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Papers for Friday, Oct 04 2024

Papers with local authors

Rohan P. Naidu, Jorryt Matthee, Ivan Kramarenko, Andrea Weibel, Gabriel Brammer, Pascal A. Oesch, Peter Lechner, Lukas J. Furtak, Claudia Di Cesare, Alberto Torralba, Gauri Kotiwale, Rachel Bezanson, Rychard J. Bouwens, Vedant Chandra, Adélaïde Claeyssens, A. Lola Danhaive, Anna Frebel, Anna de Graaff, Jenny E. Greene, Kasper E. Heintz, Alexander P. Ji, Daichi Kashino, Harley Katz, Ivo Labbe, Joel Leja, Yijia Li, Michael V. Maseda, Johan Richard, Irene Shivaei, Robert A. Simcoe, David Sobral, Katherine A. Suess, Sandro Tacchella, Christina C. Williams

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Paper 5 — arXiv:2410.01874
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Paper 5 — arXiv:2410.01874

Dwarf galaxies hold the key to crucial frontiers of astrophysics, however, their faintness renders spectroscopy challenging. Here we present the JWST Cycle 2 survey, All the Little Things (ALT, PID 3516), which is designed to seek late-forming Pop III stars and the drivers of reionization at z67. ALT has acquired the deepest NIRCam grism spectroscopy yet (7-27 hr), at JWST's most sensitive wavelengths (3-4 μm), covering the powerful lensing cluster Abell 2744. Over the same 30 arcmin2, ALT's ultra-deep F070W+F090W imaging (30 mag) enables selection of very faint sources at z>6. We demonstrate the success of ALT's novel ``butterfly" mosaic to solve spectral confusion and contamination, and introduce the ``Allegro" method for emission line identification. By collecting spectra for every source in the field of view, ALT has measured precise (R1600) redshifts for 1630 sources at z=0.28.5. This includes one of the largest samples of distant dwarf galaxies: [1015, 475, 50] sources less massive than the SMC, Fornax, and Sculptor with log(M/M)<[8.5, 7.5, 6.5]. We showcase ALT's discovery space with: (i) spatially resolved spectra of lensed clumps in galaxies as faint as MUV15; (ii) large-scale clustering -- overdensities at z=[2.50, 2.58, 3.97, 4.30, 5.66, 5.77, 6.33] hosting massive galaxies with striking Balmer breaks; (iii) small-scale clustering -- a system of satellites around a Milky Way analog at z6; (iv) spectroscopically confirmed multiple images that help constrain the lensing model underlying all science in this legacy field; (v) sensitive star-formation maps based on dust-insensitive tracers such as Paα; (vi) direct spectroscopic discovery of rare sources such as AGN with ionized outflows. These results provide a powerful proof of concept for how grism surveys maximize the potential of strong lensing fields.

Christina C. Williams, Pascal A. Oesch, Andrea Weibel, Gabriel Brammer, Aidan P. Cloonan, Katherine E. Whitaker, Laia Barrufet, Rachel Bezanson, Rebecca A. A. Bowler, Pratika Dayal, Marijn Franx, Jenny E. Greene, Anne Hutter, Zhiyuan Ji, Ivo Labbé, Sinclaire M. Manning, Michael V. Maseda, Mengyuan Xiao

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Paper 6 — arXiv:2410.01875
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Paper 6 — arXiv:2410.01875

We present the PANORAMIC survey, a pure parallel extragalactic imaging program with NIRCam observed during JWST Cycle 1. The survey obtained 530 sq arcmin of NIRCam imaging from 1-5μm, totaling 192 hours of science integration time. This represents the largest on-sky time investment of any Cycle 1 GO extragalactic NIRCam imaging program by nearly a factor of 2. The survey includes 432 sq arcmin of novel sky area not yet observed with JWST using at least 6 NIRCam broad-band filters, increasing the existing area covered by similar Cycle 1 data by 60%. 70 square arcmin was also covered by a 7th filter (F410M). A fraction of PANORAMIC data (200 sq arcmin) was obtained in or around extragalactic deep-fields, enhancing their legacy value. Pure parallel observing naturally creates a wedding cake survey with both wide and ultra-deep tiers, with 5σ point source depths at F444W ranging from 27.8-29.4 (ABmag), and with minimized cosmic variance. The 6+ filter observing setup yields remarkably good photometric redshift performance, achieving similar median scatter and outlier fraction as CANDELS (σNMAD0.07; η0.2), which enables a wealth of science across redshift without the need for followup or ancillary data. We overview the proposed survey, the data obtained as part of this program, and document the science-ready data products in the first data release. PANORAMIC has delivered wide-area and deep imaging with excellent photometric performance, demonstrating that pure parallel observations with JWST are a highly efficient observing mode that is key to acquiring a complete picture of galaxy evolution from rare bright galaxies to fainter, more abundant sources at all redshifts.

The physics of turbulence in magnetized plasmas remains an unresolved problem. The most poorly understood aspect is intermittency -- spatio-temporal fluctuations superimposed on the self-similar turbulent motions. We employ a novel machine-learning analysis technique to segment turbulent flow structures into distinct clusters based on statistical similarities across multiple physical features. We find that the previously identified intermittent fluctuations consist of two distinct clusters: i) current sheets, thin slabs of electric current between merging flux ropes, and; ii) double sheets, pairs of oppositely polarized current slabs, possibly generated by two non-linearly interacting Alfvén-wave packets. The distinction is crucial for the construction of realistic turbulence sub-grid models.

Shany Danieli, Erin Kado-Fong, Song Huang, Yifei Luo, Ting S Li, Lee S Kelvin, Alexie Leauthaud, Jenny E. Greene, Abby Mintz, Xiaojing Lin, Jiaxuan Li, Vivienne Baldassare, Arka Banerjee, Joy Bhattacharyya, Diana Blanco, Alyson Brooks, Zheng Cai, Xinjun Chen, Akaxia Cruz, Robel Geda, Runquan Guan, Sean Johnson, Arun Kannawadi, Stacy Y. Kim, Mingyu Li, Robert Lupton, Charlie Mace, Gustavo E. Medina, Yue Pan, Annika H. G. Peter, Justin I. Read, Rodrigo Córdova Rosado, Allen Seifert, Erik J. Wasleske, Joseph Wick
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Paper 14 — arXiv:2410.01884
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Paper 14 — arXiv:2410.01884

We present the Merian Survey, an optical imaging survey optimized for studying the physical properties of bright star-forming dwarf galaxies. Merian is carried out with two medium-band filters (N708 and N540, centered at 708 and 540 nm), custom-built for the Dark Energy Camera (DECam) on the Blanco telescope. Merian covers 750deg2 of equatorial fields, overlapping with the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) wide, deep, and ultra-deep fields. When combined with the HSC-SSP imaging data (grizy), the new Merian DECam medium-band imaging allows for photometric redshift measurements via the detection of Hα and [OIII] line emission flux excess in the N708 and N540 filters, respectively, at 0.06<z<0.10. We present an overview of the survey design, observations taken to date, data reduction using the LSST Science Pipelines, including aperture-matched photometry for accurate galaxy colors, and a description of the data included in the first data release (DR1). The key science goals of Merian include: probing the dark matter halos of dwarf galaxies out to their virial radii using high signal-to-noise weak lensing profile measurements, decoupling the effects of baryonic processes from dark matter, and understanding the role of black holes in dwarf galaxy evolution. This rich dataset will also offer unique opportunities for studying extremely metal-poor galaxies via their strong [OIII] emission and Hα lines, as well as [OIII] emitters at z0.4, and Lyα emitters at z3.3 and z4.8. Merian showcases the power of utilizing narrow and medium-band filters alongside broad-band filters for sky imaging, demonstrating their synergistic capacity to unveil astrophysical insights across diverse astrophysical phenomena.

Abby Mintz, Jenny E. Greene, Erin Kado-Fong, Shany Danieli, Jiaxuan Li, Yifei Luo, Alexie Leauthaud, Vivienne Baldassare, Song Huang, Annika H. G. Peter, Joy Bhattacharyya, Mingyu Li, Yue Pan
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Paper 16 — arXiv:2410.01886
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Paper 16 — arXiv:2410.01886

Using medium-band imaging from the newly released Merian Survey, we conduct a nonparametric morphological analysis of Hα emission maps and stellar continua for a sample of galaxies with 8log(M/M)<10.3 at 0.064<z<0.1. We present a novel method for estimating the stellar continuum emission through the Merian Survey's N708 medium-band filter, which we use to measure Hα emission and produce Hα maps for our sample of galaxies with seven-band Merian photometry and available spectroscopy. We measure nonparametric morphological statistics for the Hα and stellar continuum images, explore how the morphology of the Hα differs from the continuum, and investigate how the parameters evolve with the galaxies' physical properties. In agreement with previous results for more massive galaxies, we find that the asymmetry of the stellar continuum increases with specific star formation rate (SSFR) and we extend the trend to lower masses, also showing that it holds for the asymmetry of the Hα emission. We find that the lowest-mass galaxies with the highest SSFR have Hα emission that is consistently heterogeneous and compact, while the less active galaxies in this mass range have Hα emission that appears diffuse. At higher masses, our data do not span a sufficient range in SSFR to evaluate whether similar trends apply. We conclude that high SSFRs in low-mass galaxies likely result from dynamical instabilities that compress a galaxy's molecular gas to a dense region near the center.

Clarissa R. Do Ó, Saavidra Perera, Jérôme Maire, Jayke S. Nguyen, Vincent Chambouleyron, Quinn M. Konopacky, Jeffrey Chilcote, Joeleff Fitzsimmons, Randall Hamper, Dan Kerley, Bruce Macintosh, Christian Marois, Fredrik Rantakyrö, Dmitry Savranksy, Jean-Pierre Veran, Guido Agapito, S. Mark Ammons, Marco Bonaglia, Marc-Andre Boucher, Jennifer Dunn, Simone Esposito, Guillaume Filion, Jean Thomas Landry, Olivier Lardiere, Duan Li, Alex Madurowicz, Dillon Peng, Lisa Poyneer, Eckhart Spalding
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Paper 24 — arXiv:2410.01960
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Paper 24 — arXiv:2410.01960

The Gemini Planet Imager (GPI) is a high contrast imaging instrument that aims to detect and characterize extrasolar planets. GPI is being upgraded to GPI 2.0, with several subsystems receiving a re-design to improve its contrast. To enable observations on fainter targets and increase performance on brighter ones, one of the upgrades is to the adaptive optics system. The current Shack-Hartmann wavefront sensor (WFS) is being replaced by a pyramid WFS with an low-noise electron multiplying CCD (EMCCD). EMCCDs are detectors capable of counting single photon events at high speed and high sensitivity. In this work, we characterize the performance of the HNü 240 EMCCD from Nüvü Cameras, which was custom-built for GPI 2.0. Through our performance evaluation we found that the operating mode of the camera had to be changed from inverted-mode (IMO) to non-inverted mode (NIMO) in order to improve charge diffusion features found in the detector's images. Here, we characterize the EMCCD's noise contributors (readout noise, clock-induced charges, dark current) and linearity tests (EM gain, exposure time) before and after the switch to NIMO.

