Solar and Stellar Astrophysics
Evolutionary Map of the Universe: Detection of the Wolf-Rayet Star WR40
A. C. Bradley, Z. J. Smeaton, M. D. Filipovic et al. (+6 more)
We present a
radio-continuum detection of the well-known Wolf-Rayet
star WR40 at 943.5 MHz using observations from the EMU survey. We find that the shell surrounding WR40, known as RCW 58, has a flux density of 158.9+/-15.8 mJy and the
star itself is 0.41+/-0.04 mJy. The shell size is found to be 9' x 6', which matches well with the shell in Halpha and is similarly matched to the shell at 22 um in infrared. Using
Gaia data, we derive a linear size of 7.32(+/-0.34) x 4.89(+/-0.23) pc at a distance of 2.79+/-0.13 kpc. We use previous ATCA observations at 8.64, 4.80, and 2.4 GHz to determine a spectral index of WR40, which is estimated to be alpha = 0.80+/-0.11, indicating that the emission from the
star is thermal.
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All authors A. C. Bradley, Z. J. Smeaton, M. D. Filipovic, N. F. H. Tothill, R. Z. E. Alsaberi, J. D. Collier, Y. A. Gordon, A. M. Hopkins, H. Zakir
Astrophysics of Galaxies
A Mid-Infrared Spectroscopic Study of Young Stellar Objects in the SMC Region NGC 346: JWST Detects Dust, Accretion, Ices and Outflows
Nolan Habel, Omnarayani Nayak, Patrick J. Kavanagh et al. (+13 more)
We present mid-infrared spectroscopic observations of intermediate- to high-mass young
stellar objects (YSOs) in the low-
metallicity star-forming region NGC 346 located within the Small Magellanic Cloud (SMC). We conduct these integral-field-unit observations with the Mid-Infrared Instrument Medium Resolution Spectroscopy instrument on board JWST. The brightest and most active
star-forming region in the SMC, NGC 346 has a
metallicity of $\sim$1/5 $Z_{\odot}$, analogous to the era when
star formation in the early Universe ($z$$\simeq$2) peaked. We discuss the emission and absorption features present in the spectral energy distributions (SEDs) of five YSOs with coverage from 4.9-27.9$\mu$m and three other sources with partial spectral coverage. Via SED model-fitting, we estimate their parameters, finding masses ranging from 2.9-18.0 M$_{\odot}$. These targets show dusty silicates, polycyclic aromatic hydrocarbons and ices of CO$_2$, CO, H$_2$O and CH$_3$OH in their protostellar envelopes. We measure emission from H$_2$ and atomic fine-structure lines, suggesting the presence of protostellar jets and
outflows. We detect H I lines indicating ongoing
accretion and estimate
accretion rates for each source which range from 2.50x10$^{-6}$-2.23x10$^{-4}$ M$_{\odot}$yr$^{-1}$ based on H I (7-6) line emission. We present evidence for a $\sim$30,000AU protostellar jet traced by fine-structure, H I and H$_2$ emission about the YSO Y535, the first detection of a resolved protostellar
outflow in the SMC, and the most distant yet detected.
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All authors Nolan Habel, Omnarayani Nayak, Patrick J. Kavanagh, Olivia C. Jones, Margaret Meixner, Guido De Marchi, Laura Lenkic, Alec S. Hirschauer, Katia Biazzo, Jeroen Jaspers, Conor Nally, Massimo Robberto, Ciaran Rogers, Elena Sabbi, Beth A. Sargent, Peter Zeidler
Astrophysics of Galaxies
Foreground Extinction to Extended Celestial Objects – I. New Extinction Maps
G.A.Gontcharov, A.A.Marchuk, S.S.Savchenko et al. (+5 more)
We present a new two-dimensional (2D) map of total
Galactic extinction, $A_\mathrm{V}$, across the entire
dust half-layer from the Sun to extragalactic space for
Galactic latitudes $|b|>13$ deg, as well as a three-dimensional (3D) map of $A_\mathrm{V}$ within 2~kpc of the Sun. These maps are based on $A_\mathrm{V}$ and distance estimates derived from a
dataset, which utilizes
Gaia Data Release 3 parallaxes and multi-band photometry for nearly 100 million
dwarf stars. We apply our own corrections to account for significant systematics in this
dataset. Our 2D map achieves an angular resolution of 6.1~arcmin, while the 3D map offers a transverse resolution of 3.56~pc – corresponding to variable angular resolution depending on distance – and a radial resolution of 50~pc. In constructing these maps, we pay particular
attention to the
solar neighborhood (within 200~pc) and to high
Galactic latitudes. The 3D map predicts $A_\mathrm{V}$ from the Sun to any extended object within the
Galactic dust layer with an accuracy of $\sigma(A_\mathrm{V}) = 0.1$~mag. The 2D map provides $A_\mathrm{V}$ estimates for the entire
dust half-layer up to extragalactic distances with an accuracy of $\sigma(A_\mathrm{V}) = 0.07$~mag. We provide $A_\mathrm{V}$ estimates from our maps for various classes of extended celestial objects with angular size primarily in the range of 2–40~arcmin, including 19,809
galaxies and
quasars, 170
Galactic globular clusters, 458 open clusters, and several hundreds molecular clouds from two lists. We also present extinction values for 8,293 Type Ia
supernovae. Comparison of our extinction estimates with those from previous maps and literature sources reveals systematic differences, indicating large-scale spatial variations in the extinction law and suggesting that earlier 2D reddening maps based on infrared
dust emission tend to underestimate low extinction values.
