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Sun and starsarXiv:2610.20689
A Parsec-scale Circumstellar Shell Around VX Sgr: Mass Loss and RSG/T\.ZO Nature
A thin, arc-shaped shell is discovered surrounding VX Sagittarii (VX Sgr), the largest known CSM shell around an RSG at a scale r~0.59 pc. The nebula has an extinction-corrected Hα intensity I_Hα~38 R and an ionized mass ~0.1 M☉. The slow 12 km s⁻¹ peculiar velocity of VX Sgr and the lack of far-infrared emission in the arc indicate that it is not produced by a bow shock, but is likely instead steady RSG wind or ejecta that is photoionized by a nearby O- or B- type star. The nature of VX Sgr is debated in the literature as a red supergiant/hypergiant (RSG/RHG), super-AGB star, or…
We analyze co-spatial HST/ACS and JWST/NIRCam time-series photometric observations of RR Lyrae in the low-metallicity dwarf galaxy Leo P. This study provides a new opportunity to explore the properties of and potential for metal-poor RR Lyrae studies with JWST using well-understood relationships from past HST work. We identify 20 RR Lyrae in the HST imaging and 15 RR Lyrae in the JWST imaging. We determine the periods, amplitudes, and mean magnitudes for each of the RR Lyrae. We fit the Period-Wesenheit-Metallicity (PWZ) function to the HST RR Lyrae population, and obtain a Gaia-consistent RR…
The impact of nonlinear Landau damping on cosmic ray streaming and the role of external turbulence
Cosmic rays (CRs) streaming faster than the Alfv\'en speed generate Alfv\'en waves that scatter them. The saturated wave amplitude is regulated by a damping mechanism. This damping controls the CR scattering rate and drift velocity, and thus the rate at which CRs transfer momentum and energy to the ambient plasma, which sets the strength of CR feedback. In the ionized interstellar medium, nonlinear Landau damping (NLLD) is commonly invoked as the dominant damping mechanism for Alfv\'en waves. We test this assumption with fluid-PIC simulations in which thermal ions and electrons are modeled as…
A Vision for Little Red Dots in the Low-Redshift Universe with ALMA2040
The discovery of Little Red Dots (LRDs) at high redshifts with JWST has revealed a previously unknown phase of black-hole growth. However, their black-hole (BH) masses, BH-to-stellar mass ratios, cold-gas reservoirs, and depletion times remain uncertain. The recent discovery of low-redshift LRDs at zsimeq0.1 - 0.9 creates a decisive opportunity to access their low-J CO lines for measuring molecular gas reservoirs, and the nearest systems can in principle be spatially resolved. We use J1025+1402 ("The Egg") at z=0.1007, the best-studied local LRD, as a benchmark to explore the scientific…
The Impact of High-Mass Clusters on the Binary Black Hole Merger Rate over Cosmic Time
We present a cosmological calculation of the binary black hole merger rate from dense star clusters, using a textttCluster Monte Carlo (textttCMC) model grid spanning the full observed parameter space of cluster mass, metallicity, and virial radius. For the first time, we incorporate N=10⁷-particle textttCMC models into this calculation, including a new solar-metallicity model, extending the textttCMC Cluster Catalog to the most massive clusters observed in the local Universe. Using an analytic cluster formation model which convolves the cluster formation rate with delay-time distributions…
A Misaligned Debris Disk relative to the Host Star CPD-72 2713 from JWST/NIRCam Imaging
Observations of debris disks provide a valuable window to investigate the formation and evolution of planetary systems. We present high-contrast JWST/NIRCam observations of CPD-72 2713, a 24 Myr-old star that belongs to the β Pic moving group. We obtained the first scattered-light images of the disk in both F210M and F444W filters, revealing a nearly face-on orientation. Forward modeling yields disk radii of 55.4^+3.0_-3.2 AU (F210M) and 39.1^+4.6_ -2.6 AU (F444W), both significantly smaller than the thermal emission radii measured with ALMA and Herschel/PACS. This discrepancy suggests that…
Efficient numerical evolution of self-gravitating systems with dark-matter-baryon scattering
We present a fast algorithm to numerically evolve a spherically symmetric system consisting of dark matter and gas, including dark-matter-baryon scattering. The method augments the spherical N-body code NSphere, which collapses the six-dimensional phase space of a spherical collisionless system to three dimensions, with a one-dimensional Lagrangian treatment of gas. Dark-matter-baryon scattering is implemented as a Monte-Carlo process between the dark-matter numerical particles and the gas shells. We also implement an algorithm for radiative gas cooling that is valid for weak cooling. The…