H. Sun, W.-X. Li, L.-D. Liu, H. Gao, X.-F. Wang, W. Yuan, B. Zhang, A. V. Filippenko, D. Xu, T. An, S. Ai, T. G. Brink, Y. Liu, Y.-Q. Liu, C.-Y. Wang, Q.-Y. Wu, X.-F. Wu, Y. Yang, B.-B. Zhang, W.-K. Zheng, T. Ahumada, Z.-G. Dai, J. Delaunay, N. Elias-Rosa, S. Benetti, S.-Y. Fu, D. A. Howell, Y.-F. Huang, M. M. Kasliwal, V. Karambelkar, R. Stein, W.-H. Lei, T.-Y. Lian, Z.-K. Peng, A. V. Ridnaia, D.S. Svinkin, X.-Y. Wang, A.-L. Wang, D.-M. Wei, J. An, M. Andrews, J.-M Bai, C.-Y. Dai, S. A. Ehgamberdiev, Z. Fan, J. Farah, H.-C. Feng, J. P. U. Fynbo, W.-J. Guo, Z. Guo, M.-K. Hu, J.-W. Hu, S.-Q. Jiang, J.-J. Jin, A. Li, J.-D. Li, R.-Z. Li, Y.-F. Liang, Z.-X. Ling, X. Liu, J.-R. Mao, C. McCully, D. Mirzaqulov, M. Newsome, E. Padilla Gonzalez, X. Pan, G. Terreran, S. Tinyanont, B.-T. Wang, L.-Z. Wang, X.-D. Wen, D.-F. Xiang, S.-J. Xue, J. Yang, Z.-P. Zhu, Z.-M. Cai, A. J. Castro-Tirado, F.-S. Chen, H.-L. Chen, T.-X. Chen, W. Chen, Y.-H. Chen, Y.-F. Chen, Y. Chen, H.-Q. Cheng, B. Cordier, C.-Z. Cui, W.-W. Cui, Y.-F. Dai, D.-W. Fan, H. Feng, J. Guan, D.-W. Han, D.-J. Hou, H.-B. Hu, M.-H. Huang, J. Huo, S.-M. Jia, Z.-Q. Jia, B.-W. Jiang
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Paper 48 — arXiv:2410.02315
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Paper 48 — arXiv:2410.02315

Massive stars end their life as core-collapse supernovae, amongst which some extremes are Type Ic broad-lined supernovae associated with long-duration gamma-ray bursts (LGRBs) having powerful relativistic jets. Their less-extreme brethren make unsuccessful jets that are choked inside the stars, appearing as X-ray flashes or low-luminosity GRBs. On the other hand, there exists a population of extragalactic fast X-ray transients (EFXTs) with timescales ranging from seconds to thousands of seconds, whose origins remain obscure. Known sources that contribute to the observed EFXT population include the softer analogs of LGRBs, shock breakouts of supernovae, or unsuccessful jets. Here, we report the discovery of the bright X-ray transient EP240414a detected by the Einstein Probe (EP), which is associated with the Type Ic supernova SN 2024gsa at a redshift of 0.401. The X-ray emission evolution is characterised by a very soft energy spectrum peaking at < 1.3 keV, which makes it distinct from known LGRBs, X-ray flashes, or low-luminosity GRBs. Follow-up observations at optical and radio bands revealed the existence of a weak relativistic jet that interacts with an extended shell surrounding the progenitor star. Located on the outskirts of a massive galaxy, this event reveals a new population of explosions of Wolf-Rayet stars characterised by a less powerful engine that drives a successful but weak jet, possibly owing to a progenitor star with a smaller core angular momentum than in traditional LGRB progenitors.

Li-Yuan Lu, Jiang-Tao Li, Carlos J. Vargas, Taotao Fang, Robert A. Benjamin, Joel N. Bregman, Ralf-Jürgen Dettmar, Jayanne English, George H. Heald, Yan Jiang, Q. Daniel Wang, Yang Yang
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Paper 50 — arXiv:2410.02347
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Paper 50 — arXiv:2410.02347

The kinematic information of the extraplanar diffuse ionized gas (eDIG) around galaxies provides clues to the origin of the gas. The eDIG-CHANGES project studies the physical and kinematic properties of the eDIG around the CHANG-ES sample of nearby edge-on disk galaxies. We use a novel multi-slit narrow-band spectroscopy technique to obtain the spatial distribution of spectral properties of the ionized gas around NGC 891, which is often regarded as an analog of the Milky Way. We developed specific data reduction procedures for the multi-slit narrow-band spectroscopy data taken with the MDM 2.4m telescope. The data presented in this paper covers the Hα and [N II]λλ6548,6583Åemission lines. The eDIG traced by the Hα and [N II] lines shows an obvious asymmetric morphology, being brighter in the northeastern part of the galactic disk and extending a few kpc above and below the disk. Global variations in the [N II]/Hα line ratio suggest additional heating mechanisms for the eDIG at large heights beyond photoionization. We also construct position-velocity (PV) diagrams of the eDIG based on our optical multi-slit spectroscopy data and compare them to similar PV diagrams constructed with the H I data. The dynamics of the two gas phases are generally consistent with each other. Modeling the rotation curves at different heights from the galactic mid-plane suggests a vertical negative gradient in turnover radius and maximum rotation velocity, with magnitudes of approximately 3 kpc kpc1 and 2225 km s1 kpc1, respectively. Measured vertical gradients of the rotation curve parameters suggest significant differential rotation of the ionized gas in the halo, or often referred to as the lagging eDIG. Systematic study of the lagging eDIG in our eDIG-CHANGES project, will help us to better understand the dynamics of the ionized gas in the halo.

Andy Lee, Hao-Yi Wu, Andrés N. Salcedo, Tomomi Sunayama, Matteo Costanzi, Justin Myles, Shulei Cao, Eduardo Rozo, Chun-Hao To, David H. Weinberg, Lei Yang, Conghao Zhou
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Paper 57 — arXiv:2410.02497
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Paper 57 — arXiv:2410.02497

Galaxy clusters identified in optical imaging surveys suffer from projection effects: physically unassociated galaxies along a cluster's line of sight can be counted as its members and boost the observed richness (the number of cluster members). To model the impact projection on cluster cosmology analyses, we apply a halo occupation distribution model to N-body simulations to simulate the red galaxies contributing to cluster members, and we use the number of galaxies in a cylinder along the line-of-sight (counts-in-cylinders) to model the impact of projection on cluster richness. We compare three projection models: uniform, quadratic, and Gaussian, and we convert between them by matching their effective cylinder volumes. We validate our mock catalogs using SDSS redMaPPer data vectors, including cluster abundance vs. richness, stacked lensing signal, spectroscopic redshift distribution of member galaxies, and richness re-measured on a redshift grid. We find the former two are insensitive to the projection model, while the latter two favor a quadratic projection model with a width of 180 Mpc/h (equivalent to the volume of a uniform model with a width of 100 Mpc/h and a Gaussian model with a width of 110 Mpc/h, or a Gaussian redshift error of 0.04). Our framework provides an efficient and flexible way to model optical cluster data vectors, paving the way for a simulation-based joint analysis for clusters, galaxies, and shear.

The extinction law from ultraviolet (UV) to infrared (IR) (0.2-24 μm) is determined by relying on the blue-edge method and color excess ratios for some nearby molecular clouds, from low mass star forming region to massive star forming region. The observational data are collected from nine photometric surveys, along with stellar parameters from the APOGEE and LAMOST spectroscopic surveys. Within the uncertainties, the optical ratio of selective to total extinction (RGBP) does not vary substantially across the clouds, irrespective of the density, specifically RGBP=2.302±0.027, where RGBPAGBP/EGBP,GRP. The IR extinction law is consistent with \citet{Wang19_law}. The extinction law in the UV band is compromised by the shallow depth with AV2 mag and is hard to describe by one parameter R. In addition, the extinction in the WISE/W1 band is significantly larger than in the Spitzer/IRAC1 band in the dense regions, which is attributed to the ice water absorption.

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Searches for variations of fundamental constants require a comprehensive understanding of measurement errors. This paper examines a source of error that is usually overlooked: the impact of continuum placement error. We investigate the problem using a high resolution, high signal to noise spectrum of the white dwarf G191B2B. Narrow photospheric absorption lines allow us to search for new physics in the presence of a gravitational field approximately 104 times that on Earth. Modelling photospheric lines requires knowing the underlying spectral continuum level. We describe the development of a fully automated, objective, and reproducible continuum estimation method. Measurements of the fine structure constant are produced using several continuum models. The results show that continuum placement variations result in small systematic shifts in the centroids of narrow photospheric absorption lines which impact significantly on fine structure constant measurements. This effect should therefore be included in the error budgets of future measurements. Our results suggest that continuum placement variations should be investigated in other contexts, including fine structure constant measurements in stars other than white dwarfs. The analysis presented here is based on NiV absorption lines in the photosphere of G191B2B. Curiously, the inferred measurement of the fine structure constant obtained in this paper using NiV (the least negative of our measurements is Δα/α=1.462±1.121×105) is inconsistent with the most recent previous G191B2B photospheric measurement using FeV (Δα/α=6.36±0.35stat±1.84sys×105). Given both measurements are derived from the same spectrum, we presume (but in this work are unable to check) that this 3.2σ difference results from unknown laboratory wavelength systematics.

We provide a detailed commentary on the energy calibration of the TA experiment described in our paper (arXiv:2404.16948 [astro-ph.HE]). That paper concludes that the TA energy estimation, which is tied to optical measurements, might be incorrect. A response from members of the TA Collaboration (arXiv:2407.12892 [astro-ph.HE]) states that this conclusion is wrong and "stems from a misinterpretation and an incorrect application of the TA energy deposit formula". Here we demonstrate that our formula for energy deposit is not in fact a rescaled modification of the TA equation, but follows from description of the processes occurring during the passage of charged particles through 1.2 cm thick scintillator. Our estimation of the TA detector response implies the correctness of the cosmic ray spectrum derived from readings of surface detectors of the array.

X-ray observations of active galactic nuclei (AGNs) reveal relativistic reflections from the innermost regions of accretion disks, which contain general-relativistic footprints caused by spinning supermassive black holes (SMBH). We anticipate the spin of a SMBH to be stable over the human timeframe, so brightness changes in the high-energy corona above the SMBH should slightly alter relativistic reflection. In this brief review, we discuss the latest developments in modeling relativistic reflection, as well as the rapid small variation in relativistic emission disclosed by the principal component analysis (PCA) of X-ray variability in AGN. PCA studies of X-ray spectra from AGNs have shown that relativistically blurred reflection has negligible fluctuations over the course of observations, which could originate from rapid (intrahour) intrinsic variations in near-horizon accretion flows and photon rings. The PCA technique is an effective way to disclose relativistic reflection from X-ray observations of AGNs, simplifying the complexity of largely variable X-ray data for automated spectral analysis with machine learning algorithms.

Robert Pascua, Zachary E. Martinot, Adrian Liu, James E. Aguirre, Nicholas S. Kern, Joshua S. Dillon, Michael J. Wilensky, Nicolas Fagnoni, Eloy de Lera Acedo, David DeBoer

A successful detection of the cosmological 21-cm signal from intensity mapping experiments (for example, during the Epoch of Reioinization or Cosmic Dawn) is contingent on the suppression of subtle systematic effects in the data. Some of these systematic effects, with mutual coupling a major concern in interferometric data, manifest with temporal variability distinct from that of the cosmological signal. Fringe-rate filtering -- a time-based Fourier filtering technique -- is a powerful tool for mitigating these effects; however, fringe-rate filters also attenuate the cosmological signal. Analyses that employ fringe-rate filters must therefore be supplemented by careful accounting of the signal loss incurred by the filters. In this paper, we present a generalized formalism for characterizing how the cosmological 21-cm signal is attenuated by linear time-based filters applied to interferometric visibilities from drift-scanning telescopes. Our formalism primarily relies on analytic calculations and therefore has a greatly reduced computational cost relative to traditional Monte Carlo signal loss analyses. We apply our signal loss formalism to a filtering strategy used by the Hydrogen Epoch of Reionization Array (HERA) and compare our analytic predictions against signal loss estimates obtained through a Monte Carlo analysis. We find excellent agreement between the analytic predictions and Monte Carlo estimates and therefore conclude that HERA, as well as any other drift-scanning interferometric experiment, should use our signal loss formalism when applying linear, time-based filters to the visibilities.

Primordial black holes (PBHs) could compose the dark matter content of the Universe. We present the first simulations of cosmological structure formation with PBH dark matter that consistently include collisional few-body effects, post-Newtonian orbit corrections, orbital decay due to gravitational wave emission, and black-hole mergers. We carefully construct initial conditions by considering the evolution during radiation domination as well as early-forming binary systems. We identify numerous dynamical effects due to the collisional nature of PBH dark matter, including evolution of the internal structures of PBH halos and the formation of a hot component of PBHs. We also study the properties of the emergent population of PBH binary systems, distinguishing those that form at primordial times from those that form during the nonlinear structure formation process. These results will be crucial to sharpen constraints on the PBH scenario derived from observational constraints on the gravitational wave background. Even under conservative assumptions, the gravitational radiation emitted over the course of the simulation appears to exceed current limits from ground-based experiments, but this depends on the evolution of the gravitational wave spectrum and PBH merger rate toward lower redshifts.

Quasars are powered by supermassive black hole (SMBH) accretion disks, yet standard disk models are inconsistent with many quasar observations. Recently, Hopkins et al. (2024) simulated the formation of a quasar disk feeding a SMBH of mass M=1.3×107M in a host galaxy that evolved from cosmological initial conditions. The disk had surprisingly strong toroidal magnetic fields that supported it vertically from gravity and powered fast accretion. What radiation and feedback can such a system produce? To answer this, we must follow the gas to the event horizon. For this, we interpolated the accretion system onto the grid of the general-relativistic radiation magnetohydrodynamics code H-AMR and performed 3D simulations with BH spins a=0 and a=0.9375. This remapping generates spurious magnetic monopoles, which we erase using a novel divergence cleaning approach. Despite the toroidal magnetic field's dominance at large radii, vertical magnetic flux builds up at the event horizon. This causes a magnetic state transition within the inner 200 gravitational radii of the disk, where net vertical magnetic flux begins dominating the accretion flow. This powers strong winds and, if the BH spins, relativistic jets that can spin-down the BH within 510Myrs. Sometimes, vertical magnetic fields of opposite sign reach the BH, causing polarity inversion events that briefly destroy the jets and, possibly, the X-ray corona. The disk powers accretion at rates 5× the Eddington limit, which can double the BH mass in 510Myrs. When a=0.9375 (a=0), the energy in outflows and radiation equals about 60% (10%) and 100% (3%) of the accreted rest mass energy, respectively. Much of the light escapes in cool, extended 1300au photospheres, consistent with quasar microlensing and the ``big blue bump'' seen in spectral energy distributions.