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All authors G.A.Gontcharov, A.A.Marchuk, S.S.Savchenko, A.V.Mosenkov, V.B.Il'in, D.M.Poliakov, A.A.Smirnov, H.Krayani
Earth and Planetary Astrophysics
Exploring Warm Jupiter Migration Pathways with Eccentricities II. Correlations with Host Star Properties and Orbital Separation
Marvin Morgan, Brendan P. Bowler and Quang H. Tran
Warm Jupiters with orbital periods of $\approx$10-365 d represent a population of
giant planets located well within the water ice line but beyond the region of
tidal influence of their host
star relevant for high-eccentricity
tidal migration. Orbital eccentricities offer important clues about the formation and dynamical history of warm Jupiters because in situ formation and disk migration should imprint near-circular orbits whereas
planet scattering should excite eccentricities. Based on uniform Keplerian fits of 18,587 RVs targeting 200 warm Jupiters, we use hierarchical
Bayesian modeling to evaluate the impact of host
star metallicity,
stellar mass, and orbital separation on the reconstructed population-level eccentricity distributions. Warm Jupiters take on a broad range of eccentricities, and their population-level eccentricities are well modeled using a Beta distribution with $\alpha$ = 1.00$^{+0.09}_{-0.08}$ and $\beta$ = 2.79$^{+0.28}_{-0.26}$. We find that 27$^{+3}_{-4}\%$ of warm Jupiters have eccentricities consistent with near-circular orbits ($e$ $<$ 0.1), suggesting that most warm Jupiters (73$^{+3}_{-3}\%$) detected are dynamically hot. Warm Jupiters orbiting metal-rich
stars are more eccentric than those orbiting metal-poor
stars – in agreement with earlier findings – but no differences are observed as a function of
stellar host mass or orbital separation, at least within the characteristic ranges probed by our sample ($\approx$0.5–2.0 $M_{\odot}$ and 0.1–1 AU, respectively). In this sense,
metallicity plays a larger role in shaping the underlying eccentricity distribution of warm Jupiters than
stellar mass or final orbital distance. These results are broadly consistent with
planet scattering playing a major role in shaping the orbital architectures of close-in
giant planets.
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Astrophysics of Galaxies
The origin of the galaxy size-stellar metallicity relation: A semi-analytical perspective
Kai Wang
Stellar metallicity encodes the integrated effects of gas inflow,
star formation, and feedback-driven
outflow, yet its connection to
galaxy structure remains poorly understood. Using SDSS-IV MaNGA, we present the direct observational evidence that, at fixed
stellar mass, smaller central
galaxies are systematically more metal-rich, with a Spearman's rank correlation coefficient reaching $R_{\rm s}\approx -0.4$. The semi-analytical model L-
GALAXIES reproduces this anti-correlation, albeit with a stronger amplitude ($R_{\rm s}\approx -0.8$). Within this framework, the trend cannot be explained by differences in gravitational potential depth or
star formation history. Instead, smaller
galaxies attain higher
stellar metallicities because their elevated
star formation efficiencies accelerate chemical enrichment, and, at fixed
stellar mass, they inhabit less massive
haloes, which makes their recycled inflows more metal-rich. The gas-regulator model demonstrates that
star formation efficiency affects
stellar metallicity when the system has not long remained in
equilibrium, which is shown to be the case for central
galaxies with $M_{\rm star}\lesssim 10^{10.5}\rm M_\odot$ in both L-
GALAXIES and observation. The model also suggests a testable signature that, at fixed
stellar mass, larger or lower-
metallicity galaxies should inhabit more massive
haloes than their smaller and higher-
metallicity counterparts, providing a direct and testable imprint of the
galaxy size-
stellar metallicity relation on the
galaxy-
halo connection.
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Earth and Planetary Astrophysics
Exploring Warm Jupiter Migration Pathways with Eccentricities. I. Catalog of Uniform Keplerian Fits to Radial Velocities of 200 Warm Jupiters
Marvin Morgan, Brendan P. Bowler, Quang H. Tran et al. (+4 more)
Giant planets are expected to predominantly form beyond the water ice line and occasionally undergo inward migration. Unlike hot Jupiters, which can result from high-eccentricity
tidal migration, warm Jupiters between 0.1-1 AU ($\approx$10–365 d) are in many ways more challenging to explain because they reside outside the
tidal influence of their host
stars. Warm Jupiters should therefore preserve traces of their origins as their eccentricities are directly related to their past interactions. We analyze the eccentricities of 200 warm Jupiters orbiting 194 Sun-like host
stars (with FGKM spectral types) using 18,587 RV measurements across 40 high-resolution spectrographs. RVs are compiled from the literature and are supplemented with 540 new observations from MINERVA-Australis at Mt. Kent Observatory and the Habitable-zone
Planet Finder spectrograph at McDonald Observatory's Hobby-Eberly
Telescope, which are timed to improve eccentricity constraints by sampling orbits near periastron passage. The overarching goal of this program is to establish the relative importance of
giant planet migration channels through the largest homogeneous analysis of warm Jupiter orbital properties to date. In particular, we evaluate and compare the impact of different system architectures and host
star characteristics on the population-level eccentricity distributions of warm Jupiters. Here, we present the target sample, observations, orbit fitting procedure, and parameter summary statistics of our survey. All orbit fit solutions, parameter posterior chains, and merged RV tables for each system are made publicly available.
