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Physics Astrophysics

astro-ph Watch Astrophysics

Tuesday 12 May

Astrophysics of Galaxies

Strong Progenitor Age Bias in Supernova Cosmology. III. Progenitor Age as the Physical Origin of the Type Ia Supernova Magnitude Steps with Host Properties

Seunghyun Park, Young-Wook Lee, Chul Chung et al. (+4 more)

The standardized magnitude of a type Ia supernova (SN Ia) correlates with host-galaxy properties, and a host mass-step correction is now routinely included in SN Ia luminosity standardization. Given that host mass cannot directly influence SN Ia luminosity, the root cause of the step must be another latent parameter associated with host mass. Identifying this driver is essential because different host properties evolve differently with redshift, so corrections based on them can lead to divergent cosmological inferences. In recent years, direct and extensive age measurements have revealed a significant relation between host age and Hubble residual (HR). Here, using a new dataset, we confirm that this relation arises from the age dependence of the SN Ia luminosity standardization process and the resulting overcorrection. Specifically, we show that while the mass-step correction reduces the age bias by about half, the host age-bias correction fully eliminates the mass step, supporting a progenitor-age origin of the host-age–HR relation. We further demonstrate that the SN Ia magnitude steps with host mass (and specific star formation rate; sSFR) emerge from a nonlinear, step-like relation between mass (and sSFR) and progenitor age, combined with a linear progenitor-age–HR relation: the SN Ia magnitude steps are therefore projected manifestations of an underlying dependence on progenitor age. Taken together, our results show that progenitor age is the primary driver of both the strong host-age–HR relation and the apparent host-mass and host-sSFR steps.
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All authors Seunghyun Park, Young-Wook Lee, Chul Chung, Suk-Jin Yoon, Junhyuk Son, Hyejeon Cho, Young-Lo Kim

Astrophysics of Galaxies

Global and Local Infall in the ASHES Sample (GLASHES). II. Asymmetric Line Profiles around Dense Cores in 70 $\mu$m Dark Massive Clumps

Kaho Morii, Patricio Sanhueza, Qizhou Zhang et al. (+1 more)

Gravitational collapse is fundamental to star formation, yet direct kinematic evidence of infall at the core scale in high-mass star-forming regions remains poorly constrained. We present the first large-scale statistical study of infall signatures in 304 dense cores within 24 massive 70 $\mu$m-dark clumps from the GLASHES (Global and Local Infall in the ASHES Sample) survey. Using ALMA Band 6 observations of the optically thick tracers HCO$^+$ and HNC (J=3-2), we systematically characterize blue asymmetry line profiles indicative of infalling motions. We employ two complementary metrics, the velocity difference parameter ($\delta_v$) and the asymmetry parameter ($A$), to quantify infall signatures, finding consistent results across both tracers. Blue asymmetry profiles are detected in $\sim$50-60% of cores ($\delta_v<$0 or A>0). Spectral classification reveals that $\sim$60% of cores exhibit double-peaked profiles, and 34% and 39% show blue asymmetry profiles in HCO$^+$ and HNC, respectively, with the percentage increasing with core mass and surface density. Accounting for geometric effects that can obscure infall signatures, our results suggest that gravitational collapse is prevalent in and around the cores. Importantly, infall signatures are detected from the prestellar stage and become more dominant as cores' evolution proceeds. Even cores with virial parameters $\alpha_{vir} > 2$ show infall signatures, suggesting that external compression may trigger collapse in addition to self-gravity or that linewidth may include inward motion in addition to turbulence. Furthermore, a moderate correlation between clump-scale and core-scale asymmetry supports a hierarchical collapse scenario, implying a dynamic and multi-scale process of high-mass star formation.
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All authors Kaho Morii, Patricio Sanhueza, Qizhou Zhang, James M. Jackson

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

How much dark matter really matters?

Jenny Wagner

Strong gravitational lensing is a key probe to trace dark matter. It assumes that mass curves spacetime so that light from a background source is deflected on its way to the observer. If dark matter contributes the major part to a massive cosmic structure, reconstructing the latter from strong-lensing observables allows us to infer characteristics of dark matter. Standard reconstructions fit a pre-defined mass-density model to the data. In this essay, I show how these mass models over-estimate the dark-matter contents of light-deflecting masses. Eliminating these models from the reconstruction reveals that observations directly constrain local properties of light-deflecting masses. How much dark matter is really needed in strong-gravitational-lensing effects and how much do we make up by our model choices?
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Astrophysics of Galaxies

Formation of stable exoplanetary systems around pulsars by capture: An exercise in computational classical mechanics

Václav Pavlík, Steven N. Shore, Vladimír Karas et al. (+1 more)

The study of our Solar System – its formation, evolution, and long-term stability – has been ongoing for centuries and is now a standard part of scientific education. While the formation of other Solar-like exoplanetary systems is generally explained using the same mechanisms that describe our own, the discovery of exoplanets around pulsars in 1990s has raised new questions about their origin. Several scenarios were proposed, including formation by capture during a close encounter of a compact stellar-mass remnant and a pre-existing planetary system. It was, however, also conjectured that captured planets should exhibit high eccentricities and – if more planets are captured – their evolution would lead to chaos We revisit classical mechanics as applied to planetary systems. As an example and follow-up to previous works, we use an open-source high-precision $N$-body code to investigate dynamical interactions between planetary systems and stellar remnants, the orbital properties of captured planets, and their long-term stability over gigayears. We corroborate that the captured planets often exhibit high eccentricities (unlike some observed pulsar planetary systems), but we also present a student's simulation where a Jupiter-like planet undergoes a series of planet-planet encounters and planetary ejections, eventually stabilising at a low eccentricity of ~0.146. This shows that a chaotic post-capture evolution may eventually lead to long-term stability, making the dynamical formation channel viable for producing low-eccentricity systems. These results warrant more detailed investigation in future work. Beyond their astrophysical significance, they also illustrate general principles of non-linear dynamics and computation, where aspects of the analysis can even be carried out at the high-school or undergraduate level, making this type of research accessible to students at an early stage.
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All authors Václav Pavlík, Steven N. Shore, Vladimír Karas, Matyáš Fuksa

