Instrumentation and Methods for Astrophysics · Cross-listed from physics.ed-ph
gr-Orbit-Toolkit: A Python-Based Software for Simulating and Visualizing Relativistic Orbits
Milagros Delgado and Wladimir E. Banda-Barragán
Creating software dedicated to simulation is essential for teaching and research in Science, Technology, Engineering, and Mathematics (STEM). Physics lecturing can be more effective when digital twins are used to accompany theory classes. Research in physics has greatly benefited from the advent of modern, high-level programming
languages, which facilitate the implementation of user-friendly code. Here, we report our own Python-based software, the gr-orbit-toolkit, to simulate orbits in classical and general relativistic scenarios. First, we present the ordinary differential equations (ODEs) for classical and relativistic orbital accelerations. For the latter, we follow a post-Newtonian approach. Second, we describe our
algorithm, which numerically integrates these ODEs to simulate the orbits of small-sized objects orbiting around massive bodies by using Euler and Runge-Kutta methods. Then, we study a set of sample two-body models with either the Sun or a black hole in the center. Our simulations confirm that the orbital motions predicted by classical and relativistic ODEs drastically differ for bodies near the Schwarzschild radius of the central massive body. Classical mechanics explains the orbital motion of objects far away from a central massive body, but general relativity is required to study objects moving at close proximity to a massive body, where the gravitational field is strong. Our study on objects with different eccentricities confirms that our code captures relativistic orbital precession. Our convergence analysis shows the toolkit is numerically robust. Our gr-orbit-toolkit aims at facilitating teaching and research in general relativity, so a comprehensive user and developer guide is provided in the public code repository.
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Instrumentation and Methods for Astrophysics · Cross-listed from cs.LG
Classification of Transient Astronomical Object Light Curves Using LSTM Neural Networks
Guilherme Grancho D. Fernandes, Marco A. Barroca, Mateus dos Santos et al. (+1 more)
This study presents a bidirectional Long Short-Term
Memory (LSTM) neural network for classifying transient astronomical object light curves from the Photometric LSST Astronomical Time-series Classification Challenge (PLAsTiCC)
dataset. The original fourteen object classes were reorganized into five generalized categories (S-Like, Fast, Long, Periodic, and Non-Periodic) to address class imbalance. After preprocessing with padding, temporal rescaling, and flux normalization, a bidirectional LSTM network with masking layers was trained and evaluated on a test set of 19,920 objects. The model achieved strong performance for S-Like and Periodic classes, with ROC area under the curve (AUC) values of 0.95 and 0.99, and Precision-Recall AUC values of 0.98 and 0.89, respectively. However, performance was significantly lower for Fast and Long classes (ROC AUC of 0.68 for Long class), and the model exhibited difficulty distinguishing between Periodic and Non-Periodic objects. Evaluation on partial light curve data (5, 10,and 20 days from detection) revealed substantial performance degradation, with increased misclassification toward the S-Like class. These findings indicate that class imbalance and limited temporal information are primary limitations, suggesting that class balancing strategies and preprocessing techniques focusing on detection moments could improve performance.
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All authors Guilherme Grancho D. Fernandes, Marco A. Barroca, Mateus dos Santos, Rafael S. Oliveira
Astrophysics of Galaxies
ALMAGAL V. Relations between the core populations and the parent clump physical properties
D. Elia, A. Coletta, S. Molinari et al. (+54 more)
Context. The fragmentation of massive molecular clumps into smaller, potentially
star-forming cores plays a key role in the processes of high-mass
star formation. The ALMAGAL project offers high-resolution data to investigate these processes across various evolutionary stages in the
Galactic plane. Aims. This study aims at correlating the fragmentation properties of massive clumps, obtained from ALMA observations, with their global physical parameters (e.g., mass, surface density, and temperature) and evolutionary indicators (such as luminosity-to-mass ratio and bolometric temperature) obtained from Herschel observations. It seeks to assess whether the cores evolve in number and mass in tandem with their host clumps, and to determine the possible factors influencing the formation of massive cores (M > 24M_\odot). Methods. We analyzed the masses of 6348 fragments, estimated from 1.4 mm continuum data for 1007 ALMAGAL clumps. Leveraging this unprecedentedly large data set, we evaluated statistical relationships between clump parameters, estimated over about 0.1 pc scales, and fragment properties, corresponding to scales of a few 1000 au, while accounting for potential biases related to distance and observational resolution. Our results were further compared with predictions from numerical simulations. Results. The fragmentation level correlates preferentially with clump surface density, supporting a scenario of density-driven fragmentation, whereas it does not show any clear dependence on total clump mass. Both the mass of the most massive core and the core formation efficiency show a broad range and increase on average by an order of magnitude in the intervals spanned by evolutionary indicators such as clump
dust temperature and the luminosity-to-mass ratio. This suggests that core growth continues throughout the clump
evolution, favoring clump-fed over core-fed theoretical scenarios.
