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Physics Astrophysics

astro-ph Watch Astrophysics

Thursday 30 April

Earth and Planetary Astrophysics

The Solar System Notification Alert Processing System (SNAPS): Public access to SNAPS data and products

David E. Trilling, Michael Gowanlock, Revanth Munugala et al. (+5 more)

The Solar System Notification Alert Processing System, SNAPS, is a downstream broker that ingests moving object data from ZTF and LSST and serves these data and derived properties to the public. This document describes how users can access our SNAPS data and products. This is intended to be a living document that will be updated on the arXiv when significant improvements are made to our data access schemes, and will therefore always contain the most up to date information about interacting with our databases and infrastructure. This is version 1.0.
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All authors David E. Trilling, Michael Gowanlock, Revanth Munugala, Daniel R. Kramer, Maria Chernyavskaya, Erin Clark, Graceson Mule, Savannah Chappus

Astrophysics of Galaxies

Star cluster formation from turbulent clumps. V. Stellar clustering around massive stars

Aayush Gautam, Juan P. Farias and Jonathan C. Tan

Massive stars (> 8 $M_\odot$) are known to have high degrees of multiplicity, e.g., with about 60% in triples or higher-order multiples. Such high levels of multiplicity may arise during formation (primary multiplicity) or through dynamical processing of already formed stars in dense clusters (secondary multiplicity). The level of primary multiplicity is an important metric to help distinguish between different formation scenarios, such as core accretion and competitive accretion. The level of secondary multiplicity is expected to evolve with time and be sensitive to local cluster environment. Here we analyze a suite of $N$-body simulations to study bound multiplicity and local projected stellar density, $N_*$, around massive stars within gradually forming star clusters with 50% primordial binaries in the Turbulent Clump Core Accretion (TCCA) paradigm. We find that massive stars rapidly gather triple or higher-order bound companions and enhancements in local $N_*$ via dynamical processes. We study these metrics as a function of environment in a given cluster, quantifying the increasing multiplicity that arises towards cluster centers. We find that secondary multiplicity tends to decrease in more massive clusters due to their higher velocity dispersions, but rises as the mean density of the bound cluster increases. We find our $N_*$ radial profiles are shallower compared to those in the STARFORGE simulations, which form massive stars via competitive accretion. A comparison to the AFGL 5180 system suggests it is better described by TCCA models. However, a larger number of observed systems is needed to better discriminate between these formation models.
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Astrophysics of Galaxies · Cross-listed from cs.LG

Stable but Wrong: An Inference Limit in Galactic Archaeology

Zhipeng Zhang

Statistical inference in observational science typically relies on a fundamental assumption: as sample size increases and uncertainties decrease, the inferred results should converge to the true physical quantities. This assumption underpins the notion that big data lead to more reliable conclusions. In Galactic archaeology, stellar ages inferred from spectroscopic surveys are widely used to reconstruct the formation history of the Milky Way disk. The age metallicity relation (AMR) and its derived formation timescale are often regarded as key physical diagnostics of early disk evolution. This interpretation carries an implicit premise: that observational quality does not introduce systematic bias into age inference. Here we show that this premise may fail. Using a large sample of subgiant stars, we identify a region in the observational quality parameter space (signal-to-noise ratio and parallax precision) where the inferred formation timescale exhibits a systematic offset of 0.5-1 Gyr relative to an independent asteroseismic reference, while the statistical uncertainties remain small, thus producing a stable-but-wrong inference state.
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Astrophysics of Galaxies

Active Galactic Nucleus Feedback in an Elliptical Galaxy. IV. The Importance of the Jet Wind Coupling

Minhang Guo, Feng Yuan, Suoqing Ji et al. (+1 more)

This is the fourth paper of our series investigating the effects of active galactic nucleus (AGN) feedback in the evolution of an elliptical galaxy using the MACER framework. While previous works considered only AGN radiation and wind, we now add jet feedback. The values of the jet parameters are taken from small-scale general relativity MHD simulations of black hole accretion. We run three models: FullFeedback, JetOnly, and WindOnly. Time-averaged star formation rates are $10^{-1}$, $10^{-2}$, and $10^{-3} \mathrm{M}_\odot\,\mathrm{yr}^{-1}$ in JetOnly, WindOnly, and FullFeedback, respectively. Despite the higher jet power, jet feedback is less efficient than wind due to a small opening angle and low momentum flux. The much lower star formation rate in FullFeedback indicates nonlinear coupling between jet and wind, with stronger suppression than the linear sum. The AGN energy dissipation efficiency values (fraction of injected kinetic energy dissipated via turbulence and shock) are 0.64 (FullFeedback), 0.48 (WindOnly), and 0.26 (JetOnly). In the FullFeedback model the wind-jet shear results in Kelvin-Helmholtz instability, driving stronger turbulence that effectively converts AGN kinetic energy into heating.
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All authors Minhang Guo, Feng Yuan, Suoqing Ji, Bocheng Zhu

Astrophysics of Galaxies

Extended Universal Rotational Curve of Spiral Galaxies

Esha Bhatia, Paolo Salucci, Tiziano Schiavone et al. (+1 more)

In this work, we aim to advance the Universal Rotation Curve (URC) paradigm by leveraging new data and extending its observational domain. Building on previous studies that established the URC using optical rotation curves reaching the galaxy optical radius $R_{opt}$, we exploit the SPARC sample's extended HI rotation curves to construct the URC out to $2R_{opt}$. This crucial extension enables us to investigate the mass distribution of spiral galaxies in a region dominated by dark matter an important step to better constrain galaxy mass models and to explore the nature of the dark matter particle. We find that the URC constructed from the SPARC sample's extended HI rotation curves maintains its universal character out to $2R_{opt}$, with the double-normalized rotation curves collapsing onto a single profile. This extended URC provides new insights into the interplay between baryonic matter and dark matter in shaping galaxy rotation curves, particularly in the outer regions where dark matter dominates. Our results not only reinforce the URC paradigm but also refine our understanding of the mass distribution in spiral galaxies, offering new constraints on galaxy mass models and implications for the nature of dark matter.
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All authors Esha Bhatia, Paolo Salucci, Tiziano Schiavone, Sandeep Haridasu

