Instrumentation and Methods for Astrophysics
Demonstrating the integration of a photonic lantern with an all-fiber-based nulling interferometer
Jordan Diaz, Rebecca Jensen-Clem, Philip M. Hinz et al. (+12 more)
High-contrast imaging of
Solar System scale
exoplanets and protoplanets demands advancements in instrumentation to access deeper starlight suppression at smaller angular separations than today's state-of-the-art. The multi-mode to single-mode conversion capabilities of photonic lanterns (PLs) provide new avenues to implement techniques such as nulling interferometry due to the inherent spatial filtering of single-mode waveguides. In this work, we present laboratory results on an all-fiber-based focal plane nulling interferometer using off-the-shelf components operating at 1550 nm. We demonstrate the implementation of a PL for coupling light into the instrument, and compare it to the case when
laser light is directly fed into the interferometer. The integration of a PL with the interferometer evidences their potential for feeding photonic-based science instruments. Additionally, we discuss expanding the concept of the instrument for the detection of accreting protoplanets.
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All authors Jordan Diaz, Rebecca Jensen-Clem, Philip M. Hinz, Daren Dillon, Pradip Gatkine, Aditya R. Sengupta, Dan Sirbu, Sarah Tedder, Kevin Bundy, Brian Vyhnalek, Steph Sallum, Matthew C. DeMartino, Stephen Eikenberry, Peter Delfyett, Rodrigo Amezcua-Correa
Cosmology and Nongalactic Astrophysics
Gravitational waves from super-Hubble bubbles
Pulkit S. Ghoderao, Arttu Rajantie and Danièle Steer
We consider a cosmological first-order phase transition in which bubbles of true
vacuum nucleate during inflation but do not collide and percolate until the Universe has entered the radiation-dominated era. If the collisions take place soon after the end of inflation, the size of these bubbles can be significantly greater than the Hubble length. This has two important consequences for the gravitational waves produced by the bubble collisions: First, as the peak frequency is determined by the comoving bubble radius, it can be well below the MHz frequencies typical for bubble collisions at the end of inflation. Second, when comparing collisions beginning at the same time, the amplitude of the gravitational waves is greatly enhanced relative to Hubble-sized and smaller bubbles. Together, these two effects mean that gravitational waves produced by super-Hubble bubbles soon after the end of inflation can be within the observable frequency and amplitude ranges of LIGO and NANOGrav, as well as LISA and other future gravitational wave experiments. We demonstrate this with a simple illustrative model.
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Earth and Planetary Astrophysics
Atmospheric Escape Rates of Planets in Stellar Tidal Fields from 3-D Hydrodynamic Simulations
Ritika Sethi, Morgan MacLeod and Sarah Millholland
Thermally driven atmospheric escape, including photo-evaporation and core-powered mass-loss, plays a key role in shaping the
evolution of close-in
exoplanets, yet most current models rely on simplified one-dimensional descriptions of atmospheric escape. In this work, we perform 3D hydrodynamic simulations of atmospheric
outflows from a Jupiter-sized
planet embedded in the gravitational potential of a
solar-type host
star, and compare these results with 1D models to identify the regimes where they perform well and where they break down. We explore a range of configurations by varying the degree of Roche-lobe filling and the thermal state of the
outflow. We find that systems with weak
tidal influence and high-temperature winds produce nearly spherical and isotropic
outflows, whereas more Roche-lobe-filling and cooler winds develop strong anisotropy and form two-tailed structures. We show that the commonly used 1D Parker wind model performs well only in the weak-tides regime, while including
tidal corrections yields reasonable estimates of mass-loss rates and captures the mean radial density profile across all regimes, but fails to reproduce the intrinsically three-dimensional, angle-dependent nature of the flow as the
outflow transitions from spherical to tidally structured tails. Motivated by these results, we develop a physically informed Mixture Model, calibrated using our 3D simulations, that accurately predicts mass-loss rates across the parameter space explored and outperforms 1D model with
tidal corrections.
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Solar and Stellar Astrophysics
Supergranulation as a Tracer of Solar-Cycle Variability
Irina N. Kitiashvili, Andrew A. Ngo and Spiridon Kasapis
Supergranulation is one of the dominant scales of near-surface
solar convection and provides an important diagnostic for studying the interaction between convective flows, rotation, and
magnetic activity. We develop an automated framework to identify and characterize supergranular structures using subsurface horizontal-velocity maps inferred from time-distance helioseismology. The method applies
Laplacian-of-Gaussian detection to horizontal velocity divergence maps and combines this with
magnetic-field masking, divergence-based filtering, and multi-peak rejection to isolate supergranular
cells under both quiet-Sun and active conditions. Using this approach, we analyze 16 years of SDO/HMI observations spanning
Solar Cycles 24 and 25 and investigate temporal and latitudinal variations of supergranular properties. The results reveal a clear
solar-cycle dependence: the mean supergranular diameter decreases near
solar maxima and increases around
solar minima, with systematically larger supergranules in the weaker
Solar Cycle 24 than in the stronger
Solar Cycle 25. The width of the diameter distribution increases during high
magnetic activity, whereas the number of detected supergranules shows only weak cycle dependence. The mean velocity divergence within detected supergranules is strongly anticorrelated with sunspot number, indicating
magnetic suppression of divergent convective flows. Time-latitude distributions of supergranular diameter and divergence closely follow the migration of
solar activity belts, while the curl of the horizontal velocity shows weak cycle dependence but pronounced hemispheric asymmetry. These results establish supergranulation as a sensitive tracer of
solar-cycle-related changes in near-surface convection.
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Cosmology and Nongalactic Astrophysics
The Nodal Line of the Galaxy Correlation Function as a Geometric Cosmological Probe
Lado Samushia
We propose a
geometric cosmological probe: the nodal line of the anisotropic
galaxy correlation function — the locus in the plane where the function changes sign. Because the nodal line depends only on this sign, it is invariant under any amplitude rescaling, and its information is mostly independent of and complementary to BAO. In a proof-of-concept analysis of DESI DR1
galaxies, the nodal line constrains $\Omega_m h^{3/2}$ to 3% at fixed
galaxy bias, degrading to 4.8% under a 10% prior. Combined with BAO, it yields a 4.45% sound-horizon-free constraint on $H_0$.