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All authors Marvin Morgan, Brendan P. Bowler, Quang H. Tran, Robert A. Wittenmyer, Duncan J. Wright, George Zhou, Tyler R. Fairnington
Instrumentation and Methods for Astrophysics
Habitable World Discovery and Characterization: Coronagraph Concept of Operations and Data Post-Processing
Michael W. McElwain, Dimitri Mawet, Jean-Baptiste Ruffio et al. (+11 more)
The discovery and characterization of habitable worlds was the top scientific recommendation of the Astro2020 decadal survey and is a key objective of the Habitable Worlds Observatory. Biosignature identification drives exceedingly challenging observations, which require raw contrasts of roughly 10$^{-10}$ contrast and ultimately, 1$\sigma$ photometric precision of roughly 3$\times 10^{-12}$ contrast. Despite significant advances for the Nancy Grace Roman Space
Telescope's Coronagraph Instrument, technological gaps still exist in a wide range of technologies such as starlight suppression, deformable mirrors, wavefront control, low noise detectors, and high-contrast spectroscopy. Even with these new technologies matured, the Habitable Worlds Observatory must carefully obtain the observations and rely on post-processing of the data to achieve its science objectives. During the START and TAG efforts, a working group was convened to explore the Coronagraph Concept of Operations and Post Processing (COPP) in the context of the Habitable Worlds Observatory. This COPP working group evaluated coronagraphic concept of operations to enable different post processing approaches, such as reference differential imaging and angular differential imaging, polarization differential imaging, orbital differential imaging, coherent differential imaging, spectral processing, and point-spread function subtraction
algorithms that incorporate ancillary telemetry and data. Future integrated modeling simulations and testbed demonstrations are needed to determine the achievable post processing gains for each approach. We report a summary of this working group's activities and findings, as well as an outlook for maturation of these techniques and infusion into the Habitable Worlds Observatory technology portfolio.
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All authors Michael W. McElwain, Dimitri Mawet, Jean-Baptiste Ruffio, Roser Juanola Parramon, Kellen Lawson, Hervé Le Coroller, Christian Marois, Max Millar-Blanchaer, Bijan Nemati, Susan Redmond, Bin Ren, Laurent Pueyo, Christopher Stark, Scott Will
Earth and Planetary Astrophysics
Self-supervised diffusion model fine-tuning for costate initialization using Markov chain Monte Carlo
Jannik Graebner and Ryne Beeson
Global search and optimization of long-duration, low-thrust spacecraft trajectories with the indirect method is challenging due to a complex solution space and the difficulty of generating good initial guesses for the costate variables. This is particularly true in multibody environments. Given data that reveals a partial Pareto optimal front, it is desirable to find a flexible manner in which the Pareto front can be completed and fronts for related trajectory problems can be found. In this work we use conditional
diffusion models to represent the distribution of candidate optimal trajectory solutions. We then introduce into this framework the novel approach of using Markov Chain Monte Carlo
algorithms with self-supervised fine-tuning to achieve the aforementioned goals. Specifically, a random walk Metropolis
algorithm is employed to propose new data that can be used to fine-tune the
diffusion model using a reward-weighted training based on efficient evaluations of constraint violations and missions objective functions. The framework removes the need for separate focused and often tedious data generation phases. Numerical experiments are presented for two problems demonstrating the ability to improve sample quality and explicitly target Pareto optimality based on the theory of Markov chains. The first problem does so for a transfer in the Jupiter-Europa circular restricted three-body problem, where the MCMC approach completes a partial Pareto front. The second problem demonstrates how a dense and superior Pareto front can be generated by the MCMC self-supervised fine-tuning method for a Saturn-Titan transfer starting from the Jupiter-Europa case versus a separate dedicated global search.
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Astrophysics of Galaxies
WALLABY Pilot Survey: Characterizing Low Rotation Kinematically Modelled Galaxies
N. Deg, K. Spekkens, N. Arora et al. (+20 more)
Many of the tensions in cosmological models of the Universe lie in the low mass, low velocity regime. Probing this regime requires a statistically significant sample of
galaxies with well measured kinematics and robustly measured uncertainties. WALLABY, as a wide area, untargetted HI survey is well positioned to construct this sample. As a first step towards this goal we develop a framework for testing kinematic modelling codes in the low resolution, low $S/N$, low rotation velocity regime. We find that the WALLABY Kinematic Analysis Proto-Pipeline (WKAPP) is remarkably successful at modelling these
galaxies when compared to other
algorithms, but, even in idealized tests, there are a significant fraction of false positives found below inclinations of $\approx 40^{\circ}$. We further examine the 11 detections with rotation velocities below $50~\kms$ in the WALLABY pilot data releases. We find that those
galaxies with inclinations above $40^{\circ}$ lie within $1-2~\sigma$ of structural scaling relations that require reliable rotation velocity measurements, such as the baryonic Tully Fisher relation. Moreover, the subset that have consistent kinematic and photometric inclinations tend to lie nearer to the relations than those that have inconsistent inclination measures. This work both demonstrates the challenges faced in low-velocity kinematic modelling, and provides a framework for testing modelling codes as well as constructing a large sample of well measured low rotation models from untargetted surveys.
