Komatsu, Robin Ciardullo, Olivia Curtis, Dustin Davis, Daniel J. Farrow, Karl Gebhardt, Caryl Gronwall, Laura Herold, Gary J. Hill, Donghui Jeong, Chenxu Liu, Maja Lujan Niemeyer, Erin Mentuch Cooper, Shiro Mukae, Shun Saito, Ariel G. Sánchez, Donald P. Schneider