Fulya Kıroğlu, Kyle Kremer, Sylvia Biscoveanu, Elena González Prieto, Frederic A. Rasio

Dynamical interactions in dense star clusters could significantly influence the properties of black holes, leaving imprints on their gravitational-wave signatures. While previous studies have mostly focused on repeated black hole mergers for spin and mass growth, this work examines the impact of physical collisions and close encounters between black holes and (non-compact) stars. Using Monte Carlo N-body models of dense star clusters, we find that a large fraction of black holes retained upon formation undergo collisions with stars. Within our explored cluster models, the proportion of binary black hole mergers affected by stellar collisions ranges from 10% to 60%. If all stellar-mass black holes are initially non-spinning, we find that up to 40% of merging binary black holes may have components with dimensionless spin parameter χ0.2 because of prior stellar collisions, while typically about 10% have spins near χ=0.7 from prior black hole mergers. We demonstrate that young star clusters are especially important environments as they can produce collisions of black holes with very massive stars, allowing significant spin up of the black holes through accretion. Our predictions for black hole spin distributions from these stellar collisions highlight their sensitivity to accretion efficiency, underscoring the need for detailed hydrodynamic calculations to better understand the accretion physics following these interactions.

Lithium plays a crucial role in probing stellar physics and stellar and primordial nucleosynthesis, as well as the chemical evolution of our Galaxy. Stars are considered to be the main source of Li, still the identity of its primary stellar producer has long been a matter of debate. In light of recent theoretical and observational results, we investigate in this study the role of two candidate sources of Li enrichment in the Milky Way, namely AGB stars and, in particular, novae. We utilize a one-zone Galactic chemical evolution model to assess the viability of AGB stars and novae as stellar sources of Li. We use recent theoretical Li yields for AGB stars, while for novae we adopt observationally inferred Li yields and recently derived Delay Time Distributions (DTDs). Subsequently, we extend our analysis using a multi-zone model with radial migration to investigate spatial variations in the evolution of Li across the Milky Way disc and compare the results with observational data for field stars and open clusters. Our analysis shows that AGB stars fail by far to reproduce the meteoritic Li abundance. In contrast, novae appear as promising candidates within the adopted framework, allowing us to quantify the contribution of each Li source at Sun's formation and today. Our multi-zone model reveals the role of the differences in the DTDs of SN Ia and novae in shaping the evolution of Li in the various galactic zones. Its results are in fair agreement with the observational data for most open clusters, but small discrepancies appear in the outer disc.

(Abreviated) FS CMa stars belong to a diverse group of stars exhibiting the B[e] phenomenon, which is manifested mainly by the presence of forbidden emission lines and a~strong infrared (IR) excess in their spectra. Recently, a strong magnetic field has been discovered in the FS CMa star IRAS 17449+2320. Its strength and an unusually high space velocity point to a post-merger nature. Stellar mergers may provide an explanation for the complex and sometimes chaotic behaviour of some of the FS CMa stars. We did a statistical study of numerical simulations using Aarseth's NBODY6 code. We show the importance of stellar mergers of low- to intermediate-mass stars (from 1.4 to 8 M) and for B-type stars in particular. We analysed two sets of N-body simulations with different initial orbital period distributions. In the simulations, more massive binaries are treated differently than less massive binaries and the mass limit usually used is 5 M. We also used the value of 2 M to test the influence of this ambiguous limit on the results. Looking at mass, distance from their birth cluster, and velocity distributions, we investigated the statistical significance of individual spectral types in terms of merger dynamics and how merger events affect the stellar evolution. We found that around 50 \% of stars in the simulated open clusters involved in the formation of mergers are B-type stars. As a result, more than 50 \% of the merger products end up as a B-type star as well. Between 12.54 \% and 23.24 \% of all B-type stars are mergers. These results are a natural consequence of the initial mass function, initial distribution of the binary star parameters, and large range of masses for B-type stars. We present a comparison of the W component and the space velocity of the simulated mergers with a sample of observed FS CMa stars.

Ana Acebron, Claudio Grillo, Sherry H. Suyu, Giuseppe Angora, Pietro Bergamini, Gabriel B. Caminha, Sebastian Ertl, Amata Mercurio, Mario Nonino, Piero Rosati, Han Wang, Andrea Bolamperti, Massimo Meneghetti, Stefan Schuldt, Eros Vanzella

Overcoming both modeling and computational challenges, we present, for the first time, the extended surface-brightness distribution model of a strongly-lensed source in a complex galaxy-cluster-scale system. We exploit the high-resolution Hubble Space Telescope (HST) imaging and extensive Multi Unit Spectroscopic Explorer spectroscopy to build an extended strong-lensing model, in a full multi-plane formalism, of SDSS J1029+2623, a lens cluster at z=0.588 with three multiple images of a background quasar (z=2.1992). Going beyond typical cluster strong-lensing modeling techniques, we include as observables both the positions of 26 pointlike multiple images from seven background sources, spanning a wide redshift range between 1.02 and 5.06, and the extended surface-brightness distribution of the strongly-lensed quasar host galaxy, over 78000 HST pixels. In addition, we model the light distribution of seven objects, angularly close to the strongly-lensed quasar host, over 9300 HST pixels. Our extended lens model reproduces well both the observed intensity and morphology of the quasar host galaxy in the HST F160W band (with a 0''.03 pixel scale). The reconstructed source shows a single, compact, and smooth surface-brightness distribution, for which we estimate an intrinsic magnitude of 23.3 ± 0.1 in the F160W band and a half-light radius of (2.39 ± 0.03) kpc. The increased number of observables enables the accurate determination of the total mass of line-of-sight halos lying angularly close to the extended arc. This work paves the way for a new generation of galaxy cluster strong-lens models, where additional, complementary lensing observables are directly incorporated as model constraints.

Malik H. Walker, Robert C. Allen, Gang Li, George C. Ho, Glenn M. Mason, Javier Rodriguez-Pacheco, Robert F. Wimmer-Schweingruber, Athanasios Kouloumvakos

On 2022 March 10, a coronal mass ejection (CME) erupted from the Sun, resulting in Solar Orbiter observations at 0.45 au of both dispersive solar energetic particles arriving prior to the interplanetary CME (ICME) and locally accelerated particles near the ICME-associated shock structure as it passed the spacecraft on 2022 March 11. This shock was later detected on 2022 March 14 by the Advanced Composition Explorer (ACE), which was radially aligned with Solar Orbiter, at 1 au. Ion composition data from both spacecraft -- via the Solar Orbiter Energetic Particle Detector/ Suprathermal Ion Spectrograph (EPD/SIS) and the Ultra Low Energy Isotope Spectrometer (ULEIS) on ACE -- allows for in-depth analysis of the radial evolution of species-dependent ICME shock-associated acceleration processes for this event. We present a study of the ion spectra observed at 0.45 and 1 au during both the gradual solar energetic particle (SEP) and energetic storm particle (ESP) phases of the event. We find that the shapes of the spectra seen at each spacecraft have significant differences that were likely caused by varying shock geometry: Solar Orbiter spectra tend to lack spectral breaks, and the higher energy portions of the ACE spectra have comparable average flux to the Solar Orbiter spectra. Through an analysis of rigidity effects on the spectral breaks observed by ACE, we conclude that the 1 au observations were largely influenced by a suprathermal pool of He+ ions that were enhanced due to propagation along a stream interaction region (SIR) that was interacting with the ICME at times of observation.

Natalia Lahén, Antti Rantala, Thorsten Naab, Christian Partmann, Peter H. Johansson, Jessica May Hislop

So far, even the highest resolution galaxy formation simulations with gravitational softening have failed to reproduce realistic life cycles of star clusters. We present the first star-by-star galaxy models of star cluster formation to account for hydrodynamics, star formation, stellar evolution and collisional gravitational interactions between stars and compact remnants using the updated SPHGAL+KETJU code, part of the GRIFFIN-project. Gravitational dynamics in the vicinity of >3 M stars and their remnants are solved with a regularised integrator (KETJU) without gravitational softening. Comparisons of idealised star cluster evolution with SPHGAL+KETJU and direct N-body show broad agreement and the failure of simulations that use gravitational softening. In the hydrodynamical dwarf galaxy simulations run with SPHGAL+KETJU, clusters up to 900 M are formed compact (effective radii 0.11 pc) and their sizes increase by up to a factor of ten in agreement with previous N-body simulations and the observed sizes of exposed star clusters. The sizes increase rapidly once the clusters become exposed due to photoionising radiation. On average 63% of the gravitationally bound clusters disrupt during the first 100 Myr of evolution in the galactic tidal field. The addition of collisional dynamics reduces the fraction of supernovae in bound clusters by a factor of 2.6, however the global star formation and outflow histories change by less than 30%. We demonstrate that the accurate treatment of gravitational encounters with massive stars enables more realistic star cluster life cycles from the earliest stages of cluster formation until disruption in simulated low-mass galaxies.

Sarbani Basu (Dept. of Astronomy, Yale University), Wesley Antônio Machado Andrade de Aguiar (Dept. of Computer Science, Yale University), Sylvain G. Korzennik (Center for Astrophysics | Harvard &amp; Smithsonian)

We have used solar oscillation frequencies and frequency splittings obtained over solar cycles 23, 24 and the rising phase of solar cycle 25 to investigate whether the tachocline properties (jump i.e., the change in the rotation rate across the tachocline, width and position) show any time variation. We confirm that the change in rotation rate across the tachocline changes substantially, however, the change does not show a simple correlation with solar cycle unlike, for instance, changes in mode frequencies. The change during the ascending phase of solar cycle 25 is almost a mirror image of the change during the descending part of solar cycle 24, tempting us to speculate that the tachocline has a much longer period than either the sunspot or the magnetic cycle. We also find that the position of the tachocline, defined as the mid-point of the change in rotation rate, showed significant changes during solar cycle 24. The width of the tachocline, on the other hand, has showed significant changes during solar cycle 23, but not later. The change in the tachocline becomes more visible if we look at the upper and lower extents of the tachocline, defined as (position +/- width). We find that for epochs around solar maxima and minima, the extent decreases before increasing again - a few more years of data should clarify this trend. Our results reinforce the need to continue helioseismic monitoring of the Sun to understand solar activity and its evolution.

M. Veresvarska, S. Scaringi, C. Knigge, J. Paice, D.A.H. Buckley, N. Castro Segura, D. de Martino, P.J. Groot, A. Ingram, Z.A. Irving, P. Szkody

Almost all accreting black hole and neutron star X-ray binary systems (XRBs) exhibit prominent brightness variations on a few characteristic time-scales and their harmonics. These quasi-periodic oscillations (QPOs) are thought to be associated with the precession of a warped accretion disc, but the physical mechanism that generates the precessing warp remains uncertain. Relativistic frame dragging (Lense-Thirring precession) is one promising candidate, but a misaligned magnetic field is an alternative, especially for neutron star XRBs. Here, we report the discovery of 5 accreting white dwarf systems (AWDs) that display strong optical QPOs with characteristic frequencies and harmonic structures that suggest they are the counterpart of the QPOs seen in XRBs. Since AWDs are firmly in the classical (non-relativistic) regime, Lense-Thirring precession cannot account for these QPOs. By contrast, a weak magnetic field associated with the white dwarf can drive disc warping and precession in these systems, similar to what has been proposed for neutron star XRBs. Our observations confirm that magnetically driven warping is a viable mechanism for generating QPOs in disc-accreting astrophysical systems, certainly in AWDs and possibly also in (neutron star) XRBs. Additionally, they establish a new way to estimate magnetic field strengths, even in relatively weak-field systems where other methods are not available.

We study the robustness of the Baryon Acoustic Oscillation (BAO) feature in galaxy clustering in the presence of massive neutrinos. In the standard BAO analysis pipeline a reference cosmological model is assumed to boost the BAO peak through the so-called reconstruction technique and in the modelling of the BAO feature to extract the cosmological information. State-of-the art spectroscopic BAO measurements, such as the Dark Energy Spectroscopic Instrument claim an aggregate precision of 0.52% on the BAO scale, with a systematic error of 0.1% associated to the assumption of a reference cosmology when measuring and analyzing the BAO feature. While the systematic effect induced by this arbitrary choice of fiducial cosmology has been studied for a wide range of ΛCDM-like models, it has not yet been tested for reference cosmologies with massive neutrinos with the precision afforded by next generation surveys. In this context, we employ the Quijote high-resolution dark-matter simulations with haloes above a mass of M2×1013h1M, with different values for the total sum of neutrinos masses, mν[eV]=0,0.1,0,2,0.4 to study and quantify the impact of the pipeline's built-in assumption of massless neutrinos on the measurement of the BAO signal, with a special focus on the BAO reconstruction technique. We determine that any additional systematic bias introduced by the assumption of massless neutrinos is no greater than 0.1% (0.2%) for the isotropic (anisotropic) measurement. We expect these conclusions also hold for galaxies provided that neutrino properties do not alter the galaxy-halo connection.

