Loading [MathJax]/extensions/TeX/boldsymbol.js
Abstract visibility
Abstract text size

Papers for Monday, May 19 2025

A list of the previously discussed papers can be found here .

Papers with local authors

The structure of stars orbiting close to supermassive black holes (SMBHs) can be dramatically modified by tidal heating, which can in principle dissipate an energy much larger than the stellar binding energy. We use analytic models and MESA to explore the coupled dynamics of tidal heating, stellar structural evolution, orbital decay due to gravitational waves and tides, and mass transfer due to Roche lobe overflow. In contrast to more equal mass stellar binaries, the stable mass transfer rate for stars orbiting SMBHs is typically set by the tidal heating timescale (the timescale for tides to increase the stellar radius), not by the gravitational wave orbital decay timescale. The resulting stable mass transfer rate is sensitive to the tidal heating model but is plausibly 103105Myr1 (and perhaps larger), sufficient to produce low-luminosity active galactic nuclei in many galaxies. The stability of mass transfer is sensitive to where in the stellar interior the tidal energy is dissipated. MESA models confirm the expected result that mass transfer is unstable (stable) if tidal heating increases (decreases) the fraction of the star that is convective. More detailed conclusions about the stability of mass-transfer will require self-consistently calculating how the tidal heating of stars changes in response to internal structural changes produced by the tidal heating itself. Stars with tidal heating-induced mass transfer can produce a large population of low-luminosity active galactic nuclei; they may also be the progenitors of some partial tidal disruption candidates (e.g., ASASSN-14ko) as well as short period quasi-periodic eruptions (e.g., eRO-QPE2 and GSN 069). However, many repeating nuclear transients produced by tidal heating-induced mass loss are likely fainter than those detected thus far, and remain to be discovered.

Brian Lorenz, Katherine A. Suess, Mariska Kriek, Sedona H. Price, Joel Leja, Erica Nelson, Hakim Atek, Rachel Bezanson, Gabriel Brammer, Sam E. Cutler, Pratika Dayal, Anna de Graaff, Jenny E. Greene, Lukas J. Furtak, Ivo Labbé, Danilo Marchesini, Michael V. Maseda, Tim B. Miller, Abby Mintz, Ikki Mitsuhashi, Richard Pan, Natalia Porraz Barrera, Bingjie Wang, John R. Weaver, Christina C. Williams, Katherine E. Whitaker
0 votes
Paper 10 — arXiv:2505.10632
0 votes
Paper 10 — arXiv:2505.10632

We demonstrate the power of JWST-NIRCam medium-band photometry to measure emission line fluxes and study dust and star formation properties of galaxies at cosmic noon. In this work, we present photometric emission line measurements and spatially-resolved maps of Hα and Paβ for a sample of 14 galaxies at 1.3z2.4, observed by the MegaScience medium-band survey and the UNCOVER deep spectroscopic survey. We measure line fluxes directly from the medium-band photometry and compare with spectroscopic measurements from UNCOVER. We find reasonable agreement between the photometric and spectroscopic emission line fluxes for both Hα and Paβ, with scatter <0.15 dex down to emission line equivalent widths of 10Å. We also make a nebular dust measurement from the ratio Paβ / Hα, finding an average nebular AV of 1.4. Our photometric AV measurements show a slightly larger scatter of 0.5 magnitudes when compared to spectroscopic measurements; however, this scatter may be partially caused by aperture effects. Finally, we produce spatially resolved maps of Hα emission, Paβ emission, and stellar continuum. We find that offsets in Hα and Paβ emission are common, especially for galaxies with the highest AV, indicating dusty sub-structures. Furthermore, the correlation between Hα and continuum emission decreases with increasing AV, suggesting that the dustiest objects have clumpy dust and star formation distributions. Our study demonstrates the power of medium-band photometry to directly probe emission line strengths, star formation, and dust attenuation for hundreds of galaxies in UNCOVER and thousands of galaxies in upcoming JWST medium-band surveys.

Huan-Yu Teng, Fei Dai, Andrew W. Howard, Samuel Halverson, Howard Isaacson, Eiichiro Kokubo, Ryan A. Rubenzahl, Benjamin Fulton, Aaron Householder, Jack Lubin, Steven Giacalone, Luke Handley, Judah Van Zandt, Erik A. Petigura, J. M. Joel Ong, Pranav Premnath, Haochuan Yu, Steven R. Gibson, Kodi Rider, Arpita Roy, Ashley Baker, Jerry Edelstein, Chris Smith, Josh Walawender, Byeong-Cheol Lee, Yu-Juan Liu, Joshua N. Winn
0 votes
Paper 25 — arXiv:2505.10804
0 votes
Paper 25 — arXiv:2505.10804

We report an observation of the Rossiter-McLaughlin (RM) effect of the transiting planet HD 93963 Ac, a mini-Neptune planet orbiting a G0-type star with an orbital period of Pc=3.65d, accompanied by an inner super-Earth planet with Pb=1.04d. We observed a full transit of planet c on 2024 May 3rd UT with Keck/KPF. The observed RM effect has an amplitude of 1ms1 and implies a sky-projected obliquity of λ=14+1719 degrees for HD 93963 Ac. Our dynamical analysis suggests that the two inner planets are likely well aligned with the stellar spin, to within a few degrees, thus allowing both to transit. Along with WASP-47, 55 Cnc, and HD 3167, HD 93963 is the fourth planetary system with an ultra-short-period planet and obliquity measurement(s) of any planet(s) in the system. HD 93963, WASP-47, and 55 Cnc favor largely coplanar orbital architectures, whereas HD 3167 has been reported to have a large mutual inclination (100) between its transiting planets b and c. In this configuration, the probability that both planets transit is low. Moreover, one planet would quickly evolve to be non-transiting due to nodal precession. Future missions such as ESO/PLATO should detect the resulting transit duration variations. We encourage additional obliquity measurements of the HD 3167 system to better constrain its orbital architecture.

Andrea Romanelli, Mélanie Chevance, J. M. Diederik Kruijssen, Lise Ramambason, Miguel Querejeta, Mederic Boquien, Daniel A. Dale, Jakob den Brok, Simon C. O. Glover, Kathryn Grasha, Annie Hughes, Jaeyeon Kim, Steven Longmore, Sharon E. Meidt, José Eduardo Mendez-Delgado, Lukas Neumann, Jérôme Pety, Eva Schinnerer, Rowan Smith, Jiayi Sun, Thomas G. Williams
0 votes
Paper 30 — arXiv:2505.10908
0 votes
Paper 30 — arXiv:2505.10908

The matter cycle between gas clouds and stars in galaxies plays a crucial role in regulating galaxy evolution through feedback mechanisms. In turn, the local and global galactic environments shape the interstellar medium and provide the initial conditions for star formation, potentially affecting the properties of this small-scale matter cycle. In particular, spiral arms have been proposed to play a pivotal role in the star formation life cycle, by enhancing the gas density and triggering star formation. However, their exact role is still debated. In this paper, we investigate the role of spiral arms in the giant molecular cloud evolutionary life cycle and on the star formation process in a sample of 22 nearby spiral galaxies from the PHANGS survey. We measure the cloud lifetime, the feedback timescale, the typical distance between independent regions and the star formation efficiency in spiral arms and inter-arm regions separately. We find that the distributions of the cloud lifetime as well as the feedback timescale are similar in both environments. This result suggests that spiral arms are unlikely to play a dominant role in triggering star formation. By contrast, the star formation efficiency appears to be slightly higher in inter-arm regions compared to spiral arms.

Rohan P. Naidu, Pascal A. Oesch, Gabriel Brammer, Andrea Weibel, Yijia Li, Jorryt Matthee, John Chisholm, Clara L. Pollock, Kasper E. Heintz, Benjamin D. Johnson, Xuejian Shen, Raphael E. Hviding, Joel Leja, Sandro Tacchella, Arpita Ganguly, Callum Witten, Hakim Atek, Sirio Belli, Sownak Bose, Rychard Bouwens, Pratika Dayal, Roberto Decarli, Anna de Graaff, Yoshinobu Fudamoto, Emma Giovinazzo, Jenny E. Greene, Garth Illingworth, Akio K. Inoue, Sarah G. Kane, Ivo Labbe, Ecaterina Leonova, Rui Marques-Chaves, Romain A. Meyer, Erica J. Nelson, Guido Roberts-Borsani, Daniel Schaerer, Robert A. Simcoe, Mauro Stefanon, Yuma Sugahara, Sune Toft, Arjen van der Wel, Pieter van Dokkum, Fabian Walter, Darach Watson, John R. Weaver, Katherine E. Whitaker
0 votes
Paper 51 — arXiv:2505.11263
0 votes
Paper 51 — arXiv:2505.11263

JWST has revealed a stunning population of bright galaxies at surprisingly early epochs, z>10, where few such sources were expected. Here we present the most distant example of this class yet -- MoM-z14, a luminous (MUV=20.2) source in the COSMOS legacy field at zspec=14.44+0.020.02 that expands the observational frontier to a mere 280 million years after the Big Bang. The redshift is confirmed with NIRSpec/prism spectroscopy through a sharp Lyman-α break and 3σ detections of five rest-UV emission lines. The number density of bright zspec1415 sources implied by our "Mirage or Miracle" survey spanning 350 arcmin2 is >100× larger (182+329105×) than pre-JWST consensus models. The high EWs of UV lines (1535 Å) signal a rising star-formation history, with a 10× increase in the last 5 Myr (SFR5Myr/SFR50Myr=9.9+3.05.8). The source is extremely compact (circularized re=74+1512 pc), and yet resolved, suggesting an AGN is not the dominant source of light. The steep UV slope (β=2.5+0.20.2) implies negligible dust attenuation and a young stellar population. The absence of a strong damping wing may indicate that the immediate surroundings of MoM-z14 are partially ionized at a redshift where virtually every reionization model predicts a 100% neutral fraction. The nitrogen emission and highly super-solar [N/C]>1 hint at an abundance pattern similar to local globular clusters that may have once hosted luminous supermassive stars. Since this abundance pattern is also common among the most ancient stars born in the Milky Way, we may be directly witnessing the formation of such stars in dense clusters, connecting galaxy evolution across the entire sweep of cosmic time.

All other papers

Gail Zasowski, Saurabh W. Jha, Laura Chomiuk, Xiaohui Fan, Ryan Hickox, Dan Huber, Eamonn Kerins, Chip Kobulnicky, Tod Lauer, Masao Sako, Alice Shapley, Denise Stephens, David Weinberg, Ben Williams

this https URL )

The Nancy Grace Roman Space Telescope is poised to revolutionize our scientific understanding of exoplanets, dark matter, dark energy, and general astrophysics, including through an innovative community approach to defining and executing sky surveys. The Roman Observations Time Allocation Committee (ROTAC) was convened to recommend time allocations for the three Core Community Surveys (CCS) using the Wide Field Instrument (WFI): the High Latitude Wide Area Survey, the High Latitude Time Domain Survey, and the Galactic Bulge Time Domain Survey, as well as balance the time allocation for the General Astrophysics Surveys. Each CCS had a corresponding Definition Committee that collected community input and designed proposals for a nominal (in-guide) survey, as well as underguide and overguide options with smaller and larger time allocations, respectively. These options explored different ways of fulfilling the mission science requirements while maximizing general astrophysics science goals enabled by the surveys. In this report, the ROTAC lays out its recommendations for the three CCS observing designs and the WFI time allotment for CCS (74.5%) and the General Astrophysics Surveys (25.5%).