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All authors N. Deg, K. Spekkens, N. Arora, R. Dudley, H. White, A. Helias, J. English, T. O'Beirne, V. Kilborn, G. Ferrand, M. L. A. Richardson, B. Catinella, L. Cortese, H. Dénes, A. Elagali, B. -Q. For, K. Lee-Waddell, J. Rhee, L. Shao, A. X. Shen, L. Staveley-Smith, T. Westmeier, O. I. Wong
Astrophysics of Galaxies
Analysis of the plane of satellites around Milky Way- mass galaxies in the IllustrisTNG simulation
Xinghai Zhao, Guobao Tang, Paola Gonzalez et al. (+2 more)
It has been suggested that the Plane of Satellites (PoS) phenomenon may imply a tension with current $\Lambda$CDM cosmology since a Milky Way (MW)-like PoS is very rare in simulations. In this study, we analyze a large sample of satellite systems of MW-{ mass}
galaxies identified within the IllustrisTNG simulations. We analyze their spatial aspect ratio, orbital pole dispersion, Gini coefficient, radial distribution, and bulk satellite velocity relative to the host
galaxy. These are compared to properties of the observed Milky~Way PoS. We identified
galaxy samples in two virial mass ranges ($0.1 - 0.8 \times 10^{12} $ M$_\odot$ and $0.8 - 3.0 \times 10^{12}$ M$_\odot$). { We find for both mass ranges that only $\sim$ 1 percent of MW-like
galaxies contain a PoS similar to that of the MW. Nevertheless, these outliers occur naturally in $\Lambda$CDM cosmology. We analyze the formation, environment, and
evolution of the PoS for nine systems that are most MW-like in the TNG50 simulation. By using a new analysis of the local large scale structure surrounding the satellite systems, we suggest that a PoS can form from one or more of at least five different processes. Moreover, consistent with the SAGA DR3 results, we find that about 1/3 of the identified systems contain a recent infall of a LMC and/or a SMC like system. We find a tendency for about half of the satellites to have recently arrived at $z < 0.2$, indicating that a MW-like PoS is a recent and transient phenomenon.
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All authors Xinghai Zhao, Guobao Tang, Paola Gonzalez, Grant J. Mathews, Lara Arielle Phillips
Astrophysics of Galaxies
Impact of AGN and nuclear star formation on the ISM turbulence of galaxies: Insights from JWST/MIRI spectroscopy
Rogemar A. Riffel, Luis Colina, José Henrique Costa-Souza et al. (+31 more)
Active
galactic nuclei (AGN),
star formation (SF), and
galaxy interactions can drive
turbulence in the gas of the ISM, which in turn plays a role in the SF within
galaxies. The impact on molecular gas is of particular importance, as it serves as the primary fuel for SF. Our goal is to investigate the origin of
turbulence and the emission of molecular gas, as well as low- and intermediate-ionization gas, in the inner few kpc of both AGN hosts and SF
galaxies. We use JWST MIRI/MRS observations of a sample consisting of 54
galaxies at z<0.1. We present fluxes of the H2 S(5)6.9091, [Ar II]6.9853, [FeII]5.3403, and [Ar III]8.9914 lines, along with velocity dispersion from W80. For
galaxies with coronal emission, [Mg V]5.6098 is also included. Line ratios are compared to photoionization and shock models to explore the origin of the gas emission. AGNs exhibit broader emission lines than SFGs, with the largest velocity dispersions observed in
radio-strong (RS) AGNs. H2 gas is less turbulent compared to ionized gas, while coronal gas presents higher velocity dispersions. The W80 values for the ionized gas exhibits a decrease from the
nucleus out to radii of approximately 0.5–1 kpc, followed by an outward increase up to 2-3 kpc. In contrast, the H2 line widths generally display increasing profiles with distance from the center. Correlations W80 and line ratios such as H2 S(5)/[ArII] and [FeII]/[ArII] indicate that the most turbulent gas is associated with shocks, enhancing H2 and [FeII] emissions. We speculate that these shocked gas regions are produced by AGN
outflows and jet-cloud interactions in AGN-dominated sources, while in SFGs, they may be created by
stellar winds and mergers. This shock-induced gas heating may be an important mechanism of AGN (or
stellar) feedback, preventing the gas from cooling and forming new
stars.
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All authors Rogemar A. Riffel, Luis Colina, José Henrique Costa-Souza, Vincenzo Mainieri, Miguel Pereira Santaella, Oli L. Dors, Ismael García-Bernete, Almudena Alonso-Herrero, Anelise Audibert, Enrica Bellocchi, Andrew J. Bunker, Steph Campbell, Françoise Combes, Richard I. Davies, Tanio Díaz-Santos, Fergus R. Donnan, Federico Esposito, Santiago García-Burillo, Begoña García-Lorenzo, Omaira González Martín, Houda Haidar, Erin K. S. Hicks, Sebastian F. Hoenig, Masatoshi Imanishi, Alvaro Labiano, Enrique Lopez-Rodriguez, Christopher Packham, Cristina Ramos Almeida, Dimitra Rigopoulou, David Rosario, Gabriel Luan Souza-Oliveira, Montserrat Villar Martín, Oscar Veenema, Lulu Zhang
High Energy Astrophysical Phenomena · Cross-listed from gr-qc
Neural Post-Einsteinian Test of General Relativity with the Third Gravitational-Wave Transient Catalog
Yiqi Xie, Gautham Narayan and Nicolás Yunes
Gravitational waves (GWs) from compact binaries are excellent probes of
gravity in the strong- and dynamical-field regimes. We report a test of general relativity (GR) with the third GW Transient Catalog (GWTC-3) plus a few O4 events using the recently developed neural post-Einsteinian framework, both on individual events and at the population level through hierarchical modeling. We find no significant violation of GR and place a constraint that, for the first time, efficiently covers non-GR theories characterized by not only post-Newtonian deviations but also those beyond under the same theory-agnostic framework.