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Astrophysics of Galaxies
When galaxies cross cold fronts: wind tunnel simulations of ram pressure stripping
Elvis A. Mello-Terencio, Rubens E. G. Machado and Richards P. Albuquerque
Cluster collisions and mergers are among the most energetic phenomena in the low
redshift Universe. These interactions disturb the intracluster medium creating regions with density and temperature discontinuities, such as sloshing spirals. There is evidence that such environments can influence
galaxy evolution. This study aims to understand how a
galaxy that crosses an environment with discontinuities in density and temperature can be affected. To this end, a set of simulations was conducted using a wind tunnel setup into which a {MW-like mass}
galaxy was inserted. A total of eight models were created, namely two control runs and six with distinct density and temperature transitions along the tunnel, comprising simulations with low density and high density environments. Results show that
galaxies lose {considerably} more gas due to the higher density encountered when crossing denser and discontinuous regions in comparison to a constant density environment. The
star formation rate exhibits a brief enhancement when the
galaxy enters the denser section of the tunnel and {(u-i)} color index also undergoes slight changes, initially becoming bluer. However, even in the simulations with the most intense transitions, changes {in
star formation rate and color index} are not substantial, reaching at most 5% difference in relation to the control models. By the end of the simulation runs,
star formation rate and color index are similar to the control runs. These results suggest that crossing intracluster medium discontinuities can induce measurable effects in a
galaxy, but these are subtle and short-lived.
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Astrophysics of Galaxies
Too many quiescent late-type galaxies or a matter of misclassification?
J. L. Tous, S. I. Raimundo and H. Domínguez Sánchez
In the local Universe, the terms late-type and early-type are used to describe, respectively, disc
galaxies with spiral arms and more bulge-dominated systems lacking spiral structure. These morphologies are often associated with different
star formation levels, motivating the classical scenario where late-type and early-type
galaxies are seen, respectively, as
star-forming and "red and dead" systems. To build a comprehensive picture of
galaxy evolution, we must understand the relationship between morphology and
star formation, and be able to explain more exotic configurations, such as quiescence in late-type
galaxies. Large morphological catalogues are valuable tools to address these questions, but they must not be used blindly. We show that selecting quiescent
galaxies classified as late-type in these catalogues leads to a clear excess of edge-on systems, with unreliable morphologies, compared with the general
galaxy population in the Sloan Digital Sky Survey. Consequently, the fraction of quiescent late-type
galaxies in this survey could be overestimated by a factor of two. Conversely, S0
galaxies, considered early-type discs without spiral arms, are under-represented at high inclinations. We conclude that the excess of edge-on quiescent late-type
galaxies can be explained if most of these systems are misclassified edge-on S0
galaxies. We make recommendations to remove this bias.
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Astrophysics of Galaxies
Laboratory spectroscopy, theoretical characterization, and astronomical search for syn-propenethial (CH2CHCHS)
Germán Molpeceres, Carlos Cabezas, Marcelino Agúndez et al. (+5 more)
We report the laboratory characterization of the higher-energy isomer of propenethial, syn-CH2CHCHS. While the lower-energy isomer, anti-CH2CHCHS, was detected in the interstellar medium during the QUIJOTE line survey of TMC-1, we report the non-detection of the syn isomer in the same source, deriving an upper limit to its column density of 1.5 $\times$ 10$^{10}$ cm$^{-2}$. A subsequent theoretical investigation into the origin of this non-detection reveals that the most plausible formation pathway for CH2CHCHS is highly isomer-specific, producing nearly 95% of the anti isomer. This predicted branching ratio allows us to infer an even lower effective upper limit for the abundance of the syn isomer. In addition, calculations of tunneling-mediated unimolecular isomerization in the gas phase show that syn-CH2CHCHS converts to the lower-energy anti isomer on timescales of the order of 10$^{3}$ years. Overall, we conclude that the detection of syn-CH2CHCHS is highly challenging in both cold and warm interstellar environments. These results underscore the importance of electronic-structure and kinetic effects in determining isomer abundances across diverse interstellar environments.
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All authors Germán Molpeceres, Carlos Cabezas, Marcelino Agúndez, María Mallo, Yasuki Endo, Lucie Kolesniková, Gisela Esplugues, José Cernicharo
Astrophysics of Galaxies
Stellar Dynamics and Evolution of the Intermediate-Age Open Clusters NGC 2266 and NGC 2324
Cyrus Raj, D. Bisht and Ashish Raj
We present a refined astrometric and photometric analysis of the well-studied intermediate-age open clusters NGC 2266 and NGC 2324 using high-precision
Gaia DR3 data, complemented by 2MASS and LAMOST DR7 catalogs. Probable cluster members are identified using unsupervised machine learning techniques. We apply both Gaussian Mixture Models (GMMs) and pyUPMASK. We find that the GMM-based membership sample yields a cleaner, more coherent cluster sequence in the
Gaia CMDs than pyUPMASK. We identified 719 and 852 high-probability members ($P \geq 0.7$) for NGC 2266 and NGC 2324, respectively. Using the parallax method, we determine distances of 3.55 $\pm$ 0.23~kpc for NGC 2266 and 4.18 $\pm$ 0.24~kpc for NGC 2324. The radius estimates for both clusters are 7.23 $\pm$ 0.47 pc and 10.94 $\pm$ 0.63 pc. Isochrone fitting estimated ages of $1.1 \pm 0.1$~Gyr for NGC 2266 and $790 \pm 150$~Myr for NGC 2324. These age estimates were derived assuming
metallicities of $Z = 0.0084$ and $Z = 0.0038$, respectively. The King profile fitting indicates that both clusters exhibit compact, well-defined radial structures. Their
tidal radii are $8.84'$ (9.13 pc) for NGC 2266 and $10.97'$ (13.34 pc) for NGC 2324. The slopes of the present-day mass functions are $1.13\pm0.18$ for NGC 2266 and $1.24\pm0.19$ for NGC 2324, indicating a deficiency of low-mass
stars. The derived mass-function slopes are consistent with dynamical
evolution in both clusters. The clusters exhibit short relaxation times, while only NGC 2324 shows a mild indication of mass segregation. This study highlights the power of
Gaia astrometry to resolve internal structures within open clusters and refine their dynamical parameters.