Yan-Kun Qu, Zhong-Xiao Man, Yu-Peng Yang, Shuang-Xi Yi, Mei Du, Fa-yin Wang

As of December 2023, the Swift satellite has detected more than 1600 gamma-ray bursts (GRBs). We select 307 Type II GRBs for constructing the luminosity function (LF) based on the following criteria: (1) duration T902s; (2) conformity with the Amati relation for Type II GRBs; and (3) peak flux P1phcm2s1. We explore two general forms of the GRB LF: a broken power-law (BPL) LF and a triple power-law (TPL) LF. We consider three evolutionary scenarios: no evolution, luminosity evolution, and density evolution. We find that the no evolution model can be excluded, while both luminosity and density evolution models effectively account for the observations. This result is consistent with previous studies on long GRBs (LGRBs). However, our Type II GRB sample favors a BPL LF, in contrast to the preference for a TPL function discovered in Long GRBs.

Gustavo E. Medina, Ting S. Li, C. Allende Prieto, L. Beraldo e Silva, A. Bystrom, R. G. Carlberg, S. E. Koposov, M. Lambert, J. R. Najita, C. M. Rockosi, N. Kizhuprakkat, A. Riley, J. Aguilar, S. Ahlen, D. Bianchi, D. Brooks, T. Claybaugh, A. P. Cooper, A. de la Macorra, A. Dey, P. Doel, J. Forero-Romero, E. Gaztañaga, S. Gontcho A Gontcho, G. Gutierrez, M. Ishak, R. Kehoe, T. Kisner, M. Landriau, L. Le Guillou, A. Meisner, R. Miquel, F. Prada, I. Perez-Rafols, G. Rossi, E. Sanchez, D. J. Schlegel, J. H. Silber, D. Sprayberry, G. Tarle, B. A. Weaver, R. Zhou

RR Lyrae stars (RRLs) are valuable probes of both Milky Way assembly and stellar-evolution physics. Using a sample 6,240 RRLs obtained in the first year of the Dark Energy Spectroscopic Instrument (DESI) survey, we investigate the metallicity of RRLs and its correlation with their pulsation properties. We find that (1) a clear correlation between period and [Fe/H] reinforces the view that the longstanding Oosterhoff dichotomy arises from the scarcity of intermediate-metallicity Galactic globular clusters hosting sizeable RRL samples; (2) high-amplitude short-period and small-amplitude short-period variables are comparatively metal-rich, with mean [Fe/H] = 1.39±0.27 and 1.30±0.28, respectively; (3) in double-mode pulsators (RRd) the metallicity declines smoothly with increasing fundamental-mode period, and anomalous RRd stars occupy a remarkably narrow [Fe/H] range relative to classical RRd stars; (4) this spectroscopic sample let us, for the first time, place empirical constraints on the metallicity-dependent topology of the instability strip using phase-corrected effective temperatures and a large number of RRLs, where we observe an instability strip that moves towards cooler Teff with declining [Fe/H] with a width consistent with stellar-evolution models; and (5) a subset of metal-rich RRLs exhibits orbits consistent with disk membership and halo kinematics. Our results confirm the tantalizing potential of DESI for Galactic and stellar astrophysics and highlight the importance of the even larger samples of RRLs and data-processing improvements forthcoming in future DESI data releases.

Mass transfer (MT) in binary systems is a common evolutionary process that can significantly affect the structure, evolution, and final fate of both stars. In modeling MT hydrodynamics, it is usually assumed that the critical point of the flow, where the velocity exceeds the local sound speed, coincides with the inner Lagrange point (L1). However, in massive donors, radiative pressure dominates over gas pressure and the Eddington factor ΓEdd can reach or exceed unity. If there is significant momentum and/or energy exchange between gas and radiation, the critical point of the flow can shift away from L1, affecting the MT rate (˙Md). Here, we investigate the effects of radiation on MT using time-steady radiative hydrodynamic equations and the assumption of the von Zeipel theorem. We provide analytical expressions that closely approximate ˙Md and numerical solutions using a realistic equation of state. We find two main differences with respect to the traditional expressions for ˙Md. First, for Roche-lobe-underfilling donors with ΓEdd1, radiative momentum exchange leads to an exponential increase of ˙Md as a function of 1ΓEdd. We provide a simple modification of existing prescriptions that takes this effect into account. Second, we find that the photon tiring limit for super-Eddington outflows is much less restrictive near L1 than in spherical stars. We suggest that donors with super-Eddington convectively inefficient subsurface layers are able to drive MT with ˙Md102Myr1 even before overfilling their Roche lobes. We characterize the conditions for this new mode of super-Eddington-boosted MT and discuss the implications for binary evolution including the potential link to nonterminal outbursts of Luminous Blue Variables.

As a star orbits the center of its host galaxy, the trajectory is encompassed within a 3D toroid. The orbit probes all points in this toroid, unless its orbital frequencies exhibit integer ratios (commensurate frequencies), in which case a small sub-volume is traversed. commensurability is a Python package that implements a tessellation-based algorithm for identifying orbital families that satisfy commensurabilities by measuring the toroid volume traversed over orbit integration. Compared to standard orbit classification methods such as frequency analysis, tessellation analysis relies on configuration space properties alone, making classification results more robust to frequency instabilities or limited integration times. The package provides a framework for analyzing phase-space coordinates using tessellation analysis, including a subpackage for the implementation of the general tessellation algorithm. The package is to be used with a galactic dynamics library; it currently supports AGAMA, gala, and galpy.

A. Ferrara, M. Giavalisco, L. Pentericci, E. Vanzella, A. Calabrò, M. Llerena

this http URL @sns.it)

The LyC escape fraction from galaxies, fesc, is strongly boosted by galactic outflows. In the Attenuation-Free Model (AFM) accounting for the properties of z>10 galaxies, radiation-driven outflows develop once the galaxy specific star formation rate, sSFRsSFR25 Gyr1. As the cosmic sSFR increases with redshift, so does fesc(z), which, when globally averaged, grows from 0.007 to 0.6 in 0<z<20. We successfully tested the model on specific data sub-samples. Our predictions are consistent with direct measurements of fesc up to z=6.5, and provide a physical explanation for the observed decreasing trend of the mean UV galaxy spectral slope, β, towards high-z.

Kazuho Kayama, Takaaki Tanaka, Hiroyuki Uchida, Takeshi Go Tsuru, Yoshiyuki Inoue, Dmitry Khangulyan, Naomi Tsuji, Hiroaki Yamamoto

SS 433, located at the center of the W 50 radio nebula, is a binary system that ejects jets oriented east-west with precessional motion. X-ray lobes, containing compact "knots" labeled as head (e1), lenticular (e2), and ring (e3) in the east, as well as w1, w1.5, and w2 in the west, have been detected along the jets directions. Very-high-energy {\gamma}-ray emission has also been detected from regions containing these X-ray knots, suggesting highly efficient particle acceleration in the jets. In our previous study, we performed X-ray imaging spectroscopy of the western lobe of W 50 to investigate spectral variations. In this work, we extend our study to the eastern region using XMM-Newton observations to provide a more comprehensive picture of the X-ray emission from the SS 433 jets. Our results show no detectable synchrotron emission between SS 433 and the innermost knot (head). We also found that the X-ray spectrum of the eastern jet gradually steepens as one moves away from SS 433. While a similar spectral evolution is observed in the western jet, there are also noticeable differences. In the western lobe, the spectrum initially gradually steepens and then undergoes an abrupt softening outside the knot w2. However, in the eastern jet, no such rapid steepening is observed at the lenticular knot, which corresponds to w2 in the west. Furthermore, the observed brightening and spectral variations in the eastern jet cannot be explained by simply adjusting the parameters of the model used for the western side, suggesting the involvement of additional physical processes such as particle re-acceleration.

Microlensing is the method of exoplanet detection that discovers solar system analog exoplanets. These are planets low in mass located in wide orbits around their host stars. Even though thousands of exoplanets are discovered, they are mostly hot planets close to their hosts. There is a dearth of exoplanets discovered beyond the snowline where exoplanets are thought to be formed. This was recognized as a very important science issue; 2010 decadal survey declared detecting exoplanets with microlensing and measuring their masses as one of the three main science goals of NASA's next flagship mission, Nancy Grace Roman Space Telescope. Nancy Grace Roman Space Telescope is scheduled to launch in late 2026, no later than May 2027. It will observe 6 seasons of galactic bulge to discover and measure masses of 1000+ such wide orbit low mass solar system analog planets.

We use 45 galaxies from the Mapping Nearby Galaxies at Apache Point Observatory survey to study the physical drivers of star formation quenching in the Coma cluster. We measure specific star formation rate (sSFR) radial profiles for the Coma sample as well as a control sample of non-cluster field galaxies. We find that compared to the control sample, galaxies within the Coma Cluster have sSFR profiles that fall off more steeply with galactocentric radius. We then apply a toy model based on slow-then-rapid quenching via ram pressure stripping. We find that this model is able to reproduce the difference in sSFR profiles between field and Coma galaxies. These results demonstrate that ram pressure stripping plays a significant role in quenching star formation in the nearest massive galaxy cluster.

Reconstructing the initial density field of the Universe from the late-time matter distribution is a nontrivial task with implications for understanding structure formation in cosmology, offering insights into early Universe conditions. Convolutional neural networks (CNNs) have shown promise in tackling this problem by learning the complex mapping from nonlinear evolved fields back to initial conditions. Here we investigate the effect of varying input sub-box size in single-input CNNs. We find that intermediate scales (Lsub152h1Mpc) strike the best balance between capturing local detail and global context, yielding the lowest validation loss and most accurate recovery across multiple statistical metrics. We then propose a dual-input model that combines two sub-boxes of different sizes from the same simulation volume. This model significantly improves reconstruction performance, especially on small scales over the best single-input case, despite utilizing the same parent simulation box. This demonstrates the advantage of explicitly incorporating multi-scale context into the network. Our results highlight the importance of input scale and network design in reconstruction tasks. The dual-input approach represents a simple yet powerful enhancement that leverages fixed input information more efficiently, paving the way for more accurate cosmological inference from large-scale structure surveys.

A. Asensio Ramos, C. Díaz Baso, C. Kuckein, S. Esteban Pozuelo, M. G. Löfdahl

Post-facto image restoration techniques are essential for improving the quality of ground-based astronomical observations, which are affected by atmospheric turbulence. Multi-object multi-frame blind deconvolution (MOMFBD) methods are widely used in solar physics to achieve diffraction-limited imaging. We present torchmfbd, a new open-source code for MOMFBD that leverages the PyTorch library to provide a flexible, GPU-accelerated framework for image restoration. The code is designed to handle spatially variant point spread functions (PSFs) and includes advanced regularization techniques. The code implements the MOMFBD method using a maximum a-posteriori estimation framework. It supports both wavefront-based and data-driven PSF parameterizations, including a novel experimental approach using non-negative matrix factorization. Regularization techniques, such as smoothness and sparsity constraints, can be incorporated to stabilize the solution. The code also supports dividing large fields of view into patches and includes tools for apodization and destretching. The code architecture is designed to become a flexible platform over which new reconstruction and regularization methods can also be implemented straightforwardly. We demonstrate the capabilities of torchmfbd on real solar observations, showing its ability to produce high-quality reconstructions efficiently. The GPU acceleration significantly reduces computation time, making the code suitable for large datasets. The code is publicly available at this https URL.