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Cosmology and Nongalactic Astrophysics
The anisotropic expansion rate of the local Universe and its covariant cosmographic interpretation
Basheer Kalbouneh, Christian Marinoni, Roy Maartens et al. (+5 more)
Without making any assumption on the underlying geometry and metric of the local Universe, we provide a measurement of the expansion rate fluctuation field using the Cosmicflows-4 and Pantheon+ samples in the
redshift range $0.01 < z < 0.1$ ($30 \,h^{-1}\,\mathrm{Mpc} < R < 300\,h^{-1}\,\mathrm{Mpc}$). The amplitude of the anisotropic fluctuations is found to be of order a few percent relative to the monopole of the expansion rate. We further decompose the expansion rate fluctuation field into spherical harmonic components and analyze their
evolution with
redshift across the studied
redshift range. At low
redshift, the dipole is clearly dominant, with an amplitude of $\sim (2.2 \pm 0.15)\times 10^{-2}$, significantly larger than the higher–order modes. As
redshift increases, the dipole amplitude steadily decreases, reaching roughly half its value in the highest
redshift bin investigated. The quadrupole is also significant, at about half the dipole amplitude, and persists across all
redshift bins, with no clear decreasing trend, although uncertainties grow at higher
redshift. A nonzero octupole is also detected at low
redshift. The dipole, quadrupole, and octupole components are found to be aligned, exhibiting axial
symmetry around a common axis ($l = 295^\circ,\, b = 5^\circ$). We interpret the observed fluctuations in the expansion rate within the framework of covariant cosmography. Our results indicate that the multipoles of the expansion rate fluctuation field are primarily driven by a strong quadrupole in the covariant Hubble parameter, together with dipole and octupole contributions from the covariant deceleration parameter. These few parameters suffice to reconstruct the luminosity distance with high precision out to $z \sim 0.1$, in a manner that is model–independent, non–perturbative, and free from assumptions about peculiar velocities.
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All authors Basheer Kalbouneh, Christian Marinoni, Roy Maartens, Julien Bel, Jessica Santiago, Chris Clarkson, Maharshi Sarma, Jean-Marc Virey
Solar and Stellar Astrophysics
A Kinematic History of Stellar Encounters with Beta Pictoris
Jose Luis Gragera-Más, Santiago Torres, Alexander James Mustill et al. (+1 more)
Beta Pictoris is an A-type
star hosting a complex planetary system with two massive gas
giants and a prominent debris disk. Variable absorption lines in its
stellar spectrum have been interpreted as signatures of exocomets (comet-like bodies transiting the
star).
Stellar flybys can gravitationally perturb objects in the outer comet reservoir, altering their orbits and potentially injecting them into the inner system, thereby triggering exocomet showers. We aim to assess the contribution of
stellar flybys to the observed exocomet activity by reconstructing the
stellar encounter history of beta Pictoris in the past and future. We used
Gaia DR3 data, supplemented with radial velocities from complementary spectroscopic surveys, to compile a catalogue of
stars currently within 80 pc of beta Pictoris. Their orbits were integrated backward and forward in time in an axisymmetric
Galactic potential (Gala package) to identify encounters within 2 pc of the system. We identified 99 416
stars within 80 pc of beta Pictoris at present with resolved kinematics. Among these, 49
stars (including the eight components of five binaries) encounter beta Pictoris within 2 pc between -1.5 Myr and +2 Myr. For four of the binaries, the centre-of-mass trajectories also pass within 2 pc. We estimate the sample to be more than 60 % complete within 0.5 Myr of the present. Despite beta Pictoris being the eponym of its famous moving group, none of the identified encounters involved its moving group members; all are unrelated field
stars. We find no encounter capable of shaping observed disc structures, although
stellar flybys may contribute to the long-term
evolution of a potential Oort Cloud. Our catalogue constitutes the most complete reconstruction of the beta Pictoris encounter history to date and provides a robust foundation for future dynamical simulations.
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All authors Jose Luis Gragera-Más, Santiago Torres, Alexander James Mustill, Eva Villaver
Earth and Planetary Astrophysics
Detection of an NH$_3$ absorption band at 2.2 $\mu$m on Europa
A. Emran
The presence of NH$_3$-bearing components on icy planetary bodies has important implications for their geology and potential habitability. Here, I report the detection of a characteristic NH$_3$ absorption feature at 2.20 $\pm$ 0.02 $\mu$m on Europa, identified in an observation from the Galileo Near Infrared Mapping Spectrometer. Spectral modeling and band position indicate that NH$_3$-hydrate and NH$_4$-chloride are the most plausible candidates. Spatial correlation between detected ammonia signatures and Europa's microchaos, linear, and band geologic units suggests emplacement from the underground or shallow subsurface. I posit that NH$_3$-bearing materials were transported to the surface via effusive cryovolcanism or similar mechanisms during Europa's recent geological past. The presence of ammoniated compounds implies a thinner ice shell (Spohn & Schubert, 2003) and a thicker, chemically reduced, high-pH subsurface ocean on Europa (Hand et al. 2009). With the detection of NH$_3$-bearing components, this study presents the first evidence of a nitrogen-bearing species on Europa – an observation of astrobiological significance given nitrogen's essential role in the chemistry of life.
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Cosmology and Nongalactic Astrophysics
Reheating with Thermal Dissipation and Primordial Gravitational Waves
Kazuma Minami, Kyohei Mukaida and Kazunori Nakayama
In order for an inflationary universe to evolve into a hot universe, a process known as reheating is required. However, the precise mechanism of reheating remains unknown. We show that if the reheating is triggered by thermal dissipation effects, distinctive features appear in the spectrum of
primordial gravitational waves. This suggests a possible way to observationally probe the physics of reheating.