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All authors D. Elia, A. Coletta, S. Molinari, E. Schisano, M. Benedettini, Á. Sánchez-Monge, A. Traficante, C. Mininni, A. Nucara, S. Pezzuto, P. Schilke, J. D. Soler, A. Avison, M. T. Beltrán, H. Beuther, S. Clarke, G. A. Fuller, R. S. Klessen, R. Kuiper, U. Lebreuilly, D. C. Lis, T. Möller, L. Moscadelli, A. J. Rigby, P. Sanhueza, F. van der Tak, Q. Zhang, K. L. J. Rygl, M. Merello, C. D. Battersby, P. T. P. Ho, P. D. Klaassen, P. M. Koch, J. Allande, L. Bronfman, F. Fontani, P. Hennebelle, B. Jones, T. Liu, G. Stroud, M. R. A. Wells, A. Ahmadi, C. L. Brogan, F. De Angelis, T. R. Hunter, K. G. Johnston, C. Y. Law, S. J. Liu, S.-Y. Liu, Y. Maruccia, V. -M. Pelkonen, Y.-N. Su, Y. Tang, L. Testi, S. Walch, T. Zhang, H. Zinnecker
Instrumentation and Methods for Astrophysics
Mock Observations for the CSST Mission: Main Surveys – the Mock Catalogue
Cheng-Liang Wei, Yu Luo, Hao Tian et al. (+17 more)
The Chinese Space Station Survey
Telescope (CSST) is a flagship space mission, designed to carry out a large-area sky survey to explore the nature of dark matter and dark energy in the Universe. The onboard multi-band imaging and slitless spectroscopic modules will enable us to obtain photometric data for billions of
galaxies and
stars, as well as hundreds of millions of spectroscopic measurements, advancing various scientific analyses such as
galaxy clustering and weak gravitational
lensing. To support the image simulations for the main survey of the CSST mission, we present a mock catalogue of
stars and
galaxies. For
stars, the mock catalogue is generated using either Galaxia or TRILEGAL, both of which provide a range of
stellar properties to meet the requirements of CSST image simulations. For
galaxies, we built a mock light-cone up to
redshift z~3.5 from the cosmological Nbody simulation and populated the mock
galaxy catalogue from the dark mater
haloes using a semi-analytical
galaxy formation model. We then performed a full-sky ray-tracing simulation of weak gravitational
lensing to obtain
lensing shear at the position of each
galaxy in the light-cone. To support both multi-band imaging and slitless spectroscopic simulations, we computed the spectral energy distribution (SED) for each
galaxy based on its
star formation history using a supervised deep-learning model and determined the magnitudes in each band using the CSST throughputs. Finally, the properties of our mock
galaxies include positions,
redshifts,
stellar masses, shapes, sizes, SEDs,
lensing shears and magnifications. We have validated our mock catalogue against observational data and theoretical models, with results showing good overall agreement. The catalogue provides a flexible
dataset for the development of CSST image processing and can support a wide range of cosmological analyses within the CSST mission.
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All authors Cheng-Liang Wei, Yu Luo, Hao Tian, Ming Li, Yi-Sheng Qiu, Guo-Liang Li, Yue-Dong Fang, Xin Zhang, De-Zi Liu, Nan Li, Ran Li, Huan-Yuan Shan, Lin Nie, Zizhao He, Lei Wang, Xi Kang, Dongwei Fan, Yang Chen, Xiaoting Fu, Chao Liu
Earth and Planetary Astrophysics
What's Inside Matters: The Effect of Oxygen Fugacity and Initial Volatile Abundance on the Atmospheres of the TRAPPIST-1 Planets
Junellie Perez, Laura K. Schaefer, Edward Schwieterman et al. (+3 more)
The TRAPPIST-1
planets have become
prime targets for studying the atmospheric and geophysical properties of
planets around M-
dwarf stars. To effectively identify their atmospheric composition, we first must understand their geological
evolution. For this study, we focus on enhancing an existing atmosphere-interior exchange model by incorporating additional geological processes relevant to rocky
planets. We have extended the model to include the carbon cycle, which enables the model to track four key gas species - CO$_2$, CO, H$_2$O, and H$_2$ - across four planetary reservoirs: the mantle, plate, ocean, and atmosphere. Major features added include surface temperature calculations which are crucial for the carbon cycle, oxygen fugacity as a planetary interior parameter in the model, and oxidation reactions and
diffusion-limited escape calculations to the atmosphere portion of the model. We successfully validated the model for Earth and applied this model to study the effect of oxygen fugacity and initial water abundance on TRAPPIST-1 d, e and f. Our results for present-day abundances show that oxygen fugacity significantly affects the partial pressures of H$_2$ and CO$_2$ for all three
planets with minor effects for CO on two of the
planets. We also found that H$_2$ is strongly dependent on water mass fraction (WMF). The addition of atmospheric processes produced a significant difference in the H$_2$ and CO abundances at present-day. These results highlight the importance of considering interior parameters to be able to further constrain the geological
evolution of these
planets and effectively put atmosphere observations into context.
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All authors Junellie Perez, Laura K. Schaefer, Edward Schwieterman, Kevin B. Stevenson, Howard Chen, Jacob Lustig-Yaeger
Astrophysics of Galaxies
The Impact of Supermassive Black Holes on Exoplanet Habitability. I. Spanning the Natural Mass Range
Jourdan Waas, Eric S. Perlman, Manasvi Lingam et al. (+5 more)
While the influence of supermassive black hole (SMBH) activity on habitability has garnered
attention, the specific effects of active
galactic nucleus (AGN) winds, particularly ultrafast
outflows (UFOs), on planetary atmospheres remain largely unexplored. This study aims to fill this gap by investigating the relationship between SMBH mass at the
galactic center and exoplanetary habitability, given that SMBH masses are empirically confirmed to span approximately 5 orders of magnitude in
galaxies. Through simplified models, we account for various results involving the relationships between the distance from the
planet to the central SMBH and the mass of the SMBH. Specifically, we show that increased SMBH mass leads to higher atmospheric heating and elevated temperatures, greater molecular thermal velocities, and enhanced mass loss, all of which diminish with distance from the
galactic center. Energy-driven winds consistently have a stronger impact than momentum-driven ones. Crucially, ozone depletion is shown to rise with SMBH mass and decrease with distance from the
galactic center, with nearly complete ozone loss ($\sim100\%$) occurring across
galactic scales for SMBH masses $\geq 10^8 M_\odot$ in the energy-driven case. This study emphasizes that SMBH growth over
cosmic time may have produced markedly different impacts on
galactic habitability, depending on both the mass of the central black hole (BH) and the location of planetary systems within their host
galaxies.