Astrophysics of Galaxies

Turbulence and Star Formation Suppression in Elliptical Galaxies: The Role of Active Galactic Nucleus Jet Wind Interaction

Minhang Guo, Suoqing Ji, Feng Yuan et al. (+1 more)

Winds and jets are symbiotic when the accretion rate is low, according to black hole accretion theory. Both components are potentially important for active galactic nucleus (AGN) feedback, but previous works typically include only jets with free parameters. We perform hydrodynamical simulations of an isolated elliptical galaxy with both jets and winds included. The key features discriminating our simulations from others are that our simulations resolve the Bondi radius for reliable black hole accretion rate calculation and use parameters from GRMHD simulations. By selectively activating jets and winds, we examine their individual and combined effects. We find that effective AGN feedback, which is capable of generating strong turbulence and subsequently increasing central gas entropy and suppressing cool gas condensation and star formation, occurs only when both jets and winds operate simultaneously. The physical mechanism is the interaction between winds and jets: this interaction produces strong shear at their interface, leading to turbulence via the Kelvin-Helmholtz instability. In contrast, neither jets nor winds alone can generate strong turbulence due to the insufficient shear. The turbulence produced by wind-jet interaction is predominantly solenoidal in nature, giving rise to a broad energy spectrum approximately following a Kolmogorov-like power law and a dissipation rate $\sim 10^{-27}\,\mathrm{erg\,cm^{-3}\,s^{-1}}$ in the interstellar medium, consistent with observations. Our findings highlight the importance of simultaneously considering both jets and winds in studying the effects of AGN feedback in the evolution of elliptical galaxies.
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All authors Minhang Guo, Suoqing Ji, Feng Yuan, Bocheng Zhu

Wednesday 29 April

Solar and Stellar Astrophysics

Characterisation of all known multiple stellar systems within 10 pc

J. González-Payo, J. A. Caballero, C. Cifuentes et al. (+2 more)

The study of stellar multiplicity offers important constraints on the structure of the Galaxy as well as stellar and planet formation and evolution. Focusing on the most immediate solar neighbourhood benefits from obtaining both complete and accurate data for reliable statistics. Our goal is to describe the solar neighbourhood within 10 pc in terms of multiplicity by evaluating the angular and physical separations, masses, and orbital periods of the systems from the most complete volume-limited sample. We carried out a comprehensive data compilation from the Washington Double Star catalogue and the literature of all known multiple systems at any separation range, and completed this information with a common proper motion and parallax search with Gaia DR3 data. We also used public astrometric and radial-velocity data to compute orbital solutions of seven pairs. From a sample of 424 stars and brown dwarfs within 10 pc we identified 215 of them in 92 systems in double (68), triple (19), quadruple (3), and quintuple (2) configurations. All except eight pairs have been resolved. Their orbital periods range over ten orders of magnitude from about one day to millions of years. We measured precise mass and companion star fractions at different mass intervals. The multiplicity fraction smoothly decreases from 41+-11% for stars with M >= 0.50 Msun to 9.3+-7.4% for stars and brown dwarfs with M <= 0.10 Msun.
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All authors J. González-Payo, J. A. Caballero, C. Cifuentes, M. Cortés-Contreras, F. Rica

Instrumentation and Methods for Astrophysics · Cross-listed from gr-qc

The Quantum Noise Fraction and the addressable fraction in High-Frequency Gravitational Wave Detection

Sergio Gaudio

The quantum noise fraction $\beta$ – the share of a detector's noise power that is quantum in origin – bounds the sensitivity gain from any quantum technique at $\mathcal{E}_{\max}=1/\sqrt{1-\beta}$. In the kHz–GHz band the readout is a bosonic mode and $\beta=1/(2\bar{n}_{\rm th}+1+\nu)$, so quantum noise dominates only below a thermal frontier $k_BT\ln 3=\hbar\omega$ (229 MHz at 10 mK) that governs mechanical resonators and electromagnetic cavities alike. On a multimode acoustic antenna the frontier is directly observable: the logarithmic slope of $\sqrt{S_hQ}$ along the odd-overtone comb increases by exactly one half across it, for any dependence of the quality factor on overtone number. Crossing the frontier costs more in classical sensitivity than quantum enhancement returns. For a GHz bulk acoustic wave mode at 10 mK, $\beta=0.984$, but the ceiling is unattainable: with intrinsic damping the zero-point term is the bath's force noise, fixed by the fluctuation–dissipation theorem. The addressable fraction $\beta_a$ measures what a quantum technique can actually remove: at the standard quantum limit $\beta=0.992$ yet $\beta_a=0.496$, an available factor 1.41 against a ceiling of 11.0. The remaining gap to the big-bang-nucleosynthesis bound is classical.
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High Energy Astrophysical Phenomena

Multi-messenger emission from choked jets in collapsar

Zegarelli Angela, Pais Matteo, Peretti Enrico et al. (+1 more)

The death of massive stars produces central accreting compact objects and sometimes relativistic jets. Not all jets escape the stellar envelope: unsuccessful, or choked, jets dissipate their energy into a pressurized cocoon, which expands and may break out as a mildly relativistic outflow. We investigate the plasma physics of collapsing massive stars hosting choked jets through relativistic, non-resistive magnetohydrodynamical simulations. We delineate the parameter space for jet choking and quantify the acceleration rate and efficiency of charged particles at strong shocks, which are potential sources of high-energy neutrinos and electromagnetic transients. Our study focuses on blue and red supergiant progenitors, both promising candidates for jet choking.
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All authors Zegarelli Angela, Pais Matteo, Peretti Enrico, Celli Silvia

High Energy Astrophysical Phenomena

Iron He-triplet signatures of shocks in the hottest galaxy clusters. Z/W line ratio, line broadening, and electron-ion temperature equilibration

Eugene Churazov, Yuri Ralchenko, Ildar I. Khabibullin et al. (+5 more)