CoRGI in MaNGA - II. NGC 5717: cold-gas accretion and disk growth in a BGG
Large-scale stellar counter-rotation, in which two coplanar stellar components rotate in opposite directions, is usually interpreted as a signature of external gas accretion. Such systems are most often found in relatively sparse environments, where cold gas can be acquired and remain dynamically undisturbed long enough to settle into a disk. It is less clear whether this channel can operate in massive central galaxies, whose group or cluster environments can heat, strip, or perturb cold gas. Here we present NGC 5717, one of the most massive galaxies known to host a counter-rotating stellar…
How Little Red Dots Turn Blue: Evolution of Kelvin-Helmholtz Contracting Black Hole Envelopes and Observational Diagnostics
James Webb Space Telescope (JWST) observations have revealed compact, red-colored, broad-line emitters known as little red dots (LRDs), while a bluer counterpart population has been referred to as little blue dots (LBDs). Their physical connection remains unclear: they may represent different evolutionary stages of the same phenomenon, distinct populations, or different phases of the broader evolution of early galaxies and their black holes (BHs). We propose a model in which a rapidly growing BH is embedded in a geometrically thick gaseous envelope accompanied by concurrent nuclear star…
Tracing small-scale structure formation through cosmic time with strong gravitational lensing: A case for a next-generation sub-millimetre/millimetre interferometer
The nature of dark matter and the growth of supermassive black holes (SMBHs) remain major open questions in modern astrophysics. Both leave a key signature in an overlapping, largely unexplored mass range: <10⁷ M☉ dark haloes and wandering black holes. These may be undetectable directly, but detectable through gravitational perturbation of strongly lensed images, and partly or entirely distinguishable from one another through lensing data alone. We demonstrate through realistic simulations that a 255-element sub-mm/mm interferometer could probe this critical mass regime, detecting…
Probing ordered magnetic fields in galaxies across cosmic time
Magnetic fields are dynamically important across many astronomical environments, yet their origin, strength, and evolution over cosmic time remain poorly understood. Ordered magnetic fields are ubiquitous in the nearby Universe, as revealed by a range of observational techniques, but evidence for their existence at cosmological distances is scarce. Recent ALMA detections of polarised dust emission indicate that galactic-scale ordered magnetic fields, spanning up to kiloparsec scales, were already present in massive star-forming galaxies at redshifts up to z~5.6. This white paper argues that…
The Pristine survey XXIX. Data Release 2: Photometric metallicities for 15 millions stars down to G~20.5
Tailored narrow-band photometric observations are an efficient way to measure the metallicity of Milky Way stars. The Pristine survey has been mapping the northern sky since 2015 using narrow-band CaHK photometry obtained with the MegaCam imager on the Canada-France-Hawaii Telescope (CFHT). Data Release 1 (DR1) provided a high-precision absolute calibration of the survey observed before October 2022 using Gaia DR3 XP synthetic photometry, yielding photometric metallicities over ~6,500 deg², but was limited in depth to the availability of Gaia spectro-photometry (G ≲ 17.65). We present the…
Planet forming disk populations and their connection to the environment
Existing sub-mm observatories such as ALMA have provided statistics on the planet-forming mass reservoirs within circumstellar disks around stars in stellar clusters out to distances of ~400pc. However, these disks are not where most planets form. Many stars, and hence planets, form in more massive clusters, which are only found at larger distances. Environmental conditions that affect disks - such as UV radiation field, ambient gaseous mass reservoir, and stellar density - change significantly as a function of cluster mass, implying that our current knowledge of the disk population from…
The unified Bound Dark Energy–Bound Dark Matter model: theory and constraints from DESI DR2