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Instrumentation and Methods for Astrophysics
Optical Design Pathways to Fluidic Space-Assembled Reflectors & Dual-Configuration Spectrographs for Characterizing Exo-Earths
Enrico Biancalani, Edward Balaban, Ruslan Belikov et al. (+14 more)
$\textbf{Fluidic Telescopes}$ | We present a conceptual framework for optically designing space-assembled
telescopes whose primary mirror is formed $\textit{in situ}$ via the enabling, scale-invariant technology of fluidic shaping. In-space assembly of optical reflectors can solve light-gathering aperture scaling, which currently limits space-borne optical
telescopes. Our compass reduces the top-level optical design trade to three types of avenues—a fluidic pathway, a legacy one building upon the James Webb Space
Telescope, and hybrid solutions—with a focus on exo-Earths. A primarily fluidic pathway leads, in the first place, to a post-
prime-focus architecture. We apply this configuration to propose the tentative optical design for a ~1-m technology demonstrator and pathfinder for fluidic-
telescope apertures scaling up to many tens of meters in diameter. $\textbf{Dual-Configuration Spectrographs}$ | The Habitable Worlds Observatory (HWO) will be the first mission equipped for the high-contrast direct imaging and remote spectral characterization, in reflected starlight, of exo-Earths in our
galactic neighborhood. We present a novel concept for a compact, dual-configuration HWO spectrograph tailored for a broad wavelength range covering at least 600–1000 nm. Our design can interchange dispersive elements via a slider mechanism while preserving the rest of the optical path, enabling both a spectral resolving power $R$~140 integral-field spectrograph and a single- or multi-object spectrograph with $R$ on the order of 10$^3$. Although $R$~140 is near-optimal for the $O_2$ absorption $A$-band around 760 nm, higher values of $R$ can be utilized with spectral cross-correlation matched-filter techniques to enhance, e.g., HWO's atmospheric characterization capabilities.
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All authors Enrico Biancalani, Edward Balaban, Ruslan Belikov, Eduardo Bendek, Valeri Frumkin, Israel Gabay, Guangjun Gao, Qian Gong, Christine Gregg, Tyler Groff, Joseph Howard, Omer Luria, Michael McElwain, Lee Mundy, Rachel Ticknor, Sylvain Veilleux, Neil Zimmerman
Astrophysics of Galaxies
Unveiling Dynamics and Variability in Open Clusters: Insights from a Comprehensive Analysis of Six Galactic Clusters
Kuldeep Belwal, D. Bisht, Ing-Guey Jiang et al. (+6 more)
We present a kinematic and dynamical analysis of six
Galactic open clusters NGC~2204, NGC~2660, NGC~2262, Czernik~32, Pismis~18, and NGC~2437, using
Gaia~DR3. We used
Bayesian and Gaussian Mixture Model (GMM) methods to identify cluster members, but chose GMM because it's more appropriate for low-mass
stars. Estimated distances range from 1.76 to 4.20~kpc and ages from 0.199 to 1.95~Gyr, confirming their intermediate-age nature. King model fits indicate compact morphologies, with core radii of 1–10~arcmin and cluster radii of 5–24~arcmin. We identify 13 BSS and 3 YSS members, whose central concentrations suggest origins via mass transfer or
stellar collisions. The mass function slopes (0.96–1.19) are flatter than the Salpeter value, which indicates that these clusters have undergone dynamical mass segregation. Orbit integration within a
Galactic potential indicates nearly circular orbits (eccentricities 0.02–0.10), vertical excursions within $\pm$132~pc, and guiding radii near the
solar circle, suggesting disk confinement. These clusters likely formed in the thin disk and are shaped by
Galactic tidal perturbations, facilitating the rapid loss of low-mass members. Additionally, twelve variable
stars were found across four clusters using TESS light curves, including $\gamma$~Doradus and SPB pulsators, eclipsing binaries, and a yellow straggler candidate. Periods were derived via Lomb-Scargle analysis. Two eclipsing binaries (TIC~94229743 and TIC~318170024) were modeled using PHOEBE, yielding mass ratios of 1.37 and 2.16, respectively. Our findings demonstrate that integrating orbital dynamics and variable
star studies presents valuable insights into the evolutionary pathways of open clusters.
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All authors Kuldeep Belwal, D. Bisht, Ing-Guey Jiang, R. K. S. Yadav, Ashish Raj, Geeta Rangwal, Arvind K. Dattatrey, Mohit Singh Bisht, Alok Durgapal
Instrumentation and Methods for Astrophysics
TES Bolometer Design and Testing for the Tomographic Ionized-carbon Mapping Experiment Millimeter Array
Victoria L. Butler, James J. Bock, Dongwoo T. Chung et al. (+7 more)
Transition Edge Sensor (TES) bolometers are a well-established technology with a strong track record in experimental cosmology, making them ideal for current and future
radio astronomy instruments. The Tomographic Ionized-carbon Mapping Experiment (TIME), in collaboration with JPL, has developed advanced silicon nitride leg isolated superconducting titanium detectors for 200 to 300 GHz observations of the Epoch of Reionization. Compared to their MHz counterparts, bolometers operating in this frequency range are less common because of their large absorber size and fragility. TIME aims to fabricate a total of 1920 high frequency (HF) and low frequency (LF) detectors to fully populate the focal plane. TIME has successfully developed HF (230 to 325 GHz) and LF (183 to 230 GHz) wafers that are physically robust and perform well at cryogenic temperatures (300 mK). Recent laboratory tests have shown high optical efficiencies for the LF wafers (30 to 40%), but low device yield for the HFs. To address this, new HF modules have been designed with improved cabling and a reduced backshort distance, and are expected to perform similarly to LFs in a similar lab setting. We report on the development of these detectors as well as recent laboratory and on sky tests conducted at the Arizona
Radio Observatory's (ARO) 12 meter prototype
antenna at Kitt Peak National Observatory.