A merger of clusters naturally drives shocks with Mach number $\mathscr{M}\lesssim 3$ in the intra-cluster medium (ICM). This process creates several distinct signatures, including sharp surface brightness "edges", temperature, and gas velocity jumps. The low density of the ICM implies that the ionization balance and electron-ion equilibration times can be long enough to produce a set of additional observable signatures. Here, we focus on two "transient" spectral signatures accessible with the high-energy-resolution telescopes such as XRISM, even for unfavorable geometry, e.g., when we are looking inside the Mach cone of the shock, precluding the appearance of sharp edges in X-ray images. In this work, we focus on (i) the $\mathtt{Z/W}$ line ratio of the Fe~XXV triplet and (ii) the contribution of ions with $T_i>T_{\rm e}$ to the line width, which might be mistakenly interpreted as the gas turbulence. We demonstrate that the $\mathtt{Z/W}$ ratio can serve as a proxy for the non-equilibrium state of the shocked ICM and facilitate interpretation of the line broadening. We conclude that these spectral signatures are within reach with missions like XRISM and can be used to constrain the heating of electrons at the collisionless cluster shocks, as well as the rate of subsequent temperature equilibration between different particle species.
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All authors Eugene Churazov, Yuri Ralchenko, Ildar I. Khabibullin, John C. Raymond, Annie Heinrich, Irina Zhuravleva, Reinout J. van Weeren, Congyao Zhang

High Energy Astrophysical Phenomena · Cross-listed from gr-qc

Agnostically decoding gravitational wave model deficiencies in GWTC-3

Guillaume Dideron, Suvodip Mukherjee and Luis Lehner

Gravitational Wave (GW) data bring an exceptional avenue to test the underlying models of coalescing compact objects. In the regime of strong gravity and high curvature, they allow the exploration of minute deviations from the best-fit models, which are difficult to uncover with other observational modalities. These deviations can stem from departures from General Relativity (GR) or unaccounted astrophysical effects. They may not be explainable within the current description of GW strain data, or may simply be difficult to model. However, they are expected to be correlated between detectors and across the population of observed events. The recently developed SCoRe analysis pipeline leverages these properties by focusing on the correlated power between detectors and combining results from multiple events. In this paper, we apply the framework on the Third Gravitational-Wave Transient Catalog to search for source-dependent deviations. In particular, we explore whether there is evidence for a mass-scale in the observed events, which can act like a line of demarcation in their physical properties by exhibiting a deviation that is different above and below this mass-scale. This mass scale dependency naturally arises in gravitational theories described through effective field theories, due to environmental effects or in scenarios involving exotic compact objects, where the GW signature can differ from the standard binary black holes in GR. Using the 30 highest Signal-to-Noise Ratio events in the catalog, we find Bayes factors ranging from 0.16–0.5 (depending on where the threshold mass is set), thus disfavoring the hypothesis of existence of any mass-scale between $\sim 2.5$ M$_\odot$ and $60$ M$_\odot$. We also compute the distribution of excess cross-correlated power across events and find a Bayes factor of $0.07$, which agrees with expected noise statistics.
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Earth and Planetary Astrophysics

Formation and Trapping of CO2 from Cryogenic Irradiation of Carbonate

Ashma Pandya, Swaroop Chandra and Michael E. Brown

The detection of CO2 on the Jovian satellite Europa by Galileo NIMS and recent mapping of the leading side by JWST has revealed that it is most concentrated in geologically young terrains, and its v3 asymmetric stretch appears as a spectral doublet centered at 4.25 and 4.27 um. Since crystalline CO2 is unstable at Europan surface conditions, this observation implies an active source and a trapping medium, which may be separate. To this end, several hypotheses have been proposed, but no laboratory work has successfully reproduced the spectral features of CO2 on Europa so far. Radiolyzed carbonates have also been discussed as plausible precursors and host materials for CO2, though their role has not been experimentally validated in a Europa-like environment. Here, we report the first laboratory experiments investigating CO2 production from carbonate salts exposed to 10 keV electron irradiation at 50, 100, and 120 K in ultrahigh vacuum. Using diffuse reflectance FTIR spectroscopy, we observe the emergence, growth, and saturation of an absorption doublet centered near 4.25 and 4.27 um, consistent with the CO2 v3 band. Postirradiation thermal desorption studies using residual gas analysis reveal that the radiolytically formed CO2 is stable at temperatures beyond Europa's surface. This work provides the first experimental evidence that low-energy electron irradiation of carbonates in cryogenic, vacuum conditions can produce and retain CO2, and suggests that carbonates can serve as endogenous reservoirs of CO2 on irradiated icy bodies in the outer solar system.
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Solar and Stellar Astrophysics

Six New Variable Stars Discovered from Ground-Based Photometry and Characterized with TESS Data

Maksym Yu. Pyatnytskyy

We report the discovery of six new variable stars identified through an exploratory analysis of several sky fields observed by the author using a small telescope and a CMOS camera. The search employed simultaneous photometry of hundreds of objects with AstroImageJ, supplemented by custom Python-based tools developed by the author to generate aperture lists and visualize light curves across the full field of view. The variables were further characterized using TESS data, and their properties are presented. We also describe the data analysis workflow, including the software packages LCV and VS-fit, developed by the author for periodogram analysis and light-curve modelling.
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2604.27176 · 29 Apr · 20 pages, 19 figures. In v2, a misprint in Table 2 was fixed: V = 15.24 for TIC 269112450. The variability type for TIC 269112450 was changed from EA/RS to EA+BY (more suitable based on the star's characteristics); improved light curve modelling and additional details in Table 2 are also provided

Abstract PDF $STAR ×2$TSCP ×1

High Energy Astrophysical Phenomena

The major cluster merger in Abell 2034 as seen by XRISM: Strong turbulence and spectral anomalies?