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

Tunneling and tidal stripping in multifield ultralight dark matter halos

Benjamin V. Lehmann, Jackie Lodman and Thomas Steingasser

Tidal stripping is a key feature of the evolution of dark matter (DM) halos, and has major implications for the population of low-mass galaxies. In the case of ultralight DM, tidal stripping proceeds not only classically, at the tidal radius, but also via a process analogous to quantum tunneling by long-wavelength particles out of the potential of a subhalo. This modified tidal stripping behavior leads to tight constraints on the particle mass as a function of subhalo and host properties. As many models of ultralight DM predict several independent species, it is crucial to understand how these constraints can be generalized to multifield halos with different particle masses. However, numerical challenges make it difficult to directly study the tunneling process in all but the simplest multifield scenarios. We introduce a simplified approach based on semiclassical methods that entirely sidesteps the most difficult aspects of the numerical problem, and we apply this to the study of tunneling in multifield halos. Our results significantly clarify the physics of tidal stripping for ultralight DM halos even in the single-field case: we provide first-principles derivations of features of the tunneling rate previously suggested by empirical fits. We then evaluate stability bounds on two-field halos for the first time, for a wide range of density and particle mass ratios. We show that for particular parameter combinations, the stability bounds in the two-field case can be somewhat relaxed relative to the single-field case, but for much of the parameter space, the constraints become more stringent. We discuss the path towards probing realistic multifield ultralight DM halos.
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Earth and Planetary Astrophysics · Cross-listed from physics.hist-ph

On the Anticipation of Lunar Travel in the Early 20th Century: A Pedagogical Exercise

Tina A. Harriott and Cherif F. Matta

This article examines, from historical and pedagogical perspectives, Alphonse Berget's anticipation of Earth-Moon travel in Le Ciel (Larousse, 1923), decades before the beginning of the space age. The discussion is triggered by Le Ciel, a richly illustrated French popular science work, which has a devoted chapter examining lunar and interplanetary travel within a Newtonian framework. Although Berget's treatment was not developed in isolation and reflects a broader early 20th century context that included pioneers such as French aero-engineer Robert Esnault-Pelterie, the book provides a striking pedagogical synthesis of elementary celestial mechanics and scientific popularization. Unlike earlier fictional treatments such as Jules Verne's De la Terre a la Lune, Berget approached space travel using physical reasoning grounded in Newtonian gravitation. Using qualitative and semi-quantitative arguments based on the inverse-square law, he identified the principal phases of an Earth-Moon trajectory: escape from Earth, inertial translunar motion, transition through competing Earth-Moon gravitational fields, and final lunar capture and deceleration. His estimated Earth-Moon travel time of approximately 49 hours is of the same order of magnitude as Apollo mission transit times (approx. 72 h). We compare these early ideas with modern elementary concepts of astrodynamics, including restricted three-body trajectories, Lagrange-point dynamics, and distant retrograde orbits associated with the Artemis program. We also examine Berget's discussion of interplanetary travel, lunar landscapes, and human factors associated with prolonged voyages, including confinement, food supply, and travel duration. The analysis highlights the pedagogical value of historically grounded scientific reasoning underpinning spaceflight mechanics.
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Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc

Phase-resolved field-space distance criteria in ekpyrotic, bouncing and cyclic cosmologies

Marcin Postolak

The inflationary Lyth bound relates the primordial tensor amplitude to the inflaton field excursion. In ekpyrotic, bouncing and cyclic cosmologies there is no analogous universal tensor-to-field-distance relation because scalar and tensor perturbations depend on entropy conversion, matching through the bounce, and the specific mechanism that violates or evades the null energy condition. Here we propose a phase-resolved criterion for the accumulated scalar field trajectory length in a non-inflationary smoothing history. The quantity constrained in this study is not, in general, the geodesic distance between the initial and final field-space points. Rather, it is the invariant path length accumulated along the actual cosmological trajectory. Therefore, the resulting inequalities should be understood as sufficient, conservative trajectory length criteria for small-field control, not as model-independent necessary exclusions based on geodesic distance swampland reasoning. We also impose BKL (Belinski-Khalatnikov-Lifshitz) anisotropy suppression as an additional constraint on the ekpyrotic phase. In the canonical phase of the ekpyrotic contraction, we recover the known small-field scaling and embed it in a total trajectory length budget inequality. We impose three requirements: a BKL anisotropy suppression that is parameterized separately, a phenomenological cutoff-corrected distance budget inspired by tower of states logic, and observational conversion windows from residual isocurvature and non-Gaussianity. Furthermore, we propose a new master formula that provides a conditional lower limit on the value of the parameter $\epsilon_{\rm ek}$ that depends on the remaining distance available after conversion and the cosmological bounce.
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Astrophysics of Galaxies

Unveiling Hidden Lyman Alpha Emitters in the DESI DR1 Data

Jui-Kuan Chan, Ting-Wen Lan, J. Xavier Prochaska et al. (+39 more)