IRAC data have long implied that early (z6) galaxies often have very high specific star formation rates (sSFR30 Gyr1), but JWST data have shown that at least some early galaxies are forming stars far less vigorously. Here, we systematically analyze the recent star formation histories (SFHs) of a large (N=368) sample of z6 Lyman-break galaxies (LBGs) spanning 22MUV16 assembled from ACS+NIRCam imaging in the GOODS and Abell 2744 fields. We find that very low Hα-to-UV luminosity ratios (LHα/LUV) and strong recent downturns in star formation rate (SFR) are 5× more common among the UV-faintest subset of our sample (MUV=17.4) compared to the brightest subset (MUV=20.0). The frequency of high LHα/LUV and strong recent SFR upturns is approximately constant with UV luminosity. We discuss how bursty SFHs naturally reproduce this much greater diversity in recent SFHs among very UV-faint galaxies. Using public NIRSpec/prism data, we newly confirm recent strong SFR downturns among three LBGs in our sample, and validate our photometric inferences on key SFH signatures among z6 LBGs in general. Our results imply that early galaxies frequently cycle through phases of rapid stellar mass assembly and other periods of much slower growth. This yields huge (1-2 mag) fluctuations in MUV on rapid (10-30 Myr) timescales, helping explain the surprising abundance of z>10 galaxies. Finally, we caution that this burstiness causes all existing high-redshift samples (particularly line-selected samples) to be far less complete to galaxies with long recent phases of low sSFR than those currently undergoing a burst.

Born as ice-rich planetesimals, cometary nuclei were gravitationally scattered onto their current orbits in the Kuiper Belt and the Oort Cloud during the giant planets' dynamical instability in the early stages of our Solar System's history. Here, we model the thermal evolution of planetesimals during and after the giant planet instability. We couple an adapted thermal evolution model to orbital trajectories provided by \textit{N}-body simulations to account for the planetesimals' orbital evolution, a parameter so far neglected by previous thermal evolution studies. Our simulations demonstrate intense thermal processing in all planetesimal populations, concerning mainly the hyper-volatile ice content. Unlike previous predictions, we show that hyper-volatile survival was possible in a significant number of planetesimals of the Kuiper Belt and the Oort Cloud. Planetesimals ejected into the interstellar space proved to be the most processed, while planetesimals ending in the Oort Cloud were the least processed population. We show that processing differences between populations are a direct consequence of their orbital evolution patterns, and that they provide a natural explanation for the observed variability in the abundance ratios of CO on cometary populations and on the recent observations of long-distance CO-driven activity on inbound Long-period Comets.

Nancy Remage Evans, Pierre Kervella, Joanna Kuraszkiewicz, H. Moritz Günther, Richard I. Anderson, Charles Proffitt, Alexandre Gallenne, Antoine Mérand, Boris Trahin, Giordano Viviani, Shreeya Shetye

Cepheid masses continue to be important tests of evolutionary tracks for intermediate mass stars as well as important predictors of their future fate. For systems where the secondary is a B star, {\it Hubble Space Telescope} ultraviolet spectra have been obtained. From these spectra a temperature can be derived, and from this a mass of the companion M2. Once {\it Gaia} DR4 is available, proper motions can be used to determine the inclination of the orbit. Combining mass of the companion, M2, the mass function from the ground-based orbit of the Cepheid and the inclination produces the mass of the Cepheid, M1. The Cepheid system FN Vel is used here to demonstrate this approach and what limits can be put on the Cepheid mass for inclination between 50 and 130o.

Fast Radio Bursts (FRBs) are bright radio transient events, a subset of which have been localized to their host galaxies. Their high dispersion measures offer valuable insights into the ionized plasma along their line of sight, enabling them to serve as probes of cosmological parameters. One of the major challenges in contemporary cosmology is the Hubble tension -- an unresolved discrepancy between two independent methods of determining the Universe's expansion rate, yielding differing values for the Hubble constant. In this study, we analyze a sample of 64 extragalactic, localized FRBs observed by various telescopes, employing Bayesian analysis with distinct likelihood functions. Our findings suggest that FRBs serve as tracers of the Hubble constant in the late-time Universe. Notably, our results exhibit smaller error bars compared to previous studies, and the derived Hubble constant with 1σ error bars no longer overlap with those obtained from early-Universe measurements. These results underscore the continuing tension between early- and late-time measurements of the Hubble constant.

R. de la Fuente Marcos, C. de la Fuente Marcos, S. J. Aarseth

Context. Natural interstellar objects do not form isolated in deep space, but escape their natal planetary systems. Early removal from their home star systems via close flybys with still-forming planets could be the dominant ejection mechanism. However, dynamically evolved planetary systems such as the Solar System may also be a significant source of natural interstellar objects. Aims. We studied the dynamical evolution of two unusual Solar System hyperbolic comets, C/1980 E1 (Bowell) and C/2024 L5 (ATLAS), to investigate the circumstances that led them to reach moderate Solar System excess hyperbolic speeds. Methods. We used N-body simulations and statistical analyses to explore the planetary encounters that led to the ejection of C/1980 E1 and C/2024 L5, and studied their pre- and post-encounter trajectories. Results. We confirm that C/1980 E1 reached its present path into interstellar space after an encounter with Jupiter at 0.23 au on December 9, 1980. C/2024 L5 was scattered out of the Solar System following a flyby to Saturn at 0.003 au on January 24, 2022. Integrations backward in time show that C/1980 E1 came from the inner Oort cloud but C/2024 L5 could be a former retrograde, inactive Centaur. The receding velocities of C/1980 E1 and C/2024 L5 when entering interstellar space will be 3.8 and 2.8 km/s, moving towards Aries and Triangulum, respectively. Conclusions. Our results for two comets ejected from the Solar System indicate that dynamically evolved planetary systems can be effective sources of interstellar objects and provide constraints on their velocity distribution.

T. Araki, S. Chauhan, K. Chiba, T. Eda, M. Eizuka, Y. Funahashi, A. Furuto, A. Gando, Y. Gando, S. Goto, T. Hachiya, K. Hata, K. Ichimura, H. Ikeda, K. Inoue, K. Ishidoshiro, Y. Kamei, N. Kawada, Y. Kishimoto, M. Koga, A. Marthe, Y. Matsumoto, T. Mitsui, H. Miyake, D. Morita, R. Nakajima, K. Nakamura, R. Nakamura, R. Nakamura, J. Nakane, T. Ono, H. Ozaki, K. Saito, T. Sakai, I. Shimizu, J. Shirai, K. Shiraishi, A. Suzuki, K. Tachibana, K. Tamae, H. Watanabe, K. Watanabe, S. Kurosawa, Y. Urano, S. Yoshida, S. Umehara, K. Fushimi, K. Kotera, B.E. Berger, B.K. Fujikawa, J.G. Learned, J. Maricic, Z. Fu, S. Ghosh, J. Smolsky, L.A. Winslow, Y. Efremenko, H.J. Karwowski, D.M. Markoff, W. Tornow, S. Delloro, T. Odonnell, J.A. Detwiler, S. Enomoto, M.P. Decowski, K.M. Weerman, C. Grant, Ö. Penek, H. Song, A. Li, S.N. Axani, M. Garcia, M. Sarfraz

The electron antinuetrino flux limits are presented for the brightest gamma-ray burst (GRB) of all time, GRB221009A, over a range of 1.8\,-\,200\,MeV using the Kamioka Liquid Scintillator Anti Neutrino Detector (KamLAND). Using a variety of time windows to search for electron antineutrinos coincident with the GRB, we set an upper limit on the flux under the assumption of various neutrino source spectra. No excess was observed in any time windows ranging from seconds to days around the event trigger time. The limits are compared to the results presented by IceCube.

We present a study of asteroseismically derived surface gravities, masses, and radii of a sample of red giant stars both with and without confirmed planetary companions using TESS photometric light curves. These red giants were drawn from radial velocity surveys, and their reported properties in the literature rely on more traditional methods using spectroscopy and isochrone fitting. Our asteroseismically derived surface gravities achieved a precision of 0.01 dex; however, they were on average 0.1~dex smaller than the literature. The systematic larger gravities of the literature could plausibly present as a systematic overestimation of stellar masses, which would in turn lead to overestimated planetary masses of the companions. We find that the fractional discrepancies between our asteroseismically-determined parameters and those previously found are typically larger for stellar radii (10% discrepancy) than for stellar masses (<5% discrepancy). However, no evidence of a systematic difference between methods was found for either fundamental parameter. Two stars, HD~100065 and HD~18742, showed significant disagreement with the literature in both mass and radii. We explore the impacts on updated stellar properties on inferred planetary properties and caution that red giant radii may be more poorly constrained than uncertainties suggest.

José de Jesús Velázquez, Luis A. Escamilla, Purba Mukherjee, J. Alberto Vázquez

The current accelerated expansion of the Universe remains ones of the most intriguing topics in modern cosmology, driving the search for innovative statistical techniques. Recent advancements in machine learning have significantly enhanced its application across various scientific fields, including physics, and particularly cosmology, where data analysis plays a crucial role in problem-solving. In this work, a non-parametric regression method with Gaussian processes is presented along with several applications to reconstruct some cosmological observables, such as the deceleration parameter and the dark energy equation of state, in order to contribute with some information that helps to clarify the behavior of the Universe. It was found that the results are consistent with ΛCDM and the predicted value of the Hubble parameter at redshift zero is H0=68.798±6.340(1σ) km Mpc1 s1.

Various theoretical models predict existence of extended gamma-ray halo around normal galaxies, that could be produced by interactions of cosmic rays with the circumgalactic medium or by annihilation or decay of hypothetical dark matter particles. Observations of the closest massive galaxy M31 also corroborate this possibility. In this study we search for gamma-ray emission from the galaxies within 15 Mpc at energies higher than 2 GeV and try to assess its spatial extension. We use the latest catalog of local galaxies and apply a simple yet robust method of aperture photometry. By imposing the mass, energy, and spatial cuts, we selected a set of 16 late-type galaxies and found a statistically significant excess above the background level (pval=4.8×109). More importantly, our analysis shows that this excess can be ascribed to an extended source with a radius 0.3 rather than a point-like one. In contrast, 6 early-type galaxies, which satisfied the same cuts, showed no excess. Our results are supported by the stacking likelihood analysis technique. The difference between the late- and early-type galaxies and a rather irregular shape of the extended source that we found indicate that this high-energy emission is not due to DM annihilation/decay but rather originates from cosmic ray interaction with the circumgalactic medium.

Themiya Nanayakkara, Karl Glazebrook, Corentin Schreiber, Harry Chittenden, Gabriel Brammer, James Esdaile, Colin Jacobs, Glenn G. Kacprzak, Lalitwadee Kawinwanichakij, Lucas C. Kimmig, Ivo Labbe, Claudia Lagos, Danilo Marchesini, M. Martìnez-Marìn, Z. Cemile Marsan, Pascal A. Oesch, Casey Papovich, Rhea-Silvia Remus, Kim-Vy H. Tran

We present the formation histories of 19 massive (3×1010M) quiescent galaxy candidates at z3.04.5 observed using JWST/NIRSpec. This completes the spectroscopic confirmation of the 24 K-selected quiescent galaxy sample from the ZFOURGE and 3DHST surveys \citep{Schreiber2018}. Utilizing Prism 15μm spectroscopy, we confirm that all 12 sources that eluded confirmation by ground-based spectroscopy lie at z>3, resulting in a spectroscopically confirmed number density of 1.4×105Mpc3 between z34. Rest-frame UV vs VJ color selections show high effectiveness in identifying quiescent galaxies, with a purity of 90%. Our analysis shows that parametric star-formation histories (SFHs) from FAST++ and binned SFHs from Prospector on average yield consistent results, revealing diverse formation and quenching times. The oldest galaxy formed 6×1010M by z10 and has been quiescent for over 1 Gyr at z3.2. We detect two galaxies with ongoing star formation and six with active galactic nuclei (AGN). We demonstrate that the choice of stellar population models, stellar libraries, wavelength range, and nebular or AGN contributions does not significantly affect the derived average SFHs of the galaxies. The assumed SFH prior, however, influences the star formation rate at early times, where spectral diagnostic power is limited. Simulated z3 quiescent galaxies from IllustrisTNG, SHARK, and Magneticum broadly match the average SFHs of the observed sample but struggle to capture the full diversity, particularly at early stages. Our results emphasize the need for mechanisms that rapidly build stellar mass and quench star formation within the first billion years of the Universe.