Annie Heinrich, Irina Zhuravleva, Eugene Churazov et al. (+5 more)

XRISM observations to date have shown that gas kinetic pressures in the intracluster medium (ICM) tend towards the low end of predictions from cosmological simulations. Here, we present a XRISM observation of the merging cluster Abell 2034, which exhibits the broadest emission lines yet observed in a galaxy cluster. We measure a velocity dispersion of ~470 km/s, corresponding to a kinetic pressure fraction of ~15%. This places A2034 at or above the high end of the theoretical predictions for similar-mass clusters. This large velocity dispersion may reflect Mach ~0.5 turbulence in the ICM and/or result from a core disruption driven by the ongoing head-on merger. We also detect a ~380 km/s gas bulk velocity gradient along the merger axis with an opposite sign to the galaxy velocity gradient, indicating a decoupling of the cluster galaxies (and dark matter) from the ICM. Finally, we report tentative evidence of several spectral anomalies, including a suppressed Fe He$\alpha$-z line, an enhanced Fe Ly$\alpha$-2 line, and a potential absorption feature at ~8.7 keV. The first two features may be explained by the combination of a multi-component ICM and a non-equilibrium ionization state in the wake of a merger shock. Deeper XRISM observations of this cluster are required to confirm these features. This work highlights the importance of kinematic measurements across a large sample of merging clusters as well as the need for deep XRISM observations to unveil more exotic physics in the ICM.
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All authors Annie Heinrich, Irina Zhuravleva, Eugene Churazov, Congyao Zhang, Daniele Rogantini, Hannah McCall, Reinout J. van Weeren, William R. Forman

Astrophysics of Galaxies

Molecular Outflows in the Nucleus of the Nearby Compton-thick AGN NGC 3079

Ming-Yi Lin, Anne Medling, Richard Davies et al. (+14 more)

We present Northern Extended Millimeter Array (NOEMA) observations of the CO (2-1) molecular gas kinematics in the nearby Compton-thick Seyfert 2 galaxy NGC 3079, with an angular resolution of 0.5" ($\sim$40 pc). To interpret the observed CO (2-1) kinematics, we model the rotating disk using two software tools, 3D-Barolo and DysmalPy, to generate mock 3D data cubes. Both models indicate, in addition to the rotating disk, the presence of a spatially unresolved nuclear component characterized by high velocity dispersion. Analysis of the visibility data reveals that the blue-shifted, high-velocity component is spatially offset from the continuum peak by 0.17" ($\sim$ 14 pc) and exhibits line-of-sight velocities of $v$ - $v_{sys}$ = -350 to -450 km s$^{-1}$, which we interpret as a nuclear molecular outflow. We calculate a molecular gas mass outflow rate of 8.82 $M_\odot$ yr$^{-1}$, with a kinetic power ($\dot{E}_{\text{out}}$) of 3.8 $\times$ 10$^{41}$ erg s$^{-1}$ and a momentum rate ($\dot{p}_{\text{out}}$) of 2.05 $\times$ 10$^{34}$ Dyne. The momentum rate exceeds the AGN radiation momentum rate by a factor of $\sim$15, suggesting an energy-driven outflow. Furthermore, we argue that the derived kinetic power of the nuclear molecular outflow favors a jet-powered scenario that explains the slowdown and brightening of the parsec-scale radio source observed with the Very Long Baseline Array.
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All authors Ming-Yi Lin, Anne Medling, Richard Davies, Melanie Krips, Loreto Barcos-Munoz, Reinhard Genzel, Eduardo Gonzalez-Alfonso, Javier Gracia-Carpio, Dieter Lutz, Roberto Neri, Gilles Orban de Xivry, David Rosario, Allan Schnorr-Muller, Taro Shimizu, Amiel Sternberg, Eckhard Sturm, Linda Tacconi

Solar and Stellar Astrophysics

CORINOS V: Radiative transfer effects in protostellar ice observations

Will E. Thompson, Jennifer B. Bergner, Neal J. Evans II et al. (+11 more)

Recent observations of protostars with the James Webb Space Telescope have revealed unprecedented chemical complexity from their ice absorption features. However, these spectra are likely influenced by radiative transfer effects, and there is little understanding of how this impacts our ability to identify, quantify, and interpret the observed ice features. We have developed a new modeling framework to investigate the radiative transfer through icy protostellar envelopes, and apply this to the IRAS 15398-3359 protostar observed by the JWST CORINOS program. The modeled H$_2$O and CO column densities are similar to previous empirical studies, but we require a high CO$_2$/H$_2$O ratio of 76% to match the optical depth of the 15 $\mu$m band. We use our modeled continuum to calculate a 6-10 $\mu$m optical depth spectrum, and see considerable differences compared to a simple polynomial continuum model, underscoring the challenges with quantifying trace ice species in this range. For this source, we find that the observed absorption predominantly originates along the viewing line of sight between 1000 - 2000 au, peaking at the transition from the outflow cavity to the envelope; the spectra are largely insensitive to absorption from ices in the outer envelope, which extends out to 20,000 au. Lastly, we show that depending on how the line of sight intersects the cavity, the apparent CO$_2$/H$_2$O and CO/H$_2$O column density ratios can be underestimated compared to the underlying ice abundance ratios. Together this provides important context for interpreting the ice constraints derived from JWST observations of protostars.
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All authors Will E. Thompson, Jennifer B. Bergner, Neal J. Evans II, Yao-Lun Yang, Vincent Kreft, Lenore Anderson, Klaus M. Pontoppidan, L. Ilsedore Cleeves, Ewine F. van Dishoeck, Rachel E. Gross, Jeong-Eun Lee, Melissa K. McClure, Nami Sakai, Katerina Slavicinska

Astrophysics of Galaxies

uGMRT and MeerKAT observation of RXCJ0232-4420: a quiet cluster with a giant radio halo

Pralay Biswas, Ramananda Santra, Ruta Kale et al. (+1 more)

Giant radio halos are the Mpc-scale extended sources associated with the merging clusters, while the mini-halos are preferentially associated with cool-core clusters. Both trace the ICM plasma physical process, and recent low-frequency observations increasingly blur the distinction between the two classes. We present the first multi-frequency spectral analysis of the galaxy cluster RXCJ0232–4420, hosting a cool core, using uGMRT (400 and 650 MHz) and MeerKAT (1283 MHz) observations. The central radio emission extends beyond $\sim 1$ Mpc at all frequencies, confirming it as a giant radio halo. One candidate relic (in the east) has also been detected, with an extent of $\sim 300$ kpc. The integrated spectral indices of halo and candidate east relic are $\alpha = -1.17 \pm 0.17$, and $\alpha = -0.85 \pm 0.17$, respectively. The resolved spectral map of the halo is mostly uniform ($-1.0$ to $-1.3$) and does not show any radial steepening. The radio surface brightness profile is well modelled by a single exponential law, with the e-folding radius constant across frequencies. The radio halo emission is morphologically well correlated with the thermal emission. Point-to-point radio-X-ray correlation analysis gives a sublinear relationship (slope $\sim 0.80$), with no frequency evolution. The presence of Mpc-scale emission in the cool-core cluster shows that such emission can arise in dynamically intermediate systems. Our results demonstrate that merger-driven turbulence, even from minor disturbances, can sustain cluster-wide particle re-acceleration without destroying the cool core.
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All authors Pralay Biswas, Ramananda Santra, Ruta Kale, Viral Parekh