The unified Bound Dark Energy–Bound Dark Matter (BDE-BDM) model derives both the dark energy and the whole of the dark matter from a single supersymmetric SU(3) gauge group with N_f=6 flavors. Gauge-coupling unification predicts the scale at which it condenses, Λc=34⁺¹⁶₋₁₁~eV, before any cosmological data are used, so the dark-energy sector adds no parameter to those of ΛCDM and the dark-matter sector adds only one. Fitting DESI DR2 BAO, Planck CMB, Planck+ACT DR6 CMB lensing, and three supernova compilations (PantheonPlus, Union3.1, DES-Dovekie) gives, for Union3.1, Λc=43.67±0.13~eV, inside…
HI rotation curves and mass-size relation for 568 galaxies from the Apertif Wide-area Extragalactic Survey
The extended HI rotation curves of galaxies are one of the most powerful tools for studying galaxy evolution and for testing different dark matter and modified gravity models. However, their sample sizes have historically been limited to a few hundred galaxies, mostly due to the survey speed of radio interferometers. Here, we present a first data release of HI kinematic models from the Apertif Wide-area Extragalactic Survey (AWES). Starting from 1924 galaxies detected in HI, we constructed 568 reliable kinematic models, which provide rotation curves, velocity dispersion profiles, surface…
Wandering intermediate-mass black holes and off-nuclear tidal disruption events from early star clusters
Off-nuclear tidal disruption events (TDEs) reveal evidence for massive black holes outside galactic centers, but the origins of this wandering population remain uncertain. We investigate wandering intermediate-mass black holes (IMBHs) formed through runaway stellar collisions in dense, high-redshift star clusters and predict their TDE signatures across cosmic time. Our semi-analytic model samples clusters associated with low-mass subhalos at 7<z<20 and uses merger trees from the IllustrisTNG TNG50 simulation to follow the assembly of 15 elliptical galaxies with stellar masses of 10⁹-10¹¹~M☉…
Nonlocal Gravity, Restricted CPL Dynamics and DESI Constraints
Nonlocal modifications of gravity provide a theoretically motivated framework in which cosmic acceleration can emerge dynamically without introducing a fundamental cosmological constant. We revisit the cosmological predictions of the Maggiore–Mancarella nonlocal R Box⁻²R model, with particular emphasis on its background dynamics and observational viability in light of recent DESI baryon acoustic oscillation measurements. A key feature of the theory is its predictive character: for fixed standard cosmological parameters, each value of the nonlocal parameter determines a specific effective pair…
An Attenuation Bump at z=9.3: Probing Dust Diversity at Cosmic Dawn
We report the identification of a UV attenuation bump in the Black Pearl, a galaxy at a spectroscopic redshift of 9.3335 observed with JWST/NIRSpec as part of the ZENITH and EMBER surveys. This is the highest-redshift UV bump reported to date, probing dust properties only approximately 500 Myr after the Big Bang. The feature is directly detected as a broad depression in the rest-frame UV continuum and is well described by a local Drude profile, with a central wavelength of 2132+/-17 Angstroms, an FWHM of 413+/-54 Angstroms, and a peak attenuation of 0.21+/-0.02 mag. Joint spectrophotometric…
A model for the ongoing subcluster interaction in Centaurus
Intracluster globular clusters (GCs) preserve the hierarchical and chemical history of galaxy cluster assembly. The nearby Centaurus cluster is believed to be undergoing an interaction between two subclusters, Cen 30 and Cen 45, which should leave an imprint on its intracluster GCs. We aim to characterise the GC population in Centaurus and constrain its recent assembly history, ultimately constructing an interaction scenario consistent with the observational evidence. Using deep VLT/FORS imaging in the V and I bands, we select GC candidates around the cluster centre based on morphology and…
Has JWST Seen Everything? Hunting for "NIRCam-dark" Dusty Star-Forming Galaxies at z simeq 6 - 9 with ALMA2040
JWST/NIRCam has recovered the stellar counterparts of many ALMA-detected, formerly HST-dark galaxies, yet ALMA has started identifying dusty star-forming galaxies (DSFGs) at z>6 that remain extremely faint or undetected even with NIRCam. These "NIRCam-dark" DSFGs may trace a missing rapid-growth phase connecting UV-luminous galaxies at z>10 to massive quiescent galaxies at z≳4. So far, the small, heterogeneously selected NIRCam-dark sample is insufficient to determine their abundance or role in the evolution of massive galaxies. We show that a blind 1.3-mm continuum survey with ALMA2040 can…