Ke Fang, Francis Halzen, Sebastian Heinz, John S. Gallagher

The recent observation of high-energy neutrinos from the Galactic plane implies an abundant population of hadronic cosmic-ray sources in the Milky Way. We explore the role of the coronae of accreting stellar-mass black holes as such astroparticle emitters. We show that the particle acceleration and interaction timescales in the coronal region are tied to the compactness of the X-ray source. Thus, neutrino emission processes may similarly happen in the cores of active galactic nuclei and black hole X-ray binaries (XRB), despite of their drastically different masses and physical sizes. We apply the model to the well-measured XRB Cygnus X-1 and find that the cascaded gamma rays accompanying the neutrino emission naturally explain the GeV emission that only presents during the source's hard state. We show that XRB coronae could contribute significantly to the Galactic cosmic-ray and Galactic plane neutrino fluxes. Our model predicts variable high-energy neutrino emission from bright Galactic XRBs that may be observed by IceCube and future neutrino observatories.

V. S. Titov, C. Downs, T. Török, J. A. Linker, M. Prazak, J. A. Qiu

We generalize a magnetogram-matching Biot-Savart law (BSL) from planar to spherical geometry. For a given coronal current density J, this law determines the corresponding magnetic field ˜B under the condition that its radial component vanishes at the surface. The superposition of ˜B with a potential magnetic field defined by the given surface radial field, Br, provides the entire magnetic configuration, in which Br remains unchanged by the currents. Using this approach, we (1) upgrade our regularized BSLs for constructing coronal magnetic flux ropes (MFRs) and (2) propose a new method for decomposing a measured photospheric magnetic field as B=Bpot+BT+B˜S, where the potential, Bpot, toroidal, BT, and tangential poloidal, B˜S, fields are determined by Br, Jr, and the surface divergence of BBpot, respectively, all derived from magnetic data. Our BT is identical to the one in the alternative decomposition by Schuck et al. (2022), while Bpot and B˜S are very different from their poloidal fields BP< and BP>, which are {\it potential} and refer to {\it different} surface sides. In contrast, our B˜S is generally {\it nonpotential} and, as Bpot and BT, refers to the {\it same} upper side of the surface, rendering our decomposition more complete and consistent. We demonstrate that it allows one to identify the footprints and projected surface-location of MFRs, as well as the direction and connectivity of their currents, especially for weak or complex configurations, which is very important for modeling and analyzing observed pre-eruptive configurations and their eruptions.

C. Gibson, F. Kıroğlu, J. C. Lombardi Jr., S. C. Rose, H. D. Vanderzyden, B. Mockler, M. Gallegos-Garcia, K. Kremer, E. Ramirez-Ruiz, F. A. Rasio

Tidal disruption events (TDEs) are an important way to probe the properties of stellar populations surrounding supermassive black holes. Observed spectra of several TDEs, such as ASASSN-14li, show high nitrogen to carbon abundance ratios, leading to questions about their progenitors. Disrupting an intermediate- or high-mass star that has undergone CNO processing, increasing the nitrogen in its core, could lead to an enhanced nitrogen TDE. Galactic nuclei present a conducive environment for high-velocity stellar collisions that can lead to high mass loss, stripping the carbon- and hydrogen-rich envelopes of the stars and leaving behind the enhanced nitrogen cores. TDEs of these stripped stars may therefore exhibit even more extreme nitrogen enhancement. Using the smoothed particle hydrodynamics code StarSmasher, we provide a parameter space study of high-velocity stellar collisions involving intermediate-mass stars, analyzing the composition of the collision products. We conclude that high-velocity stellar collisions can form products that have abundance ratios similar to those observed in the motivating TDEs. Furthermore, we show that stars that have not experienced high CNO processing can yield low-mass collision products that retain even higher nitrogen to carbon abundance ratios. We analytically estimate the mass fallback for a typical TDE of several collision products to demonstrate consistency between our models and TDE observations. Lastly, we discuss how the extended collision products, with high central to average density ratios, can be related to repeated partial TDEs like ASASSN-14ko and G objects in the Galactic Center.

Planets in compact multi-transiting systems tend to exhibit self-similarity with their neighbors, a phenomenon commonly called "peas-in-a-pod". Previous studies have identified that this self-similarity appears independently among super-Earths and sub-Neptunes orbiting the same star. In this study, we investigate whether the peas-in-a-pod phenomenon holds for planets in the radius gap between these two categories (located at 1.8R). Employing the Kepler sample of planets in multi-transiting systems, we calculate the radius ratios between radius gap planets and their neighbors. We find that in systems in possession of a radius gap planet, there is a statistically significant deficit of planet pairs with radius ratios near unity, at the level of 34σ. We find that neighbors to radius gap planets actually exhibit reverse size-ordering (that is, a larger inner planet is followed by an outer smaller planet) more often than they exhibit self-similarity. We go on to compare whether the period ratios between neighboring planets also differ, and find that radius gap planets are likelier to reside in mean motion resonance with neighbors, compared to non-gap planets (particularly in the 3:2 configuration). We explore the possibility that systems with a radius gap planet may be modified by a process other than photoevaporation or core-powered mass loss. The appearance in tandem of unusual size-ordering of gap planets in multi-planet systems, together with unusual spacing, furnishes potential supporting evidence in favor of giant impacts sculpting the radius distribution to some degree.

Zhao-Qiang Shen, Wen-Hao Li, Kai-Kai Duan, Wei Jiang, Zun-Lei Xu, Chuan Yue, Xiang Li

The DArk Matter Particle Explorer (DAMPE) is a cosmic-ray detector as well as a pair-converting γ-ray telescope. The effective area, reflecting the geometrical cross-section area, the γ-ray conversion probability and the photon selection efficiency, is important in the γ-ray analyses. In the work, we find a significant time variation in the effective area, as large as 4%/yr at 2 GeV for the high-energy trigger. We derive the data-based correction factors to the effective areas and apply corrections to both the effective areas and the exposure maps. The calibrated exposure can be 12% smaller than the Monte Carlo one on average at 2 GeV. The calibration is further verified using the observation of the Vela pulsar, showing the spectral parameters with the correction are more consistent with those in the Fermi-LAT catalog than the ones without correction. All the corrections are now implemented in the latest version of the DAMPE γ-ray analysis toolkit DmpST.

We show that the non-thermal radio to X-ray emission following the neutron star merger GW\,170817 is consistent with synchrotron emission from a collisionless shock driven into the interstellar medium (ISM) by a conical radially stratified outflow observed 0.25~rad off-axis, with a power-low mass dependence on momentum, M(>γβ)(γβ)5, maximum Lorenz factor γ10, opening (half-)angle 0.2~rad, and total energy of 1051erg. The temporal dependence of the flux during its rising phase is determined by the radial stratification structure, which determines the rate at which outflow energy is deposited in the ISM. This is in contrast with highly relativistic, γ100, structured jet models, where the angular jet structure determines the time dependence through the gradual "unveiling" by deceleration of larger angular sections of the jet (which are initially "hidden" by relativistic beaming), typically leading to a predicted flux decline after the peak that is faster than observed. Our model predicts a dependence on the observing angle, which is different than that predicted by highly relativistic jet models. Particularly, similar merger events observed closer to the symmetry axis are predicted to show a similarly extended duration of flux increase with time. Our analysis demonstrates that the data do not require a highly relativistic γ100 component, but the presence of such a component with opening angle 0.2~rad and energy 1051~erg cannot be excluded.

Pedro A. Ovando Ramirez (1), Y. D. Mayya (1), Lino H. Rodriguez-Merino (1), Luis Lomeli-Nunez (2), Bolivia Cuevas Otahola (3), Daniel Rosa-Gonzalez (1), Luis Carrasco (1) ((1) INAOE, Puebla, Mexico, (2) FURJ, Rio de Janeiro, Brazil (3) FCE-BUAP, Puebla, Mexico)

We present the results from spectroscopic and photometric analysis of 17 globular cluster (GC) candidates in the Irr II galaxy NGC 3077. The GC candidates were selected on the Hubble Space Telescope (HST) images and were cleaned of foreground Galactic stars using the GAIA parameters. We carried out aperture photometry using the multi-band archival images from SDSS, and 2MASS of all candidates, and low resolution (R= 1000) spectroscopic observations of 12 GC candidates and three suspected foreground stars using the OSIRIS/MOS mode at the Gran Telescopio Canarias (GTC). Age, metallicity and extinction values were determined both using spectroscopic and photometric data, independently. We find three of the 17 candidates are old (age >10 Gyr), metal-poor ([Fe/H]<-1.0 dex), massive (mass>10^5 Msun) GCs with characteristics similar to the classical GCs in the Milky Way. The rest are intermediate-age clusters (IACs) with typical ages of 3 to 4 Gyr, and in general metal-rich clusters. The radial velocities of both populations are within 100 km/s of the recessional velocity of the host galaxy. A relatively large population of IACs and low value of GC specific frequency (Sn=0.7) suggest that the pre-interaction galaxy was actively forming stars and star clusters, and is unlikely to be a dE as suggested in some previous works.

Kenneth E. Goodis Gordon, Theodora Karalidi, Kimberly M. Bott, Nicholas F. Wogan, Giada N. Arney, Mary N. Parenteau, Tiffany Kataria, Victoria S. Meadows

The search for life beyond the Solar System remains a primary goal of current and near-future missions, including NASA's upcoming Habitable Worlds Observatory (HWO). However, research into determining the habitability of terrestrial exoplanets has been primarily focused on comparisons to modern-day Earth. Additionally, current characterization strategies focus on the unpolarized flux from these worlds, taking into account only a fraction of the informational content of the reflected light. Better understanding the changes in the reflected light spectrum of the Earth throughout its evolution, as well as analyzing its polarization, will be crucial for mapping its habitability and providing comparison templates to potentially habitable exoplanets. Here we present spectropolarimetric models of the reflected light from the Earth at six epochs across all four geologic eons. We find that the changing surface albedos and atmospheric gas concentrations across the different epochs allow the habitable and non-habitable scenarios to be distinguished, and diagnostic features of clouds and hazes are more noticeable in the polarized signals. We show that common simplifications for exoplanet modeling, including Mie scattering for fractal particles, affect the resulting planetary signals and can lead to non-physical features. Finally, our results suggest that pushing the HWO planet-to-star flux contrast limit down to 1 × 1013 could allow for the characterization in both unpolarized and polarized light of an Earth-like planet at any stage in its history.

Fast radio bursts are brief, highly dispersed bursts detected in the radio band, originating from cosmological distances. The only such event detected in the Milky Way galaxy, FRB 20200428DD, was associated with an X-ray burst emitted by a magnetar named SGR J1935+2154, revealing the first case of a multi-wavelength counterpart of an FRB. Counterparts in other wavelengths accompanying or following FRBs, as well as the bright emission associated with the progenitor of the FRB engine, have been proposed in various FRB models, but no robust detection has been made so far. In general, FRBs as we know them are not favorite multi-messenger emitters. Nonetheless, possible neutrino and gravitational wave emission signals associated with FRBs or FRB-like events have been discussed in the literature. Here I review these suggested multi-wavelength and multi-messenger counterparts of FRBs or FRB-like events and the observational progress in searching for these signals. The topics include multi-wavelength (X-rays, γ-rays, optical) emission and neutrino emission from FRBs within the framework of the magnetar source models and possible FRB-like events associated with gravitational waves.

Hye-Jin Park, Andrew J. Battisti, Emily Wisnioski, Luca Cortese, Mark Seibert, Kathryn Grasha, Barry F. Madore, Brent Groves, Jeff A. Rich, Rachael L. Beaton, Qian-Hui Chen, Marcie Mun, Naomi M. McClure-Griffiths, W.J.G. de Blok, Lisa J. Kewley

We present the spatially resolved relationship between the dust-to-gas mass ratio (DGR) and gas-phase metallicity (Zgas or 12+log(O/H)) (i.e., DGR-Zgas relation) of 11 nearby galaxies with a large metallicity range (1.5 dex of 12+log(O/H)) at (sub-)kpc scales. We used the large field-of-view (> 3') optical pseudo-Integral Field Spectroscopy data taken by the TYPHOON/PrISM survey, covering the optical size of galaxies, combining them with multi-wavelength data (far-UV to far-IR, CO, and HI 21 cm radio). A large scatter of DGR in the intermediate metallicity galaxies (8.0 < 12+log(O/H) < 8.3) is found, which is in line with dust evolution models, where grain growth begins to dominate the mechanism of dust mass accumulation. In the lowest metallicity galaxy of our sample, Sextans A (12+log(O/H) < 7.6), the star-forming regions have significantly higher DGR values (by 0.5-2 dex) than the global estimates from literature at the same metallicity but aligns with the DGR values from metal depletion method from Damped Lyman Alpha systems and high hydrogen gas density regions of Sextans A. Using dust evolution models with a Bayesian MCMC approach suggests: 1) a high SN dust yield and 2) a negligible amount of photofragmentation by UV radiation, although we note that our sample in the low-metallicity regime is limited to Sextans A. On the other hand, it is also possible that while metallicity influences DGR, gas density also plays a role, indicating an early onset of dust grain growth in the dust mass build-up process despite its low metallicity.