Solar and Stellar Astrophysics

Dust cloud lifetimes of Scallop-shell stars

Simon Daley-Yates, Moira M. Jardine and Luke Bouma

We investigate the survival of dust trapped in magnetically confined cool gas clouds (or prominences) around rapidly rotating M-dwarfs exhibiting the “scallop-shell” light-curve morphology. Using a two-dimensional magnetohydrodynamic simulation, we extend previous coronal prominence models to include a passive tracer field to allow for a single injection of collisionally charged dust grains. The tracer evolution reveals how recurrent centrifugal breakouts–the slingshot process–remove dust and gas from the prominence while chromospheric evaporation replenishes gas from below. For our simulated star, which has $R_{\ast} = 0.6 R_{\odot}$, $M_{\ast} = 0.3 M_{\odot}$, and $P_{\ast} = 0.32$ days, the resulting dust content decays exponentially with a minimum half-life of approximately 6 stellar rotations, representing a lower limit set by our assumption of fully coupled dust and gas dynamics. Synthetic velocity-phase diagnostics show a single, phase-locked feature that fades steadily, reproducing the behaviour of dips seen in TESS and K2 light curves. Comparison with observed river plots suggests a natural classification: (i) persistent, non-decaying features formed by quiescent prominences below co-rotation; (ii) gradually fading features produced by slingshot prominences near co-rotation; and (iii) abrupt disappearances linked to magnetic reconnection and flare-driven ejections. These results demonstrate that dust-bearing prominences–undergoing repeated slingshots–can persist for tens of rotations, linking the observed longevity of the scallop-shell photometric features with the dynamic cycle of prominence slingshot ejections.
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Solar and Stellar Astrophysics

The A Supergiant Eclipsing Binary BM Cas: An Evolved, Intermediate Mass System

T. J. Davidge

The evolutionary state of the 198 day eclipsing binary BM Cas is examined using spectra that cover five orbital cycles. Radial velocities measured from SiII 6347 and SiII 6371 track the motion of the primary, and a mass function is found that is similar to that obtained by Popper(1977) from MgII 4481. Absorption from a circumsystem shell complicates efforts to measure stellar velocities from FeII lines. Many of the characteristics of Halpha emission and absorption that are associated with the shell vary in sync with the motion of the primary, and it is suggested that the shell may form from material that exits the system from L2. The infrared spectral-energy distribution departs from that of an A supergiant only at wavelengths > 5um, and models are examined in which the secondary is obscured by an opaque envelope. Archived V band photometry is compared with model light curves, and it is concluded that the A supergiant is close to filling, or is filling, its Roche lobe, and that the as-yet undetected secondary may be more massive than the primary. Based on the overall properties of BM Cas and its environment, we suggest that it is an Algol or post-Algol system, in which the A supergiant was originally the more massive component. If this is the case then the stars in BM Cas had intermediate initial masses. Some of the photometric characteristics of the primary are indicative of alpha Cyg-type variability.
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Cosmology and Nongalactic Astrophysics

Geodesically Complete Curvature-Bounce Inflation

Damien A. Easson

The early universe need not be described by an incomplete inflationary phase connected to a separate, more exotic prehistory. Recent results show that, within non-static FRW cosmology, only positive spatial curvature permits a nonsingular, geodesically complete universe with ANEC-respecting matter. We construct a geodesically complete closed $k=+1$ bounce-plus-inflation cosmology in ordinary general relativity, sourced by a single canonical scalar field with a positive vacuum offset. The bounce is supported by curvature rather than exotic stress energy: the matter content satisfies the NEC throughout and violates only the strong energy condition, as in any accelerated expansion. The solved branch remains sub-Planckian and evolves onto a curvature-diluted slow-roll phase with inflationary observables consistent with current constraints. The pivot-scale predictions are $n_s=0.9617$, $r=0.0045$ at $N_*=55$ and $n_s=0.9650$, $r=0.0037$ at $N_*=60$. Direct evolution of closed-universe infrared perturbations shows regular tensor and scalar propagation through the bounce and inflationary era, with the physical curvature perturbation freezing in the standard way. This gives a minimal explicit realization of a complete early-universe cosmology in the closed FRW branch selected by completeness and ANEC compatibility.
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Astrophysics of Galaxies

Galaxy Zoo Bar Lengths: A Catalogue of Measurements from Hubble Space Telescope Images and the Evolution of Galactic Bar Structure at z < 1

Tenley Hutchinson-Smith, Brooke D. Simmons, Karen L. Masters et al. (+12 more)

Understanding the role of galactic scale bars in disk galaxy evolution requires detailed measurements of bar properties across galaxies hosting bars at many redshifts. We present measurements of bar lengths and widths in a sample of 8230 disk galaxies from Hubble Space Telescope (HST) Legacy surveys. The highest-redshift barred galaxies in the sample have $z \sim 3$; most have $z \leq 1$. Using a mass-complete sample from the COSMOS field, we examine bar properties and evolution within $0.25 < z < 1$ in galaxies with stellar mass $\log(M_{\ast}/M_{\odot}) \geq 9.5$. The lowest-mass galaxies in our sample have similar star formation rate (SFR) distributions whether or not they host bars. For galaxies with $\log(M_{\ast}/M_{\odot}) \geq 10$, barred galaxies are more likely to be quiescent or quenched, consistent with bars mainly participating in slow quenching processes. The median physical bar length increases with increasing stellar mass. Relative bar lengths and widths (as a fraction of disk radius) peak at stellar mass $\log(M_{\ast}/M_{\odot}) \sim 10.25$, and change together with mass such that the median ratio, a proxy for bar strength, does not significantly change with stellar mass. Bars in our sample tend to be slightly ($\approx 13$%) weaker at higher redshift. Quiescent and quenching galaxies have longer and wider bars than those in galaxies on or above the star-forming sequence, especially at lower redshift and higher masses; at the low-mass end of our sample, starburst galaxies host relatively longer and stronger bars. Our findings are consistent with other results from studies at both higher and lower redshift, cementing the fundamental importance of bars in disk galaxy evolution.
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All authors Tenley Hutchinson-Smith, Brooke D. Simmons, Karen L. Masters, Alison Coil, Izzy Garland, Tobias Géron, Sandor Kruk, Chris Lintott, Rebecca Smethurst, Amauri Tapia, Kyle Willett, Elisabeth Baeten, Sylvia Beer, Michael L. Peck, Julianne Wilcox