ALMA2040: Understanding the Early Assembly of Galaxies - The Formation of Star-Forming Clumps and their Role in Shaping Galaxy Evolution
Astrophysics seeks to explain how galaxies form and evolve through the interplay of stars, gas, and dust. Giant molecular clouds (GMCs), the main reservoirs and sites of star formation, link the cold interstellar medium to the birth of stars and stellar structures. Their properties reflect galactic disk conditions, and their evolution is shaped by stellar feedback and host-galaxy dynamics. Studying GMCs across cosmic time is therefore key to understanding how gas turns into stars and drives galaxy evolution. Hubble Space Telescope and James Webb Space Telescope observations reveal compact…
Pulsars are exceptionally stable clocks, and a compact dark-matter object passing near the line of sight to a pulsar delays its pulses through the Shapiro effect. The number of detectable transits is set by the integral over the dark-matter density along the line of sight connecting the Earth and the pulsar. Established pulsars in pulsar timing arrays are typically within one kiloparsec of the Earth and hence sit in a dark-matter density comparable to our local value. In this work, we explore globular clusters in the inner Galaxy as targets to search for compact dark matter. These…
Understanding how the first galaxies assembled their stellar mass at cosmic dawn is a central frontier of modern astrophysics. JWST has now revealed an unexpected population of ultraviolet-bright galaxies at z>10, whose intense emission points towards a rapid stellar mass growth that challenges current models of early galaxy assembly. Yet, the cold gas fueling this growth remains hidden: current ALMA sensitivity restricts routine detection to only the brightest ionized-gas tracers such as [OIII] 88μm, while [CII] 158μm, a key coolant and gas-mass proxy of the neutral interstellar medium…
A Search for Dust in the Outflow of the HH212 Class 0 Protostellar System
Perhaps the most visually striking phenomenon during star formation is the ejection of material along the direction of the protostar's rotational axis. Observed in the form of molecular outflows and/or atomic jets, these features carry away mass, energy and angular momentum from the system. Given the known dust content of protoplanetary disks, and the energetics of outflows, it has been suggested that it should be possible to lift dust from disks via winds, yet limited observational evidence has been presented in the literature. Any detection of dust within protostellar outflows not only puts…
Beyond Mergers: the Role of Metallicity in Forming a Reservoir of Massive and Detached Binary Black Hole Systems
Isolated binary evolution is a key pathway to forming binary black hole (BBH) mergers. However, the observed gravitational-wave population indicates it may not account for all mergers, especially those with high primary black hole mass (≳ 30 M☉). Using the binary population synthesis code textttPOSYDON, we simulate populations of binary systems at eight metallicities from 10⁻⁴ to 2 Z☉ and classify each BH-forming binary as a merging BBH, a detached BBH, or a system disrupted during BH formation. We find that metallicity shapes these populations differently, especially for high BH masses (≳ 25…
The ALMA-QUARKS Survey. IV. Core Mass Function and Evolutionary Trends in Core Formation Efficiency and Chemistry
The ALMA-QUARKS (Querying Underlying Mechanisms of Massive Star Formation with ALMA-Resolved Gas Kinematics and Structures) survey targets 139 massive protoclusters selected from the ATOMS survey. The targets were observed at 1.3~mm wavelength with an angular resolution of ~0.3^′′, corresponding to ~10³~au at the sample's median distance of ~3.8~kpc. Using textttgetsf, we identify 3374 dense cores and classify them as starless, protostellar, hot core, or Hsc ii region candidates based on spectral-line diagnostics (e.g., H30α, CH₃CN, and CH₃OH) and CO outflow associations. The resulting…
Millimeter-wavelength observations provide a uniquely sensitive window into the physics of cosmic explosions, from supernovae (SNe) and tidal disruption events (TDEs) to nova eruptions, stellar mergers and electromagnetic counterparts to gravitational wave (GW) sources. Over the past decade, discoveries across the transient sky have revealed that many of the most informative phases of shock interaction, particle acceleration and jet formation unfold at frequencies above the traditional cm-wave domain, where synchrotron self-absorption weakens and thermal, nonthermal and dust components can be…