Emma L. Miles, Colby Ostberg, Stephen R. Kane, Ondrea Clarkson, Cayman T. Unterborn, Tara Fetherolf, Michael J. Way, Sadie G. Welter

As the discovery of exoplanets progresses at a rapid pace, the large number of known planets provides a pathway to assess the stellar and planetary properties that govern the climate evolution of terrestrial planets. Of particular interest are those planetary cases that straddle the radius boundary of being terrestrial or gaseous in nature, such as super-Earth and sub-Neptune exoplanets, respectively. The known exoplanet, TOI-2285 b, is one such case, since it lies at the radius boundary of super-Earth and sub-Neptune (Rp=1.74 R), and receives a relatively high instellation flux since its orbit exists within both the Habitable Zone (HZ) and Venus Zone (VZ). Here, we present an analysis of the planetary interior and climate to determine possible evolutionary pathways for the planet. We provide volatile inventory estimates in terms of the planet's bulk density and interior composition. We performed climate simulations using ROCKE-3D that provide a suite of possible temperate scenarios for the planet for a range of topographical and initial surface water assumptions. Using the outputs of the climate simulations, we modeled JWST transmission and emission spectroscopy for each scenario. Our results demonstrate that there are temperate scenarios consistent with the known planetary properties, despite the planet's estimated steam atmosphere, and its location relative to the VZ.

Conor A. Nixon, Bruno Bézard, Thomas Cornet, Brandon Park Coy, Imke de Pater, Maël Es-Sayeh, Heidi B. Hammel, Emmanuel Lellouch, Nicholas A. Lombardo, Manuel López-Puertas, Juan M. Lora, Pascal Rannou, Sébastien Rodriguez, Nicholas A. Teanby, Elizabeth P. Turtle, Richard K. Achterberg, Carlos Alvarez, Ashley G. Davies, Katherine de Kleer, Greg Doppmann, Leigh N. Fletcher, Alexander G. Hayes, Bryan J. Holler, Patrick G. J. Irwin, Carolyn Jordan, Oliver R. T. King, Nicholas W. Kutsop, Theresa C. Marlin, Henrik Melin, Stefanie N. Milam, Edward M. Molter, Luke Moore, Yaniss Nyffenegger-Péré, James O'Donoghue, John O'Meara, Scot C. R. Rafkin, Michael T. Roman, Arina Rostopchina, Naomi Rowe-Gurney, Carl Schmidt, Judy Schmidt, Christophe Sotin, Tom S. Stallard, John A. Stansberry, Robert A. West

Saturn's moon Titan undergoes a long annual cycle of 29.45 Earth years. Titan's northern winter and spring were investigated in detail by the Cassini-Huygens spacecraft (2004-2017), but the northern summer season remains sparsely studied. Here we present new observations from the James Webb Space Telescope (JWST) and Keck II telescope made in 2022 and 2023 during Titan's late northern summer. Using JWST's mid-infrared instrument, we spectroscopically detected the methyl radical, the primary product of methane break-up and key to the formation of ethane and heavier molecules. Using the near-infrared spectrograph onboard JWST, we detected several non-local thermodynamic equilibrium CO and CO2 emission bands, which allowed us to measure these species over a wide altitude range. Lastly, using the near-infrared camera onboard JWST and Keck II, we imaged northern hemisphere tropospheric clouds evolving in altitude, which provided new insights and constraints on seasonal convection patterns. These observations pave the way for new observations and modelling of Titan's climate and meteorology as it progresses through the northern fall equinox, when its atmosphere is expected to show notable seasonal changes.

In a previous work 2305.04946, we found that supernova and baryon acoustic oscillation data support the hypothesis that late time cosmic acceleration is caused by the potential energy of a scalar field descending its potential, as suggested by holographically defined models of quantum gravity. In this note, we update our analysis using the Dark Energy Survey 5 year supernova data set (DES-SN5YR) and the baryon acoustic oscillation data from the Dark Energy Spectroscopic Instrument Data Release 2 (DESI DR2). Approximating the scalar potential via a first order Taylor series VV0+V1ϕ about the present value, and making use of only recent-time data from DES-SN5YR and DESI DR2, we find that the slope parameter is constrained as V1=1.49±0.25 in a standard likelihood analysis. This is naively a >5σ discrepancy with ΛCDM (which has V1=0), though a more detailed analysis not assuming a Gaussian likelihood distribution suggests 4σ significance. Based only on the Δχ2=13.7 improvement of fit while ignoring parameter space volumes disfavours ΛCDM at a 3σ significance level. These significance measures are substantially improved from our previous analysis using older data sets. We also reproduce the DESI DR2 parameter constraints based on the same combination of data and find that the ΛCDM is more strongly disfavoured in the context of the linear potential extension (dubbed V0V1) as compared with the w0wa extension of ΛCDM. A caveat is that for both w0wa and V0V1, much of the significance relies on the historical z<0.1 supernova samples included in the DES-SN5YR data set.

The astrophysical implications of particle photoproduction interactions involving nuclei is considered here, based on the most recent empirical data on particle photoproduction interactions off protons. The implications of photoproduction with helium nuclei are also discussed and compared with gamma-p interactions. It is found that gamma-He interactions, assuming the cosmological abundance of He, produce approximately 10% of the pions as compared with gamma-p interactions. In addition to the production of pions, we also discuss the relative effect of excited nucleon decay leading to single and double pion production, as well as rho, eta, omega and K meson production and decay channels, all of which produce to neutrinos and gamma-rays. The production of mesons other than pions is found not to be significant for producing gamma-rays and neutrinos from astrophysical sources. It is further shown that, for astrophysical gamma-p interactions that lead to gamma-ray and neutrino production, the decay of the Delta(1232) resonance channel clearly dominates, all other production channels being effectively negligible.

Stuart McAlpine, Jens Jasche, Metin Ata, Guilhem Lavaux, Richard Stiskalek, Carlos S. Frenk, Adrian Jenkins

this http URL

We present the first results from the Manticore project, dubbed Manticore-Local, a suite of Bayesian constrained simulations of the nearby Universe, generated by fitting a physical structure formation model to the 2M++ galaxy catalogue using the BORG algorithm. This field-level inference yields physically consistent realizations of cosmic structure, leveraging a nonlinear gravitational solver, a refined galaxy bias model, and physics-informed priors. The Manticore-Local posterior realizations evolve within a parent cosmological volume statistically consistent with LCDM, demonstrated through extensive posterior predictive tests of power spectra, bispectra, initial condition Gaussianity, and the halo mass function. The inferred local supervolume shows no significant deviation from cosmological expectations; notably, we find no evidence for a large local underdensity. Our model identifies high-significance counterparts for fourteen prominent galaxy clusters each within one degree of its observed sky position. Across the posterior ensemble, these counterparts are consistently detected with 2-4 sigma significance, and their reconstructed masses and redshifts agree closely with observational estimates, confirming the inference's spatial and dynamical fidelity. The peculiar velocity field recovered by Manticore-Local achieves the highest Bayesian evidence across five datasets, surpassing state-of-the-art models. Unlike methods yielding only point estimates or using simplified dynamics, Manticore-Local provides a full Bayesian posterior over cosmic structure and evolution, enabling rigorous uncertainty quantification. These results establish Manticore-Local as the most advanced constrained realization suite of the Local Universe to date, offering a robust statistical foundation for future studies of galaxy formation, velocity flows, and environmental dependencies in our cosmic neighbourhood.

Ambra Nanni, Michael Romano, Darko Donevski, Joris Witstok, Irene Shivaei, Michel Fioc, Prasad Sawant

JADES-GS-z6-0, a high-redshift galaxy (z6.7) recently observed as part of the James Webb Space Telescope (JWST) Advanced Deep Extragalactic Survey (JADES), exhibits a distinct bump in its rest-frame ultraviolet (UV) spectrum indicative of a large quantity of hydrocarbon grains, a sign of rapid metal and dust enrichment in its interstellar medium (ISM). This galaxy serves as an ideal case for examining rapid dust formation processes in the early universe. We investigated diverse dust production channels from a possible maximal formation redshift of zform17, enabling dust contributions from asymptotic giant branch (AGB) stars over the longest possible timescale. Our model simultaneously reproduces key spectral features of JADES-GS-z6-0 such as its Balmer decrement, UV slope, and UV bump. The match is obtained by adopting a star-formation history in which a burst at 600~Myr accounts for approximately 30\% of the galaxy's final stellar mass. Our findings indicate two pathways for the formation of hydrocarbon grains, such as polycyclic aromatic hydrocarbons (PAHs): (1) efficient dust accretion within the ISM, necessitating a low depletion of metals into dust grains from Type II supernovae (10\%), or (2) dust production predominantly by Type II supernovae, requiring a high depletion fraction (73\%) without dust accretion. We further demonstrate that PAHs are unlikely to originate solely from AGB stars or from shattering of large grains in the ISM. The evolution of the UV slope with redshift points to a complex and bursty star formation history for galaxies observed by JADES.

Aims. This study investigates the role of primordial black holes (PBHs) in shaping cosmic radiation backgrounds--the cosmic X-ray background (CXB), the Lyman-Werner background (LWB), and the cosmic radio background (CRB)--and evaluates their viability as dark matter (DM) candidates based on observational constraints and theoretical limits. Methods. PBH accretion is modelled using analytical frameworks that include electron advection-dominated accretion flows (eADAF), standard advection-dominated accretion flows (ADAF), luminous hot accretion flows (LHAF), and thin disks. Emission from PBHs in both dark matter halos and the intergalactic medium (IGM) is computed. We assess the impact of variations in model assumptions, such as halo gas density profiles, gas velocities, and emission models. The results are compared with observational limits and theoretical thresholds to constrain the PBH fraction as DM for masses between 1 and 100 solar masses Results. PBHs may contribute up to 99, 93, 80, and 91 per cent of the unresolved soft X-ray background for masses of 1, 10, 33, and 100 solar masses, respectively, and about 33-39 per cent of the hard X-ray background. These contributions limit the PBH DM fraction to 7e-3, 6e-4, 6e-4, and 7e-4, respectively, in our baseline model. These constraints are consistent with those from the LWB, ensuring molecular cooling and early star formation are preserved. However, explaining the radio background excess and the EDGES signal would require PBH fractions well above these limits. For 1 solar mass, excluding ADAF subregimes relaxes the constraint to 3e-2, highlighting the sensitivity to accretion physics. Variations in model assumptions introduce only minor differences in the predicted backgrounds.