Solar and Stellar Astrophysics

Characterizing six seismic solar analogs observed by Kepler, K2, and HERMES

R. A. García, S. Mathur, G. T. Hookway et al. (+31 more)

Solar analogs, stars that closely match the fundamental properties of the Sun, provide key benchmarks for testing stellar structure and evolution across different ages and activity levels. Their detailed characterization helps place the Sun in context within the broader population of solar-like stars. This study presents the characterization of six seismic solar analogs observed by the NASA Kepler and K2 missions. Combining asteroseismic constraints from space-based photometry with high-resolution spectroscopy and Gaia astrometry, we derived their fundamental parameters and assessed their resemblance to the Sun. Global seismic properties and individual oscillation modes were extracted from the photometric light curves, while atmospheric parameters were obtained from data collected by the HERMES spectrograph at the Mercator telescope. Stellar modeling using seven independent stellar evolution codes yielded consistent masses, radii, and ages. These stars have masses between 0.91 and 1.04~$\mathrm{M}_\odot$, radii between 0.95 and 1.08~$\mathrm{R}_\odot$, and ages from about 1.8 to 9.1~Gyr, with typical systematic uncertainties of $\pm$ 0.02~$\mathrm{M}_\odot$, $\pm$ 0.01~$\mathrm{R}_\odot$, and $\pm$ 0.7~Gyr, respectively. One star, EPIC~206064678, exhibits properties very similar to those of the Sun, with $M = 1.016 \pm 0.033\,\mathrm{M}_\odot$, $R = 0.990 \pm 0.011\,\mathrm{R}_\odot$, and an age of $5.40 \pm 0.12$\,Gyr. It can therefore be considered a close solar twin, although it is slightly older and more metal-rich ($0.25 \pm 0.07$\,dex). Four targets display binarity signatures and all exhibit very low chromospheric activity. This work broadens the sample of well-characterized seismic solar analogs towards a larger sample of metallicities and ages, providing new references for comparative stellar studies and future asteroseismic investigations.
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All authors R. A. García, S. Mathur, G. T. Hookway, D. Godoy-Rivera, T. Masseron, J. Bétrisey, G. Buldgen, C. Lindsay, T. S. Metcalfe, O. J. Scutt, A. Stokholm, P. G. Beck, O. Benomar, G. R. Davies, A. Jiménez, J. Merc, M. B. Nielsen, E. Panetier, F. Pérez Hernández, L. Borg, S. N. Breton, L. Debacker, A. Escorza, D. H. Grossmann, A. Hamy, B. Liagre, M. N. Lund, S. Mathis, D.B. Palakkatharappil, A. R. G. Santos, V. Delsanti, L. González-Cuesta, V. Fox, N. Proust

High Energy Astrophysical Phenomena · Cross-listed from physics.flu-dyn

Compressible Navier-Stokes Flow in Schrödinger-Type Variables

James R. Beattie, Max Sokolova, Khush Negandhi et al. (+1 more)

Fluid equations are nonlinear, dissipative, and non-Hamiltonian, which makes their relation to Schrödinger evolution and quantum algorithms nontrivial. We derive an exact Eulerian Cole-Hopf-type reformulation of isothermal compressible Navier-Stokes (NS) flow in Schrödinger-type amplitude variables. To our knowledge, this gives the first exact Cole-Hopf-type Schrödinger-variable reformulation of compressible NS flow. In two dimensions, a Helmholtz decomposition separates the velocity into compressive and vortical potentials, whose logarithmic transforms yield two scalar imaginary-time Schrödinger-type equations with nonlinear self-consistent potentials. We show that the mixed density-compressive amplitude $\Psi_\alpha=\rho^\alpha\Theta^{1-2\alpha}$, where $\rho$ is the density, $\Theta$ is the compressive amplitude, and $\alpha\neq 0,\,1/2$, satisfies a nonlinear Schrödinger-type equation with a vector-potential-coupled Laplacian. The transformed system is exactly equivalent to compressible NS and is nonlocal only through Helmholtz and Poisson projections. In three dimensions, the density-carrying equation retains the same vector-potential-coupled structure, while the solenoidal sector admits a compressible analogue of Ohkitani's incompressible NS Cole-Hopf formulation. Unlike unitary hydrodynamic Schrödinger-flow representations, the present equations are imaginary-time heat or drift-diffusion equations with self-consistent potentials, but they remain an exact change of variables for compressible NS. A two-dimensional Kelvin-Helmholtz unstable shear-layer calculation verifies the transformed equations against a direct compressible NS simulation. The formulation exposes operator structures that may be useful for reduced flow descriptions, quantum algorithms for operator evolution, and quantum partial differential equation solvers.
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All authors James R. Beattie, Max Sokolova, Khush Negandhi, Bart Ripperda

Solar and Stellar Astrophysics

A high-resolution K-band spectral atlas of massive stars

V. M. Kalari and W. D. Vacca

A high-resolution ($\sim$45000), high signal-to-noise ($>$100) K-band spectral atlas of massive stars is presented. It includes 81 stars consisting of known optical standards, spanning spectral and luminosity subclasses from O2 to O9, and supergiant luminosity and spectral subclasses from O2-B1. The telluric-corrected reduced spectra are publicly available, and are discussed here.
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Astrophysics of Galaxies

Chaotic Molecular Gas in Five Dusty Star-forming Galaxies in the Spiderweb Protocluster at $z = 2.16$