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All authors Jourdan Waas, Eric S. Perlman, Manasvi Lingam, Emily Lohmann, Jackson Kernan, Francesco Tombesi, Amedeo Balbi, Alessandra Ambrifi
Solar and Stellar Astrophysics
The Dawes Review 13: A New Look at The Dynamic Radio Sky
Tara Murphy and David L. Kaplan
Astronomical objects that change rapidly give us insight into extreme environments, allowing us to identify new phenomena, test fundamental physics, and probe the Universe on all scales. Transient and variable
radio sources range from the cosmological, such as gamma-ray bursts, to much more local events, such as massive
flares from
stars in our
Galactic neighbourhood. The capability to observe the sky repeatedly, over many frequencies and timescales, has allowed us to explore and understand dynamic phenomena in a way that has not been previously possible. In the past decade, there have been great strides forward as we prepared for the revolution in time domain
radio astronomy that is being enabled by the SKA Observatory
telescopes, the SKAO pathfinders and precursors, and other `next generation'
radio telescopes. Hence it is timely to review the current status of the field, and summarise the developments that have happened to get to our current point. This review focuses on image domain (or `slow') transients, on timescales of seconds to years. We discuss the physical mechanisms that cause
radio variability, and the classes of
radio transients that result. We then outline what an ideal image domain
radio transients survey would look like, and summarise the history of the field, from targeted observations to surveys with existing
radio telescopes. We discuss methods and approaches for transient discovery and classification, and identify some of the challenges in scaling up current methods for future
telescopes. Finally, we present our current understanding of the dynamic
radio sky, in terms of source populations and transient rates, and look at what we can expect from surveys on future
radio telescopes.
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Earth and Planetary Astrophysics
Historical Surveys to Rubin First Look: Absolute Colors of trans-Neptunian objects
Milagros Colazo and Alvaro Alvarez-Candal
We present a comprehensive photometric study of trans-Neptunian objects (TNOs) by combining data from SDSS, Col-OSSOS, DES, and the recent Rubin First Look (RFL) data. Our database comprises 43 677 measurements in the u, g, r, i, and z filters, from which we derived 2 193 phase curves for 781 unique objects. From these data, we computed 2 542 absolute color measurements for 633 objects, allowing a statistical characterization of phase coloring effects. Our results show correlations between colors at opposition and their variation with phase angle, indicating that redder (bluer) objects tend to become redder (bluer) as the phase angle increases. With a larger sample and the application of phase corrections, the colors show no strong bimodality nor correlation with orbital parameters. Notably, our
dataset includes the first photometric measurements from Rubin Observatory during RFL, covering eight objects: five newly discovered TNOs and three previously known. These early LSST observations occupy sparsely sampled regions of parameter space, particularly at faint magnitudes, highlighting the discovery and characterization potential of the full survey.
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Instrumentation and Methods for Astrophysics
Optimization of lenslet arrays for PRIMA Kinetic Inductance Detectors
Sumit Dahal, Thomas R. Stevenson, Nicholas P. Costen et al. (+10 more)
The PRobe far-Infrared Mission for Astrophysics (PRIMA) is a cryogenically cooled 1.8-m space
telescope designed to address fundamental questions about the
evolution of
galactic ecosystems, the origins of planetary atmospheres, and the buildup of
dust and metals over
cosmic time. PRIMA will achieve unprecedented sensitivity in the 24 - 261 $\mu$m wavelength range, enabled by background-limited kinetic inductance detectors (KIDs) cooled to 120 mK. For PRIMA's Far-InfraRed Enhanced Survey Spectrometer (FIRESS) instrument, we have developed monolithic kilopixel silicon lenslet arrays to efficiently couple incident radiation from the
telescope's fore-optics onto the KID absorber elements. These three-dimensional lenslet arrays are fabricated using grayscale lithography, followed by deep reactive ion etching (DRIE), and are anti-reflection (AR) coated with a quarter-wavelength thick deposition of Parylene-C. The lenslet arrays are aligned and bonded to the KID arrays using a thin layer of epoxy through a flip-chip bonder. In this work, we report on the optimized fabrication, lens design, AR coating, and bonding processes developed for the FIRESS lenslet arrays. We characterize brassboard lenslet arrays fabricated to meet the specifications of the FIRESS low and high spectral bands, demonstrate stepped-thickness AR-coatings to achieve high efficiency across broad wavelength ranges, and present spectral transmission measurements of the AR coating and the epoxy bonding layers.
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All authors Sumit Dahal, Thomas R. Stevenson, Nicholas P. Costen, Nat DeNigris, Jason Glenn, Gang Hu, Christine A. Jhabvala, Ricardo Morales-Sanchez, Jessica B. Patel, Manuel A. Quijada, Ian Schrock, Frederick H. Wang, Edward J. Wollack
Cosmology and Nongalactic Astrophysics
Jeans Model for the Shapes of Self-interacting Dark Matter Halos
Yilber Fabian Bautista, Andrew Robertson, Laura Sagunski et al. (+2 more)
The Jeans model is a semi-analytical approach to modeling self-interacting dark matter (SIDM) that works remarkably well to reproduce the spherically-averaged
halo profiles from observations and simulations of relaxed
galaxies and
galaxy clusters. However, SIDM
halos are not spherically symmetric in general since they respond to nonspherical
baryon distributions and retain nonsphericity from their initial collapse. In this work, we generalize the Jeans model to describe SIDM density profiles and
halo shapes beyond spherical
symmetry. Observational tests via
halo shapes are especially important for testing SIDM in massive
galaxies, $M_{\rm 200} \sim 10^{12} - 10^{13} \; \Msun$, where SIDM and collisionless dark matter
halos can have indistinguishable spherically-averaged profiles but distinct
halo shapes. We validate our model by comparing to cosmological simulations with
baryons for both SIDM with $\sigmam = 1 \cmg$ and collisionless cold dark matter. Our approach differs from previous work in this direction, taking into account the fact that multiple scatterings are required to impact the shape of the
halo, as well as being computationally inexpensive to implement. The nonspherical Jeans model can be used in conjunction with
halo shape observations (e.g., from gravitational
lensing or X-ray data) to directly constrain dark matter self-interactions.