Armin Mang Román, Peter Zeidler, Wolf-Rainer Hamann, Lidia M. Oskinova, Matthew J. Rickard, Sabela Reyero Serantes, Helge Todt, John S. Gallagher, Derck Massa, Daniel Pauli, Varsha Ramachandran, Elena Sabbi, Andreas Sander

Determining how much mass is removed by stellar winds is crucial to understanding massive star evolution and feedback. However, traditional spectroscopic diagnostics in the UV and optical are not sensitive enough to characterize weak stellar winds of OB stars in low-metallicity environments. A new tool to access weak stellar winds is provided by spectroscopy in the infrared (IR). Stellar atmosphere models indicate that the hydrogen Brα line at λ\,4.05\,μm is a useful mass-loss rate indicator, particularly at low metallicity. The unprecedented capabilities of the NIRSpec spectrograph on board of the \emph{James Webb Space Telescope} (JWST) allow us to measure this line in spectra of massive stars in other galaxies. In this work, we present the first NIRSpec spectra of O-type stars in the Small Magellanic Cloud (SMC), which has a metallicity of only 20\% Solar. Our sample consists of thirteen stars with spectral types ranging from O2 to O9.5 including supergiants, giants, and dwarfs. The stars belong to NGC\,346, the most massive young cluster in the SMC. We describe the observing strategy and data reduction, highlighting the treatment of the nebular background emission. The spectra cover the 2.8--5.1 μm wavelength range, and we detect the Brα line in emission in each of our sample stars. Using a combination of spectral and photometric data ranging from the UV to the IR, we improve the measurements of stellar luminosity and reddening. A first qualitative comparison of the observed Brα line with stellar atmosphere models shows its potential as a wind diagnostic for weak-winded stars.

Boshun Yang, Nikolaus Vogt, Susanne M Hoffmann

The 1408 CE "guest star" recorded in Chinese historical texts presents a compelling case for identifying a historical stellar transient. While previous studies debated its nature as a meteor, comet, or nova, we re-evaluate the event using original Ming Dynasty records, including a newly found memorial from the imperial court. The object, described as stationary for over ten days, yellow, and luminous (resembling a "Zhou Bo virtue star"), is inconsistent with cometary behavior. Positional analysis locates it near the Niandao asterism (modern Cygnus-Vulpecula region) within the Milky Way, with a derived brightness of -4 to 0 mag. Light-curve stability over ten days and color descriptions align with a slow nova or a supernova. We cross-correlated the historical coordinates with modern catalogs and found a few possible counterparts. Among them, CK Vul - a luminous red nova remnant from 1670 to 1672 - is the most interesting candidate. Could its progenitor system have experienced a precursor classical nova eruption circa 1408 prior to the merger ~200 years later? We also examine cataclysmic variables and planetary nebulae within the 100 square-degree search field, though most lack sufficient brightness or age characteristics. This study emphasizes the value of integrating detailed historical records with contemporary astrophysical data to resolve long-standing controversies over ancient transients. The 1408 event likely represents a rare, well-documented nova, offering insights into pre-modern stellar phenomena and their modern counterparts.

Two populations of dwarf galaxies can be associated with the Milky Way (MW): the disrupted dwarfs that fully merged with it in the past and the surviving satellites that orbit around it in the present time. In this work, we analyzed the chemical composition of the cold gas in both populations of dwarfs associated with MW like galaxies in the ARTEMIS simulations. We found that, at fixed stellar mass, disrupted dwarfs have lower gas phase metallicity and are more alpha-enhanced than surviving dwarfs. We also noticed that disrupted satellites accreted earlier and with higher SF gas fractions had lower metallicity and higher [Mg/Fe] at fixed mass. In the case of surviving dwarfs, we obtained a similar trend for both gas-phase metallicity and [Mg/Fe] abundance.

Krishnendu Mandal, Alexander G. Kosovichev, Valery V. Pipin, Sylvain G. Korzennik

Helioseismic signatures of dynamo waves have recently been discovered in variations of the solar differential rotation, offering valuable insights into the type of dynamo mechanism operating in the solar convection zone. To characterize these variations, we analyze p-mode frequency-splitting data estimated using time intervals of various lengths to enhance the signal-to-noise ratio in inversions of zonal flows. We introduce a novel time-dependent inversion method that inherently smooths the solution over time, eliminating the need for separate post-processing smoothing. By applying this approach to observational data from the SOHO Michelson Doppler Imager, SDO Helioseismic Magnetic Imager, and Global Oscillation Network Group, we identify similar dynamo wave patterns in both the zonal acceleration and the zonal flow throughout the entire convection zone. Our analysis shows that while using longer time series smooths out temporal variations, the fundamental features observed in the short time series (i.e. 72-day long) persist when inverting datasets covering different time periods. These findings reinforce earlier detections and offer further validation of solar dynamo models. We additionally investigate the dimensionless radial gradient of rotation. Its value is close to -1 and increases in the deeper layers, remaining nearly constant from the equator to mid-latitudes within the depth range of 13 to 35 Mm below the surface; the results at high latitudes remain somewhat inconclusive. The variation of this quantity displays a torsional oscillation-like pattern, albeit with certain differences.

Sub-parsec (sub-pc) binary supermassive black holes (BSBHs) should be common from galaxy mergers, yet direct evidence has been elusive. We present HST/WFC3IR F160W imaging for a sample of 8 candidate sub-pc BSBHs at redshifts z~0.1--0.5, as well as cross-comparison with a sample of ordinary quasars with archival HST/WFC3 IR F160W images. These 8 candidate sub-pc BSBHs were identified from multi-epoch spectroscopic surveys of quasars (including both typical quasars and those with single-peaked velocity-offset broad lines). whose broad Hβ lines are significantly offset (by ~< a few hundred km/s) from the systemic redshifts. We directly test the prediction that the host galaxies of BSBHs would have a higher fraction of disturbed morphologies and younger stellar bulges from recent interactions than those of control quasars. After careful subtraction of the central quasar light, our candidate BSBH hosts show a statistically undifferentiated distribution of host asymmetry, indicative of a similar fraction of recent mergers. While a significantly larger sample is needed to place this result on a much firmer statistical ground, it opens questions as to the timescale differences between galaxy merger and BSBH formation, or the efficacy of the radial-velocity-shift--based selection of sub-pc BSBH candidates.

To investigate the role of morphology in galaxy evolution, we analyze the relationships between galaxy structure, star formation, and HI gas content. Using multi-band images from the DESI Legacy Imaging Surveys, we perform detailed structural decompositions on a representative local galaxy sample from xGASS. Structural components and color properties are examined as functions of deviations from the star formation main sequence (ΔSFRMS) and HI gas deficiency (ΔfHI). We find that bulge fractions decrease with higher ΔSFRMS and lower stellar mass, indicating that star-forming galaxies are predominantly disc-dominated, while quiescent galaxies are bulge-dominated. The slope of the color (gr) versus ΔSFRMS relationship decreases from low to high stellar masses and from outer to inner regions, with greater color variation in massive galaxies. Color gradients are predominantly negative, becoming shallower in lower-mass galaxies and in the outer disk regions. We also identify inflection points in the color gradient and bulge fraction relations with ΔSFRMS, with main-sequence galaxies having the lowest bulge fractions and steepest color gradients. At fixed stellar mass, we observe only a slight correlation between bulge fraction and HI deficiency. However, outer disk colors show a stronger dependence on HI content than inner regions, and color gradients flatten as ΔfHI increases. These results suggest that HI gas is more closely linked to star-forming, disc-dominated systems, supporting the idea that gas accretion fuels star formation primarily in galaxy disks.

Starspots are ubiquitous in young, low mass stars, yet their impact on the spectral classification and fundamental parameter inference of pre main sequence stars has been largely overlooked. In this study, we demonstrate that cool starspots systematically distort spectral morphology and bias derived effective temperatures, surface gravities, and luminosities in non accreting Weak Lined T Tauri Stars (WTTS). Using a sample of 56 WTTS with high resolution, broad band X-Shooter spectra, we perform two temperature spectral fits that explicitly account for spot coverage and temperature contrast. These composite models consistently outperform traditional single temperature fits, particularly in the 3350 4000 K regime, where spot contributions dominate the red optical and near infrared flux. Moreover, we propose that surface gravity discrepancies between optical and infrared measurements are a natural consequence of spot dominated emission in PMS stars that is accentuated by observational uncertainty. We find that single temperature models can overestimate effective temperatures by up to 700 K and underestimate log g by 1-2 dex. Using spot-corrected effective temperatures, we derive masses and ages from traditional, magnetic, and spotted evolutionary models, finding that spot corrections systematically raise inferred masses by up to 80 percent and stellar ages by up to 0.5 dex. These discrepancies are strongest for stars in the 0.3 to 0.8 solar mass range. Using starspots as a proxy for magnetic topology, we find evidence that a shift from largely axisymmetric to non axisymmetric magnetic fields dominated by small scale structures coincides with the formation of a radiative core during the pre main sequence, effectively separating convective and interface dynamo regimes.

Sanghyeon Han, Motonari Tonegawa, Ho Seong Hwang, Yohan Dubois, Juhan Kim, Yonghwi Kim, Oh-Kyoung Kwon, Jaehyun Lee, Owain N. Snaith, Brad K. Gibson, Changbom Park

We investigate the redshift evolution of intrinsic alignments of the shapes of galaxies and subhalos with the large-scale structures of the universe using the cosmological hydrodynamic simulation, Horizon Run 5. To this end, early-type galaxies are selected from the simulated galaxy catalogs based on stellar mass and kinematic morphology. The shapes of galaxies and subhalos are computed using the reduced inertia tensor derived from mass-weighted particle positions. We find that the misalignment between galaxies and their corresponding dark-matter subhalos decreases over time. We further analyze the two-point correlation between galaxy or subhalo shapes and the large-scale density field traced by their spatial distribution, and quantify the amplitude using the nonlinear alignment model across a wide redshift range from z=0.625 to z=2.5. We find that the intrinsic alignment amplitude, ANLA, of galaxies remains largely constant with redshift, whereas that of dark matter subhalos exhibits moderate redshift evolution, with a power-law slope that deviates from zero at a significance level exceeding 3σ. Additionally, ANLA is found to depend on both the stellar mass and kinematic morphology of galaxies. Notably, our results are broadly consistent with existing observational constraints. Our findings are in good agreement with previous results of other cosmological simulations.