Jaclyn B. Champagne, Helmut Dannerbauer, Jose Manuel Perez-Martinez et al. (+4 more)

Measuring the properties of cold molecular gas available for intense star formation in galaxy protoclusters at $z>2$ is a crucial step in understanding large scale structure formation. We present ALMA observations of CO(3$-$2) in five dusty star-forming galaxies within $\sim0.5-4$ cMpc of the core of the Spiderweb protocluster at $z=2.16$ to measure the molecular gas mass and kinematics in the most starbursting members of the protocluster. All five galaxies exhibit evidence for disturbed kinematics including non-Gaussian CO line profiles, irregular spatial morphology, and strong residuals when fitting the galaxies with a classical disk model. This could be indicative of an elevated merger rate in the outskirts of the mature Spiderweb protocluster, as all of the galaxies in our sample have multiple companions detected in H$\alpha$. Both the gas fractions and the gas depletion timescales of the galaxies are similar to field relations at cosmic noon, indicative of the fact that their prodigious star formation rates are compensated by similarly high gas masses. The most massive galaxies, as well as all of the galaxies identified as X-ray AGN in previous works, have gas fractions $<30$%, compared to the sample average of 49%, indicating declining availability of gas for star formation. Finally, we find that the gas fractions and specific star formation rates decline with distance from the Spiderweb Galaxy, supporting the reversal of the SFR density–radius relation in high-redshift protoclusters.
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All authors Jaclyn B. Champagne, Helmut Dannerbauer, Jose Manuel Perez-Martinez, Caitlin M. Casey, Shuowen Jin, Matthew Lehnert, Jorge A. Zavala

Astrophysics of Galaxies

SPYGLASS. VII-B. Tracing the Fragments of Massive Star Formation Using Low-Mass Associations

Ronan Kerr, Adam L. Kraus, Jonathan C. Tan et al. (+6 more)

New observations from the Gaia spacecraft have traced an emerging demographic of low-mass associations disconnected from larger associations or GMCs. The first of these associations were recently characterized, but the star-forming environments they trace remain unknown. Using new velocities and ages alongside literature catalogs, we uncover the origins of 16 low-mass associations ($M\lesssim100$ M$_{\odot}$, $\tau\lesssim50$ Myr) using dynamical traceback. We reveal that three groups of currently disparate populations share common formation sites, comprising the Leo, CaNMoS, and AquENS associations. Twelve of 16 associations have plausible connections to larger complexes, six of which form while moving outward from well-established multi-generational star-forming events that drive known or suspected bubbles. We find that feedback from the oldest co-spatial and co-moving relatives of these associations can explain the current morphologies of the Local and Orion-Eridanus Bubbles, along with the formation of related associations like Sco-Cen and Orion OB1. Most remaining populations show evidence for triggered star formation. In the Leo Association, high vertical velocities and a deceleration signature suggest that it formed out of an intermediate velocity cloud colliding with gas in Orion, which would make it the first known case of star formation in one of these clouds. The other newly defined associations show similar asymmetric velocity signatures, such as CaNMoS, which may trace bubble-driven acceleration or a cloud collision. We conclude that the lowest-mass young associations remain undiscovered, and that these populations may have a critical role revealing the small gas overdensities that trace the processes sculpting galactic star formation.
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All authors Ronan Kerr, Adam L. Kraus, Jonathan C. Tan, Julio Chanamé, Facundo Pérez Paolino, Joshua S. Speagle, Juan P. Farias, José G. Fernández-Trincado, Keith Hawkins

Astrophysics of Galaxies

Dwarf Galaxies Hosting Extreme Star-Forming Regions and (Variable) AGNs at Radio Wavelengths

John-Michael Eberhard and Amy E. Reines

We present a detailed study of radio-detected dwarf galaxies (with stellar masses less than 3 billion solar masses) to characterize extreme star formation and search for (variable) radio AGNs. Our sample comes from Reines et al. (2020) (arXiv:1909.04670), who used the Karl G. Jansky Very Large Array (VLA) with 0.25 arcsecond resolution to observe 111 dwarf galaxies with lower-resolution (5 arcsecond) detections in the Faint Images of the Radio Sky at Twenty Centimeters (FIRST) survey. While that work identified and focused on 13 compact radio AGN candidates in dwarf galaxies, here we focus on 16 compact radio sources consistent with star formation in dwarf galaxies. We find that these objects are dominated by thermal HII regions with ages less than 10 Myr, and the most extreme sources have ionizing luminosities requiring the equivalent of around 10,000 to 100,000 O-type stars. We also investigate the dwarf galaxies detected in FIRST but not detected in the high-resolution follow-up observations. Using the infrared-radio correlation parameter, we identify eight sources consistent with radio-excess AGNs. Five of these objects plus another 15 dwarf galaxies have no corresponding detections in the VLA Sky Survey (VLASS) indicating variability between the FIRST and VLASS observations. The FIRST radio luminosities of these sources are significantly higher than expected for supernova-related emission, suggesting the radio variability is likely associated with AGNs. Together, these results provide new context for the presence of compact star formation and massive black holes in dwarf galaxies, and highlight the utility of radio variability and multi-resolution data for identifying the dominant power sources in low-mass systems.
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Earth and Planetary Astrophysics

Searching for GEMS: Three warm Saturns and a super-Jupiter orbiting four early M-dwarfs

Pranav H. Premnath, Paul Robertson, Shubham Kanodia et al. (+33 more)