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All authors Yilber Fabian Bautista, Andrew Robertson, Laura Sagunski, Adam Smith-Orlik, Sean Tulin
Earth and Planetary Astrophysics
Detectability of resolved hydrogen lines from the accretion shock at gas giants and their circumplanetary discs
Gabriel-Dominique Marleau, Thomas Henning, Roy van Boekel et al. (+3 more)
Fewer gas
giants have been caught in their
accretion phase than mature ones are known. Extremely Large
Telescope (ELT) instruments will have a higher sensitivity and a smaller inner working angle than tools up to now, which should increase search yields. We examine what METIS, the first-generation ELT spectrograph with R=1e5, can reveal about accreting gas
giants. We focus on the accessible hydrogen recombination lines, mainly Brackett alpha and Pfund-series lines. Our approach is general but we take PDS70b as a fiducial case. It is similar to WISPIT2b. To calculate high-resolution line profiles, we combine a semianalytical multi-D description of the flow onto an accreting
planet and its circumplanetary disc (CPD) with local non-LTE shock-emission models. We assume the limiting scenario of no extinction, appropriate for gas
giants in gaps, and negligible contribution from magnetospheric
accretion. We use simulated detector sensitivities to compute needed observing times. Both the
planet- and the CPD-surface shocks contribute to the line, which has a Gaussian core but wider, asymmetrical wings. The line is much narrower than the free-fall velocity, and in fact has a nearly constant FWHM=30–40 km/s at low densities. For our fiducial
accretion rate onto PDS70b, the Br-a line peak excess is as strong as the photospheric continuum, modulated mostly by H2O features. At Br-a, already the continuum of PDS 70 b yields a per-bin S/N=12 in 4h. With ProDiMo, we estimate the CPD not to hinder the detection of the line emission. The peak excess should require only 10 min to reach S/N=3. For pure shock emission, the line shape is barely sensitive to the planetary or system parameters. A complex profile would indicate that magnetospheric
accretion contributes significantly. The high spectral resolution of METIS will help reveal line shapes even of faint accretors with great fidelity.
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All authors Gabriel-Dominique Marleau, Thomas Henning, Roy van Boekel, Myriam Benisty, Yuhiko Aoyama, Inga Kamp
High Energy Astrophysical Phenomena
Hydrogen-Poor Superluminous Supernovae in the Nebular Phase: Spectral Diversity Due to Ejecta Ionization as a Probe of the Power Source
Peter K. Blanchard, Edo Berger, Sebastian Gomez et al. (+6 more)
We present a large sample of 39 nebular-phase optical spectra of 25 hydrogen-poor superluminous
supernovae (SLSNe-I) and jointly analyze them with previously published spectra of 12 events. We measure the properties of key emission features, namely those at 6300, 7300, and 7774 angstroms (associated with [O I], [Ca II]/[O II], and O I, respectively), and find that SLSNe exhibit much wider spectral diversity than normal SNe Ic, primarily in the line ratio $L_{7300}/L_{6300}$, which is highly sensitive to ejecta ionization. Some events exhibit weak [O I] and a clear [O II] contribution to the 7300 angstrom feature, enhancing the ratio, along with [O III] lines at 4363 and 5007 angstroms. Other SLSNe show weak or no lines of ionized oxygen. Moreover, we find that the population exhibits decreasing $L_{7300}/L_{6300}$ over time, while a few outliers instead display sustained high or increasing ratios for extended periods. The ratio $L_{7300}/L_{6300}$ is also correlated with the rise and decline times of the light curves, with slower events exhibiting higher ionization, the first robust connection between early light curve and late-time spectral properties, likely due to the magnetar's impact: slower-evolving SLSNe are generally powered by engines with longer
spin-down timescales, which deposit more energy at later phases. Among the events with decreasing $L_{7300}/L_{6300}$, SLSNe with high ionization are on average powered by magnetars with higher thermalized
spin-down power, a correlation that is most significant for events with $M_{\rm ej}\lesssim12$ M$_{\odot}$. The ionization in the outliers with increasing $L_{7300}/L_{6300}$ may be due to late CSM interaction. $L_{7300}/L_{6300}$ and its
evolution are therefore key diagnostics of SLSN engines and progenitor mass loss.
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All authors Peter K. Blanchard, Edo Berger, Sebastian Gomez, Matt Nicholl, Ryan Chornock, Harsh Kumar, Raffaella Margutti, Daichi Hiramatsu, Huei Sears
Earth and Planetary Astrophysics
Indirect forces in disc-planet interaction
Roman R. Rafikov, Nicolas P. Cimerman, Callum W. Fairbairn et al. (+1 more)
Gravitational coupling between a protoplanetary disc and an embedded
planet is often studied in a frame attached to a central
star. This frame is non-inertial because of the
stellar reflex motion, leading to indirect forces arising in the
star-
planet-disc system. Here we examine the impact produced by these forces on several aspects of disc-
planet coupling using analytical and numerical means. We explore how neglecting indirect forces changes (1) the spatial pattern of the surface density perturbation in the disc, (2) the calculation of the torque exerted on the disc by the
planet, and (3) the torque on the
planet exerted by the disc. For low-mass
planets, in the linear regime, the differences in the perturbation pattern are only in its $m=1$ azimuthal harmonic, with an amplitude increasing with the distance from the
star. In this regime both the torque on the
planet and the deposition torque density in the disc are only weakly affected by non-inclusion of indirect forces, corroborating some results of studies neglecting indirect forces altogether. For higher mass
planets, a broader range of azimuthal harmonics of the perturbation are affected. Also, indirect forces have a stronger effect on the planetary torque and on
planet migration in the Type II regime. We highlight the importance of including the planetary indirect force in the calculation of the torque on the disc (if disc
evolution accounts for indirect force) to ensure conservation of angular momentum carried by the
planet-driven density waves. The corresponding indirect torque has an oscillatory, radially-diverging character.