Zhenlin Tan, Wenting Wang, Jiaxin He, Yike Zhang, Vicente Rodriguez-Gomez, Jiaxin Han, Zhaozhou Li, Xiaohu Yang

We adopt the two point correlation function (2PCF) as a statistical tool to quantify the spatial clustering of halo stars, for galaxy systems spanning a wide range in host halo virial mass (11.25<log10M200c/M<15) and redshifts (0<z<1.5) from the IllustrisTNG simulations. Consistent with a previous study \cite[][Paper I]{2024ApJ...961..223Z}, we identify clear correlations between the strength of the 2PCF signals and galaxy formation redshifts, but over a much wider mass range. We find that such correlations are slightly stronger at higher redshifts, and get weakened with the increase of host halo mass. We demonstrate that the spatial clustering of halo stars is affected by two factors: 1) the clustering gets gradually weakened as time passes (phase mixing); 2) newly accreted stars at more recent times would increase the clustering. For more massive galaxy systems, they assemble late and the newly accreted stars would increase the clustering. The late assembly of massive systems may also help to explain the weaker correlations between the 2PCF signals and the galaxy formation redshifts in massive halos, as their 2PCFs are affected more by recently accreted stars, while formation redshift characterizes mass accretion on a much longer timescale. We find that the orbits of satellite galaxies in more massive halos maintain larger radial anisotropy, reflecting the more active accretion state of their hosts while also contributing to their stronger mass loss rates.

Blurred reflection features are commonly observed in the X-ray spectra of accreting black holes. In the presence of high-quality data and with the correct astrophysical model, X-ray reflection spectroscopy is a powerful tool to probe the strong gravity region of black holes, study the morphology of the accreting matter, measure black hole spins, and test Einstein's theory of General Relativity in the strong field regime. In the past 10-15 years, there has been significant progress in the development of the analysis of these reflection features, thanks to both more sophisticated theoretical models and new observational data. However, the next generation of X-ray missions (e.g. eXTP, Athena, HEX-P) promises to provide unprecedented high-quality data, which will necessarily require more accurate synthetic reflection spectra than those available today. In this talk, I will review the state-of-the-art in reflection modeling and I will present current efforts to develop a new generation of reflection models with machine learning techniques.

Nobuyuki Sakai, Tomoya Yamada, Yoshiyuki Inoue, Ellis R. Owen, Tomonari Michiyama, Ryota Tomaru, Yasushi Fukazawa

Radio-quiet Seyfert galaxies have been detected in GeV gamma-rays by the Fermi Large Area Telescope (LAT), but the origin of much of this emission is unclear. We consider the nearby example, the Seyfert galaxy GRS 1734-292, which exhibits weak starburst and jet activities that are insufficient to explain the observed gamma-ray flux. With the first detailed multi-wavelength study of this source, we demonstrate that an active galactic nucleus (AGN) disk wind can account for its gamma-ray emission. Using a lepto-hadronic emission model based on a shocked ambient medium and a shocked wind region created by an AGN accretion disk wind, we identify two viable scenarios that are consistent with the Fermi-LAT data and multi-wavelength observations: a hadronic pp-dominated scenario and a leptonic external Compton-dominated scenario. Both of these show that future observations with the Cherenkov Telescope Array (CTA) and the Southern Wide-field Gamma-ray Observatory (SWGO) could detect TeV emission from a disk wind in GRS 1734-292. Such a detection would substantially improve our understanding of cosmic ray acceleration efficiency in AGN disk wind systems, and would establish radio-quiet Seyfert galaxies as cosmic ray accelerators capable of reaching ultra-high energies.

Alexander Williamson, Pascal J. Elahi, Richard Dodson, Jonghwan Rhee, Qian Gong

The next generation of radio astronomy telescopes are challenging existing data analysis paradigms, as they have an order of magnitude larger collecting area and bandwidth. The two primary problems encountered when processing this data are the need for storage and that processing is primarily I/O limited. An example of this is the data deluge expected from the SKA-Low Telescope of about 300 PB per year. To remedy these issues, we have demonstrated lossy and lossless compression of data on an existing precursor telescope, the Australian Square Kilometre Array Pathfinder (ASKAP), using MGARD and ADIOS2 libraries. We find data processing is faster by a factor of 7 and give compression ratios from a factor of 7 (lossless) up to 37 (lossy with an absolute error bound of 1e-3). We discuss the effectiveness of lossy MGARD compression and its adherence to the designated error bounds, the trade-off between these error bounds and the corresponding compression ratios, as well as the potential consequences of these I/O and storage improvements on the science quality of the data products.

Low-energy spin-polarized electrons (SPEs) are thought to cause symmetry breaking and could explain the origin of homochirality of prebiotic molecules such as amino acids and sugars. Here we study the effect of cosmic rays (CRs) on the emission of SPEs from aligned grains in dense protostellar environments and explore the SPE effects on chiral asymmetry of prebiotic molecules. We first show that icy grains in protostellar environments can align with magnetic fields due to magnetically enhanced radiative torque mechanism. We then study the production of thermal electrons by CR ionization of the H2 gas and the CR-induced UV radiation using the attenuated CR spectra in dense cores obtained from a continous slowing down model. Next, we show that thermal electrons with initial random spins captured by aligned grains will quickly become spin-polarized due to the Barnett effect, converting unpolarized incident electrons into SPEs. We calculate the rate of photoemission of such SPEs by CRs-induced UV radiation and secondary electron emission from aligned grains and find that the photoemission by CRs-induced UV radiation is dominant. Finally, we calculate the total production rate of SPEs inside aligned dust grains by CRs. Low-energy secondary SPEs from aligned grains induced by CRs would cause the chiral asymmetry of chiral prebiotic molecules formed in the ice mantle of aligned grains, in analogous to UV circularly polarized light. We propose that amino acids and sugars of chiral assymmetry detected in meteorite/asteroids/comets might be formed in the ice mantle of grains under the irradiation of SPEs released from aligned grains by CRs in protostellar environments.

Mrinmoy Sarkar, Santosh Joshi, Marc-Antoine Dupret, Otto Trust, Peter De Cat, Eugene Semenko, Patricia Lampens, Aruna Goswami, David Mkrtichian, Drisya Karinkuzhi, Ilya Yakunin, Archana Gupta

We present the results of an asteroseismic study of HD 118660 (TIC 171729860), being a chemically peculiar (mild Am) star exhibiting δ Scuti (δ Sct) pulsations. It is based on the analysis of two sectors of time-series photometry from the space mission TESS and seismic modelling. It yielded the detection of 15 and 16 frequencies for TESS sectors 23 and 50, respectively. The identified pulsation modes include four radial (=0) and five dipolar (=1) ones. The radial modes are overtones with order n ranging from 3 and 6. Such high values of n are theoretically not expected for stars with the effective temperature of HD 118660 (Teff7550K ) located near the red edge of the δ Sct instability strip. To estimate the asteroseismic parameters, we have generated a grid of stellar models assuming a solar metallicity (Z=0.014) and different values for the convective overshooting parameter (0.1αov0.3). We conclude that the analysis of the radial modes is insufficient to constrain αov and Z for δ Sct stars. The value for the equatorial velocity of HD 118660 derived from the seismic radius and the rotational frequency is consistent with values found in the literature.

Context. Dust grains in circumstellar envelopes are likely to have a spread-out temperature distribution. Aims. To investigate how trends in temperature distribution between small and large grains affect the hot corino chemistry of complex organic molecules (COMs) and warm carbon-chain chemistry (WCCC). Methods. A multi-grain multi-layer astrochemical code with an up-to-date treatment of surface chemistry was used with three grain temperature trends: grain temperature proportional to grain radius to the power -1/6 (Model M-1/6), to 0 (M0), and to 1/6 (M1/6). The cases of hot corino and WCCC chemistry were investigated, for a total of six models. The essence of these changes is for the main ice reservoir - small grains - having higher (M-1/6) or lower (M1/6) temperature than the surrounding gas. Results. The chemistry of COMs shows better agreement with observations in models M-1/6 and M1/6 than in Model M0. Model M-1/6 shows best agreement for WCCC because earlier mass-evaporation of methane ice from small grains induces the WCCC phenomenon at lower temperatures. Conclusions. Models considering several grain populations with different temperatures can more precisely reproduce circumstellar chemistry.

Lennart R. Baalmann, Silvan Hunziker, Arthur Péronne, James W. Kirchner, Karl-Heinz Glassmeier, David M. Malaspina, Lynn B. Wilson III, Christoph Strähl, Shivank Chadda, Veerle J. Sterken

Dust particle impacts on the Wind spacecraft were detected with its plasma wave instrument Wind/WAVES. Frequency analysis on this dust impact time series revealed spectral peaks indicative of a solar rotation signature. We investigated whether this solar rotation signature is embedded in the interplanetary or interstellar dust (ISD) and whether it is caused by co-rotating interaction regions (CIRs), by the sector structure of the interplanetary magnetic field (IMF), or by external effects. We performed frequency analysis on subsets of the data to investigate the origin of these spectral peaks, comparing segments of Wind's orbit when the spacecraft moved against or with the ISD inflow direction and comparing the time periods of the ISD focusing and defocusing phases of the solar magnetic cycle. A superposed epoch analysis of the number of dust impacts during CIRs was used to investigate the systematic effect of CIRs. Case studies of time periods with frequent or infrequent occurrences of CIRs were compared to synthetic data of dust impacts affected by CIRs. We performed similar case studies for time periods with a stable or chaotic IMF sector structure. The superposed epoch analysis was repeated for a time series of the spacecraft floating potential. Spectral peaks were found at the solar rotation period of ~27d and its harmonics at 13.5d and 9d. This solar rotation signature may affect both interplanetary and ISD. The appearance of this signature correlates with the occurrence of CIRs but not with the stability of the IMF sector structure. The CIRs cause, on average, a reduction in the number of dust impact detections. Periodic changes of the spacecraft's floating potential were found to partially counteract this reduction by enhancing the instrument's sensitivity to dust impacts; these changes of the floating potential are thus unlikely to be the cause of the solar rotation signature.

We present our new general relativistic Monte Carlo (MC)-based neutrino radiation hydrodynamics code designed to solve axisymmetric systems with several improvements. The main improvements are as follows: (i) the development of an extended version of the implicit MC method for multi-species radiation fields; (ii) modeling of neutrino pair process rates based on a new numerically efficient and asymptotically correct fitting function for the kernel function; (iii) the implementation of new numerical limiters on the radiation-matter interaction to ensure a stable and physically correct evolution of the system. We apply our code to a black hole (BH)-torus system with a BH mass of 3M, BH dimmensionless spin of 0.8, and a torus mass of 0.1M, which mimics a post-merger remnant of a binary neutron star merger in the case that the massive neutron star collapses to a BH within a short time scale (10ms). We follow the evolution of the BH-torus system up to more than 1s with our MC-based radiation viscous-hydrodynamics code that dynamically takes into account non-thermal pair process. We find that the system evolution and the various key quantities, such as neutrino luminosity, ejecta mass, torus Ye, and pair annihilation luminosity, are broadly in agreement with the results of the previous studies. We also find that the νeˉνe pair annihilation can launch a relativistic outflow for a time scale of 0.1s, and it can be energetic enough to explain some of short-hard gamma-ray bursts and the precursors. Finally, we calculate the indicators of the fast flavor instability directly from the obtained neutrino distribution functions, which indicate that the instability can occur particularly near the equatorial region of the torus.

This paper traces the 37 years of my career dedicated to the development of integral field spectroscopy (IFS), highlighting significant milestones and advancements. This extensive journey encompasses three generations of IFS: the initial prototype TIGER at CFHT, the first generation including OASIS at CFHT and SAURON at WHT, the second generation with MUSE at VLT, and the potential third generation represented by the Wide-field Spectroscopic Telescope (WST) project. Throughout, I discuss the lessons learned at each stage and provide my perspective on the future of IFS.