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All authors Victoria L. Butler, James J. Bock, Dongwoo T. Chung, Abigail T. Crites, King Lau, Ian Lowe, Dan P. Marrone, Evan C. Mayer, Benjamin J. Vaughan, Michael Zemcov
Cosmology and Nongalactic Astrophysics
4MOST Cosmology Redshift Survey (CRS): Clustering Properties of CRS Bright Galaxy and Luminous Red Galaxy Target Catalogues
Behnood Bandi, Antoine Rocher, Aurélien Verdier et al. (+6 more)
The 4-metre Multi-Object Spectroscopic
Telescope Cosmology
Redshift Survey (4MOST CRS) will obtain 5.4 million spectroscopic
redshifts over ~5700 deg^2 to map large-scale structure and enable measurements of
baryon acoustic oscillations, growth rates via
redshift-space distortions, and cross-correlations with weak-
lensing surveys. We validate the target selections, photometry, masking, systematics, and
redshift distributions of the bright
galaxy (BG) and luminous red
galaxy (LRG) target catalogues selected from the Dark Energy Spectroscopic Instrument (DESI) Legacy Survey DR10.1 (LS) imaging. We measure the angular two-point correlation function, $w(\theta)$, test masking strategies, and recover
redshift distributions via cross-correlation with DESI DR1 spectroscopy. For BGs, we adopt LS MASKBITS that veto bright
stars and extended sources; for LRGs, we pair these with unblurred coadds of the WISE imaging (unWISE) W1 artefact masks. These choices suppress small-scale excess power without imprinting large-scale modes. A Limber-scaling test across BG $r$-band magnitude slices shows that, after applying the scaling, the $w(\theta)$ curves collapse to a near-common power law, demonstrating photometric uniformity with depth and consistency between the North and South
Galactic Caps. Cross-correlations with DESI spectroscopy recover the expected N(z), albeit with high shot noise at the brightest magnitudes. For LRGs, angular clustering in photo-$z$ slices ($0.4\le z<1.0$) is consistent between the Dark Energy Camera Legacy Survey (DECaLS) and Dark Energy Survey (DES) footprints and is well described by an approximate power law once photo-$z$ smearing is included;
halo-occupation fits are consistent with recent LRG studies. Together, these tests indicate that the masks and target selections yield reliable clustering statistics, supporting precision large-scale structure analyses with 4MOST CRS.
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All authors Behnood Bandi, Antoine Rocher, Aurélien Verdier, Jon Loveday, Zhuo Chen, Johan Richard, Jean-Paul Kneib, Tom Shanks, Michael J. I. Brown
Astrophysics of Galaxies
Modeling Emission-Line Surface Brightness in a Multiphase Galactic Wind: An O VI Case Study
Zirui Chen, Zixuan Peng, Kate H. R. Rubin et al. (+6 more)
We present a fast and robust analytic framework for predicting surface brightness (SB) of emission lines in
galactic winds as a function of radius up to $\sim 100$ kpc out in the circum-
galactic medium. We model multiphase structure in
galactic winds by capturing emission from both the volume-filling hot phase (T $\sim 10^{6-7}$ K) and turbulent radiative mixing layers that host intermediate temperature gas at the boundaries of cold clouds (T $\sim 10^4$ K). Our multiphase framework makes significantly different predictions of emission signatures compared to traditional single-phase models and explains the paucity of OVI SB measurements in the literature. After accounting for ram pressure
equilibrium between the cold clouds and hot wind in supersonic
outflows, non-
equilibrium ionization effects, and energy budgets other than mechanical energy from core-collapse
supernovae, our OVI SB predictions qualitatively match observational results. Our framework provides constraints on the optimal
galactic wind properties that facilitate OVI emission observations, including
star formation rate surface density, hot phase mass loading factor, and thermalization efficiency factor. These constraints are consistent with existing observations and can help inform future target selections.
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All authors Zirui Chen, Zixuan Peng, Kate H. R. Rubin, Timothy M. Heckman, Matthew J. Hayes, Yakov Faerman, Crystal L. Martin, S. Peng Oh, Drummond B. Fielding
Astrophysics of Galaxies
Mapping the Stellar Kinematics in the Central 240 Parsecs of M87 with the James Webb Space Telescope
Refa M. Al-Amri, Jonelle L. Walsh, Emily R. Liepold et al. (+2 more)
The supermassive black hole (SMBH) in the
giant elliptical
galaxy M87 is one of the most well-studied in the local universe, but the
stellar- and gas-dynamical SMBH mass measurements disagree. As this
galaxy is a key anchor for the upper end of the SMBH mass$-$host
galaxy relations, we revisit the central $3''\times 3''$ ($\sim 240\times240$ pc) region of M87 with the Near Infrared Spectrograph (NIRSpec) integral field unit (IFU) on the James Webb Space
Telescope (JWST). We implement several improvements to the reduction pipeline and obtain high signal-to-noise spectra ($S/N \sim 150$) in single $0.''05 $ spaxels across much of the NIRSpec field of view. We measure the detailed shape of the
stellar line-of-sight velocity distribution, parameterized by Gauss-Hermite moments up to $h_8$, in $\sim 2800$ spatial bins, substantially improving upon the prior high angular resolution studies of the M87
stellar kinematics. The NIRSpec data reveal velocities with $V \sim \pm 45$ km s$^{-1}$, velocity dispersions that rise sharply to $\sim$$420$ km s$^{-1}$ at a projected radius of 0.$''$45 (36 pc), and a slight elevation in $h_4$ toward the
nucleus. We comprehensively test the robustness of the kinematics, including using multiple velocity template libraries and adopting different
polynomials to adjust the template spectra. We find that the NIRSpec
stellar kinematics seamlessly transition to recently measured large-scale
stellar kinematics from optical Keck
Cosmic Web Imager (KCWI) IFU data. These combined NIRSpec and KCWI kinematics provide continuous coverage from parsec to kiloparsec scales and will critically constrain future
stellar-dynamical models of M87.