We present an automatic method based on machine-learning convolutional neural network (CNN) architecture to detect Lyman alpha emitters (LAE) hidden in the Data Release 1 spectroscopic dataset of the Dark Energy Spectroscopic Instrument (DESI). Those LAEs mostly have incorrect redshift estimations because the current DESI pipeline is not designed to detect and measure the redshifts of galaxies at $z>2$. To uncover those sources, we first visually inspect thousands of DESI spectra and construct a sample, consisting of both LAEs and non-LAEs, for training and testing the CNN-based model to (1) detect LAEs in DESI spectra and (2) determine their Ly$\alpha$ redshifts. The final model yields $95.2\%$ purity and $95.9\%$ completeness for detecting LAEs. We apply this model to approximately $2\times10^{6}$ spectra of sources targeted as emission-line galaxies and detect 19,685 LAEs from $z\sim2$ to $3.5$ within 12 minutes with a single GPU, illustrating the high efficiency of this model for identifying LAEs. The detected LAEs are mostly at the bright end of the luminosity function with Ly$\alpha$ luminosity $L_{\rm Ly\alpha} \gtrsim 10^{43}$ erg/s. The high signal-to-noise composite spectrum of the detected LAEs further shows various spectral features, including P-Cygni profiles of metal lines and MgII emission lines, possible indicators of Lyman continuum escape fraction, revealing the rich astrophysical information in this LAE sample. Finally, this sample can be used to train and validate the pipelines for redshift determination of LAEs for the preparation of the DESI-II survey.
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All authors Jui-Kuan Chan, Ting-Wen Lan, J. Xavier Prochaska, Shun Saito, J. Aguilar, S. Ahlen, D. Bianchi, D. Brooks, A. Cuceu, A. de la Macorra, Biprateep Dey, P. Doel, A. Font-Ribera, J. E. Forero-Romero, E. Gaztañaga, Satya Gontcho A Gontcho, G. Gutierrez, C. Hahn, J. Jimenez, R. Joyce, S. Juneau, D. Kirkby, A. Kremin, M. Landriau, M. Manera, A. Meisner, R. Miquel, J. Moustakas, S. Nadathur, W. J. Percival, C. Poppett, F. Prada, I. Pérez-Ràfols, G. Rossi, E. Sanchez, D. Schlegel, M. Schubnell, J. Silber, D. Sprayberry, G. Tarlé, B. A. Weaver, H. Zou

Cosmology and Nongalactic Astrophysics

Measuring cosmic bulk flow with kinetic Sunyaev-Zel'dovich velocity reconstruction

Suroor Seher Gandhi, Matthew C. Johnson, Jordan Krywonos et al. (+1 more)

Cosmic bulk flow–the volume-averaged peculiar velocity of matter–serves as a fundamental test of the Cosmological Principle when probed on gigaparsec (Gpc) scales. Historically, however, measurements of cosmic bulk flow have been limited to $R\lesssim 100\ h^{-1}{\rm Mpc}$. We present an application of kinetic Sunyaev-Zel'dovich (kSZ) velocity reconstruction to constrain the bulk flow on cosmological scales, over a volume of effective radius $R\sim2000\ h^{-1} {\rm Mpc}$. We use the WISE$\times$SuperCOSMOS and unWISE galaxy catalogs, combined with CMB temperature maps from Planck to reconstruct large-scale velocities in six tomographic bins spanning $0.1\lesssim z \lesssim 1.5$. We place some of the tightest upper limits to date on bulk velocity at $200 \lesssim R\,[h^{-1}{\rm Mpc}]\lesssim 2000$, finding results fully consistent with the $\Lambda$CDM bulk flow expectation. Our unWISE constraints are in strong tension with the CatWISE quasar number-count dipole measurement if that dipole is due to a coherent bulk flow $\sim 370\ {\rm km\,s^{-1}}$ at $R\sim1000\ h^{-1}{\rm Mpc}$. We also derive constraints on the matter power spectrum at low-$k$ ($k\lesssim10^{-3}\, {\rm Mpc}^{-1}$) with low-$z$ ($z\sim 1$) galaxy samples. Alongside these cosmological constraints, we introduce a novel approach to map the optical depth bias–an inherent astrophysical degeneracy in kSZ velocity reconstruction–across different data combinations. Our work bridges the theoretical gap between bulk flow and kSZ-reconstructed velocities, and expands the horizon of bulk velocity measurements out to Gpc scales.
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All authors Suroor Seher Gandhi, Matthew C. Johnson, Jordan Krywonos, Michael J. Hudson

Astrophysics of Galaxies

Photometric determination of the mass accretion rates of pre-main sequence stars. IX. Recent star formation in the periphery of NGC 346

Christiaan Dik and Guido De Marchi

We studied the properties of star formation and the characteristics of young stars in a quiet region located beyond the outskirts of the prominent star-forming cluster NGC 346 in the Small Magellanic Cloud (SMC). Utilising observations from the Hubble Space Telescope across the broad V and I bands, as well as the narrow Halpha band, we identified populations with ages of roughly 10, 60, 400 Myr and of 5 Gyr through isochrone comparison. We successfully identified 137 bona fide pre-main sequence (PMS) candidates exhibiting Halpha excess with a significance level of 5 sigma, accompanied by an Halpha line emission equivalent width exceeding 20 Å. Physical parameters for these PMS stars were determined, including mass, age, accretion luminosity, and mass accretion rate. Most PMS stars have an age around 16 Myr and an average mass of 0.80 \pm 0.16 M_sun. The median mass accretion rate for all 137 PMS stars is estimated to be about 8.0 x 10^(-9) M_sun/yr. While this rate is lower than that observed in the NGC 346 cluster itself, it is comparable with those measured for PMS stars in low-density star-forming regions in the SMC, despite the absence of apparent clustering and nebulosity. Furthermore, our analysis reveals that the ratios of accreting and non-accreting PMS stars to non-PMS stars and their mass accretion rate correlate with their distance from a group of hot massive stars in the vicinity. This suggests that the ultraviolet radiation emitted by these massive stars might erode the circumstellar discs of nearby PMS stars. Lastly, the overlap between our studied region and observations from the James Webb Space Telescope reveals that some of the identified PMS stars display near-infrared excess.
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Cosmology and Nongalactic Astrophysics