Sagnick Mukherjee, David K. Sing, Guangwei Fu, Kevin B. Stevenson, Stephen P. Schmidt, Harry Baskett, Patrick McCreery, Natalie H. Allen, Katherine A. Bennett, Duncan A. Christie, Carlos Gascón, Jayesh Goyal, Éric Hébrard, Joshua D. Lothringer, Mercedes López-Morales, Jacob Lustig-Yaeger, Erin M. May, L. C. Mayorga, Nathan Mayne, Lakeisha M. Ramos Rosado, Henrique Reggiani, Zafar Rustamkulov, Kevin C. Schlaufman, K. S. Sotzen, Daniel Thorngren, Le-Chris Wang, Maria Zamyatina

Aerosols are common in exoplanet atmospheres, but their formation-whether through gas condensation or photochemical reactions-remains uncertain. We report a 6σ detection of limb asymmetry in the transmission spectrum of WASP-94A b, revealing a cloud-covered (11σ) cooler morning limb and a clear hotter evening limb with strong H2O absorption (10σ). Models suggest cloud droplets formed near mbar pressures are lofted to 0.01 mbar by strong vertical dynamics in the morning limb. They evaporate when circulated to the hotter evening limb, requiring a minimum 280 K (3σ) limb-to-limb temperature difference. We confirm that aerosols in hot Jupiters like WASP-94A b can have clouds cycling between day and night sides instead of photochemical hazes. Ignoring these effects severely biases inferred chemical abundances, showing limb-resolved spectroscopy is critical for characterizing the formation mechanisms of transiting exoplanets-from gas giants to terrestrial exoplanets, indicating the need to reassess inferences from a decade's worth of Hubble Space Telescope observations.

We perform a precise calculation of the EFT conditional likelihood for large-scale structure (LSS) via the saddle-point expansion method in the presence of primordial non-Gaussianities (PNG). The precision is manifested at two levels: one corresponding to the consideration of higher-order noise terms, and the other to the inclusion of contributions around the saddle points. In computing the latter, we encounter the same issue of the negative modes as in the context of false vacuum decay, which necessitates deforming the original integration contour into the combination of the steepest descent contours to ensure a convergent and real result. We demonstrate through detailed calculations that, upon the incorporation of leading-order PNG, both types of extensions introduce irreducible field-dependent contributions to the conditional likelihood. This insight motivates the systematic inclusion of additional effective terms within the forward modeling framework. Our work facilitates Bayesian forward modeling under non-Gaussian initial conditions, thereby enabling more stringent constraints on the parameters describing PNG.

Markarian 231 (Mrk 231) is one of the brightest ultraluminous infrared galaxies (ULIRGs) known to date. It displays a unique optical-UV spectrum, characterized by a strong and perplexing attenuation in the near-UV, associated with a sudden polarization peak. Building on previous spectro-photometric modeling, we investigated the hypothesis that the core of Mrk 231 may host a binary SMBH system. In this scenario, the accretion disk of the primary, more massive SMBH is responsible for the optical-UV spectrum. The disk of the secondary, less massive SMBH, would be expected to essentially emit in the far UV. We applied this model to archival photometric and polarimetric data of Mrk 231 and tried to obtain the best fit possible. To support our findings, we performed radiative transfer calculations to determine the spatial disposition of each main component constituting Mrk 231. We find that a binary SMBH model can reproduce both the observed flux and polarization of Mrk 231 remarkably well. We infer that the core potentially hosts a binary SMBH system, with a primary SMBH of about 1.6x10^8 solar masses and a secondary of about 1.1x10^7 solar masses , separated by a semimajor axis of 146 this http URL secondary SMBH drives a degree of polarization of 3 % between 0.1 and 0.2 {\mu}m, with a corresponding polarization position angle of about 134° , which is consistent with scattering within an accretion disk. The primary SMBH and the structure around it are responsible for a degree of polarization of 23 % between 0.3 and 0.4 {\mu}m with a corresponding polarization position angle of about 96° , that is possibly attributed to scattering within the quasar's wind. Finally, our model predicts the existence of a second peak in polarized flux in the far-ultraviolet, a telltale signature that could definitively prove the presence of a binary SMBH.

En Chen, Xi Chen, Min Fang, Xuepeng Chen, Qianru He, Tian Yang

We report that the formation of the twin-bubble system N65 and N65bis may be caused by the cloud-cloud collision (CCC) from the Bullet Nebula. The blue-shifted 13CO gas component (N65a [47, 55] km s1) is associated with the twin-bubble system, while the red-shifted 13CO gas component (N65b [55, 62] km s1) is linked to the Bullet Nebula. The distinct signatures of CCC, such as the bridge feature, the U-shape cavity and the complementary distribution with displacement, are found between N65a and N65b. The collision timescale is estimated to be 1.15 to 2.0 Myr, which is consistent with the dynamical ages of the two \HII regions in N65a (0.73 Myr for N65bis and 1.19 Myr for N65, respectively), indicating their CCC-related origin. A total of 354 young stellar objects (YSOs) are founded, which are clustered into eight MST (Minimum Spinning Tree) groups. The distribution of M1 (at the post-frontal edge) and M2, M3, M4 (at the pre-frontal edge) suggests that the CCC triggers star formation along the collision path of b=0.35, with younger YSOs present at the pre-frontal edge. Therefore, the bipolar morphology of the twin-bubble system can be interpreted by the collision of N65a and N65b along b=0.35 about 2 Myr ago.

Francesco Pistis, Michele Fumagalli, Matteo Fossati, Trystyn Berg, Elena S. Mangola, Rajeshwari Dutta, Margherita Grespan, Angela Iovino, Katarzyna Małek, Sean Morrison, David N. A. Murphy, William J. Pearson, Ignasi Pérez-Ráfols, Matthew M. Pieri, Agnieszka Pollo, Daniela Vergani

Context. Ongoing and upcoming large spectroscopic surveys are drastically increasing the number of observed quasar spectra, requiring the development of fast and accurate automated methods to estimate spectral continua. Aims. This study evaluates the performance of three neural networks (NN) - an autoencoder, a convolutional NN (CNN), and a U-Net - in predicting quasar continua within the rest-frame wavelength range of 1020 Å to 2000 Å. The ability to generalize and predict galaxy continua within the range of 3500 Å to 5500 Å is also tested. Methods. The performance of these architectures is evaluated using the absolute fractional flux error (AFFE) on a library of mock quasar spectra for the WEAVE survey, and on real data from the Early Data Release observations of the Dark Energy Spectroscopic Instrument (DESI) and the VIMOS Public Extragalactic Redshift Survey (VIPERS). Results. The autoencoder outperforms the U-Net, achieving a median AFFE of 0.009 for quasars. The best model also effectively recovers the Lyα optical depth evolution in DESI quasar spectra. With minimal optimization, the same architectures can be generalized to the galaxy case, with the autoencoder reaching a median AFFE of 0.014 and reproducing the D4000n break in DESI and VIPERS galaxies.

Liheng Yang, Xiaoli Yan, Jun Zhang, Zhike Xue, Zhe Xu, Jincheng Wang, Yijun Hou, Yian Zhou, Defang Kong, Roslan Umar, Xinsheng Zhang, Qiaoling Li, Liping Yang

Recurrent small-scale eruptions are fascinating phenomena in the solar atmosphere. However, their underlying physical mechanisms remain unclear. On 2021 May 23, five recurrent jetlets (J1-J5) were observed continuously ejecting from a satellite spot located at the north edge of AR 12824. Using high-resolution, multi-wavelength data from NVST, SDO, and IRIS, we investigate the physical characteristics of these jetlets and their relationship with the satellite spot. The widths of these jetlets range from 1300 to 2900 km, their lifetimes range span 3 to 10 minutes, and their projection speeds vary from 152.8 to 406.0 km s1. During the eruptions, the satellite spot moved northwest at a low speed of 376 ± 12 m s1. Its area gradually decreased due to magnetic cancellation with surrounding positive magnetic field, resulting in an average cancellation rate of 1.3×1018 Mx hr1. Dark lanes that separated from the satellite spot and small pores were observed to move toward nearby these features or dark lanes with opposite polarities, eventually disappearing during the magnetic cancellation process. J4 was driven by an eruption of a micro-filament. Spectral observations revealed a redshift on the right side of J4 and a blueshift on the left side of its base, suggesting a counterclockwise rotation. The horizontal magnetic field of the satellite spot consistently exhibited a vortex structure throughout its evolution until it vanished. The nonlinear force-free field extrapolation confirms that the satellite spot serves as one footpoint of a mini-flux rope. These observations reveal that these jetlets might result from three-dimensional null-point magnetic reconnection, initiated by the continuous eruption of a mini-flux-rope or multiple mini-flux-ropes, driven by sustained magnetic cancellation.

Ana Mitrašinović, Branislav Vukotić, Teodora Žižak, Miroslav Micic, Milan M. Ćirković

The potential of galaxies to host habitable planets is central to astrobiology, tightly linked to galaxy-scale evolution and cosmological processes. Using IllustrisTNG, we revisit the proposed local peak in the mass-metallicity relation for small, metal-rich, star-forming galaxies (Cloudlet) as an indicator of enhanced galactic habitability. We refine the earlier analysis by applying updated filtering criteria to identify a more refined sample, further selecting objects based on their history. This process resulted in a confirmed sample of 97 dwarf galaxies, alongside 519 additional structures of uncertain origin, potentially comprising both numerical artefacts and unrecognised physical systems. Under these stricter conditions, the proposed bimodality in galactic habitability is strongly diminished. However, the astrobiological potential of metal-rich dwarfs, most of which are compact remnants of more massive galaxies that underwent tidal stripping, is a thrilling area of exploration. Although dense stellar environments are traditionally seen as inhospitable, recent studies highlight the role of dynamic environments in enhancing the distribution of biological material. Furthermore, the potential habitability of tidal structures formed in the aftermath of galactic interactions is a fascinating possibility. Our findings suggest that non-traditional structures support conditions favourable for life, opening up exciting new avenues for astrobiological research. This research underscores the need for a holistic approach to studying habitability that moves beyond planetary and stellar-focused frameworks to incorporate the broader galactic environment. Understanding the interactions between galaxies, their evolution, and the influence of their surroundings is essential to developing a more comprehensive model of how and where life might emerge and persist across the Universe.

Adrian Kazakov (1), Anna Milillo (1), Alessandro Mura (1), Stavro Ivanovski (2), Valeria Mangano (1), Alessandro Aronica (1), Elisabetta De Angelis (1), Pier Paolo Di Bartolomeo (1), Alessandro Brin (1), Luca Colasanti (1), Miguel Escalona-Moran (3), Francesco Lazzarotto (4), Stefano Massetti (1), Martina Moroni (1), Raffaella Noschese (1), Fabrizio Nuccilli (1), Stefano Orsini (1), Christina Plainaki (5), Rosanna Rispoli (1), Roberto Sordini (1), Mirko Stumpo (1), Nello Vertolli (1) ((1) INAF-IAPS, Rome, Italy, (2) INAF-Osservatorio Astronomico di Trieste, Trieste, Italy, (3) Augmented Intelligence Lab, Salceda de Caselas, Spain, (4) INAF-Osservatorio Astronomico di Padova, Padova, Italy, (5) ASI - Italian Space Agency, Rome, Italy)

this https URL . This article is identical to v2.5 of the aforementioned collection: DOI this https URL

Surface information derived from exospheric measurements at planetary bodies complements surface mapping provided by dedicated imagers, offering critical insights into surface release processes, interactions within the planetary environment, space weathering, and planetary evolution. This study explores the feasibility of deriving Mercury's regolith elemental composition from in-situ measurements of its neutral exosphere using deep neural networks (DNNs). We present a supervised feed-forward DNN architecture - a multilayer perceptron (MLP) - that, starting from exospheric densities and proton precipitation fluxes, predicts the chemical elements of the surface regolith below. It serves as an estimator for the surface-exosphere interaction and the processes leading to exosphere formation. Because the DNN requires a comprehensive exospheric dataset not available from previous missions, this study uses simulated exosphere components and simulated drivers. Extensive training and testing campaigns demonstrate the MLP's ability to accurately predict and reconstruct surface composition maps from these simulated measurements. Although this initial version does not aim to reproduce Mercury's actual surface composition, it provides a proof of concept, showcasing the algorithm's robustness and capacity for handling complex datasets to create estimators for exospheric generation models. Moreover, our tests reveal substantial potential for further development, suggesting that this method could significantly enhance the analysis of complex surface-exosphere interactions and complement planetary exosphere models. This work anticipates applying the approach to data from the BepiColombo mission, specifically the SERENA package, whose nominal phase begins in 2027.