Jets and outflows operate across the full cosmic mass scale from young stellar objects (YSOs) and X-ray binaries (XRBs) to active galactic nuclei (AGN), gamma-ray bursts (GRBs), and tidal disruption events (TDEs), shaping many time-domain and multi-messenger transients. Key questions concern on how jets are launched, accelerated and collimated; where and how they dissipate energy and accelerate particles; and how they couple to their environments to set electromagnetic counterpart diversity and feedback. Millimeter and sub-millimeter observations uniquely address these questions by tracking…
uGMRT Polarization Observations with Walsh Modulation
In this report, we discuss the performance of the Walsh phase-switching scheme for Band 4 (550-750 MHz) polarimetric observations with the upgraded GMRT (uGMRT). We have carried out test observations with the Walsh modulation enabled and disabled, using the polarized calibrator 3C138 as the target and unpolarized calibrator 3C147 for amplitude, phase and leakage calibration. The two Walsh datasets (ON & OFF) were processed using identical flagging, calibration, and imaging procedures. The Walsh ON data showed smoother leakage solutions and lower residual scatter in the Stokes I, Q, U data…
Multi-Method Machine Learning Classification of Astronomical Sources with Rubin Data Previews: a Spectroscopy-Free Approach with DP1 and DP2
We present a multi-method machine-learning study for the binary photometric classification of point-like and extended sources in the Rubin Observatory Data Preview 1 (DP1) and Data Preview 2 (DP2). The workflow runs on the Rubin Science Platform using DP1 and DP2 ugrizy photometry, the DP1 ancillary photometric-redshift catalog, and the Monster astrometric and photometric reference catalog, without relying on external spectroscopy. Six methods (SVM, Random Forest, XGBoost, k-Nearest Neighbors, an Artificial Neural Network, and a soft Voting ensemble) are benchmarked in the deepest DP1 field…
What fuels the growth of stars and black holes in galaxies through cosmic time? The physics and chemistry of the interstellar medium in distant galaxies
The interplay between the baryonic matter in galaxies (gas, dust, stars) has a fundamental role in our understanding of galaxy formation and evolution through cosmic time. The (sub)mm regime provides a unique window to measure the physical conditions and chemistry in the cold and dusty gas reservoirs that fuel the formation of new stars and the growth of massive black holes in distant galaxies. Large sub(mm) interferometers have made a revolutionary impact mapping the cold gas and dust in galaxies beyond the local universe. However, significant progress is hampered by limited spectral-line…
The optical colors of hidden spiral-like features in nine Virgo early–type dwarfs
Dwarf early-type galaxies (ETGs) are abundant in nearby clusters and provide a key laboratory for studying environmentally driven galaxy transformation. Although dwarf ETGs were once considered structurally simple, deep imaging has revealed embedded spiral-like features (e.g., bars and spiral arms) in some of them, contributing only a small fraction of the total light. Their origin at dwarf scales remains uncertain. As a pilot study, we investigate spiral-like features in nine Virgo dwarf ETGs with clear embedded arms, using optical colors to test whether these features differ from the…
Modal estimation of high-order wavefront drifts on coronagraphic testbeds for high-contrast direct imaging of exoplanets
Long-term wavefront stability will be critical for the upcoming Habitable Worlds Observatory which aims to directly image exo-Earths. Mechanical and thermal instabilities induce slow, high-order wavefront errors which can degrade the contrast and in turn, the scientific yield of the observatory. Dark zone maintenance (DZM) has been proposed as a high-order wavefront sensing and control strategy to maintain contrast despite wavefront error drifts. This approach uses an Extended Kalman Filter (EKF) to estimate the electric field at each pixel in the dark zone of the science camera. However…
Correlated Radio Frequency Interference Monitor for Radio Telescopes