Unveiling $f(R)$ Gravity with Void-Galaxy Cross-Correlation Multipoles

Yue Nan

Cosmic voids provide low-density environments where the scalar fifth force predicted by $f(R)$ modified gravity can be weakly screened. We present a semi-analytical calculation of the monopole, dipole, and quadrupole of the void-galaxy cross-correlation function $\xi^{s}(s,\mu)$ in redshift space for the Hu-Sawicki $f(R)$ model ($n=1$), combining scale-dependent growth induced by the scalaron with nonlinear spherical shell dynamics. The same framework can be generalized to metric $f(R)$ theories for which $G_{\rm eff}(k,a)/G$ is specified in the quasi-static limit. Our key results are: (1)~the monopole deviation from $\Lambda{\rm CDM}$ grows from $+2.8\%$ for large voids ($r_v=30 h^{-1}{\rm Mpc}$) to $+29.7\%$ for small voids ($r_v=11.7 h^{-1}{\rm Mpc}$) at $|f_{R0}|=10^{-5}$, a distinctive size-dependent signature of the Compton-scale scalaron response, with $\lambda_C\approx 8 h^{-1}{\rm Mpc}$; (2)~nonlinear evolution amplifies the modified-gravity signal by $\mathcal{A}_0\approx 4$, bringing it within reach of ongoing and upcoming spectroscopic surveys such as DESI, Subaru PFS, Euclid, and Roman; (3) the gravitational potential contains a finite-range Yukawa component, producing a radially dependent dipole signature complementary to the density and velocity multipoles; (4) for the fiducial Hu-Sawicki evolution, the signal generally decreases toward higher redshift as the scalaron Compton wavelength becomes shorter, but remains potentially detectable at Stage-IV spectroscopic void samples. We show that the void-scale transition in the modified-gravity response, the joint sensitivity to density, velocity, and fifth-force contributions, and the nonlinear amplification around void shells make redshift-space void-galaxy multipoles a powerful semi-analytical probe of $f(R)$ gravity and effective dark-energy inhomogeneities in modified gravity.
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Solar and Stellar Astrophysics

Elemental Abundances in the Binary Star V505 Per

Zohreh Safari Forushani, Catherine A. Pilachowski, Gloria Koenigsberger et al. (+2 more)

We present a detailed chemical abundance analysis of the eclipsing binary system V505 Per. High resolution spectra were analyzed using the MOOG spectrum analysis code, and we determined abundances not only for iron and lithium but also for Si, Na, Ca, Mn, and Ni, elements that have not previously been analyzed in detail for this system. Abundances were computed across 15 temperature points using model atmospheres, with stellar parameters refined by minimizing abundance trends with excitation potential. We determined effective temperatures of T_eff = 6650 +/- 50 K for the primary and T_eff = 6550 +/- 50 K for the secondary, with iron abundances of [Fe/H] = -0.10 +/- 0.06 and [Fe/H] = -0.19 +/- 0.07, respectively. Most [X/Fe] ratios are consistent with solar values, though manganese is deficient. Our analysis of the effective temperatures shows that both stars lie on the hot edge of the lithium dip, consistent with Koenigsberger et al. (2025), which may help resolve the inconsistency noted of the stars lithium abundance within the dip by Baugh et al. (2013).
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All authors Zohreh Safari Forushani, Catherine A. Pilachowski, Gloria Koenigsberger, Derek Sikorski, Maria Cordero

High Energy Astrophysical Phenomena

Precessing Black Hole Jets and Galactic Fossils

Maria J. Rodriguez

The Galactic Center gamma-ray excess (GCE) – a surplus of gamma-ray radiation around SgrA$^{\star}$ – has remained without a consensus interpretation for more than fifteen years. Dark-matter annihilation and unresolved millisecond-pulsar populations remain the leading candidates, yet neither connects the excess to the past activity of SgrA$^{\star}$ traced by the Fermi and eROSITA bubbles. We propose a common-origin scenario in which a contribution to the GCE arises as a fossil hadronic imprint of the same SgrA$^{\star}$ outburst associated with the bubbles. We develop a model of SgrA$^{\star}$ with a precessing paraboloidal Blandford-Znajek (BZ) jet launched from a tilted, magnetically arrested accretion disc during a ~ 7.5 Myr active phase ending ~2.6 Myr ago. In this picture, the jet drives the bipolar expansion of the Fermi/eROSITA bubbles – contributing, alongside wider-angle outflows, to their observed extent – and injects hadronic cosmic rays at the Galactic Center. We couple the analytic BZ injection to a two-zone diffusion numerical solver to compute the resulting GCE surface brightness and verify internal consistency: the proton Larmor radius remains small compared to the jet coherence scale, ensuring magnetic confinement of the cosmic-ray population, while attenuation of the produced $\gamma$ rays in the interstellar medium is negligible, leaving the medium effectively transparent. Isolating the jet contribution alone yields a spin-dependent, irreducible hadronic floor: for a SgrA$^{\star}$ spin of a$^{\star} = 0.9$, we find a robust floor at the few-percent to $\sim 10\%$ level of the observed GCE surface brightness across the inner ten degrees, highlighting a previously unexplored component relevant for comprehensive models of the GCE.
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Instrumentation and Methods for Astrophysics · Cross-listed from eess.SY

Basilisk and Docker for Reproducible GN&C Simulation: A Workflow Reference

Anubhav Gupta

Basilisk is an open-source astrodynamics simulation framework widely used for spacecraft guidance, navigation, and control (GN&C) research and development. Despite its flexibility and computational capabilities, configuring Basilisk consistently across heterogeneous development environments presents practical challenges due to dependency management, operating system compatibility, and software configuration requirements. This paper presents a Docker-based containerization workflow for Basilisk that encapsulates the complete build environment, dependencies, and simulation infrastructure within a portable container image. The workflow is demonstrated through a progression of simulation scenarios of increasing complexity, from standalone orbital dynamics scripts to BSKSim-based attitude dynamics and control simulations with Monte Carlo analysis. The BSKSim class hierarchy, dynamics model architecture, flight software implementation, and scenario execution patterns are described in detail. The presented workflow provides a self-contained implementation reference for GN&C engineers and researchers seeking reproducible and portable Basilisk simulation environments. This work expands upon a workshop presentation delivered at the 46th Rocky Mountain AAS GN&C Conference, February 2024, available at https://doi.org/10.5281/zenodo.15008785.
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Astrophysics of Galaxies

Self-consistent dynamical modelling of the Milky Way bar with orbital frequency analysis

Zachary Langford, Robyn Sanderson, Madeline Lucey et al. (+1 more)