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All authors Roman R. Rafikov, Nicolas P. Cimerman, Callum W. Fairbairn, Alexander J. Dittmann
High Energy Astrophysical Phenomena
XSNAP: An X-ray Supernova Analysis Pipeline with Application to the Type II Supernova 2024ggi
Ferdinand, W. V. Jacobson-Galán, M. M. Kasliwal et al. (+1 more)
X-ray observations of Type II
supernovae (SNe II) probe the physics of
supernova (SN) shocks and the mass-loss histories of their progenitor
stars. We present multi-epoch, X-ray observations of SN II 2024ggi ($D \approx 7.2 \ \rm Mpc$) from ${\it Swift}$-XRT, ${\it Chandra}$ and ${\it XMM}$, which cover $\sim 1 - 344$ days since first light. We analyze these observations using a new open-source Python package called $\texttt{XSNAP}$, which standardizes a unified command-line interface for instrument-specific reduction and spectral extraction. $\texttt{XSNAP}$ introduces application programming interfaces for per-epoch spectral modeling through $\texttt{PyXspec}$ and $\texttt{emcee}$ Markov chain Monte Carlo fitting. We employ ${\tt XSNAP}$ to model the multi-epoch X-ray spectra of SN 2024ggi with an absorbed thermal bremsstrahlung model and calculate a steady progenitor mass-loss rate of $(6.2\pm0.2)\times10^{-5}\,M_{\odot}\,\mathrm{yr^{-1}}$ $(v_{\rm wind} = 20 \ \rm km \ s^{-1})$, for which the detected X-ray emission traces the final 117 years before explosion. The software is publicly available on GitHub, with a released package on the Python Package Index (PyPI).
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All authors Ferdinand, W. V. Jacobson-Galán, M. M. Kasliwal, Erez A. Zimmerman
Astrophysics of Galaxies
REBELS-IFU: Spatially Resolved Ionizing Photon Production Efficiencies of 12 Bright Galaxies in the Epoch of Reionization
Lena Komarova, Mauro Stefanon, Andres Laza-Ramos et al. (+15 more)
Measuring the ionizing
photon production efficiency $\xi_{\mathrm{ion,0}}$ – the ratio of ionizing
photon output rate $Q_{\rm H^0}$ to UV continuum luminosity $L_{\rm UV}$ – in
galaxies at $z > 6$ is crucial for constraining their contribution to
cosmic reionization. We present integrated and spatially resolved measurements of $\xi_{\mathrm{ion,0}}$ for 12 exceptionally bright ($M_\mathrm{UV} \sim -22$ mag)
star-forming
galaxies at $z \sim 7$ from the REBELS survey. These measurements are based on JWST NIRSpec/IFU PRISM spectroscopy, probing the rest-frame UV and optical regime. Notably, in 8 of the 12
galaxies, the spectral coverage includes H$\alpha$, enabling self-consistent
dust attenuation estimates in both the ionized gas and
stellar continuum via the Balmer decrement and rest-UV slope, respectively. We find global $\log\xi_{\mathrm{ion,0}}$ values ranging from $25.19\pm0.11$ to $25.61\pm0.11$, with a weighted mean of $25.44\pm0.15$, consistent with the canonical value of $\sim25.3$. Using a sample of 25
star-forming clumps within these
galaxies, we explore local variations in LyC production efficiency, finding a broader range, from $24.52\pm0.21$ to $26.18\pm0.61$. We identify strong correlations between $\xi_{\mathrm{ion,0}}$ and specific
star formation rate,
star formation surface density, H$\beta$ equivalent width, and
stellar mass. Clumps with the highest $\xi_{\mathrm{ion,0}}$ exhibit $\mathrm{EW}_0(\mathrm{H}\beta) \ge 150$ Angstrom, consistent with young
stellar ages. From previous Ly$\alpha$ measurements in three
galaxies, we estimate a typical Ly$\alpha$ escape fraction of $f_{\rm esc, Ly\alpha} \sim 2\%$, suggesting similar or lower escape fractions for LyC
photons. Combining this with our H$\alpha$ measurements, we infer ionized bubble sizes $\sim 1$ pMpc, aligned with expectations from Ly$\alpha$-detected systems and reionization models.
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All authors Lena Komarova, Mauro Stefanon, Andres Laza-Ramos, Hiddo S. Algera, Manuel Aravena, Rychard J. Bouwens, Rebecca Bowler, Elisabete da Cunha, Pratika Dayal, Andrea Ferrara, Rebecca Fisher, Themiya Nanayakkara, Lucie E. Rowland, Sander Schouws, Renske Smit, Laura Sommovigo, Daniel P. Stark, Paul van der Werf
Astrophysics of Galaxies
REBELS-IFU: Steeply rising star formation histories and the importance of dust obscuration in massive $z \simeq7$ galaxies revealed by multi-wavelength observations
R. Fisher, R. A. A. Bowler, R. K. Cochrane et al. (+15 more)
Reliable
star formation rate (SFR) measurements are essential for understanding early
galaxy evolution, yet derived values rely on several assumptions. To address this problem, we investigate the SFRs of 12 massive ($9~<~\log(M_{\star}/{\rm M}_{\odot})~<~10$) Lyman-break
galaxies at $z=6.5-7.7$, drawn from the Atacama Large Millimeter/submillimeter Array (ALMA) Reionization Era Bright Emission Line Survey (REBELS) program. The multi-wavelength data, including JWST NIRSpec IFU spectroscopy and ALMA observations, make this a unique sample for investigating SFR tracers at this epoch. We compare SFRs derived from the rest-UV, H$\alpha$, and far-infrared emission, and from spectral energy distribution (SED) fits. We apply robust
dust attenuation corrections, which are crucial since between $50-80$ per cent of the
star formation is obscured, and find a
stellar-to-nebular attenuation ratio of $f=0.50\pm0.08$, consistent with local
star-forming
galaxies. The majority of the derived total SFRs (medians $25-120$ ${\rm M}_{\odot}$ yr$^{-1}$) place the REBELS
galaxies systematically above $z=7$ literature
star-forming main-sequence relations, and our best-fit
star formation histories (SFHs) rise more steeply than lower-mass
galaxies at the same
redshift. We show that these rising SFHs mean commonly used luminosity-to-SFR conversion factors, derived assuming a constant SFH over given timescales, overestimate the SFRs averaged over these timescales for our
galaxies. We provide updated luminosity-to-SFR calibrations for $z\simeq7$
galaxies with rising SFHs, showing that commonly assumed rest-UV conversion factors overestimate the $100$ Myr average SFR by a factor of $\simeq3$. Finally, we investigate burstiness indicators in the REBELS-IFU
galaxies, finding that the rising SFHs imply that the H$\alpha$-to-UV luminosity ratio is an unreliable probe of bursty
star formation.