Till Sawala (1 and 2), Meri Teeriaho (1) ((1) University of Helsinki, (2) Durham University)

The so-called "Giant Arc" is a sparse pattern of MgII absorbers spanning approximately 740 comoving Mpc, whose discovery has been claimed to contradict the large-scale homogeneity inherent to the standard cosmological model. We previously showed that, with the same algorithm and parameters used for its discovery, very similar patterns are abundant in uniform random distributions, and among equivalent halo samples in a cosmological simulation of the standard model. In a response, the original discoverers of the "Giant Arc" have argued that these parameters were only appropriate for their specific observational data, but that a smaller linking length should be used for control studies, in which case far fewer patterns are detected. We briefly review and disprove these arguments, and demonstrate that large patterns like the "Giant Arc" are indeed ubiquitous in a statistically homogeneous universe.

Linh Han Than, Klaus Scherer, Horst Fichtner

The special relativistic generalization of isotropic regularized kappa distributions is derived and compared to that of the original Olbertian (or standard) kappa distributions. It is demonstrated that for the latter the kappa parameter is even stronger limited than in the non-relativistic case, while for the former all positive kappa values remain possible. After a derivation of the non-relativistic limits, the pressures of the distributions are studied as a specific case of the moments of both the relativistic standard and regularized kappa distributions.

Context. Mounting evidence has shown that EUV waves consist of a fast-mode magnetohydrodynamic (MHD) wave (or shock wave) followed by a slower nonwave component, as predicted by the magnetic fieldline stretching model. However, not all observed events display both wavefronts, particularly the slower nonwave component. Even in case that the slower nonwave component is present, the intensity distribution often exhibits strong anisotropy. Aims. This study is intended to unveil the formation condition of the slower nonwave component of EUV waves. Methods. We analyzed the EUV wave event on 8 March 2019, and compared the EUV wave intensity map with the extrapolation coronal potential magnetic field. Data-inspired MHD simulation was also performed. Results. Two types of EUV waves are identified, and the slower nonwave component exhibits strong anisotropy. By reconstructing 3D coronal magnetic fields, we found that the slower nonwave component of EUV waves is more pronounced in the regions where magnetic fields are backward-inclined, which is further reproduced by our MHD simulations. Conclusions. The anisotropy of the slower nonwave component of EUV waves is strongly related to the magnetic configuration, with backward-inclined field lines favoring their appearance. The more the field lines are forward-inclined, the weaker such wavelike fronts are.

Kosuke Aizawa, Ryosuke Akizawa, Scott Cray, Shaul Hanany, Shotaro Kawano, Jürgen Koch, Kuniaki Konishi, Rex Lam, Tomotake Matsumura, Haruyuki Sakurai, Ryota Takaku

We present designs and fabrication of sub-wavelength anti-reflection (AR) structures on alumina for infrared absorptive filters with passbands near 30, 125, and 250 GHz. These bands are widely used by ground-based instruments measuring the cosmic microwave background radiation. The designs are tuned to provide reflectance of 2% or less for fractional bandwidths between 51% and 72%, with each of the three primary bands containing two sub-bands. We make the sub-wavelength structures (SWS), which resemble a two-dimensional array of pyramids, using laser ablation. We measure the shapes of the fabricated pyramids and show that for incidence angles up to 20 degrees the predicted in-band average reflectance is 2% or less, in agreement with the design. The band average instrumental polarization is less than 3×103.

We performed a search for new dwarf galaxies in a direction towards the southwestern part of the Local Void using the data on DESI Legacy Imaging Surveys. In a sky area of 1000 square degrees, we discovered 12 candidates to nearby dwarfs with a high confidence. Four of them are probable new companions to the nearby galaxy M\,83 and others are isolated objects. We found also 20 nearby dwarf candidates with a low confidence. Almost all of the detected galaxies are classified as late type dwarfs. A new cluster of bluish stars with an angular diameter of 0.9 is revealed by us at a high galactic latitude, b=29. Being at a distance of 70 kpc, it can be a globular cluster associated with the Milky Way stellar stream Sagittarius dSph or a new ultra-faint satellite of the Milky Way.

Casper Farret Jentink, Francesco Pepe, Christophe Lovis, Christian Schwab, François Wildi, Andrew Clawson

High-resolution spectroscopy (R>50,000) in astronomy typically uses echelle-type spectrographs, which excel for exoplanet detection via radial velocity but compromise throughput for atmospheric characterization. We propose and test a novel method to achieve very high spectral resolution with significantly higher throughput within a limited bandpass using a tuned, high fringe-density volume phase holographic (VPH) grating in double pass. Using a wavelength-tunable laser, we measured the dispersion and diffraction efficiency of this setup, finding that our tested VPH grating reaches a diffraction-limited resolving power >140,000 in double pass with a peak diffraction efficiency of 79% for unpolarized light. Based on current manufacturing capabilities, we estimate double-pass diffraction efficiencies >50% with resolving powers >200,000 are achievable from visible to near-infrared wavelengths, limited only by detector size.

Iris D. Boer, Harrison Nicholls, Tim Lichtenberg

Climate transitions on exoplanets offer valuable insights into the atmospheric processes governing planetary habitability. Previous pure-steam atmospheric models show a thermal limit in outgoing long-wave radiation, which has been used to define the inner edge of the classical habitable zone and guide exoplanet surveys aiming to identify and characterize potentially habitable worlds. We expand upon previous modelling by treating (i) the dissolution of volatiles into a magma ocean underneath the atmosphere, (ii) a broader volatile range of the atmospheric composition including H2O, CO2, CO, H2, CH4 and N2, and (iii) a surface temperature- and mantle redox-dependent equilibrium chemistry. We find that multi-component atmospheres of outgassed composition located above partially or fully-molten mantles do not exhibit the characteristic thermal radiation limit that arises from pure-steam models, thereby undermining the canonical concept of a runaway greenhouse limit, and hence challenging the conventional approach of using it to define an irradiation-based habitable zone. Our results show that atmospheric heat loss to space is strongly dependent on the oxidation and melting state of the underlying planetary mantle, through their significant influence on the atmosphere's equilibrium composition. This suggests an evolutionary hysteresis in climate scenarios: initially molten and cooling planets do not converge to the same climate regime as solidified planets that heat up by external irradiation. Steady-state models cannot recover evolutionary climate transitions, which instead require self-consistent models of the temporal evolution of the coupled feedback processes between interior and atmosphere over geologic time.

We study the magnetic reconnection during a flare by investigating flare ribbon dynamics using observations and data-constrained magnetohydrodynamics (MHD) simulation. In particular, we estimate the reconnection flux and the reconnection flux rates using flare ribbons of an M1.1 flare hosted by the active region 12184 utilizing the technique developed by Qiu et al. (2002, ApJ, 565, 1335). The reconnection flux and corresponding flux rates are found to be 10^20 Mx and 10^18 Mx/s respectively. To understand the flare onset and the origin of flare ribbons, we perform an MHD simulation initiated by the non-force-free-field extrapolation. Importantly, the extrapolated configuration identifies a three-dimensional (3D) magnetic neutral point and a flux rope in the flaring region, which is crucial to the flaring activity. The reconnection initiates at the null point and, subsequently the flux rope rises and appears to reconnect there, which is favorable for the eruption of the filament. The surrounding field lines also seem to take part in the null point reconnection. In later stage, a current sheet is formed below the null point ensuing a secondary reconnection near an X-type topology, further contributing to the energy release process in the flare. We trace the footpoint evolution of the field lines lying over the flare ribbons and find a significant similarity between the observed flare ribbons and the evolution of footpoints computed from the MHD simulation. We estimated induced electric field during the flare and found it to be .52 V/cm, a slight less value, as per many past literatures. Additional findings are the enhancement of vertical current density near the flaring ribbons, a signature of successive reconnections near the null point. Overall, the present work contributes to the understanding of the ribbon formation in a flaring process and the involved magnetic reconnection.

S. Molinari, J.D. Soler, V.-M. Pelkonen, A. Nucara, E. Schisano, A. Traficante, C. Mininni, M. Benedettini, A. Coletta, D. Elia, S. Pezzuto

The PRIMAger instrument on board the proposed PRIMA satellite will offer the unprecedented capability to obtain hundreds of square-degree maps in polarised emission at sub-arcminute resolution in four Far-IR bands. This will open a unique window to study magnetic fields in our Galaxy. PRIMAGAL, a proposed survey of polarized dust emission in the Milky Way Galactic Plane will determine the strength and orientation of magnetic fields towards several thousands of filamentary clouds in a wide range of linear masses, column densities, evolution, star-formation rates and efficiencies, and Galactic environment. This survey will address for the first time in a statistically significant fashion the role that magnetic fields play in shaping the formation, evolution and fragmentation of dense ISM filaments down to a minimum scale of 0.4 pc up to 8 kpc distance from the Sun. A 4-band polarization survey of the Galactic Plane with |b|<1° (a total of 720 sq. deg.) can be executed by PRIMAger in about 1200 hours including all mapping and instrument overhead.

Inflation in cosmology is a specific stage preceding the Big Bang, aimed at solving both old background problems and new perturbation issues. Single-field inflation is a candidate to illustrate the picture of the initial universe, and various potential functions lead to different scenarios during the inflationary stage. This paper introduces two essential parameters: the spectral index and the tensor-to-scalar ratio detected from the initial power spectrum, derived from the action of the scalar field and using approximation that the potential is flat. A brief overview of the origins of Starobinsky Inflation, Chaotic Inflation, Small Field Inflation, and Natural Inflation is also presented, along with their mathematical representations. Finally, the results derived from various inflation models regarding the index and ratio are tested using the Planck data, and the deviations in each model are analyzed.