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Instrumentation and Methods for Astrophysics
Map Multi-Tool: A Map-Based Approach to Modeling Beam Systematics for Cosmic Microwave Background Experiments
Cesiley L. King, Alec Hryciuk, Jeff McMahon et al. (+2 more)
Cosmic microwave background (CMB) experiments use simulations of instrumental systematic effects to ensure high-fidelity measurements of cosmological parameters. Quantifying the expected magnitude of these effects enables experiments to improve designs, set performance requirements, and understand potential measurement biases from residual systematics. Here we present a new simulation framework, called Map Multi-Tool (MMT), which models beam-related systematics for CMB instruments using a map-based approach. The pipeline convolves simulated sky realizations with distorted intensity and polarization beams, including leakage effects, to produce sky maps and power spectra. These outputs can then be used as inputs for cosmological parameter
estimators. this framework enables efficient evaluation of such systematic effects. We demonstrate the capabilities of MMT with examples of non-ideal beams induced by electrical readout crosstalk and detector time constant response. The electrical crosstalk example considers eight different schemes for a time-division multiplexed readout architecture, and shows how they lead to different levels of angular power spectrum leakage for row-switching and inductive crosstalk. The detector time constant example demonstrates how associated uncertainties can alter CMB spectra at high multipoles and bias cosmological parameters. These examples illustrate some of MMT's broad capabilities to inform critical design and calibration decisions to mitigate systematic effects in CMB instruments.
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All authors Cesiley L. King, Alec Hryciuk, Jeff McMahon, Johanna M. Nagy, John E. Ruhl
Astrophysics of Galaxies
Constraining young massive cluster properties with radio-continuum observations: The Arches cluster
M. Cano-González, R. Schödel, A. Alberdi et al. (+4 more)
The Arches cluster, located in the
Galactic Centre (GC) is one of the best astrophysical laboratories to study the properties of massive
stars and young massive clusters (YMCs). However, several fundamental parameters of the Arches cluster remain uncertain. Our goal is to constrain key cluster parameters (cluster age, mass, and initial mass function, IMF) by comparing the observed
stellar radio flux density distribution of the Arches cluster to those derived from a set of synthetic clusters. We use the deep X-band (10 GHz) Very Large Array data from our previous
radio continuum study of the Arches cluster. We model each simulated cluster with three parameters: age, mass, and IMF slope. We use three different
stellar evolutionary models: GENEC, PARSEC, and MIST at two different
metallicities,
solar ($Z=0.014$) and super-
solar ($Z=0.020$). We run Markov-chain Monte-Carlo simulations for each model/
metallicity combination in order to explore parameter space. All models and
metallicities return preferred ages in the $2\lesssim t_{\rm age}/{\rm Myr}\lesssim 3$ range. We obtain an IMF slope of $\alpha_{\rm IMF}=-1.85^{+0.28}_{-0.20}$, averaged over all models, where uncertainties are dominated by the degeneracy between cluster mass and IMF slope. If we use the IMF slope from previous infrared studies as prior, the cluster mass distributions peak at $\sim2.7\times10^4\, M_\odot$ and we can establish a lower limit at $\gtrsim2\times10^4 M_\odot$ for the Arches cluster mass.
Radio continuum observations of their most massive
stars can be used to constrain YMC parameters. In the case of the Arches cluster, age can be determined regardless of prior spectroscopic information, which can be useful to characterise newly discovered YMCs in the GC. Our results support the idea that a top-heavy IMF may be preferred in the GC or in YMCs in general.
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All authors M. Cano-González, R. Schödel, A. Alberdi, F. Najarro, J. Moldón, M. Pérez-Torres, F. Nogueras-Lara
Instrumentation and Methods for Astrophysics
Shack-Hartmann wavefront sensor slope measurement algorithm robust to scintillation and sensor saturation
Timothée Vene, Laurent M Mugnier, Aurélie Montmerle-Bonnefois et al. (+1 more)
High throughput optical communication links require the use of adaptive optics (AO) to compensate for atmospheric
turbulence even in strong perturbation conditions and at low elevation. Considering the intensity fluctuations brought by scintillation, we present a new slope measurement
algorithm for the Shack–Hartmann wavefront sensor (SHWFS), based on a joint maximum likelihood approach. We show that this
estimator is robust to sensor saturation and widens by more than two orders of magnitude the intensity range exploitable for reliable slope measurements compared to classical
algorithms. Consequently, by increasing the intensity assigned to the wavefront sensor, we also increase the number of valid measurements despite sensor saturation.
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All authors Timothée Vene, Laurent M Mugnier, Aurélie Montmerle-Bonnefois, Jean-Marc Conan
Instrumentation and Methods for Astrophysics
The Wide-field Spectroscopic Telescope (WST): design trade-offs for the low-resolution multi-object spectrograph instrument
Dimitri Buffat, Will Saunders, Kjetil Dohlen et al. (+10 more)
The Wide-field Spectroscopic
Telescope (WST) is a planned 12-meter-class dedicated spectroscopic facility designed to address key scientific challenges through large spectroscopic surveys. This paper presents design and performance trade-offs for the Low-Resolution Multi-Object Spectrograph (MOS-LR) instrument. With a multiplex of 30,000 covering a field of view of 3.1 square degrees, this instrument will provide unprecedented survey efficiency, an order of magnitude beyond those of current facilities. Covering the 370 to 930 nm range at a resolving power of 3,000 with a sky-projected fiber diameter of 1 arcsec, this instrument faces extreme challenges in design, manufacturing, and maintenance. We present a systematic approach to trading off optical and mechanical design options, taking into account constraints such as volume and mass, but also projected availability of detectors and gratings etc.