We present an update to the frequency analysis method for measuring the properties of a galactic bar. The method involves computing the fundamental frequencies of orbits in rotating, N-body-derived potential models, classifying the stars as members of bar supporting orbits, and finding the extent of the apo-centre distribution. In this work, we apply an updated classification criterion designed to isolate the so-called "Warm" inner Lindblad resonance (ILR) orbits. These orbits have been shown to contain the looped x1 orbits, which dominate the "shoulder regions" of the bar and largely contribute to the radial extent. We apply this method to existing Gaia, APOGEE, and OGLE data of more than 200,000 stars to constrain the properties of the Milky Way bar. We find that multiple bar lengths and pattern speeds are consistent with the data to within 5 percent.
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All authors Zachary Langford, Robyn Sanderson, Madeline Lucey, Jason A. S. Hunt

Earth and Planetary Astrophysics

Modeling and Analysis of Main-Belt Asteroidal Dust Flux and Velocity Distribution at Inner Planets

Aanchal Sahu and Jayesh Pabari

Interplanetary dust in the inner solar system originates from multiple sources, including short-period comets and main-belt asteroids. In this work, we focus specifically on the dynamical evolution of asteroid-derived dust using N-body simulations that incorporates solar gravity, planetary perturbations, radiation pressure, Poynting-Robertson drag and solar wind forces. We quantify dust fluxes for Mars, Venus and Mercury across an important mass range, which are essential inputs for ablation process on Mars/Venus and for contributing in the impact process on Mercury. We have also derived impact velocity distributions and compared with existing literature. In addition, we examine how close-encounter velocities depend on the orbital elements linking dust energetics directly to the orbital architecture of the dust population. Our results show that the calibrated asteroidal flux agrees excellently with the scaled Grün model for Mars (0.04 orders of magnitude offset) and Venus (0.09 orders), and with the Müller (2002) model for Mercury (0.04 orders). The velocity distributions reveal a decoupling between flux and impact velocity: low-eccentricity grains dominate the flux, while high-eccentricity grains control the high-velocity tail. These findings have direct implications covering: (i) For atmosphere-less bodies like Mercury, the high-velocity tail affects impact processes and exosphere generation; (ii) For Mars and Venus, the flux-dominated low-velocity population determines meteoroid ablation rates and metal layer formation; (iii) Our calibrated fluxes provide inputs for comparison with future observations from different missions and also, for modeling impact-driven surface modification across the inner solar system.
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Cosmology and Nongalactic Astrophysics

Late-time reconstruction of non-minimally coupled gravity with a smoothness prior

Gen Ye, Anton Chudaykin, Camille Bonvin et al. (+1 more)

We present a non-parametric, model-independent reconstruction of the cosmological background and perturbation dynamics in non-minimally coupled theories of gravity. Within the Effective Field Theory of dark energy framework, we reconstruct the time-dependent cosmological constant, $\Lambda(t)$, and the non-minimal coupling function, $\Omega(t)$, from cosmological data. To ensure stability, we apply a correlated smoothness prior that restricts the reconstruction to the space of sufficiently smooth functions. Using CMB, DESI BAO, Type Ia supernovae, CMB-ISW lensing cross-correlations, and large-scale 3x2pt DES Year 3 data, we find a $2.8\sigma$ hint for a non-minimal coupling. For the dark energy equation of state, our results indicate a preference for the existence of crossing of the phantom divide, $w_{DE}=-1$, at $z<0.8$. The non-minimal coupling effect stabilizes dark energy perturbations, providing a viable physical interpretation of the phantom crossing scenario. Our work paves the way for model-agnostic searches for signatures of modified gravity in cosmological data.
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All authors Gen Ye, Anton Chudaykin, Camille Bonvin, Martin Kunz

Cosmology and Nongalactic Astrophysics

Impact of Calibration Systematics on Dark Energy Constraints from LSST Type Ia Supernovae

Jonah Medoff, Christopher W. Stubbs and Dillon Brout

The Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST) will deliver an unprecedented Type Ia supernova (SN) sample, making photometric calibration systematics a dominant source of uncertainty in dark energy constraints. We perform a comprehensive analysis of calibration systematic effects in LSST, quantifying how uncertainties in the LSST passbands propagate into biases in SN distance moduli and, consequently, the dark energy equation of state parameters. Specifically, we examine how the inferred values and uncertainties of $w_0$ and $w_a$ shift as a function of the amplitude of passband systematics. For linear passband tilts, we find that the best-fit ($w_0$,$w_a$) shifts by $\sim$0.025$\sigma$ and the $w_0-w_a$ contour area increases by $\sim$5% for each 1%/100nm increase in tilt, while for quadratic passband tilts, our results are less conclusive and warrant further exploration. This analysis will help inform the calibration accuracy required for LSST to achieve its goals in constraining dark energy.
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Earth and Planetary Astrophysics

Trajectory-Agnostic Asteroid Detection in TESS with Deep Learning

Brian P. Powell, Jorge Martinez-Palomera, Amy Tuson et al. (+3 more)

We present a novel method for extracting moving objects from TESS data using machine learning. Our approach uses two stacked 3D U-Nets with skip connections, which we call a W-Net, to filter background and identify pixels containing moving objects in TESS image time-series data. By augmenting the training data through rotation of the image cubes, our method is robust to differences in speed and direction of asteroids, requiring no assumptions for either parameter range which are typically required in "shift-and-stack" type algorithms. We also developed a novel method for learned data scaling that we call Adaptive Normalization, which allows the neural network to learn the ideal range and scaling distribution required for optimal data processing. We built a code for creating TESS training data with asteroid masks that served as the foundation of our effort (tess-asteroid-ml), which we publicly released for the benefit of the community. Our method is not limited to TESS, but applicable for implementation in other similar time-domain surveys, making it of particular interest for use with data from upcoming missions such as the Nancy Grace Roman Space Telescope and NEOSurveyor.
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All authors Brian P. Powell, Jorge Martinez-Palomera, Amy Tuson, Christina Hedges, Jessie Dotson, Jordan Caraballo-Vega