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All authors R. Fisher, R. A. A. Bowler, R. K. Cochrane, L. E. Rowland, M. Stefanon, H. S. B. Algera, M. Aravena, R. Bouwens, E. da Cunha, P. Dayal, A. Ferrara, J. A. Hodge, H. Inami, L. Komarova, R. Smit, L. Sommovigo, D. P. Stark, P. P. van der Werf
High Energy Astrophysical Phenomena
The Quiescent Merging Nature of the Coma Cluster Revealed by ICM Velocity Structure
E. Gatuzz, J. Sanders, A. Liu et al. (+4 more)
The hot gas permeating
galaxy clusters-the intracluster medium (ICM)-is a key tracer of their assembly history and internal dynamics. Understanding the motion of this gas provides critical insight into processes such as mergers,
turbulence, and energy dissipation in the largest gravitationally bound structures in the Universe. The Coma cluster is a nearby, massive system long suspected to be dynamically disturbed. Previous high-resolution X-ray spectroscopy with the XRISM mission revealed bulk motions in the cluster core and southern regions. Here we present new XRISM Resolve observations of a northern region in Coma, which reveal a coherent velocity gradient of nearly $530 km/s across the cluster from south to north. We find that the hot gas in this northern region exhibits modest line-of-sight motions and uniform thermodynamic properties, indicating relatively mild local disturbances. The consistent levels of
turbulence throughout the cluster suggest that the energy from a past merger has been distributed on large scales. These findings provide compelling evidence for an off-axis merger event and demonstrate how high-resolution X-ray spectroscopy can uncover subtle dynamical signatures in the ICM, offering important constraints for simulations of cluster
evolution.
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All authors E. Gatuzz, J. Sanders, A. Liu, A. Fabian, C. Pinto, D. Eckert, S. Walker
High Energy Astrophysical Phenomena
Hybrid Simulations of Supersonic Shear Flows: I) Particle Acceleration
Naixin Liang and Damiano Caprioli
Supersonic flows are ubiquitous in warm and cool media; their dissipation leads to heating, generation of nonthermal particles, and amplification of background
magnetic fields. We present 2D hybrid (kinetic ions - fluid electrons) simulations of decaying shear flows across the subsonic-to-supersonic transition, finding that the canonical Kelvin-Helmholtz instability in subsonic cases gives way to the formation of shocklets in supersonic shears, where dissipation is faster and nonthermal particles are produced. We discuss the dependence on the flow Mach number of particle acceleration, the viscosity induced by kinetic effects, and the production of
magnetic turbulence. We outline the potential impact of these findings for
turbulence in the warm interstellar medium, for molecular clouds, and for
accretion disks, leaving to a companion paper the discussion of the effects on the shear of self-generated and pre-existing energetic particles.
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Solar and Stellar Astrophysics
KOALA, a new ATLAS9 database – I. Model atmospheres, opacities, fluxes, bolometric corrections, magnitudes and colours
A. Mucciarelli, P. Bonifacio and C. Lardo
We present the KOALA database, a new set of LTE, line-blanketed model atmospheres calculated with the code ATLAS9, together with the corresponding Opacity Distribution Functions and emergent fluxes. The latter were used also to calculated G-band bolometric corrections and theoretical magnitudes and colours for several photometric systems, i.e. UBVRI, 2MASS, Hypparcos-Tycho, SDSS, Galex, Euclid and
Gaia DR3. With respect to the previous grids of ATLAS9 model atmospheres, we adopted the
solar mixture by Caffau/Lodders and we extend the sampling in
metallicity (from -5.0 to -2.5 dex with step of 0.5 dex, and from -2.5 dex to +0.5 dex with step of 0.25 dex) and in [alfa/Fe] (from -0.4 to +0.4 dex with a step of 0.2 dex). Also, we provide a finer sampling in Teff for Teff lower than 7000 K. This finer grid allows for more accurate interpolation of colours and in many cases it makes not necessary to compute a new model atmosphere, since one of the grid can be used directly. A total of 51663 model atmospheres and emergent fluxes have been computed. Finally, we discuss the impact of [M/H] and [alfa/Fe] on the thermal and pressure structures of the model atmospheres and on theoretical colours.
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High Energy Astrophysical Phenomena
Intra-night optical polarization monitoring of blazars
Aristeidis Polychronakis, Ioannis Liodakis, Anastasia Glykopoulou et al. (+20 more)
Blazars are known for their extreme variability across the electromagnetic spectrum. Variability at very short timescales can push the boundaries between competing models offering us much needed discriminating power. This is particularly true for polarization variability that allows us to probe particle acceleration and high-energy emission models in blazars. Here we present results from the first pilot study of intra-night optical polarization monitoring conducted using RoboPol at the Skinakas Observatory and supplemented by observations from the Calar Alto, Perkins, and Sierra Nevada observatories. Our results show that while variability patterns can widely vary between sources, variability on timescales as short as minutes is prevalent in blazar jets. The amplitude of variations are typically small, a few percent for the polarization degree and less than 20 degrees for the polarization angle, pointing to a significant contribution to the optical emission from a turbulent
magnetic field component, while the overall stability of the polarization angle over time points to a preferred
magnetic field orientation.