Ainun Azhari (1, 2, 3), Tadafumi Matsuno (3, 4), Wako Aoki (1, 2), Miho N Ishigaki (1, 2, 5), Eline Tolstoy (3) ((1) Astronomical Science Program, Graduate Institute for Advanced Studies, SOKENDAI, (2) National Astronomical Observatory of Japan, (3) Kapteyn Astronomical Institute, University of Groningen, (4) Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, (5) Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, The University of Tokyo)

this http URL is the compiled version with the complete Appendix A.3 table. Please include it as an ancillary file

The r-process production in the early universe has been well constrained by the extensive studies of metal-poor stars. However, the r-process enrichment in the metal-rich regime is still not well understood. In this study, we examine the abundance ratios of Th and Eu, which represent the actinides and lanthanides, respectively, for a sample of metal-rich disk stars. Our sample covers 89 giant stars in the Kepler field with metallicities 0.7[Fe/H]0.4 and ages from a few hundred Myr to 14 Gyr. Age information for this sample is available from stellar seismology, which is essential for studying the radioactive element Th. We derive Th and Eu abundances through χ2 fitting of high-resolution archival spectra (R80,000) observed with the High Dispersion Spectrograph (HDS) at the Subaru Telescope. We create synthetic spectra for individual stars using a 1D LTE spectral synthesis code, Turbospectrum, adopting MARCS model atmospheres. Our study establishes the use of a less extensively studied Th II line at 5989 angstrom, carefully taking into account the blends of other spectral lines to derive the Th abundance. We successfully determine Eu abundance for 89 stars in our sample and Th for 81 stars. For the remaining 8 stars, we estimate the upper limits of Th abundance. After correcting the Th abundance for the decay, we find no correlation between [Th/Eu] and [Fe/H], which indicates that actinides production with respect to lanthanides does not depend on metallicity. On the other hand, we find a positive correlation of [Th/Eu] with age, with a slope of 0.10±0.04. This may hint at the possibility that the dominant r-process sources are different between the early and late universe.

Eva-Maria Ahrer, Siddharth Gandhi, Lili Alderson, James Kirk, Johanna Teske, Richard A. Booth, Catriona H. McDonald, Duncan A. Christie, Alastair B. Claringbold, Rebecca Nealon, Vatsal Panwar, Dimitri Veras, Hannah R. Wakeford, Peter J. Wheatley, Maria Zamyatina

The discovery of hot Jupiters that orbit very close to their host stars has long challenged traditional models of planetary formation and migration. Characterising their atmospheric composition - mainly in the form of the carbon-to-oxygen (C/O) ratio and metallicity - can provide insights into their formation locations and evolution pathways. With JWST we can characterise the atmospheres of these types of planets more precisely than previously possible, primarily because it allows us to determine both their atmospheric oxygen and carbon composition. Here, we present a JWST NIRSpec/G395H transmission spectrum from 2.8-5.1μm of WASP-94Ab, an inflated hot Jupiter with a retrograde misaligned orbit around its F-type host star. We find a relatively cloud-free atmosphere, with absorption features of H2O and CO2 at detection significances of 4σ and 11σ, respectively. In addition, we detect tentative evidence of CO absorption at 3σ, as well as hints of sulphur with the detection of H2S at a 2.5σ confidence level. Our favoured equilibrium chemistry model determines a C/O ratio of 0.49+0.080.13 for WASP-94Ab's atmosphere, which is substellar compared to the star's C/O ratio of 0.68±0.10. The retrieved atmospheric metallicity is similar to the star's metallicity as both are 2× solar. We find that this sub-stellar C/O ratio and stellar metallicity can be best explained by pebble accretion or planetesimal accretion in combination with large-distance migration of the planet.

In this short paper, we investigate the impact of selecting only a subset of bright galaxies to provide redshift information for a dark standard siren measurement of the Hubble constant H0. Employing gravitational-wave observations from the Third Gravitational-Wave Transient Catalogue (GWTC-3) in conjunction with the GLADE+ galaxy catalogue, we show that restricting to bright galaxy subsets can enhance the precision of the H0 estimate by up to 80% in the most favorable scenario. A comprehensive assessment of systematic uncertainties is still required. This work lays the foundation for employing alternative tracers -- such as brightest cluster galaxies (BCGs) and luminous red galaxies (LRGs) -- in gravitational-wave cosmology, particularly at redshifts where conventional galaxy catalogues offer limited coverage.

J. Alfonso-Garzón, J. van den Eijnden, N.P.M. Kuin, F. Fürst, A. Rouco-Escorial, J. Fabregat, P. Reig, J.M. Mas-Hesse, P.A. Jenke, C. Malacaria, C. Wilson-Hodge

this https URL , corresponding to preprint: arXiv:2312.08080

An error was detected in the code of one of the components considered to model the optical/UV emission of the Galactic ULX pulsar Swift J0243.6+6124 during its 2017 giant outburst. This led to an overestimation of the contribution from the X-ray heated surface of the Be star. The addition of the X-ray irradiation of a misaligned Be disk to our model is proposed to explain the observations. Preliminary results of the updated model provide good fit to the data.

Rahul Sharma, Chetana Jain, Biswajit Paul, Anjan Dutta, Vikram Rana

The detection and characterization of periodic X-ray signals are crucial for identifying new compact objects and studying the mechanisms powering their emission. We report on the timing and spectral variability of CXOU J204734.8+300105, a proposed eclipsing polar-type cataclysmic variable (CV) candidate. This source has been observed once with Chandra and twice with XMM-Newton, revealing several intriguing and conflicting features in its X-ray emission. The Chandra observation showed a periodicity of 6000 s with an eclipse-like feature. The X-ray light curve from 2017 XMM-Newton observation showed a period of 2000 seconds without any apparent eclipse, while the simultaneous optical light curve from OM showed a period of 6000 seconds. This variability raises questions about the true nature of the source. Spectral analysis indicates a multi-component emission and emission lines due to Fe. The spectral characteristics are consistent with those observed in other CV systems. Additionally, we identified optical and near-infrared counterparts from various catalogues. Our findings suggest a dynamic and evolving accretion environment of CXOU J204734.8+300105.

We report results on the radial velocity dispersion profile built out to the outskirts of NGC 4147, a Milky Way globular cluster with detected strong tidal tails. The cluster was chosen to probe, from an observational point of view, recent simulations that suggest that rising velocity dispersion profiles at large distance from the clusters' centers would be seen in globular clusters without tidal tails. From GEMINI@GMOS spectra, centered in the infrared CaII triplet region, of selected stars located along the onset of NGC 4147's tidal tails, we measured their radial velocities and overall metallicities. The derived metallicities were used to ultimately assessing on the highly-ranked cluster candidates of 9 stars, located between ~ 7 and 33 pc from the cluster's center, suitable for testing the aforementioned simulations. We complemented the present radial velocities with others available in the literature for cluster's members, and built a cluster velocity dispersion profile which suggests a mostly flat or slightly rising profile at large distances from the cluster's center. This outcome confirms that kinematically hot outermost cluster's stars are seen in NGC 4147, which disproves the recent model predictions. Nevertheless, the mean velocity dispersion of the outermost cluster's stars agrees with NGC 4147 being formed in a 10^8-10^9Mo dwarf galaxy with a cored dark matter profile that later was accreted on to the Milky Way.

The systemic recoil velocity (vsys) distribution of millisecond pulsars (MSPs) is essential for understanding the MSP formation and estimating the retention fractions of MSPs in star clusters, which can potentially be determined with astrometric studies that take into account MSPs' long-term dynamic evolution and the scarcity of radial velocity measurements. We compiled 65 isolated (or field) MSP systems (including lone MSPs) that are well astrometrically determined, and calculated their transverse peculiar (or space) velocities \boldsymbol{v}_\perp and Galactic heights z. We find that the observed Galactic-longitude components v_\mathrm{l} of \boldsymbol{v}_\perp can be well described by a linear combination of three normal distributions. Assuming that 1) v_\mathrm{l} are statistically stable over time (the "stable-v_\mathrm{l}" assumption), and 2) \boldsymbol{v}_\mathrm{sys} directions are uniformly distributed (the "isotropic-\boldsymbol{v}_\mathrm{sys}" assumption), the MSP v_\mathrm{sys} distribution can be approximated by a linear combination of three Maxwellian components. Our dynamical population synthesis analysis based on the derived v_\mathrm{sys} distribution verified the "stable-v_\mathrm{l}" assumption in the parameter space of this work, and estimated the initial and the current Galaxy-wide scale heights of isolated MSP systems to be about 0.32 kpc and 0.66 kpc, respectively. According to the MSP v_\mathrm{sys} distribution, \sim13% of all the MSPs born in a globular cluster (GC) with the nominal 50 \mathrm{km~s^{-1}} central escape velocity can be retained. Therefore, the v_\mathrm{sys} distribution of isolated MSP systems may account for the high number of MSPs discovered in GCs, which implies that MSPs in star clusters may follow the same formation channel(s) as isolated MSP systems.

Pierre Marchand, Audrey Coutens, Antoine Espagnet, Fernando Cruz-Sáenz de Miera, Jean-Christophe Loison, Valentine Wakelam

Chemical modeling and synthetic observations are powerful methods to interpret observations, both requiring a knowledge of the physical conditions. In this paper, we present the Analytical Protostellar Environment (APE) code, which aims at making chemical simulations and synthetic observations accessible. APE contains a physical model of protostellar evolution (including the central object, the envelope, the protoplanetary disk and the outflow) as well as interfaces to publicly available codes to perform chemical simulations, radiative transfer calculations, and synthetic interferometry imaging. APE produces density and temperature maps of protostellar systems. The code can also follow individual particles throughout their journey in a collapsing core. APE includes a treatment of the dust grain size-distribution to compute opacities self-consistently for subsequent radiative transfer. We show an example of application of APE by computing chemical abundance maps of CO, CN, CS, H2CO, and CH3OH in a Class I protostellar system. We also performed synthetic ALMA observations of their molecular emission assuming an edge-on source inclination. The moment 0 maps of CO, CS, and H2CO display an X-shaped emission similar to what is observed toward the Class I source IRAS 04302+2247.

James A. Barron, Gregg A. Wade, Gonzalo Holgado, Sergio Simón-Díaz

Surface magnetic fields are detected in less than 10\% of the massive O-type star population and even less frequently among `old' massive stars approaching the terminal-age main sequence (TAMS). It is unclear to what extent the rarity of magnetic detections in massive stars near the TAMS is due to magnetic field decay or observational biases. We report the detection of a weak surface magnetic field in the O-type giant 63~Oph (T_{\mathrm{eff}}=35.0\pm0.3\,kK, \log g=3.51\pm0.03) from new ESPaDOnS circularly polarized spectra. The mean longitudinal field strength associated with the magnetic detection is \langle B_{z}\rangle=84\pm14\,G, which we use to set a lower limit on the dipolar field strength of B_{\mathrm{p}}\geq300\pm50\,G. We report Balmer line equivalent widths (EW) and radial velocity (RV) measurements from the analysis of spectra primarily obtained by the IACOB project with the FEROS, FIES and HERMES spectrographs. We identify a dominant period of \sim19.8\,d in the EWs which we attribute to the effects of a rotating magnetosphere under the Oblique Rotator Model. We do not identify any coherent signals in a time-series analysis of archival Hipparcos, ASAS-SN and K2 photometry. Our findings show that 63~Oph may be a rare link between strongly magnetic massive stars detected on or near the zero-age main sequence and weakly-magnetic O-type supergiants. Additional observations are needed to fully constrain 63~Oph's magnetic field geometry and magnetospheric properties.