Jake Harkett, Leigh N. Fletcher, Oliver R. T. King, Michael T. Roman, Henrik Melin, Heidi B. Hammel, Ricardo Hueso, Agustín Sánchez-Lavega, Michael H. Wong, Stefanie N. Milam, Glenn S. Orton, Katherine de Kleer, Patrick G. J. Irwin, Imke de Pater, Thierry Fouchet, Pablo Rodríguez-Ovalle, Patrick M. Fry, Mark R. Showalter

Jupiter's Great Red Spot (GRS) was mapped by the James Webb Space Telescope (JWST)/Mid-Infrared Instrument (4.9-27.9 micron) in July and August 2022. These observations took place alongside a suite of visual and infrared observations from; Hubble, JWST/NIRCam, Very Large Telescope/VISIR and amateur observers which provided both spatial and temporal context across the jovian disc. The stratospheric temperature structure retrieved using the NEMESIS software revealed a series of hot-spots above the GRS. These could be the consequence of GRS-induced wave activity. In the troposphere, the temperature structure was used to derive the thermal wind structure of the GRS vortex. These winds were only consistent with the independently determined wind field by JWST/NIRCam at 240 mbar if the altitude of the Hubble-derived winds were located around 1,200 mbar, considerably deeper than previously assumed. No enhancement in ammonia was found within the GRS but a link between elevated aerosol and phosphine abundances was observed within this region. North-south asymmetries were observed in the retrieved temperature, ammonia, phosphine and aerosol structure, consistent with the GRS tilting in the north-south direction. Finally, a small storm was captured north-west of the GRS that displayed a considerable excess in retrieved phosphine abundance, suggestive of vigorous convection. Despite this, no ammonia ice was detected in this region. The novelty of JWST required us to develop custom-made software to resolve challenges in calibration of the data. This involved the derivation of the "FLT-5" wavelength calibration solution that has subsequently been integrated into the standard calibration pipeline.

Joanne Tan, Guang Yang, Jonelle L. Walsh, W. N. Brandt, Bin Luo, Franz E. Bauer, Chien-Ting Chen, Mouyuan Sun, Yongquan Xue

Tidal disruption events (TDEs) could be an important growth channel for massive black holes in dwarf galaxies. Theoretical work suggests that the observed active galactic nuclei (AGNs) in dwarf galaxies are predominantly TDE-powered. To assess this claim, we perform variability analyses on the dwarf-hosted AGNs detected in the 7 Ms Chandra Deep Field-South (CDF-S) survey, with observations spanning 16 years. Based on the spectral energy distribution (SED) modeling with X-CIGALE, we select AGNs hosted by dwarf galaxies (stellar mass below 1010 M). We focus on X-ray sources with full-band detections, leading to a sample of 78 AGNs (0.122 z 3.515). We fit the X-ray light curves with a canonical TDE model of t5/3 and a constant model. If the former outperforms the latter in fitting quality for a source, we consider the source as a potential TDE. We identify five potential TDEs, constituting a small fraction of our sample. Using true- and false-positive rates obtained from fitting models to simulated light curves, we perform Bayesian analysis to obtain the posterior of the TDE fraction for our sample. The posterior peaks close to zero (2.56%), and we obtain a 2-σ upper limit of 9.80%. Therefore, our result indicates that the observed AGNs in dwarf galaxies are not predominantly powered by TDEs.

Stacking the public Planck CMB temperature maps (NILC, SMICA, SEVEM, or Commander) on galaxy clusters from Planck catalogues reveals substantial residual contamination from thermal Sunyaev-Zeldovich (tSZ) emission. Unexpectedly, stacking "tSZ-free" CMB maps, like the Planck SMICA-noSZ CMB map or the Planck Constrained ILC (CILC) CMB map, still shows noticeable non-zero residual contamination from galaxy clusters. We demonstrate that this persisting residual stems from neglected relativistic SZ (rSZ) corrections in the CMB map estimation. Employing the component separation method outlined in Remazeilles & Chluba (2020) on Planck data, we map the rSZ first-order moment field y(TeˉTe) over the sky for different pivot temperatures ˉTe ranging from 2 to 10 keV. Stacking these y(TeˉTe)-maps on Planck galaxy clusters exhibits either an intensity decrement or increment at the centre, contingent upon whether ˉTe is above or below the actual ensemble-averaged cluster temperature Te. For the pivot value ˉTe=5 keV, a vanishing intensity is observed in the stacked Planck y(TeˉTe)-map, enabling us to infer the average gas temperature of Te5 keV for the Planck galaxy clusters. Building upon this finding, we revisit the Planck tSZ-free CMB map by deprojecting the complete rSZ emission using CILC, assuming an rSZ spectrum with Te=5 keV. Our new, rSZ-free Planck CMB map, when stacked on Planck galaxy clusters, shows a clear cancellation of the residual SZ contamination in contrast to prior (non-relativistic) tSZ-free Planck CMB maps. Our map-based approach provides compelling evidence for an average temperature of the Planck galaxy clusters of Te=4.9±2.6 keV using the rSZ effect.

Determining the spatial curvature (Ωk) independent of cosmic microwave background observations plays a key role in revealing the physics of the early universe. The Hubble tension is one of the most serious issues in modern cosmology. We investigate halo catalogs identified from N-body simulations at z=2 and 3, mimicking high-redshift galaxy surveys. We measure redshift-space correlation functions of halos from the two snapshots. We detect clear features of baryon acoustic oscillations and redshift-space distortions. We find that we can obtain a few percent constraints on both the geometric distances and growth of structure at the distant universe in future surveys. By taking into account the information of the underlying matter power spectrum, we demonstrate that we can also achieve constraint on the Hubble constant H0 with a few percent as well as the spatial curvature with |Ωk|0.1 by observing galaxies with the number density with ˉng104( h3 Mpc3). Our analysis provides a timely forecast for the upcoming spectroscopic surveys, which target emission line galaxy or dusty star-forming galaxy samples.

James Walsh, Daniel G. Gass, Raul Ramos Pollan, Paul J. Wright, Richard Galvez, Noah Kasmanoff, Jason Naradowsky, Anne Spalding, James Parr, Atılım Güneş Baydin

SDO-FM is a foundation model using data from NASA's Solar Dynamics Observatory (SDO) spacecraft; integrating three separate instruments to encapsulate the Sun's complex physical interactions into a multi-modal embedding space. This model can be used to streamline scientific investigations involving SDO by making the enormous datasets more computationally accessible for heliophysics research and enable investigations that require instrument fusion. We discuss four key components: an ingestion pipeline to create machine learning ready datasets, the model architecture and training approach, resultant embeddings and fine-tunable models, and finally downstream fine-tuned applications. A key component of this effort has been to include subject matter specialists at each stage of development; reviewing the scientific value and providing guidance for model architecture, dataset, and training paradigm decisions. This paper marks release of our pretrained models and embedding datasets, available to the community on Hugging Face and this http URL.

Lucas D. Smith, Nicholas Cannady, Regina Caputo, Carolyn Kierans, Nicholas Kirschner, Iker Liceaga-Indart, Julie McEnery, Zachary Metzler, A. A. Moiseev, Lucas Parker, Jeremy Perkins, Makoto Sasaki, Adam J. Schoenwald, Daniel Shy, Janeth Valverde, Sambid Wasti, Richard Woolf, Aleksey Bolotnikov, Thomas J. Caligiure, A. Wilder Crosier, Jack Fried, Priyarshini Ghosh, Sean Griffin, J. Eric Grove, Elizabeth Hays, Emily Kong, John Mitchell, Bernard Phlips, Clio Sleator, D.J. Thompson, Eric Wulf, Anna Zajczyk

The ComPair balloon instrument is a prototype gamma-ray telescope that aims to further develop technology for observing the gamma-ray sky in the MeV regime. ComPair combines four detector subsystems to enable parallel Compton scattering and pair-production detection, critical for observing in this energy range. This includes a 10 layer double-sided silicon strip detector tracker, a virtual Frisch grid low energy CZT calorimeter, a high energy CsI calorimeter, and a plastic scintillator anti-coincidence detector. The inaugural balloon flight successfully launched from the Columbia Scientific Balloon Facility site in Fort Sumner, New Mexico, in late August 2023, lasting approximately 6.5 hours in duration. In this proceeding, we discuss the development of the ComPair Since balloon payload, the performance during flight, and early results.

Lalitha Sairam, Thomas A. Baycroft, Isabelle Boisse, Neda Heidari, Alexandre Santerne, Amaury H.M.J. Triaud, Gavin A.L. Coleman, Yasmin T. Davis, Magali Deleuil, Guillaume Hébrard, David V. Martin, Pierre F.L. Maxted, Richard P. Nelson, Daniel Sebastian, Owen J. Scutt, Matthew R. Standing

Circumbinary planets - planets that orbit both stars in a binary system - offer the opportunity to study planet formation and orbital migration in a different environment compare to single stars. However, despite the fact that > 90% of binary systems in the solar neighbourhood are spectrally resolved double-lined binaries, there has been only one detection of a circumbinary planet orbitting a double-lined binary using the radial velocity method so far. Spectrally disentangling both components of a binary system is hard to do accurately. Weak spectral lines blend with one another in a time-varying way, and inaccuracy in spectral modelling can lead to an inaccurate estimation of the radial-velocity of each component. This inaccuracy adds scatter to the measurements that can hide the weak radial-velocity signature of circumbinary exoplanets. We have obtained new high signal-to-noise and high-resolution spectra with the SOPHIE spectrograph, mounted on the 193cm telescope at Observatoire de Haute-Provence (OHP) for six, bright, double-lined binaries for which a circumbinary exoplanet detection has been attempted in the past. To extract radial-velocities we use the DOLBY code, a recent method of spectral disentangling using Gaussian processes to model the time-varying components. We analyse the resulting radial-velocities with a diffusive nested sampler to seek planets, and compute sensitivity limits. We do not detect any new circumbinary planet. However, we show that the combination of new data, new radial-velocity extraction methods, and new statistical methods to determine a dataset's sensitivity to planets leads to an approximately one order of magnitude improvement compared to previous results. This improvement brings us into the range of known circumbinary exoplanets and paves the way for new campaigns of observations targeting double-lined binaries.

Richard A. N. Brooks, Nicolás Garavito-Camargo, Kathryn V. Johnston, Adrian M. Price-Whelan, Jason L. Sanders, Sophia Lilleengen

The infall of the LMC into the Milky Way (MW) has dynamical implications throughout the MW's dark matter halo. We study the impact of this merger on the statistical properties of populations of simulated stellar streams. Specifically, we investigate the radial and on-sky angular dependence of stream perturbations caused by the direct effect of stream-LMC interactions and/or the response of the MW dark matter halo. We use a time-evolving MW--LMC simulation described by basis function expansions to simulate streams. We quantify the degree of perturbation using a set of stream property statistics including the misalignment of proper motions with the stream track. In the outer halo, direct stream--LMC interactions produce a statistically significant effect, boosting the fraction of misaligned proper motions by ~25% compared to the model with no LMC. Moreover, there is on-sky angular dependence of stream perturbations:~the highest fractions of perturbed streams coincide with the same on-sky quadrant as the present-day LMC location. In the inner halo, the MW halo dipole response primarily drives stream perturbations, but it remains uncertain whether this is a detectable signature distinct from the LMC's influence. For the fiducial MW--LMC model, we find agreement between the predicted fraction of streams with significantly misaligned proper motions, ˉϑ>10, and Dark Energy Survey data. Finally, we predict this fraction for the Vera Rubin Large Synoptic Survey Telescope (LSST) footprint. Using LSST data will improve our constraints on dark matter models and LMC properties as it is sensitive to both.

We consider the effects of granulation with a complex geometry of a magnetic carpet on the genesis of waves and plasma flows in a quiet-region of the solar atmosphere. Our aim is to perform numerical experiments on the self-generated and self-evolving solar granulation in a magnetic carpet representing the parts of the large-scale magnetized solar atmosphere, where waves and flows are basic inherent physical processes occurring continuously. We perform numerical experiments with the use of the JOANNA code which solves non-ideal and non-adiabatic two-fluid equations for ions+electrons and neutrals treated as two separate fluids. In these experiments, we assume that the plasma is hydrogen, and initially described by magnetohydrostatic equilibrium which is accompanied with a magnetic carpet. Parametric studies with different values of magnetic field show that its higher values result in larger magnitudes of ion-neutral velocity drift, thus ensuring larger heating and plasma flows. The present model addresses that in the highly dynamic solar chromosphere, waves, heating and plasma flows may collectively couple different layers of the solar atmosphere, and this entire process crucially depends on the local plasma and magnetic field properties. We suggest that waves and flows are the natural response of the granulation process in the quiet-Sun.

Giulia M. Ronca, Galina Chikunova, Karin Dissauer, Tatiana Podladchikova, Astrid M. Veronig

Coronal dimmings are regions of reduced emission in the lower corona, observed after coronal mass ejections (CMEs) and representing their footprints. In order to investigate the long-term evolution of coronal dimming and its recovery, we propose two approaches that focus on both the global and the local evolution of dimming regions: the fixed mask approach and the pixel boxes approach. We present four case studies (September 6, 2011; March 7, 2012; June 14, 2012; and March 8, 2019) in which a coronal dimming is associated with a flare/CME eruption. We identified the dimming region by image segmentation, then restricted the analysis to a specific portion of the dimming and tracked the time evolution of the dimming brightness and area. In addition, we studied the behavior of small subregions inside the dimming area, of about 3x3 pixels, to compare the recovery in different regions of the dimming. Three out of the four cases show a complete recovery 24 hours after the flare/CME eruption. The recovery of the brightness follows a two-step trend, with a steeper and quicker segment followed by a slower one. In addition, some parts of the dimming, which may be core dimmings, are still present at the end of the analysis time and do not recover within 3 days, whereas the peripheral regions (secondary dimmings) show a full recovery. We demonstrate that the primary mechanism for recovery identified in the observations is the expansion of coronal loops into the dimming region, which gradually increase their intensity. Our developed approaches enable the analysis of dimmings alongside these bright structures, revealing different timescales of recovery for core and secondary/twin dimming regions. Combined with magnetic field modeling, these methods lay the foundation for further systematic analysis of dimming recovery and enhance the knowledge gained from already-analyzed events.