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All authors Aristeidis Polychronakis, Ioannis Liodakis, Anastasia Glykopoulou, Dmitry Blinov, Ivan Agudo, Svetlana G. Jorstad, Beatriz Agis-Gonzalez, Sara Capecchiacci, Alberto Floris, Sebastian Kielhmann, John A. Kypriotakis, Dimitrios A. Langis, Nikos Mandarakas, Karan Pal, Francisco J. Aceituno, Giacomo Bonnoli, Victor Casanova, Gabriel Emery, Juan Escudero Pedrosa, Jorge Otero-Santos, Daniel Morcuende, Alfredo Sota, Vilppu Piirola
Earth and Planetary Astrophysics
TESS Investigation – Demographics of Young Exoplanets (TI-DYE) IV: a Jovian radius planet orbiting a 34 Myr Sun-like star in the Vela association
Madyson G. Barber, Andrew W. Mann, Andrew Vanderburg et al. (+17 more)
The discovery of infant (< 50 Myr), close-in (<30-day period)
planets is vital in understanding the formation mechanisms that lead to the distribution of mature transiting
planets as discovered by Kepler. Despite several discoveries in this age bin, the sample is still too small for a robust statistical comparison to older
planets. Here we report the validation of TOI-6448 b, an 8.8 +/- 0.8 Re
planet on a 14.8 day orbit. TOI-6448 was previously identified to be a likely member of Vela Population IV. We confirm the
star's membership and re-derive the age of the cluster using isochrones, variability, and gyrochronology. We find the
star, and thus
planet, to be 34 +/- 3 Myr. Like other young
planets, TOI-6448 b lands in a region of parameter space with few older
planets. While just one data point, this fits with prior findings of an excess of 5-11Re
planets around young
stars far beyond what can be explained by reduced sensitivity at young ages. Our ongoing search of Vela, Taurus-Auriga, Sco-Cen, and Orion are expected to reveal dozens more < 50 Myr transiting
planets.
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All authors Madyson G. Barber, Andrew W. Mann, Andrew Vanderburg, Khalid Barkaoui, Karen A. Collins, Sebastian Carrazco-Gaxiola, Phil Evans, Matthew J. Fields, Michael Gillon, Todd J. Henry, Katharine M. Hesse, Wei-Chun Jao, Emmanuel Jehin, Sydney Jenkins, Tim Johns, David R. Rodriguez, Richard P. Schwarz, William C. Storch, Cristilyn N. Watkins, Francis P. Wilkin
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Keeping It Renormalizable: Minimal Baryogenesis induced Asymmetric Dark Matter
Miguel Escudero, Thomas Hambye and Chandan Hati
Many asymmetric dark matter scenarios have been proposed to date. Among them, perhaps the most motivated ones are those in which the dark matter asymmetry is induced from the
baryon/
lepton asymmetries via chemical equilibration without any new sources of CP violation. However, most of the models put forward along these lines have been excluded by now and/or are based on complicated setups. In this letter, we present a new, simple, and viable scenario. It assumes only two new fields: a scalar singlet and an inert scalar doublet, and is based only on renormalizable interactions, that slowly generate the dark matter asymmetry from the Standard Model
Higgs asymmetry. The model allows for the direct detection of dark matter in the upcoming generation of experiments, and the inert doublet is predicted to be light enough to be potentially produced and observed at the LHC and future
colliders, $m_{H'}<580\,{\rm GeV}$.
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Cosmology and Nongalactic Astrophysics
The signature of major mergers on the hydrostatic mass bias of galaxy clusters
Isac Barranco-Llorca, David Vallés-Pérez, Susana Planelles et al. (+1 more)
While
galaxy cluster masses are fundamental cosmological observables, estimates based on intra-cluster medium observations rely on hydrostatic
equilibrium, introducing a systematic bias. We investigate how mergers drive the time
evolution of this hydrostatic mass bias, identifying the dominant physical mechanisms and their dependence on dynamical state and merger history. Using a high-resolution AMR Eulerian+$N$-body cosmological simulation, we analyse a sample of cluster mergers within $1.5 \leq z \leq 0$, comparing true and hydrostatic masses derived from gas density and temperature profiles, and tracing their
evolution. At $z=0$, the hydrostatic mass bias shows a mild correlation with dynamical state. During major mergers, the bias follows a characteristic trend: a sharp negative dip around the merger time, a transient positive peak, and a gradual return to pre-merger levels. This behaviour is primarily driven by morphological and dynamical reconfigurations of the gas density within the ICM, while thermodynamical processes play a secondary role. The pattern shows no strong dependence on secondary parameters, such as mass ratio or impact parameter, but it can be fitted to a simple time-dependent functional form. This trend is present at radii $r\le R_{\mathrm{vir}}$, although with reduced amplitude and shorter timescales as the radius decreases. Hydrostatic mass bias is closely linked, albeit in a non-trivial way, with the merging history of
galaxy clusters. We find that the bias values are weakly correlated with the dynamical state of clusters. Nevertheless, our results give a robust estimation of the hydrostatic mass bias values in the pre-merger, merging, and post-merger phases. These findings highlight the importance of delving deeper into the observational assessment of cluster assembly state in order to improve mass estimations for cosmological analyses.