Radio frequency interference (RFI) is one of the biggest challenges facing current radio astronomy experiments. Telescopes like the Canadian Hydrogen Observatory and Radio transient Detector (CHORD) need to accurately identify RFI to deliver on their science goals. For applications like HI intensity mapping for precision cosmology, long integrations consisting of hundreds to thousands of hours are needed, and thorough RFI flagging is required to avoid contaminating deep datasets. Currently, many major precision cosmology instruments are facing systematic limitations that include unflagged RFI…
Study of pulse jitter characteristics of PSR J1744-1134: Towards high precision pulsar timing with InPTA
Variations in the shapes of individual pulses introduce a broadband noise component in pulsar times of arrival beyond what is expected from radiometer noise, referred to as the jitter noise. This noise limits the timing accuracy and, consequently, the sensitivity required for the detection of nanohertz gravitational waves using pulsar timing arrays. Accurate characterization of jitter noise, including its amplitude and frequency dependence, is therefore essential for each pulsar. In this work, we present the first detailed study of jitter noise in PSR J1744-1134 over the frequency range…
FUGUE: A New GPU-accelerated General Relativistic Magnetohydrodynamics Code with Weak-Field Multipole Self-Gravity and Quasi-Stationary Kerr Black Hole Evolution
We present FUGUE, a new GPU-accelerated code for general relativistic magnetohydrodynamics (GRMHD). The code supports an optional quasi-stationary update of the Kerr black hole mass and spin, as well as weak-field multipole self-gravity computed with a spherical harmonic Poisson solver. The calculations using high-order multipoles in the Poisson solver are expensive, so the self-gravity solver is well suited for GPU acceleration. The code uses shock-capturing methods and a second-order Runge–Kutta (RK2) scheme for time integration. We validate the code with hydrodynamic, magnetohydrodynamic…
Galaxy evolution is governed by the baryon cycle: gas accreted from the cosmic web and circumgalactic medium condenses into molecular gas, forms stars, and is redistributed by stellar and AGN feedback. Tracing the molecular phase is therefore essential to understanding how galaxies acquire, consume, and eject their baryons. Yet current molecular-gas surveys remain limited by sensitivity, area, cosmic variance, and spectral bandwidth. ALMA2040 would combine a ~10× sensitivity improvement with ≳512 GHz simultaneous frequency coverage, delivering ~100× faster mapping at fixed depth and a further…
Self Calibrated Galaxy Groups from the DESI DR1 Bright Galaxy Survey
We present a galaxy group catalog built from Data Release 1 of the Dark Energy Spectroscopic Instrument (DESI) Bright Galaxy Survey, using the Self Calibrated Group Finder. The algorithm uses clustering data from the observed sample to calibrate the Group Finder's free parameters, rather than simulations. The catalog contains 2,229,741 galaxies from ~2680 deg² of sky with 3-pass coverage and r-band fluxes lt 19.5. The catalog classifies all galaxies in the flux-limited sample as centrals or satellites and estimates host dark matter halo masses. We show the satellite fraction f_sat, luminosity…
Optimization of multi-resolution observation strategies for cosmic microwave background experiments
Cosmic microwave background (CMB) observations are increasingly performed by using a combination of both small aperture telescopes (SATs) and large aperture telescopes (LATs) to extract information across a wide variety of angular scales. The observation strategy of the telescopes must balance the restrictions of the observing site, instrument constraints, and a variety of science goals. We present a general framework for simulating the performance of different observation strategies. Using this framework, we focus primarily on the inflationary science goal and determine the optimal LAT…
Understanding the mechanisms that heat the Sun's chromosphere and corona to temperatures far exceeding those of the solar photosphere below remains one of the central challenges in solar physics. Small-scale, rapidly evolving processes - including shocks, turbulence, magnetohydrodynamic waves, reconnection-driven jets, and nano-flares - are thought to contribute significantly to the heating budget. However, direct observational constraints on their spatial, temporal, and spectral signatures remain hard to obtain. At millimeter wavelengths, optically thick thermal emission provides a…
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