A new method for determining the accelerating potential above the polar caps of radio pulsars with an arbitrary inclination angle of the magnetic axis to the rotation axis has been proposed. The approach has been based on the concept of a vacuum gap, the height and shape of the upper boundary of which are found self-consistently together with the solution of the corresponding Poisson equation. In turn, information about the accelerating potential has made it possible to determine the transverse profiles of the secondary plasma density. It has also been shown that the effect of inverse Compton scattering on the considered processes is insignificant.

The advancement in the observational cosmology of the early universe such as Cosmic Microwave Background (CMB) observations, puts severe constraints on the inflationary models. Many inflationary models have been ruled out by CMB, nevertheless the models ruled out in standard cold inflationary scenarios can be resurrected in modified gravity models. In this regard we examine the dynamics of inflation within the framework of Einstein-Gauss-Bonnet (EGB) Gravity using the new slow-roll approximation methods proposed in Pozdeeva et al. (2024). We consider the Mutated Hilltop inflation model (Pal et al., 2010; Pinhero and Pal, 2019) due to its origin from super-gravity, a naturally perfect choice to study the impact of EGB on inflationary observables such as tensor-to-scalar ratio (r) and scalar spectral index (n_s). The period of reheating following the inflationary phase is also examined, and for the {\it Planck'18} permitted values of n_s, constraints on the reheating temperature (T_{re}) are computed for various equations of states during reheating (\omega_{re}).

Lynne A. Hillenbrand, Adolfo S. Carvalho, Dan Stern, Michael Connelley, Facundo Pérez Paolino, Ahaan Shetty, Zachariah Milby, Howard Isaacson

We present a newly appreciated FU Ori outburst event that began in 2019 and reached a peak in early 2021. Suspected young stellar object WISE J054452.25+333009.6 experienced substantial brightening, in excess of -5 mag at optical wavelengths and -2.5 mag at mid-infrared wavelengths. The time from near-quiescence to peak brightness was approximately 24 months. Optical and near-infrared spectra confirm that the outbursting source (hereby designated FUOr-Aur 0544+3330) shows all the hallmarks of the FU Ori class, including the Li I indicator of stellar youth. The mix of ionized and neutral atomic lines, alongside prominent molecular absorption features, is consistent with the expected change in spectral type from earlier in the optical to later-type in the near-infrared. The closest analog among well-studied FU Ori objects is V1515 Cyg. Both sources have unusually narrow-lined absorption spectra that can be explained by a face-on disk orientation, such that disk-broadening is minimized and wind-induced blueshift (in e.g. H\alpha, NaD, Ca II) is maximized. Both the optical through infrared spectral energy distribution and high-resolution spectrum are well-fit by a pure-accretion disk model. Adopting a distance of d=1.5 kpc, the accretion and central star parameters are: \dot{M} = 10^{-5.48} M_\odot yr^{-1}, M_* = 0.17 \ M_\odot, and R_\mathrm{inner} = 1.04 \ R_\odot. Other fitted values are disk inclination i=5.9 deg and source extinction A_V=1.83 mag. These parameters yield accretion luminosity L_\mathrm{acc} = 8.4\ L_\odot and maximum disk temperature T_{\rm{max}} = 6218 K.

P. Chris Fragile, Deepika A. Bollimpalli, Jeremy D. Schnittman, Cesare Harvey

We utilize the Monte-Carlo radiation transport code, \pan, to create images, spectra, polarization maps, and light curves from a set of general relativistic magnetohydrodynamic simulations of tilted, truncated, black hole accretion disks. Truncation can have spectral and polarization signatures all its own; tilt introduces both inclination and azimuthal dependencies into the spectra and polarization; and precession and oscillations of the tilted accretion flow inside the truncation radius (what we posit to be the "corona") introduce time dependencies or periodicity to all of this. We use the ray-traced results from our simulations to evaluate the feasibility of measuring these effects, particularly in the context of current and future X-ray polarization observatories. Such detections could greatly improve our understanding of the geometry of accretion disks and coronae in the hard state, the physics of quasi-periodic oscillations (QPOs), and how system properties evolve as sources approach the hard-to-soft state transition.

J. Prathap, A. M. Hopkins, J. Afonso, M. Bilicki, M. Cowley, S. M. Croom, Y. Gordon, S. Phillipps, E. M. Sadler, S. S. Shabala, U. T. Ahmed, S. Amarantidis, M. J. I. Brown, R. Carvajal, D. Leahy, J. R. Marvil, T. Mukherjee, J. Willingham, T. Zafar

This study characterises the radio luminosity functions (RLFs) for SFGs and AGN using statistical redshift estimation in the absence of comprehensive spectroscopic data. Sensitive radio surveys over large areas detect many sources with faint optical and infrared counterparts, for which redshifts and spectra are unavailable. This challenges our attempt to understand the population of radio sources. Statistical tools are often used to model parameters (such as redshift) as an alternative to observational data. Using the data from GAMA G23 and EMU early science observations, we explore simple statistical techniques to estimate the redshifts in order to measure the RLFs of the G23 radio sources as a whole and for SFGs and AGN separately. Redshifts and AGN/SFG classifications are assigned statistically for those radio sources without spectroscopic data. The calculated RLFs are compared with existing studies, and the results suggest that the RLFs match remarkably well for low redshift galaxies with an optical counterpart. We use a more realistic high redshift distribution to model the redshifts of (most likely) high redshift radio sources and find that the LFs from our approach match well with measured LFs. We also look at strategies to compare the RLFs of radio sources without an optical counterpart to existing studies.

Rafael Ottersberg, Antoine Pommerol, Linus Leo Stöckli, Lorenzo Obersnel, André Galli, Axel Murk, Peter Wurz, Nicolas Thomas

We study the evolution of the Vis-NIR reflectance spectrum of salty granular ice analog samples in a simulation chamber under conditions relevant to the surface of Europa. A novel application and custom calibration of a thermopile sensor enabled the measurement of the surface temperature of the samples in far infrared emission. This allows the kinetics of the observed changes to be scaled to equivalent timescales on Europa. We observed significant changes in the depth and shape of the broad water absorption bands for all samples on timescales of a few thousand years of equatorial conditions on Europa. This effect should be taken into account if quantitative predictions about bulk composition are made based on remote-sensing data. A narrow absorption feature attributed to hydrohalite formed during the sublimation of the sodium chloride sample. We used near-infrared spectroscopy in an irradiation chamber to assess the stability of this narrow feature under electron irradiation. We find that the radiation environment present on Europa dehydrates the hydrohalite on short timescales. Therefore, we expect hydrohalite not to be present on the surface, unless erupted very recently (< 10 yr) or located in thermal anomalies (> 145 K). Thus, a detection of hydrohalite would clearly indicate recent activity.

Active galactic nuclei formation and evolution is currently an open puzzle. Their enormous mass is not explainable via sub-Eddington accretion and the frequent presence of relativistic jets at high-z, commonly linked with spinning black holes, suggest a less effective accretion process. NVSS J151002+570243 is part of this population, being the most distant blazar consistently detected by Fermi/LAT, hence hosting a powerful jet. We tested the hypothesis of a super-Eddington accretion process for this source by modeling its big blue bump with a set of accretion disk emission models. We first tested a standard geometrically thin, optically thick \alpha-disk, obtaining a mass of LogM/M_\odot=8.65\pm0.19 consistent with virial-based results and a significantly sub-Eddington accretion rate \lambda=0.02\pm0.01. We then focused on the analytic approximations of two numerical models that take into account the General Relativity effects of a spinning black hole (reasonable due to the presence of a jet) and a close-to- or super-Eddington accretion rate (KERBB and SLIMBH). Despite the focus on super-critical accretion, these models confirm a surprisingly low Eddington ratio, of the order of 3\%. The hypothesis of a continuous accretion at this measured rate is unrealistic, since it would imply a seed black hole mass of \sim10^6-10^8M_\odot at redshift z=20. Hence we explore the possibility of a continuous super-critical accretion starting from a \sim10^2M_\odot seed, that would spin up the black hole and eventually contribute in launching the relativistic jet. The measured low accretion rate would thus happen only once the jet is active. This idea would reconcile the black holes with large masses accreting at somewhat slow rates that are observed at z>4, with the need of an extremely fast evolution, by allowing the formation of stellar-size black hole seeds even as late as at z\sim8.

Cosmological observations of the recent universe suggest that dark energy equation of state parameter w is growing with time, departing from a cosmological constant for which w=-1. Standard quintessence models allow for a varying w\geq-1, but observations report that a phantom regime, w<-1, is quickly reached in the past. Often discarded because of uncertainties or parametrisation, we rather propose here to embrace the reality of this phantom regime. We revisit an elegant mechanism that accounts for it, thanks to a coupling of quintessence field(s) to matter (and possibly radiation). We show that this allows for steep scalar potentials, and illustrate this with string-inspired models, where V=V_0\, e^{-\lambda\, \varphi} and \lambda \geq \sqrt{2}. Those provide solutions in very good agreement with observations, including the phantom regime. We then discuss poles that can appear in w, making it diverge at recent times (z\leq 4), and that could be detected by observations. We finally comment on an Early Dark Energy-like feature, that systematically appears for free from the models considered, and could be of interest for the Hubble tension.

Spontaneous CP violation during the electroweak phase transition can induce a twisting of the magnetic field configuration of Standard Model dumbbells, resulting in sizable intergalactic magnetic fields and a small baryon asymmetry, in agreement with observations. We demonstrate this by coupling the electroweak gauge group of the Standard Model to an axion-like particle with a non-vanishing velocity. Studying the resulting monopole, string and dumbbell configurations, we conclude that the helicity fraction of the magnetic fields generated at the electroweak phase transition is roughly given by the dimensionless axion velocity.

We numerically investigate the orbital dynamics of a two-dimensional galactic model, emphasizing the influence of stable and unstable manifolds on the evolution of orbits. In our analysis we use evaluations of the system's Lagrangian descriptors to reveal the structure and location of manifolds. In addition, we perform extensive computations of the forward and backward in time evolution of ensembles of orbits, which allow us to study the future and past dynamics of the model by constructing its so-called origin-fate maps. Focusing on the properties of the escape of orbits from the central regions of the model's configuration space, we analyze various aspects of the orbits' evolutions, like the time an orbit needs to escape from the central region, the total time it spends at the exterior areas of the galaxy, as well as the number of its escapes and reentries from and to the central region. Furthermore, we follow the past and future evolution of orbits keeping track of the regions from which they leave the central parts of the galaxy, and relate different orbital behaviors with the enhancement of specific morphological features in the system's configuration space. Our results indicate that the stable (unstable) manifolds mainly influence the orbital characteristics of the model in the future (past).

We study graviton-photon conversion in the presence of stochastic magnetic fields. Assuming Gaussian magnetic fields that may possess nontrivial helicity, and unpolarized gravitational waves (GWs) as the initial state, we obtain expressions for the intensity and linear/circular polarizations of GWs after propagation over a finite distance. We calculate both the expectation values and variances of these observables, and find their nontrivial dependence on the typical correlation length of the magnetic field, the propagation distance, and the photon plasma mass. Our analysis reveals that an observationally favorable frequency range with narrower variance can emerge for the intensity, while a peak structure appears in the expectation value of the circular polarization when the magnetic field has nonzero helicity. We also identify a consistency relation between the GW intensity and circular polarization.