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All authors Isac Barranco-Llorca, David Vallés-Pérez, Susana Planelles, Vicent Quilis
High Energy Astrophysical Phenomena
Non-conservative Mass Transfer as a Formation Channel for Gaia Black Hole System
Aleksandra Olejak, Jakub Klencki, Alejandro Vigna-Gomez et al. (+6 more)
The detected
Gaia systems hosting compact objects challenge standard models of binary
star evolution. In particular, if the observed black hole (BH) systems evolved in isolation, they are expected to have undergone a mass transfer phase. Given their highly unequal masses, such mass transfer is dynamically unstable within standard models, leading to a
stellar merger or a short-period binary. In contrast, the observed systems have much wider orbits than predicted, making their formation within conventional evolutionary frameworks difficult to reconcile. Using detailed binary
evolution calculations, we test whether non-conservative mass transfer, in which most of the mass is lost from the system carrying the specific angular momentum of the donor's center of mass, can explain the properties of two
Gaia BH systems. This mass-loss geometry differs from standard isotropic re-emission from the accretor's vicinity. We find that our mass-loss geometry model reproduces the orbital periods of the two
Gaia BH systems remarkably well over a wide range of initial conditions, offering a plausible formation pathway. We speculate this may point to enhanced eruptive mass loss, potentially driven by high-opacity subsurface layers in the donor prior to Roche-lobe overflow, consistent with preferentially bipolar
outflows observed in luminous blue variables. Alternatively, it may indicate the need for more sophisticated mass-transfer prescriptions that account for highly unequal Roche-lobe sizes, sub-synchronous rotation, and possible self-
accretion. Similar mechanisms may operate in other post-mass-transfer systems facing analogous evolutionary challenges, including
Gaia neutron-
star and white-
dwarf binaries, stripped-envelope Wolf-Rayet
stars, and low-mass X-ray binaries.
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All authors Aleksandra Olejak, Jakub Klencki, Alejandro Vigna-Gomez, Selma E. de Mink, Lieke van Son, Jakub Cehula, Jakob Stegmann, Taeho Ryu, David D. Hendriks
Astrophysics of Galaxies
Large-Scale Structure in COSMOS-Web: Tracing Galaxy Evolution in the Cosmic Web up to $z \sim 7$ with the Largest JWST Survey
Hossein Hatamnia, Bahram Mobasher, Sina Taamoli et al. (+31 more)
We present a reconstruction of the large-scale structure using the James Webb Space
Telescope's (JWST) COSMOS-Web program to trace environmentally driven
galaxy evolution up to $z\sim7$. We applied a weighted kernel density estimation method to 160,000
galaxies with robust photometric
redshifts. We find that
stellar mass has a positive correlation with density at all
redshifts, stronger for quiescent
galaxies (QGs) at $z\lesssim2.5$, while at higher
redshifts ($2.5\lesssim z\lesssim5.5$) this trend is confined to extreme overdense environments, consistent with early mass assembly in proto-clusters. The
star-formation rate (SFR) shows a negative trend with density for QGs at $z\lesssim1.2$, reversing at $z\gtrsim1.8$, while
star-forming
galaxies (SFGs) show a mild positive correlation up to $z\sim5.5$. The specific SFR remains nearly flat for SFGs and declines with density for QGs at $z\lesssim1.2$. Moreover, mass and environmental quenching efficiencies show that mass-driven processes dominate at $z\gtrsim2.5$, the two processes act with comparable strength between $0.8\lesssim z\lesssim2.5$, and environmental quenching becomes stronger for low-mass
galaxies ($M_\star\lesssim10^{10} M_\odot$) at $z\lesssim0.8$. These findings reveal that large-scale structure drives
galaxy evolution by enhancing early mass assembly in dense regions and increasingly suppressing
star formation in low-mass systems at later times, establishing the environmental role of the
cosmic web across
cosmic history. COSMOS-Web, the largest JWST survey, provides accurate and deep photometric
redshifts, reaching 80% mass completeness at $\log(M_\star/M_\odot)\sim8.7$ at $z\sim7$, enabling the first view of how environments shaped
galaxy evolution from the epoch of reionization to the present day.
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All authors Hossein Hatamnia, Bahram Mobasher, Sina Taamoli, Jeyhan S. Kartaltepe, Caitlin M. Casey, Hollis B. Akins, Malte Brinch, Nima Chartab, Nicole E. Drakos, Andreas L. Faisst, Steven L. Finkelstein, Maximilien Franco, Finn Giddings, Ghassem Gozaliasl, Ali Hadi, Aryana Haghjoo, Santosh Harish, Olivier Ilbert, Pascale L. Jablonka, Shuowen Jin, Ali Ahmad Khostovan, Anton M. Koekemoer, Ronaldo Laishram, Daizhong Liu, Matteo Maturi, Henry Joy McCracken, Crystal L. Martin, Lauro Moscardini, Diana Scognamiglio, Marko Shuntov, Greta Toni, Alexander de la Vega, John R. Weaver, Lilan Yang
Earth and Planetary Astrophysics
An Analytical Model for the Eccentricity Cascade: Hot Jupiter Formation via S-type Instability
Eritas Yang and Yubo Su
A widely explored pathway for hot Jupiter (HJ) formation is high-eccentricity migration driven by von Zeipel-Lidov-Kozai cycles induced by an exterior companion. However, for a distant or low-mass companion, this mechanism typically demands that the
planet's initial orbit be very nearly perpendicular to that of the companion. In previous work (Yang et al. 2025), we demonstrated that such fine-tuning can be circumvented in the HAT-P-7 system due to the presence of an intermediate body that efficiently couples the orbits of the
planet and the distant companion – a mechanism we termed the eccentricity cascade (EC). In this work, we analytically characterize the dynamics governing the EC and delineate the parameter space within which it effectively operates. Our qualitative results are as follows: (i) The proto-HJ's eccentricity is most efficiently excited when the inner triple is on the verge of dynamical instability, (ii) the addition of a distant fourth body allows this instability to be approached gradually, and (iii) the instability mechanism is closely related to the stability of circumstellar (S-type)
planets in binaries. By deriving an analytic criterion for S-type instability, we obtain closed-form expressions describing the onset of the EC. Our results show that efficient HJ formation via the EC occurs across a broad range of intermediate perturbers, highlighting its potential as a robust migration channel.
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