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All authors Refa M. Al-Amri, Jonelle L. Walsh, Emily R. Liepold, Chung-Pei Ma, Jenny E. Greene
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
A Limit on the Total Lepton Number in the Universe from BBN and the CMB
Valerie Domcke, Miguel Escudero, Mario Fernandez Navarro et al. (+1 more)
At temperatures below the QCD phase transition, any substantial
lepton number in the Universe can only be present within the
neutrino sector. In this work, we systematically explore the impact of a non-vanishing
lepton number on Big Bang Nucleosynthesis (BBN) and the
Cosmic Microwave Background (CMB). Relying on our recently developed framework based on momentum averaged
quantum kinetic equations for the
neutrino density
matrix, we solve the full BBN reaction network to obtain the abundances of
primordial elements. We find that the maximal
primordial total
lepton number $L$ allowed by BBN and the CMB is $-0.12 \,(-0.10) \leq L \leq 0.13\,(0.12) $ for NH (IH), while specific
flavor directions can be even more constrained. This bound is complementary to the limits obtained from avoiding
baryon overproduction through sphaleron processes at the electroweak phase transition since, although numerically weaker, it applies at lower temperatures and is obtained completely independently. We publicly release the C++ code COFLASY-C on GitHub which solves for the
evolution of the
neutrino quantum kinetic equations numerically.
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All authors Valerie Domcke, Miguel Escudero, Mario Fernandez Navarro, Stefan Sandner
Earth and Planetary Astrophysics
DIPSY: A new Disc Instability Population SYnthesis, II. The Populations of Companions Formed Through Disc Instability
O. Schib, C. Mordasini, A. Emsenhuber et al. (+1 more)
We applied the global end-to-end model described in Paper~I of this series to perform a population synthesis of companions formed via disc instability (DI). By using initial conditions compatible with both observations and hydrodynamical simulations, and by studying a large range of primary masses (0.05-5 Msol), we can provide quantitative predictions of the outcome of DI. In the baseline population, we find that ~10 % of the discs fragment, and about half of these end up with a surviving companion after 100 Myr. 75% of the companions are in the brown
dwarf regime, 15 % are low-mass
stars, and 10 %
planets. At distances larger than ~100 au, DI produces planetary-mass companions on a low percent level. Inside of 100 AU, however, planetary-mass companions are very rare (low per mill level). The average companion mass is ~30 Mj scaling weakly with
stellar mass. Most of the initial fragments do not survive on a Myr timescale; they either collide with other fragments or are ejected, resulting in a population of free-floating objects (about 1-2 per
star). We also quantify several variant populations to critically assess some of our assumptions used in the baseline population. DI appears to be a key mechanism in the formation of distant companions with masses ranging from low-mass
stars down to the planetary regime, contributing, however, only marginally to planetary mass objects inside of 100 AU. Our results are sensitive to a number of physical processes, which are not completely understood. Two of them, gas
accretion and clump-clump collisions, are particularly important and need to be investigated further.
Magnetic fields and heavy-element
accretion have not been considered in our study, although they are also expected to affect the inferred population. We suggest acknowledging the importance of the gravito-turbulent phase, which most protoplanetary discs experience.
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All authors O. Schib, C. Mordasini, A. Emsenhuber, R. Helled
Earth and Planetary Astrophysics
DIPSY: A new Disc Instability Population SYnthesis, I. Modeling, evolution of individual systems, and tests
O. Schib, C. Mordasini, A. Emsenhuber et al. (+1 more)
Disc instability (DI) is a model aimed at explaining the formation of companions through the fragmentation of the circumstellar gas disc. Furthermore, DI could explain the formation of part of the observed exoplanetary population. We aim to provide a new comprehensive global model for the formation of companions via DI. The latter leads for the companions to orbital migration and damping of the eccentricities and inclinations. As it evolves, the disc is continuously monitored for self-
gravity and fragmentation. When the conditions are satisfied, one (or several) clumps are inserted. The
evolution of the clumps is then followed in detail. We showcased the model by performing a number of simulations for various initial conditions, from simple non-fragmenting systems to complex systems with many fragments. We confirm that the DIPSY model is a comprehensive and versatile global model of companion formation via DI. It enables studies of the formation of companions with planetary to low
stellar masses around primaries with final masses that range from the brown
dwarf to the B-
star regime. We conclude that it is necessary to consider the many interconnected processes such as gas
accretion, orbital migration, and N-body interactions, as they strongly influence the inferred population of forming objects. It is also clear that model assumptions play a key role in the determination of the systems undergoing formation.
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All authors O. Schib, C. Mordasini, A. Emsenhuber, R. Helled