High Energy Astrophysical Phenomena

Reproducing morphological features in the supernova remnant G11.2-0.3 by simulating jittering jets

Muhammad Akashi and Noam Soker

We hydrodynamically simulate a core-collapse supernova (CCSN) explosion by launching three pairs of jets in the framework of the jittering-jets explosion mechanism (JJEM), and reproduce a morphology of two opposite circum-jet rings and a bar of dense gas perpendicular to the rings' axis, resembling these morphological features in the CCSN remnant SNR G11.2-0.3. The first pair of wide jets is very energetic; it triggers the explosion and inflates two bubbles that compress the material in an expanding shell. The bubbles also compress material in a plane perpendicular to the jet axis. The second pair of wide jets removes material from this plane, beside along a bar that is on an axis perpendicular to the two pairs' axes. The jets of the third pair, now of narrow jets, penetrate the expanding shell and compress material to their sides to form two opposite rings. These morphological features are qualitatively similar to those observed in the point-symmetric CCSN remnant G11.2-0.3. As competing theoretical CCSN explosion mechanisms cannot explain point-symmetric CCSN remnants, our study provides some support for the claim that the JJEM is the primary explosion mechanism of CCSNe.
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Solar and Stellar Astrophysics

How plasma coupling and convective-zone depth shape the rotation of solar-mass stars

Ana Brito and Ilídio Lopes

Stellar rotation on the main sequence is a complex function of mass and age, displaying multiple regimes whose physical origin remains only partially understood. In particular, the connection between the diversity of observed rotation rates and the internal structure and thermodynamic properties of stellar interiors is still unclear. We investigated how the depth of the convective zones and the degree of plasma coupling, quantified through the plasma coupling parameter, relate to the observed rotation rates of solar-mass stars. We used a grid of $1 \, M_\odot$ MESA stellar models with a wide range of metallicities to identify the best-matching models for 243 main-sequence stars with measured rotation periods. We then examined correlations between their rotation rates and both the structural properties of the convective zones and the corresponding convective plasma coupling parameter. For this sample, rotation rates show only weak correlations with either the convective-zone depth or the plasma coupling parameter when considered independently. However, during the first two-thirds of the main-sequence lifetime, the correlation strengthens when both factors are considered jointly through a combined convective coupling index, indicating a moderate and statistically significant relationship. For older stars, these correlations weaken and lose significance, although the thermodynamic component becomes relatively more influential. These trends suggest that microphysical plasma properties may contribute to the regulation of angular momentum loss and may be connected to the onset of weakened magnetic braking.
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Earth and Planetary Astrophysics

An Ultra-Short Period Super-Earth and a Sub-Neptune Orbiting the K dwarf TOI-4311

Yoshi Nike Emilia Eschen, Thomas G. Wilson, Andrew Collier Cameron et al. (+95 more)

We report the discovery and characterisation of the multi-planetary system around TOI-4311, a K dwarf kinematically between the Galactic thick disk and Hercules stream. TOI-4311 hosts an ultra-short-period super-Earth (P$\sim$0.99 d, $1.376\substack{+0.077\\-0.080}$ R$_\oplus$) and a longer period sub-Neptune (P$\sim$15 d, $2.47\substack{+0.12\\-0.11}$ R$_\oplus$) that was first detected in the TESS photometry. Using follow-up observations with CHEOPS and HARPS, we refine the planetary radius of both planets, derive the mass of planet b ($4.5\substack{+1.5\\-1.4}$ M$_\oplus$) and confirm the planetary nature of planet c. Intriguingly, a third periodic signal is clearly detected in our HARPS RVs that we cannot link to stellar activity. This signal could be attributed to a third planet (P$\sim$38 d, Msin(i)=$26.4\substack{+6.3\\-6.8}$ M$_\oplus$) in the system, however with the current photometric dataset we do not find a transit. Our dynamical analysis highlights that this potential outer planet would remain stable. Using the precise radius and mass for TOI-4311 b we model its interior structure and find that it is very dense given the host star's galactic kinematics and chemistry. Hence this system could challenge current formation theories and provide insights into planet formation across the galaxy.
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All authors Yoshi Nike Emilia Eschen, Thomas G. Wilson, Andrew Collier Cameron, Alexander James Mustill, Jo Ann Egger, Solène Ulmer-Moll, Davide Gandolfi, Alexis M. S. Smith, Olivier D. S. Demangeon, Sérgio G. Sousa, Andrea Bonfanti, Alexandre C. M. Correia, Vardan Adibekyan, Gaia Lacedelli, Alexis Brandeker, Camilla Pezzotti, Babatunde Akinsanmi, Yann Alibert, Roi Alonso, Tamas Bárczy, David Barrado, Susana C. C. Barros, Wolfgang Baumjohann, Willy Benz, Nicolas Billot, Luca Borsato, Christopher Broeg, Amadeo Castro-González, Szilard Csizmadia, Patricio E. Cubillos, Melvyn B. Davies, Magali Deleuil, Adrien Deline, Brice-Olivier Demory, Aliz Derekas, Giuseppe Di Persio, Billy Edwards, David Ehrenreich, Anders Erikson, Andrea Fortier, Luca Fossati, Malcolm Fridlund, Kosmas Gazeas, Michaël Gillon, Manuel Güdel, Maximilian N. Günther, Alexis Heitzmann, Ch. Helling, Kate G. Isaak, Jon M. Jenkins, Tatiana Keller, Laszlo L. Kiss, Daniel Kitzmann, Judith Korth, Kristine W. F. Lam, Jacques Laskar, Alain Lecavelier des Etangs, Adrien Leleu, Monika Lendl, Demetrio Magrin, Pierre F. L. Maxted, Bruno Merín, Christoph Mordasini, Valerio Nascimbeni, Göran Olofsson, Hugh P. Osborn, Roland Ottensamer, Isabella Pagano, Enric Pallé, Gisbert Peter, Glen Petitpas, Daniele Piazza, Giampaolo Piotto, Don Pollacco, Didier Queloz, Roberto Ragazzoni, Nicola Rando, Heike Rauer, Ignasi Ribas, Nuno C. Santos, Gaetano Scandariato, Damien Ségransan, Avi Shporer, André M. Silva, Attila E. Simon, Richard Southworth, Manu Stalport, Sophia Sulis, Gyula M. Szabó, Stéphane Udry, Bernd Ulmer, Valérie Van Grootel, Julia Venturini, Eva Villaver, Nicholas A. Walton, Sebastian Wolf, Carl Ziegler, Tiziano Zingales