Learning about the chemical evolution of the universe is crucial to understanding the formation of the first stars and structure formation in the early universe. To find out how elements are produced via nucleosynthesis and how their relative amounts have evolved with time, abundance trends of stars with different metallicities can be established and compared. In this study, we present a spectrum of a very metal-poor star, HE 23154240, with [Fe/H] = 2.89 based on a Magellan/MIKE high-resolution visual light spectrum. The star has a radial velocity of +41.9 km s1, an effective temperature of 5181 K, a surface gravity of 2.24 dex, and a microturbulence of 1.61 km s1. The α-elements and the iron peak elements agree well with the abundance trend. The low abundance of [Sr/Ba] and [C/Fe] suggests that HE 23154240 is accreted and formed in a dwarf galaxy. The value of [Ba/Eu] suggests the operation of a limited r-process. The abundance pattern of [Mg/Fe] and [Si/Fe] in HE 23154240 and its metallicity indicated that the star is formed from the gas enriched by a Type II supernova of a massive Pop III star. The abundance pattern fits Population III supernova yields moderately. The star's kinematic behavior shows that the star has a retrograde orbit and is moving away from the galactic center and out of the galactic disk to the south, and although the star is located in the halo of the Milky Way, it didn't form in the Milky Way but was rather formed in a small dwarf galaxy that was later absorbed by the Milky Way.

Primordial black holes (PBHs) from the early Universe that can contribute to dark matter (DM) abundance have been linked to gravitational wave observations. Super-massive black holes (SMBHs) at the centers of galaxies are expected to modify distribution of DM in their vicinity, and can result in highly concentrated DM spikes. We revisit PBH merger rates in the presence of DM spikes, tracking their history. We find novel peaked structure in the redshift-evolution of PBH merger rates at low redshifts around z5. These effects are generic and are present for distinct PBH mass functions and spike profiles, and also can be linked to peaked structure in redshift evolution of star formation rate. Redshift evolution characteristics of PBH merger rates can be distinguished from astrophysical black hole contributions and observable with gravitational waves, enabling them to serve as probes of DM in galactic centers.

We employed advanced ionisation equilibrium models that we developed in Dufresne et. al. (2024), which include charge transfer and density effects, to model UV stellar irradiances for a sample of stars. Our sample includes ϵ Eridani (K2 V), α Centauri A (G2 V), Procyon (F5 V) and Proxima Centauri (M5.5 Ve). We measured line fluxes from STIS datasets and used O IV and O V as density diagnostics to find the formation pressure of ions in the transition region (TR) and adopted a simple Differential Emission Measure (DEM) modelling. Our findings indicate significant improvements in modelling spectral lines from anomalous ions such as Si IV, C IV and N V of the Li- and Na-like sequences, which produce the strongest lines in the UV. For example, the Si IV lines were under-predicted by a factor of five and now are within 40% the observed fluxes. The improved models allow us to obtain for the first time reliable estimates of some stellar chemical abundances in the TR. We compared our results with available photospheric abundances in the literature and found no evidence for the First Ionisation Potential (FIP) effect in the TR of our stellar sample. Finally, we compared our results with the solar TR that can also be described by photospheric abundances.

Modified Newtonian Dynamics (MOND) has long been known to fail in galaxy clusters, implying a residual missing mass problem for clusters in this context. Here, using mass profiles derived from strong- and weak-lensing shear, as well as magnification data, for a sample of clusters from the CLASH survey, we characterize the density profile of this residual MOND missing mass in the central Mpc of galaxy clusters. In line with results obtained in the literature from the hydrostatic equilibrium of hot gas, we find that an inner constant density core and an outer power-law slope between 4 and 6 provides a good description within 1 Mpc. We also show that the data in the central parts of clusters can be even better represented by a `dark mass-follows-gas' profile with an exponential cut-off. Clusters with X-ray emitting gas masses Mgas1014M display a remarkable uniformity for the missing-to-hot-gas density ratio in the inner parts, of order 10, and for the exponential cut-off radius, of order 450 kpc. Clusters with lower observed gas mass display larger and more scattered values for both the density ratio and cut-off radius. These lensing results can in principle serve as a crucible for relativistic theories of MOND in galaxy clusters, or for any other tentative hypothesis regarding the nature of the clusters residual missing mass in the MOND context.

Hagai Netzer, Michael R. Goad, Aaron J. Barth, Edward M. Cackett, Keith Horne, Chen Hu, Erin Kara, Kirk T. Korista, Gerard A. Kriss, Collin Lewin, John Montano, Nahum Arav, Ehud Behar, Michael S. Brotherton, Doron Chelouche, Gisella de Rosa, Elena Dalla Bonta, Maryam Dehghanian, Gary J. Ferland, Carina Fian, Yasaman Homayouni, Dragana Ilic, Shai Kaspi, Andjelka B. Kovacevic, Hermine Landt, Luka C. Popovic, Thaisa Storchi-Bergmann, Jian-Min Wang, Fatima Zaidouni

The local (z=0.0315) AGN Mrk 817, was monitored over more than 500 days with space-borne and ground-based instruments as part of a large international campaign AGN STORM 2. Here, we present a comprehensive analysis of the broad-band continuum variations using detailed modeling of the broad line region (BLR), several types of disk winds classified by their optical depth, and new numerical simulations. We find that diffuse continuum (DC) emission, with additional contributions from strong and broad emission lines, can explain the continuum lags observed in this source during high and low luminosity phases. Disk illumination by the variable X-ray corona contributes only a small fraction of the observed continuum lags. Our BLR models assume radiation pressure-confined clouds distributed over a distance of 2-122 light days. We present calculated mean-emissivity radii of many emission lines, and DC emission, and suggest a simple, transfer-function-dependent method that ties them to cross-correlation lag determinations. We do not find clear indications for large optical depth winds but identify the signature of lower column density winds. In particular, we associate the shortest observed continuum lags with a combination of tau(1 Ryd) approx. 2 wind and a partly shielded BLR. Even smaller optical depth winds may be associated with X-ray absorption features and with noticeable variations in the width and lags of several high ionization lines like HeII and CIV. Finally, we demonstrate the effect of torus dust emission on the observed lags in the i and z bands.

Anthony E. Mirasola, Nathan Musoke, Mark C. Neyrinck, Chanda Prescod-Weinstein, J. Luna Zagorac

It is generally assumed that scalar field dark matter halos would contain solitonic cores -- spherically symmetric ground state configurations -- at their centers. This is especially interesting in the case of ultralight dark matter (ULDM), where the solitons sizes are on the order of galaxies. In this work, we show that the paradigm of a spherically symmetric soliton embedded in the center of each halo is not universally valid in a scenario with multiple interacting scalar fields. In particular, sufficiently strong repulsive interspecies interactions make the fields immiscible. In such models, the ground state configuration can fall into a number of different phases that depend on the fields' relative densities, masses, and interaction strengths. This raises the possibility that the inner regions of ULDM halos are more complex and diverse than previously assumed.

Magnetic flux ropes (FRs) are twisted structures appearing on the sun, predominantly in the magnetically concentrated regions. These structures appear as coronal features known as filaments or prominences in Hα observations, and as sigmoids in X-ray, EUV observations. Using the continuous vector magnetic field observations from \textit{Helioseismic and Magnetic Imager} onboard \textit{Solar Dynamics Observatory}, we study the evolution of the magnetic fields in the active regions (ARs) to understand the conditions of twisted flux formation. While ARs emerge and evolve further, flux motions such as shearing and rotation are efficient mechanisms to form twisted flux ropes. Magnetic helicity quantifies the twisted magnetic fields and helicity injection through photosphere leads to its accumulation in the corona. Therefore, coronal helicity accumulation leads to twisted FR formation and its eruption. The magnetic helicity injection is seen to evolve distinctly in the regions of flux rope formation and eruption. The ARs that are associated with eruptive activity are observed with helicity injection predominantly with one sign over a period of a few days. The ARs that inject helicity with a changing sign are unlikely to form twisted FRs because coronal helicity during the period of one sign of injected helicity gets cancelled by the opposite sign of injection in the later period. As a result, the coronal field reconfigures from shared to potential structure. For a given AR, the upper limit of helicity that could cause a CME eruption is not yet understood, which can be the subject of future studies of ARs. Magnetic reconnection plays a crucial role in both the initiation and driving of FR eruptions after their formation. Data-driven simulations of the AR evolution provide more insights on the flux rope formation and its onset of eruption.

Michael Poon, Marta L. Bryan, Hanno Rein, Caroline V. Morley, Gregory Mace, Yifan Zhou, Brendan P. Bowler

We constrain the angular momentum architecture of VHS J125601.92-125723.9, a 140 ± 20 Myr old hierarchical triple system composed of a low-mass binary and a widely-separated planetary-mass companion VHS 1256 b. VHS 1256 b has been a prime target for multiple characterization efforts, revealing the highest measured substellar photometric variability to date and the presence of silicate clouds and disequilibrium chemistry. Here we add a key piece to the characterization of this super-Jupiter on a Tatooine-like orbit; we measure its spin-axis tilt relative to its orbit, i.e. the obliquity of VHS 1256 b. We accomplish this by combining three measurements. We find a projected rotation rate vsinip=8.7±0.1km s1 for VHS 1256 b using near-IR high-resolution spectra from Gemini/IGRINS. Combining this with a published photometric rotation period indicates that the companion is viewed edge-on, with a line-of-sight spin axis inclination of ip=90±18. We refit available astrometry measurements to confirm an orbital inclination of io=23+1013. Taken together, VHS 1256 b has a large planetary obliquity of ψ=90±25. In total, we have three measured angular momentum vectors for the system: the binary orbit normal, companion orbit normal, and companion spin axis. All three are misaligned with respect to each other. Although VHS 1256 b is tilted like Uranus, their origins are distinct. We rule out planet-like scenarios including collisions and spin-orbit resonances, and suggest that top-down formation via core/filament fragmentation is promising.

Linear theory predicts that primordial magnetic fields (PMFs) enhance the matter power spectrum on small scales. However, the linear approximation breaks down on sufficiently small scales where PMF-induced baryon perturbations back-react onto the magnetic fields. Previous studies assumed that the baryon power spectrum would be sharply suppressed in this non-linear regime, based on arguments related to the magnetic Jeans scale. For the first time, we perform dedicated magnetohydrodynamic (MHD) simulations to investigate the transition from the linear to the non-linear regime. Our simulations confirm the expected linear behavior on large scales. In the non-linear regime, however, we find that the dimensionless baryon power spectrum saturates to an O(1) value, which contrasts with previous analytical expectations. Additionally, our results show that several past studies overestimated the total matter power spectrum by orders of magnitude near the transition to non-linearity. Thus, the results presented in this work are useful to obtain more accurate constraints on PMFs from structure formation processes and/or different tracers of cosmic structures.

M. Dorsch, C. S. Jeffery, A. Philip Monai, C. A. Tout, E. J. Snowdon, I. Monageng, L. J. A. Scott, B. Miszalski, V. M. Woolf

Magnetic fields with strengths ranging from 300 to 500 kG have recently been discovered in a group of four extremely similar helium-enriched hot subdwarf (He-sdO) stars. Besides their strong magnetic fields, these He-sdO stars are characterised by common atmospheric parameters, clustering around Teff = 46500K, logg close to 6, and intermediate helium abundances. Here we present the discovery of three additional magnetic hot subdwarfs, J123359.44-674929.11, J125611.42-575333.45, and J144405.79-674400.93. These stars are again almost identical in terms of atmospheric parameters but, at B 200kG, their magnetic fields are somewhat weaker than those previously known. The close similarity of all known He-sdOs implies a finely-tuned origin. We propose the merging of an He white dwarf with a H+He white dwarf. A differential rotation at the merge interface may initiate a toroidal magnetic field that evolves by a magnetic dynamo to produce a poloidal field. This field is either directly visible at the surface or may diffuse towards the surface if initially buried. We further discuss a broad absorption line centred at about 4630Å that is common to all magnetic He-sdOs. This feature may not be related to the magnetic field but instead to the intermediate helium abundances in these He-sdO stars, allowing the strong He II 4686Å line to be perturbed by collisions with hydrogen atoms.