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All authors Dimitri Buffat, Will Saunders, Kjetil Dohlen, Laurence Tresse, David Lee, Roland Bacon, Andrea Bianco, Laurane Fréour, Roelof de Jong, Etienne Burtin, Olaf Iwert, Virgile Meyer, Elizabeth George
Solar and Stellar Astrophysics
An Halpha survey of infrared bow-shocks around OB-type stars
Kuljeet Singh Saddal, Michaela Kraus, Dieter H. Nickeler et al. (+3 more)
Bow shocks (BSs) around massive
stars are commonly identified in mid-infrared (MIR) surveys. In contrast, systematic optical investigations of these structures remain scarce with only a few possible detections reported so far. We performed a targeted Halpha imaging survey of 78 IR BS candidates compiled from literature catalogues. Observations were obtained with multiple ground-based facilities and complemented with archival MIR images from Spitzer and WISE. For the detected bow structures, geometrical parameters were measured, and the bows were classified based on the parameters of their central
stars, the measured stand-off distances and adopted plausible ISM conditions Clear arc-shaped Halpha nebulae are detected in 15 objects, with one additional BS discovered serendipitously. A further 35 objects exhibit diffuse Halpha emission associated with complex background structures, while 28 show no detectable Halpha emission. The Halpha and IR morphologies generally trace the same large-scale structures, although most of the IR arcs lie slightly closer to the
star and appear broader than their optical counterparts. We find that several systems are consistent with radiation-supported BSs, bow waves or
dust waves, while others remain compatible with classical wind-supported BSs. This survey demonstrates that a fraction of IR BS candidates around OB
stars also exhibit detectable ionised gas structures in Halpha, and both
stellar wind momentum and radiation pressure can contribute to shaping these structures. No correlation is found between the detection of an Halpha BS and the
stellar parameters, and the overlap in objects observed in Halpha and in the
radio regime was too small for firm conclusions. Future spectroscopic observations will be required to determine the physical conditions and kinematics of the ionised gas and to further constrain the nature of these BS systems.
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All authors Kuljeet Singh Saddal, Michaela Kraus, Dieter H. Nickeler, Tiina Liimets, Sergey Karpov, Olga V. Maryeva
High Energy Astrophysical Phenomena
R-process nucleosynthesis from magnetar giant flares in neutron star–white dwarf mergers: A unified picture for peculiar long gamma-ray bursts
Shu-Qing Zhong, Long Li, Le Zou et al. (+3 more)
Peculiar long gamma-ray bursts (GRBs), exemplified by GRBs 211211A and 230307A, exhibit a long-duration multi-component
prompt emission, an X-ray plateau in their afterglow, and a kilonova signature. Their origin remains highly debated. In this work, we present a unified picture for these events based on
neutron star–white
dwarf (NS–WD) mergers involving a pre-merger magnetar and a massive WD. In this picture,
tidal disruption of the WD forms a constant-
entropy accretion disk. Hyperaccretion from this disk onto the NS during the early
accretion phase amplifies its toroidal
magnetic field to strengths sufficient to trigger repeated magnetar
giant flares (GFs). The main burst (MB) of the
prompt emission consists of a “forest” of initial spikes from these GFs, while the subsequent
magnetic propeller phase generates the extended emission (EE) and naturally explains the observed MB–EE trough. Crucially, the $e^{\pm}$-$\gamma$ fireball associated with each GF initial spike shocks the NS crust, leading to crustal ejection that synthesizes r-process heavy elements via the $\alpha$-rich freeze-out mechanism, thereby resolving the r-process deficit in conventional NS–WD hydrodynamic simulations. The ensemble of such fireballs over the MB duration collectively yields $M_{\rm ej}\gtrsim 10^{-5}-10^{-3}\,M_\odot$ of ejecta, sufficient to power the observed kilonova signature when further boosted by the
spin-down of the post-merger magnetar. Meanwhile, the
spin-down radiation also powers the X-ray plateau. This tidally disrupted NS–WD merger picture provides a self-consistent framework that unifies the
prompt emission, afterglow, kilonova, and r-process nucleosynthesis observed in peculiar long GRBs.
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All authors Shu-Qing Zhong, Long Li, Le Zou, Ji-Gui Cheng, Yan-Zhi Meng, Jia-Hong Gu
Instrumentation and Methods for Astrophysics
Modelling Radio Frequency Interference on the Lunar Farside
Charlie K. Ashe, Ella J. Marshall, Evan F. Keane et al. (+3 more)
Technological progress is a double-edged sword in the world of
radio astronomy: improvements in
antennas, receivers, and digital backends increase sensitivity, but rapid growth in terrestrial and orbital communications has caused a steep rise in
radio-frequency interference (RFI). Modern
datasets have become increasingly contaminated by RFI that is difficult to remove and can mimic or obscure astrophysical signals, complicating the search for objects such fast
radio bursts (FRBs),
pulsars, and technosignatures. The lunar farside has such been proposed as a site for
radio-quiet observations, motivating missions such as the Lunar Farside Transients and Technology
Telescope (LFT3) and others. However, planned lunar missions may introduce intended and unintended
radio emissions into this protected environment. We use a LFT3-like instrument to model the
evolution of the apparent lunar farside RFI environment over the coming years. Using a planned lunar mission catalogue and models for intended and unintended emissions, we estimate the received RFI over the 0.1-2700 MHz frequency range. We find that while intended emissions are concentrated near communications bands, particularly 2.4-2.6 GHz, unintended emissions contaminate broad regions of the LFT3 band. We further find that, under the assumptions of our model, uniform UEMR shielding of at least 30 dB is required to place the maximum interference below the sensitivity of a LFT3-like instrument; more sensitive
telescopes would require higher UEMR shielding. We predict that the lunar farside will remain usable for LFT3-like observations, but will become increasingly contaminated as the lunar satellite population grows. This highlights the decreasing window of opportunity for measurements of the lunar farside's
radio quiet environment and should inform future mission design and policy choices for the protection of Moon-based
radio science.
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All authors Charlie K. Ashe, Ella J. Marshall, Evan F. Keane, Steve Prabu, Richard Lynch, David R. DeBoer
Solar and Stellar Astrophysics
A Modern ConvNet for Solar Filament Detection
J. R. Hu, Q. Hao, Z. Zheng et al. (+3 more)
Automated
solar filament detection using deep learning faces several challenges. Semantic
segmentation of
solar filaments is a complicated multiscale feature extraction task with long-tail distribution. Furthermore, a large-scale, highly complete, and finely detailed
dataset has become mandatory for providing abundant information. To address these challenges, we present a series of machine learning approaches to develop a
solar filament detection workflow that performs superbly. First, we manually annotated a small-scale
solar filament
dataset based on H$\alpha$ spectra called MHAS. Next, we developed the Multiscale ORiented DENdritic (MORDEN) model, a semantic
segmentation model focusing on multiscale feature extraction. We also introduced the Dense Conditional Random Field (DenseCRF) and Density-Based Spatial Clustering of Applications with Noise (DBSCAN) methods for post-processing. Using the proposed workflow, we generated a large-scale, high-quality
dataset called AHAS. Experimental results demonstrate that MORDEN outperforms several existing
solar filament semantic
segmentation models with open access. DenseCRF has been demonstrated to effectively capture fine edge details. We also evaluated the effects of data scaling and the reliability of DBSCAN and found that both approaches yield satisfactory performance. Multiple visualization results substantiate our quantitative findings. Our work provides a foundation for maximizing the potential of deep learning models for
solar filament detection.