We report the confirmation and characterization of four transiting giant planets orbiting early-M dwarfs discovered by the Searching for Giant Exoplanets around M-dwarf Stars (GEMS) survey: TOI-7189 b, TOI-7265B b, TOI-7393 b, and TOI-7394B b. Joint modeling of TESS and ground-based photometry with precision radial velocities from the Habitable-zone Planet Finder and NEID spectrographs yields self-consistent orbital and physical parameters for all systems. The planets have short orbital periods ($P = 1.25-4.17$ days), masses spanning from $0.5\,M_{\rm J}$ to $2.1\,M_{\rm J}$, and radii comparable to Jupiter ($0.95\,R_{\rm J} < R_p < 1.02\,R_{\rm J}$). TOI-7189 b ($0.50\,M_{\rm J}$), TOI-7265B b ($0.71\,M_{\rm J}$), and TOI-7393 b ($0.61\,M_{\rm J}$) are Saturn-like in mass and density, whereas TOI-7394B b is a dense super-Jupiter ($2.10\,M_{\rm J}$, $\rho_p \approx 2.4$ g cm$^{-3}$) on a 1.25-day orbit. All hosts are early-M dwarfs with a narrow range of stellar properties, enabling a controlled comparison of giant-planet outcomes around low-mass stars. Three systems orbit super-solar metallicity stars, while TOI-7393 ($\mathrm{[Fe/H]} = -0.35 \pm 0.16$) is the most metal-poor GEMS host identified to date, and exhibits kinematics approaching the thin/thick-disk transition, suggestive of an older stellar population. Together, these systems reveal substantial diversity in the masses and bulk properties of short-period giant planets orbiting early-M dwarfs, demonstrating that markedly different planetary outcomes can arise around stars with otherwise similar fundamental properties.
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All authors Pranav H. Premnath, Paul Robertson, Shubham Kanodia, Caleb I. Cañas, Arvind F. Gupta, Michael Rodruck, Te Han, Henry A. Kobulnicky, Andrea S.J. Lin, Andrew Monson, Libby Allely, Cooper Bailey, Alexina Birkholz, Zack Beagle, Philip Choi, Nez Evans, Mark E. Everett, Anna Fong, S. Nick Justice, Ian Karfs, Sage Santomenna, Elsa Van Dyke, Arissa Williams, Chad F. Bender, William D. Cochran, Scott A. Diddams, Rachel B. Fernandes, Mark R. Giovinazzi, Samuel Halverson, Daniel M. Krolikowski, Suvrath Mahadevan, Michael W. McElwain, Joe P. Ninan, Arpita Roy, Gudmundur Stefansson, Jason T. Wright

High Energy Astrophysical Phenomena

Unveiling the dynamics of the ultra-fast outflow in IRAS 13224-3809 with X-ray spectroscopy

Pierpaolo Condò, Francesco Tombesi, Marco Laurenti et al. (+9 more)

IRAS 13224-3809 is one of the most intensively studied narrow-line Seyfert 1 galaxies, with a rich literature reporting diverse and sometimes contrasting interpretations of its complex X-ray spectra and variability. Notably, a fast and variable ultra-fast outflow (UFO) was discovered in this source, sparking debate over its nature and driving mechanisms. Motivated by these open questions, we present a systematic, time- and flux-resolved reanalysis of the full 2016 XMM-Newton (1.5 Ms) and NuSTAR (500 ks) datasets, employing careful background treatment and equal-count spectral selections. We uniformly apply three spectral models, including photo-ionized absorption, broad emission, and relativistic reflection, to all intervals. We unambiguously confirm the presence of a strong, variable outflow with velocities exceeding 0.2$c$, and find that models including absorption consistently reveal robust physical trends: a velocity-luminosity correlation of the UFO, persistently large line widths, and no compelling equivalent-width-flux anti-correlation. When emission or reflection components are included, the significance of the absorption features decreases, but significant UFO detections remain in most intervals. We also report clear evidence for rapid acceleration of the wind in response to X-ray flares, with the outflow carrying momentum and kinetic power sufficient to drive an efficient AGN feedback. The observed rapid response favors magnetic driving, analogous to coronal mass ejections, over radiative acceleration. Our results reconcile contrasting previous claims and underline the need for high-resolution spectroscopy to resolve the wind substructure. The observed UFO variability and structure are consistent with a multiphase, clumpy wind produced by thermal and hydrodynamic instabilities, with magnetic reconnection providing the rapid acceleration mechanism.
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All authors Pierpaolo Condò, Francesco Tombesi, Marco Laurenti, Alfredo Luminari, Riccardo Middei, Enrico Piconcelli, Massimo Gaspari, Giorgio Lanzuisi, Roberto Serafinelli, Alessia Tortosa, Luca Zappacosta, Fabrizio Nicastro

Astrophysics of Galaxies

Coupling between stellar and HI lopsidedness in Milky Way-type galaxies from the Auriga Superstars cosmological simulations

Arianna Dolfi, Facundo A. Gómez, Rebekka Bieri et al. (+5 more)

Lopsidedness is common in disk galaxies, yet its origin and evolution remain unclear. Previous studies typically examined stellar and gas asymmetries separately, but a combined analysis offers a stronger probe of the mechanisms driving lopsidedness, recent galaxy evolution, and environment. We analyze the density and kinematics of stellar and atomic hydrogen (HI) components in nine Milky Way type galaxies from the Auriga Superstars cosmological zoom-in simulations. The high stellar mass resolution improves the visibility of disk features while reducing noise, enabling a detailed study of dynamical processes in a cosmological context. Morphological and kinematical lopsidedness are quantified using the first Fourier mode (m=1) of the face-on mass distribution and radial velocity maps, measured consistently for stars and gas between 0.5 and 1 stellar optical radius. At z=0, morphological lopsidedness in old stars (>0.5Gyr) strongly correlates with HI, tracing distortions in the global gravitational potential. In contrast, young stars (<0.5Gyr) trace asymmetric star formation along spiral arms. Stellar morphological and kinematical lopsidedness are strongly correlated, whereas HI shows a weaker correlation, with kinematic asymmetries dominating. We also find an anti-correlation between stellar lopsidedness and bar strength. Strongly barred galaxies tend to host more symmetric disks and higher central stellar mass densities. Tracing lopsidedness evolution over time, tidal interactions with massive satellites (mass ratio >1:50) induce coherent lopsidedness in both stars and HI. In contrast, smooth gas accretion mainly affects HI and young stars, leaving the total stellar component largely symmetric. Overall, these results demonstrate that lopsidedness is a powerful diagnostic of internal disk evolution, gas accretion, and environmental interactions across cosmic time.
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All authors Arianna Dolfi, Facundo A. Gómez, Rebekka Bieri, Francesca Fragkoudi, Robert J. J. Grand, Antonela Monachesi, Ruediger Pakmor, Freeke van de Voort