Astrophysics of Galaxies

A tool of Hierarchical cOre ideNtification and Kinematic property AssIgnment (HONKAI) for Dense Cores

Jiawei Liu, Zhiyuan Ren, Di Li et al. (+8 more)

Infrared dark clouds (IRDCs) contains cold dense gas at the earliest stage of massive star and cluster formation. In studying the IRDCs, a universal and fundamental task is to resolve their internal hierarchical structures. Various packages and algorithms were developed for this purpose, but with most of them mainly focused on certain individual steps in data processing. In this work, we build a more automatic procedure for multi-band structure measurement HONKAI (Hierarchical cOre ideNtification and Kinematic property AssIgnment), which can resolve the elemental components including cores and clumps, disentangle the velocity components in spectral data, measure their physical properties, and generate a catalogue for all the measured properties. We use honkai for a joint study towards three IRDCs observed in 850 $\mu$m dust continuum with James Clerk Maxwell Telescope (JCMT) and the $^{13}CO$ $(1-0)$ data cube with the Purple Mount Observatory 14-m telescope. 193 dense cores in 16 clumps are identified. As major dynamical properties, a large amount of the cores (136 out of 193) are measured to have large virial ratio of $R_{\rm vir}>1$, but their mass-size relation is bellow the threshold for massive star formation. Meanwhile, core mass function (CMF) also exhibits a steeper slope towards high-mass end compared to more evolved core samples. These three properties in accordance suggest that although many IRDC cores are self-gravitating, only a small fraction are seemingly possible to form high-mass stars. In subsequent core evolution, some further mass assembly trend may be involved to facilitate the high-mass star formation.
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All authors Jiawei Liu, Zhiyuan Ren, Di Li, Jinjin Xie, Gary A. Fuller, Yuchen Xing, Xin Lyu, Fengwei Xu, Chen Wang, Fanyi Meng, Sihan Jiao

Astrophysics of Galaxies

Proximate damped Lyman-$\alpha$ systems as tracers of quasar feedback

Patrick Petitjean

Active galactic nuclei (AGN) profoundly affect the interstellar medium of their host galaxies through intense radiation fields and powerful winds. Characterising this feedback is essential for understanding galaxy formation and evolution. Here we revisit the origin of proximate damped Lyman-$\alpha$ absorbers (PDLAs), which trace cold gas within 3000 km/s of the quasar redshift, and interpret their kinematics and physical properties within a unified framework. We searched the SDSS DR16 database for low-ionisation metal absorption-line systems at the quasar redshift (referred to as ProxSys). This approach enables us to identify and classify different types of proximate absorbers, including so-called Ghostly systems, coronagraphic DLAs (DLA-Cor), standard DLAs, and sub-DLAs, based on the presence of strong Lyman-alpha absorption, partial covering signatures, or excited atomic transitions such as SiII*. We find that about 13% of ProxSys belong to the Ghostly or DLA-Cor classes and exhibit strong absorption from excited species. The different classes of ProxSys form a continuous sequence characterised by decreasing SiII*, CIV, and NV absorption strengths and dust content. Their velocity distributions reveal multiple kinematic components. Standard DLAs cluster within 1000km/s of the quasar systemic redshift, consistent with gas in the host galaxy, whereas Ghostly and SiII* bearing systems display broader distributions, including outflows reaching -2000 km/s and a smaller population of inflowing clouds up to +1200 km/s. Median stacked spectra confirm that Ghostly and coronagraphic systems arise in dense, compact gas partially covering the quasar emission regions. These results support a scenario in which cold, dense clouds participate in a dynamic cycle of inflow and outflow in the vicinity of quasars, consistent with chaotic cold accretion.
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Astrophysics of Galaxies

Non-LTE atmosphere models of very luminous sources and their applicability to Little Red Dots, quasi-stars, and similar objects

Fabrice Martins, Daniel Schaerer and Rui Marques-Chaves

We investigate whether atmosphere models traditionally used for massive stars with strong winds can produce synthetic spectra morphologically similar to those of Little Red Dots (LRDs). We compute atmosphere models and synthetic spectra with the code CMFGEN. The models assume a thermalized radiation field at the inner boundary, parameterized by a temperature varying between 5000 and 12000~K. We adopt a typical luminosity of 1e10 Lsun. The models are spherical, assume an expanding atmosphere, and are computed under non-LTE conditions and for several metallicities. The spectral energy distribution (SED) is different from a blackbody, with a blue optical spectrum. Broad hydrogen emission lines are produced, their wings being formed by electron scattering. The SED near the Balmer and Paschen limit is rather continuous. A Balmer break is predicted for the coolest temperature models provided the wind density is reduced. The SED and Balmer decrement of most LRDs is reproduced by the models, provided they are dust-attenuated with Av~1.9-2.7. Assuming the absorbed luminosity is re-radiated in the infrared, the energy output at these wavelengths is consistent with observational constraints. The models predict FeII, oxygen and calcium lines. OI lines at 8446 A and 1.129 um are produced mostly by Lybeta fluorescence. The strength of emission lines from metals depends on input temperature, metallicity, and details of the radiative transfer models. CMFGEN atmosphere models predict a large number of spectral properties observed in many LRDs. They struggle to simultaneously produce a genuine Balmer break and strong emission lines. Whether they are more relevant or not to explain LRDs' spectra compared to alternative models is unclear, leaving open the question of the physical conditions in LRDs.
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Cosmology and Nongalactic Astrophysics