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All authors J. R. Hu, Q. Hao, Z. Zheng, P. F. Chen, C. Li, Y. Meng
Astrophysics of Galaxies
Time-Domain Dust Astrophysics. I. Polarization Flares, Polarization-Angle Reverberation, and Fossil Imprints in Supernova-Illuminated Clouds
Thiem Hoang
Cosmic transients can enhance the local radiation field on timescales of days to months. Using the time-domain \TransRAT\ framework, which self-consistently follows grain heating,
alignment, rotational disruption, and switching of the
alignment axis between the
magnetic field (B) and the radiation direction (k), we predict the time-dependent
dust polarization of a dense cloud, represented by a homogeneous one-zone model, illuminated by a Type~IIP
supernova over a range of source–cloud distances. We identify four key signatures. First, for $D\lesssim1$~pc, a polarization
flare develops within days to weeks, marked by sharp increases in both thermal
dust polarization and extinction-polarization efficiency; this is followed by a polarization dip as radiative torque disruption (RAT-D) destroys the large aligned grains. Second, the peak wavelength of extinction polarization, $\lambda_{\rm max}$, shifts blueward as the minimum aligned-grain size decreases. Third, the transition from B-RAT to k-RAT produces an abrupt polarization-angle rotation of up to $45^{\circ}$ in our fiducial geometry. Fourth, as the transient fades, the return to B-RAT generates a polarization-angle reverberation governed by Larmor precession. At $D>1$~pc, SN-induced polarization properties can persist long after the radiation has faded. These fossil imprints offer the most practical near-term observational test: clouds near
supernova remnants younger than the relaxation timescale of $\sim10\,t_{\rm gas}$ with $t_{\rm gas}$ gas damping time, should exhibit elevated polarization and blueshifted $\lambda_{\max}$ today. Time-dependent
dust polarization can therefore probe
dust physics,
dust properties, and pristine pre-shock
magnetic fields in real time, while fossil imprints preserve a record of past explosions.
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Solar and Stellar Astrophysics
Identification of unresolved binaries in the VVV b294 tile: A Pro-Am collaboration using the Virtual Observatory
M. Cortés-Contreras, P. Cruz, E. Solano et al. (+22 more)
Stellar binaries and multiples are common objects. Their identification and characterization are primarily limited by the angular resolution of current instrumentation, survey depth and dynamic range. Towards the
Galactic plane,
stellar crowding further complicates these studies. We aim to identify unresolved binaries with good astrometric solutions and M
dwarf primaries in the b294 field from the Vista Variables in the Vía Láctea (VVV) survey using publicly available data. We examine the catalogue of M
dwarfs within 500 pc in the b294 tile, employing binarity tracers based on statistical parameters from
Gaia Data Release 3, multi-band photometry, and information in the literature. We reassess the astrometric and photometric parameters typically used for binary detection, establishing new boundaries and validating existing ones in the dense
stellar field examined. We compare these results with those obtained in the
solar vicinity. We present 990 unresolved binary candidates and 43 previously known binaries, including five possible triple systems. These represent the 13% of the catalogue, rising to 14.9% in well-covered regions. Binary-model SED fitting yields effective temperatures for 98 primary
stars, with the properties of their secondary candidates indicating that nearly half may be substellar objects. We select 120 of the most promising binary candidates. Tangential velocities, where calculated, place 95% of the studied binary candidates within the young disc population (tau <= 1 Ga). We demonstrate that the influence of nearby
Gaia detections on the statistical parameters is small, allowing constraints similar to those that are applied in less crowded regions.
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All authors M. Cortés-Contreras, P. Cruz, E. Solano, J. L. Navarro, T. Poyato Romero, R. Benavides Palencia, C. Cagigal-Olay, M. Zamora Rodríguez, A. Ginard, S. Langa, J. González-Edo, P. L'Huillier Seguel, E. M. Nicola, V. Pallares-López, M. A. Almela Rubert, J. A. Cano Díez, J. E. Donate Lucas, N. Echevarria Sainz-Ezquerra, A. Elbaz-Sanz, J. M. Espinosa Gallardo, G. Gurrea-Ysasi, J. C. Mora, C. Morales-Socorro, J. M. Perales, A. Romar
Instrumentation and Methods for Astrophysics
The beamformed trigger of RNO-G: its design and in-field performance
RNO-G Collaboration: S. Agarwal, J. A. Aguilar, N. Alden et al. (+75 more)
The
Radio Neutrino Observatory in Greenland (RNO-G) is a
neutrino detector under construction at Summit Station, with 8 out of a planned 35 stations currently deployed. We have designed and deployed a new phased array (PA) trigger based on delay-and-sum beamforming and power integration. This trigger improves detector performance by suppressing thermal noise and better targeting
neutrino-induced Askaryan signals. The new PA trigger has been deployed since the 2025 season. The trigger performance has been characterized using test pulses and calibration pulsers both in the lab and in-situ, and we find across these tests a 25% average reduction in the signal-to-noise ratio (SNR) needed to trigger on signals. Simulations are shown to be representative of the detector, and simulated trigger efficiencies are within 10% of measured data. Following the in-situ trigger validation, we use data-driven trigger performance to inform simulations of the detector effective volumes. The PA trigger increases our effective volume significantly, by over a factor of 2 below 0.1 EeV and at least a factor of 1.3 at the highest energies of 100 EeV.
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All authors RNO-G Collaboration: S. Agarwal, J. A. Aguilar, N. Alden, S. Ali, P. Allison, M. Betts, D. Besson, A. Bishop, O. Botner, S. Bouma, S. Buitink, R. Camphyn, J. Chan, S. Chiche, B. A. Clark, K. Couberly, D. Dakroub, K. D. de Vries, C. Deaconu, P. Giri, C. Glaser, H. Gui, A. Hallgren, J. C. Hanson, S. Hassiki, K. Helbing, B. Hendricks, J. Henrichs, N. Heyer, C. Hornhuber, E. Huesca Santiago, K. Hughes, A. Jaitly, A. Karle, J. L. Kelley, C. Kopper, M. Korntheuer, M. Kowalski, I. Kravchenko, R. Krebs, M. Kugelmeier, D. Kullgren, R. Lahmann, C.-H. Liu, Y. Liu, M. J. Marsee, K. Mulrey, M. Muzio, A. Nelles, A. Novikov, A. Nozdrina, E. Oberla, N. Punsuebsay, M. Ravn, Z. Riesen, A. Rifaie, D. Ryckbosch, F. Schlüter, O. Scholten, P. Schriefer, D. Seckel, M. F. H. Seikh, Z. S. Selcuk, J. Stachurska, J. Stoffels, S. Toscano, D. Tosi, J. Tutt, N. van Eijndhoven, A. G. Vieregg, A. Vijai, H. Warnhofer, D. Washington, C. Welling, D. R. Williams, P. Windischhofer, S. Wissel, A. Zink
Astrophysics of Galaxies
Cosmic ray heating of cold streams: Implications for the gas supply and growth of massive galaxies
Ellis R. Owen, Nicolas Ledos, Evangelia Ntormousi et al. (+3 more)
Recent observations have demonstrated the presence of
cosmic rays (CRs) in
cosmic-web filaments. Cold streams supply gas inflows from these filaments into massive
galaxies during the
cosmic noon. As these streams are expected to be magnetised, external
cosmic-web CRs may become entrained with this inflowing gas. We aim to determine whether this externally-supplied CR population can deposit energy to alter or disrupt the supply of cold gas to
galaxies. We couple a spectrally-resolved CR transport calculation to a
redshift-dependent analytical model of magnetised cold streams in
galaxy haloes and investigate whether externally-supplied CRs can modify gas supply through this channel. We find CR energy deposition can alter the thermal state of cold streams. Dense stream cores remain largely resilient and only experience weak heating. Their temperature is raised by less than a factor of 10, which is insufficient to overcome radiative cooling at the stream-CGM interface. In more diffuse streams, and in partially mixed interface gas of the most massive
haloes near the virial radius, CR heating becomes strong enough that radiative cooling can no longer balance it, and the gas is heated toward or above the mixing-layer temperature. This weakens the stability of the stream, making it more susceptible to disruption. Complete evaporation is possible only in extreme cases. Cold streams are therefore more vulnerable to CR heating at larger galactocentric radii, higher
halo masses, and in more diffuse or partially-mixed stream material. By preferentially heating diffuse gas, externally supplied CRs may introduce additional selectivity into cold-gas
accretion that modifies the gas supply and growth of massive
galaxies. These CRs weaken fragile streams and erode their cold envelope, and may cause surviving cold flow components to appear thinner and more sharply confined far into
galaxy haloes.
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All authors Ellis R. Owen, Nicolas Ledos, Evangelia Ntormousi, Shinsuke Takasao, Kentaro Nagamine, Sebastiano Cantalupo
Solar and Stellar Astrophysics
A survey for variable young stars with small telescopes - XI. Spot Lifetimes and Coverage Distributions
Dirk Froebrich, Carys Herbert, Aleks Scholz et al. (+47 more)
We present a homogeneous analysis of rotational variability and spot properties in young
stellar objects across multiple
star-forming regions observed by the Hunting Outbursting Young
Stars (HOYS) project. From over 2000 candidate members, we identify 144 YSOs with robust periodic signals and well-constrained multi-band amplitudes. The sample has a median age of $\sim$1~Myr, effective temperatures of 3500–6500~K (masses $\sim$0.6–2~M$_\odot$), and is dominated by Class~2 objects, one third of which exhibit inner disc
dust emission. The rotation period distribution is strongly bimodal, with 55 percent fast rotators ($P<5.5$~d) and 45 percent slow rotators. Fast rotators are predominantly inner disc-less, whereas slow rotators include both disc-bearing and disc-free systems, indicating that disc braking alone cannot explain the observed rotational states. We derive spot properties from multi-band amplitudes and find that, after correcting for observational biases, the intrinsic cold-spot coverage distribution of fast rotators is well described by an exponential function. This implies that small spot coverages are intrinsically much more common than large ones, consistent with
stochastic magnetic flux emergence governing spot formation. In contrast, slow rotators show a pronounced deficit of small cold spots. After considering observational biases and alternative physical explanations, we conclude that small spots on slowly rotating YSOs have significantly shorter lifetimes. These results provide new evidence that
magnetic surface structure and its
evolution depend on
stellar rotation, placing new empirical constraints on models of
magnetic activity and angular momentum
evolution in young
stars.