Discriminating Planck Reionisation Histories with the kSZ Effect

M. Douspis, A. Gorce, S. Ilić et al. (+5 more)

The epoch of reionisation is a key phase in cosmic history, but its detailed evolution remains poorly constrained by current cosmic microwave background (CMB) observations. We investigate whether the kinetic Sunyaev-Zel'dovich (kSZ) effect can discriminate among reionisation histories consistent with current large-scale CMB constraints. Using histories derived from Planck data, we compute the corresponding kSZ angular power spectra within an analytical framework. The allowed histories fall into two broad classes, 'late' and 'early' start, yielding distinct kSZ signatures, which remain clearly separable even when accounting for modelling uncertainties in both the reionisation scenario, $x_e(z)$, and the properties of early galaxies. Current kSZ measurements ($\sim$0-3 $\mu$K$^2$) tend to favour `late' reionisation models but are not yet sensitive enough to definitely distinguish between the scenarios - a measurement of the kSZ power spectrum at $\ell \sim 2000$ with $\sim$0.4 $\mu$K$^2$ sensitivity, achievable in the coming years, will be sufficient to do so. This work demonstrates that CMB data alone can constrain the reionisation midpoint $z_\mathrm{re}$ with extremely narrow error bars ($7.94<z_\mathrm{re}<8.17$), even when effectively marginalising over modelling uncertainties.
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All authors M. Douspis, A. Gorce, S. Ilić, L. McBride, M. Muñoz-Echeverría, E. Pointecouteau, L. Salvati, M. Tristram

Solar and Stellar Astrophysics · Cross-listed from physics.atm-clus

Hyperfine-Resolved Rovibrational and Rotational Spectroscopy of OH$^+$ ($X ^3\Sigma^-$)

Weslley G. D. P. Silva, Lea Schneider, Urs U. Graf et al. (+6 more)

The OH$^+$ ($X ^3\Sigma^-$) radical cation has been investigated by combining a 4 K 22-pole ion trap apparatus with high-resolution IR and THz radiation sources. Applying different types of action spectroscopic methods, the fundamental vibrational band in the 3 $\mu$m range and the spin manifold of the $N=1 \leftarrow 0$ rotational transition around 1 THz have been extended and refined. Additionally, the spin manifold of the $N=2 \leftarrow 1$ rotational transition, scattered around 2 THz, has been measured for the first time with microwave accuracy. Although all hyperfine components of the pure rotational transitions are affected by considerable Zeeman splittings, a simulation of their contours allowed us to extract the field-free center frequencies with high accuracy. A global fit combining rovibrational and pure rotational transitions from the literature with those newly obtained in this work was performed, leading to improvements in the spectroscopic constants of OH$^+$, particularly those in the ground vibrational state.
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All authors Weslley G. D. P. Silva, Lea Schneider, Urs U. Graf, Holger S. P. Müller, Pavol Jusko, Arshia M. Jacob, Dominik Riechers, Stephan Schlemmer, Oskar Asvany

High Energy Astrophysical Phenomena

Periodic Emission Frequency Modulation in a Hyperactive Fast Radio Burst

Rui-Nan Li, Hao-Tian Lan, Zhen-Yin Zhao et al. (+3 more)

Fast radio bursts (FRBs) are intense, short-duration radio transients of mysterious origin. They have been detected across a wide range of frequencies from 110 MHz to 8 GHz. Their spectral properties, remaining poorly understood, are essential for understanding the intrinsic radiation mechanism and propagation effects. Here, we report the discovery of a periodic modulation in the central emission frequency of FRB 20240114A, based on more than one thousand bursts collected by an ultra-wideband receiving system. The burst central frequencies reveals a significant modulation with a period of $\sim 112$ days. The statistical significance of this detected periodicity exceeds $6\sigma$ for both the Lomb-Scargle and phase-folding methods. Within a single period, the central emission frequency exhibits a systematic drift from lower to higher values. We evaluate several physical mechanisms for this unique spectral evolution. The free-free absorption together with cyclotron resonant absorption in a binary system or free precession models could potentially explain such behavior. The discovery of this periodic frequency modulation unveils a new layer of complexity in the underlying radiation mechanism and propagation effect of FRBs.
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All authors Rui-Nan Li, Hao-Tian Lan, Zhen-Yin Zhao, Qin Wu, Fa-Yin Wang, Zi-Gao Dai

Instrumentation and Methods for Astrophysics · Cross-listed from stat.ME

Power Studies For Two-Sample and Goodness-of-Fit Methods For Multivariate Data

Wolfgang Rolke

We present the results of a large number of simulation studies regarding the power of various goodness-of-fit as well as non-parametric two-sample tests for multivariate data. In two dimensions this includes both continuous and discrete data, in higher dimensions continuous data only. In general no single method can be relied upon to provide good power, any one method may be quite good for some combination of null hypothesis and alternative and may fail badly for another. Based on the results of these studies we propose a fairly small number of methods chosen such that for any of the case studies included here at least one of the methods has good power. The studies were carried out using the R packages MD2sample and MDgof, available from CRAN.
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High Energy Astrophysical Phenomena

Catching UHE Neutrinos with HERON

Andrew Zeolla

The Hybrid Elevated Radio Observatory for Neutrinos, or HERON, is a newly proposed ultrahigh energy Earth-skimming tau neutrino detector. Ultrahigh energy tau neutrinos which skim the Earth may produce $\tau$-leptons which escape into the atmosphere and initiate up-going extensive air showers. The HERON concept consists of 24 compact phased radio arrays, embedded within a larger sparse array of 360 standalone antennas, distributed along a mountain range and designed to capture the radio emission of these up-going extensive air showers. Due to the high elevation observation sites and the long propagation length of radio, HERON achieves a very large instantaneous effective area towards the horizon, and thus excels at the detection of astrophysical transient events such as gamma-ray bursts. With the excellent pointing resolution offered by the sparse array, HERON would be capable of conducting UHE neutrino astronomy and could be incorporated into the broader network of multi-messenger instruments. Here, we detail the HERON concept and describe the science which can be accomplished with it.
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