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All authors Dirk Froebrich, Carys Herbert, Aleks Scholz, Benjamin W. Ryan, Siegfried Vanaverbeke, Jochen Eislöffel, Cledison Marcos da Silva, Michel Michaud, Kathy Griffiths, Ari M. Siqueira, Thomas Urtly, Francisco C. Soldán Alfaro, George Fleming, Gregg L. Ruppel, Domenico Licchelli, Stephen R.L. Futcher, Ivan L. Walton, Matthias Kolb, Mario Morales Aimar, Geoffrey Stone, Yenal Öğmen, Simon Francis Dawes, Franz-Josef Hambsch, Nick J. Quinn, Juan-Luis González-Carballo, Franky Dubois, José Luis Salto González, Adam Popowicz, Krzysztof Bernacki, Slawomir Bednarz, Tim Nelson, Tony Vale, Tonny Vanmunster, Georg Piehler, Stephen C. Percy, Jordi Berenguer Amatller, Jacopo Fallai, Amritanshu Vajpayee, Faustino García de la Cuesta, Rafael Castillo García, Dawid Moździerski, Krzysztof Kotysz, Przemysław J. Mikołajczyk, Holly Stokes-Geddes, Matthew D. Dickers, Ivana I. Grozdanova, Chiara F. Kawohl, Aashini L. Patel, James S. Urquhart, Tim M. Kinnear
High Energy Astrophysical Phenomena
Evolution of Calvera and Descendants of Calvera-like Central Compact Objects
Ali Arda Gencali, Unal Ertan, Fatmanur Ertugrul et al. (+2 more)
Calvera (1RXS J141256.0+792204) is an isolated
neutron star recently classified as a central compact object (CCO) after its association with the
supernova remnant (SNR) candidate G118.4+37.0. In this work, we investigate the long-term
evolution and descendants of Calvera and the CCOs with similar initial conditions in the fallback disc model. We show that the observed
spin period, period derivative, and X-ray luminosity of Calvera can be reproduced simultaneously with a
magnetic field strength of $\simeq 4 \times 10^{10}$ G at the pole of the
neutron star at an age of $\sim 10^4$ yr which is consistent with the estimated SNR age of the source. In the model, the lack of ordinary
radio pulsations is due to ongoing mass
accretion on to the
star. From our simulations, we estimate that the source will become an ordinary
radio pulsar (RP) after the termination of the
accretion. The source will
spin down under the weak dipole torque alone as an RP for a very long time ($\gtrsim 10^8$ yr) after the inactivation of the disc. From our simulations, we find that most of the CCOs with initial conditions similar to those of Calvera also become RPs which remain above or close to the upper border of the
pulsar death valley after the inactivation of their discs. In the period-period derivative diagram, there is indeed a cluster of RPs in the region where the descendants of Calvera-like CCOs are estimated to be located in our model.
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All authors Ali Arda Gencali, Unal Ertan, Fatmanur Ertugrul, Seyda Demirok, Ndiogou Niang
High Energy Astrophysical Phenomena
Transport Properties of the MRI in Differentially Rotating Neutron Stars
Harshraj Bandyopadhyay, Peter Hammond and David Radice
We perform three-dimensional, high-resolution, general-relativistic magnetohydrodynamics (GRMHD) simulations of the magnetorotational instability (MRI) in differentially rotating
neutron stars. We consider both high-mass models which collapse either promptly, or due to the outward transport of angular momentum removing rotational support, and lower-mass models, which remain stable even after solid-body rotation has been achieved. We measure effective transport coefficients of the resulting turbulent flow, shear-viscosity $\alpha_{\rm vis}$, mixing-length $\ell_{\rm mix}$, and mean-field dynamo $\alpha_{\rm DYN}$-parameter, and their correlations with mean-flow parameters, such as rest-mass density $\rho$, characteristic wavelength of the MRI $\lambda_{\rm MRI}$, and vertical Alfvén velocity $v_A$. At saturation, $\ell_{\rm mix}$ and $\alpha_{\rm DYN}$ correlate with $\lambda_{\rm MRI}$ and $v_A$ respectively, as expected from dimensional analysis. However, both quantities show deviations of roughly an order of magnitude from the values predicted on the basis of these correlations. They are also highly intermittent in space and time. The mixing length is found to be largely independent of density, calling into question the $\ell_{\rm mix}(\rho)$ ansatz used in many general-relativistic large-eddy simulations. Our results show that, while the effects of MRI-induced
turbulence might be qualitatively reproduced by simulations that employ transport coefficients chosen using dimensional-analysis considerations, fully-resolved GRMHD simulations are needed to make quantitative predictions.
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Solar and Stellar Astrophysics
On the Modeling of Kink Oscillations in Fine-Structured Coronal Loops with Field-aligned Nonlinear Longitudinal Disturbances
Shakti Singh, Balveer Singh, V. S. Pandey et al. (+3 more)
We investigate the influence of nonlinear longitudinal disturbances, triggered by an initial field-aligned velocity flow, on the damping of standing kink oscillations in fine-structured, cool coronal loop strands under isobaric conditions. Using two-dimensional ideal MHD simulations, we model different realistic flow geometries, bounded, unbounded, and external, and quantify their impact on wave excitation, damping, and energy leakage. Our modelled loop strand incorporates strong density contrasts ($d = 5$ and $d = 20$), providing a configuration consistent with cool-loop observations from Hinode/SOT and SDO/AIA. Our results show that while the nonlinear disturbances exert mild influence on the oscillation period, they substantially modify the damping time. Unbounded flows yield the strongest damping, reducing the damping time by up to $\sim 25\%$ compared to bounded flows, caused by enhanced wave-flow coupling and scattering. Longitudinally inhomogeneous flows further intensify the damping, with high-density strands exhibiting faster convergence toward the uniform-flow limit. In cases with supersonic internal flow, slow sausage-mode harmonics and weak slow shocks are additionally excited, indicating the generation of mixed-mode wave responses in flow-dominated loops. These findings demonstrate that realistic, spatially extended nonlinear disturbances play a significant role in the damping of kink oscillations and should be incorporated into forward modeling and coronal seismology diagnostics.
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All authors Shakti Singh, Balveer Singh, V. S. Pandey, Shilpa Patra, Preeti Verma, Peter H. Yoon
Instrumentation and Methods for Astrophysics · Cross-listed from hep-ex
Dark Matter Searches with Sodium Iodide Detectors
Maria Martinez, Reina H. Maruyama and Maria Luisa Sarsa
The search for the identity of dark matter remains one of the most intriguing challenges in physics today, driving innovative advances in experiment and theory. Thallium-doped sodium iodide (NaI) detectors have played a pivotal role in this context. This review outlines the scientific landscape surrounding NaI detectors, emphasizing their role in the broader context of dark matter research. We begin with a brief description of characteristics that make these detectors well-suited for dark matter detection. We then provide a historical overview and explore the results from the DAMA/NaI and DAMA/LIBRA experiments, which have reported annual modulation signals consistent with dark matter interactions–a signal that to date no other experiment has replicated. We discuss recent results from NaI-based experiments launched, in part, to resolve this tantalizing anomaly. We conclude with a summary of the status and prospects for current and future NaI-based dark matter searches.
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Cosmology and Nongalactic Astrophysics
Updated 1.1% Precision Values of the Hubble Constant with Corrected Pantheon+ and Dark Energy Survey (DES)-DOVEKIE Type Ia Supernovae
Shouvik Roy Choudhury
We update the Hubble constant measurement with corrected Pantheon+ and DES-DOVEKIE
supernovae. The use of DES-DOVEKIE here is the first application of DES-DOVEKIE to a distance-ladder $H_0$ determination. Recent reanalyses of
supernova datasets have put Pantheon+, DES-DOVEKIE, and Union3.1 samples on the same footing with regard to the evidence of dynamical dark energy ($3.2$–$3.4\sigma$), and thus an update on the Hubble constant is the next logical step. The $H_0$ Distance Network (H0DN) baseline is $73.499\pm0.809$ km s$^{-1}$ Mpc$^{-1}$, a $7.1\sigma$ tension with the
cosmic microwave background (CMB) determination in a $\Lambda$ cold-dark-matter ($\Lambda$CDM) cosmology, $H_0^{\rm CMB,\Lambda CDM}=67.24\pm0.35$ km s$^{-1}$ Mpc$^{-1}$. A revised host-mass correction applied to the older Pantheon+ changes 114 of the total 1701 apparent-magnitude rows. The calibrator
supernovae are not affected, but 52 of the 277 Hubble-flow rows are. Applying only these magnitude corrections, with the H0DN covariance,
redshifts, and velocities unchanged, gives $H_0=73.264\pm0.806$ km s$^{-1}$ Mpc$^{-1}$ and a $6.85\sigma$ Hubble tension. This is our main baseline result and the update for the astrophysics community. Alternatively, replacing the complete Hubble-flow treatment with the corrected Pantheon+ data gives $73.139\pm0.791$ km s$^{-1}$ Mpc$^{-1}$ and $6.82\sigma$. For DES-DOVEKIE, 220
supernovae span $0.025\le z_{\rm HD}\le0.151$ in Hubble-diagram
redshift, and 196 of them overlap with corrected Pantheon+. These overlaps determine the offset used to place the public DES-DOVEKIE distance
moduli on the H0DN apparent-magnitude scale. Holding this offset fixed gives $H_0=73.267\pm0.828$ km s$^{-1}$ Mpc$^{-1}$ and a $6.70\sigma$ tension. Extending to $z_{\rm HD}\simeq0.3$ raises $H_0$. However, both rises are smaller than the H0DN uncertainty. Neither update resolves the Hubble tension. (abridged)
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Astrophysics of Galaxies
Kinetic and H-atom product study of the C + C6H6 reaction at low temperatures
Kevin M. Hickson and Jean-Christophe Loison
The reactions of atomic carbon in its ground electronic state configuration, C(3P), are potentially important processes in astrochemistry due to the large abundance of C(3P) atoms in the interstellar medium (ISM) and its high overall reactivity towards a wide range of molecules. Although benzene, C6H6, has not been detected in the dense ISM, its presence at high abundance levels is inferred through the detection of functionalized derivatives. Here we present a combined experimental and astrochemical modeling investigation of the gas-phase C(3P) + C6H6 reaction. Experimentally, rate constants were determined over the 50-296 K range using the Laval nozzle technique coupled with pulsed
laser photolysis and
laser induced fluorescence for C(3P) generation and detection respectively. Product yields of atomic hydrogen, H(2S) were also measured at 177 and 296 K to provide some information on the product channels of the reaction. The measured rate constants are very large, between 3.3 and 5.7 x 10-10 cm3 s-1 indicating the fast, barrierless nature of the reaction, while the H-atom yields are all below 10 % when compared to the C(3P) + C2H4 reference reaction. As the C(3P) + C6H6 reaction is not currently included in astrochemical databases, its influence on the simulated abundances of C6H6 and related species was tested using a gas-grain model of dense interstellar clouds. The C(3P) + C6H6 reaction is shown to be the main loss process for interstellar benzene, while different hypotheses regarding the product channels are discussed in the context of observations to shed light on the preferred formation pathways.
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Solar and Stellar Astrophysics · Cross-listed from hep-ph
A High-Precision Numerical Framework for Time-Varying Solar Neutrino Flux with Full Earth Matter Oscillation Corrections for Global Underground Laboratories
Keyu Han, Isabella Yin, Kaoru Yagi et al. (+3 more)
Solar neutrinos have been studied for over half a century to test both the Standard
Solar Model and the electroweak sector of the Standard Model of particle physics. Contemporary experiments are now entering an era of high-precision measurements, demanding corresponding theoretical predictions with sub-percent accuracy to enable meaningful comparison. In this paper, we identify and analyze the essential physical and computational components required to compute
solar neutrino fluxes with high fidelity, and present a unified, computationally efficient framework. This framework incorporates: (i) the time-varying Earth-Sun distance; (ii) Earth matter effects modeled using both one-dimensional (1D) and three-dimensional (3D) Earth electron-density profiles; and (iii) a fast, Strang-splitting-based implementation of the Mikheyev-Smirnov-Wolfenstein (MSW)
neutrino propagation formalism, enabling rapid, large-scale scans over
neutrino trajectories and energy grids. We deliver site-specific predictions for the China Jinping Underground Laboratory (CJPL) and other underground laboratories actively engaged in
solar neutrino programs.
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All authors Keyu Han, Isabella Yin, Kaoru Yagi, Kevin Yifan Jiang, Xiangpan Ji, Shaomin Chen
Astrophysics of Galaxies
A Split-Flux Method for Dust-Gas Two-Fluid Simulations from Strong to Weak Coupling
Kazunari Iwasaki
We develop a new method for simulating pressureless fluids of neutral
dust coupled to magnetohydrodynamic gas through
dust-gas drag. It has been pointed out that, in the strong-coupling regime,
dust-gas multifluid methods suffer from artificial variations in the
dust-to-gas mass ratio when the
dust and gas are evolved with independent numerical fluxes. This problem arises from inconsistencies between the
dust and gas mass fluxes. In the strong-coupling limit, the
dust-to-gas mass ratio is advected with the local gas velocity. Recently, a new method based on the Harten-Lax-van Leer (HLL) solver was proposed. This method constructs the
dust mass flux so that it is consistent with the gas mass flux, and successfully reduces artificial variations in the
dust-to-gas mass ratio. Here, we develop a Split-Flux method that can be coupled to an HLLD gas solver. Through various numerical experiments, we show that the Split-Flux method suppresses artificial variations in the
dust-to-gas mass ratio, while preserving the low numerical diffusivity of the HLLD solver.
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