Solar and Stellar Astrophysics
Investigating the Influence of Radiative Feedback in Bright-Rimmed Cloud 44
Rishi C, Neelam Panwar, Thomas J. Haworth et al. (+9 more)
Radiative feedback from massive
stars plays a central role in the
evolution of molecular clouds and the interstellar medium. This paper presents a multi-wavelength analysis of the bright-rimmed cloud, BRC 44, which is located at the periphery of the Hii region Sh2-145 and is excited by the massive
stars in the region. We use a combination of archival and newly obtained infrared data, along with new optical observations, to provide a census of young
stellar objects (YSOs) in the region and to estimate
stellar parameters such as age, mass etc. The spatial distribution of YSOs visible in the optical wavelength suggests that they are distributed in separate clumps compared to the embedded YSOs and are relatively older. Near-Infrared (NIR) spectroscopy of four YSOs in this region using the TANSPEC mounted on the 3.6m Devasthal Optical
Telescope (DOT) confirms their youth. From Spectral Energy Distribution (SED) fitting, most of the embedded YSO candidates are in their early stage of
evolution, with the majority of them in their Class II and some in Class I stage. The relative proper motions of the YSOs with respect to the ionizing source are indicative of the rocket effect in the BRC. The 12CO, 13CO, and C18O observations with the Purple Mountain Observatory are used to trace the distribution of molecular gas in the region. A comparison of the cold molecular gas distribution with simple analytical model calculations shows that the cloud is in the compression stage, and massive
stars may be influencing the formation of young embedded
stars in the BRC region due to radiative feedback.
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All authors Rishi C, Neelam Panwar, Thomas J. Haworth, Yan Sun, Saurabh Sharma, R. K. Yadav, D.K. Ojha, H.P. Singh, Jessy Jose, Ajay Kumar Singh, Jincen Jose, Shubham Yadav
Astrophysics of Galaxies
Questing a Coherent Definition of Weak-line Quasars and its Physical Implications
Xiaoqiang Cheng, Jianfeng Wu and Qiaoya Wu
Weak-line
quasars (WLQs) are a subset of type 1
quasars with remarkably weak high-ionization broad emission lines but normal optical/UV continua. Using 371,091
quasars from SDSS DR16, we define WLQs by analyzing outliers in three relations: the L1350-CIV blueshift, the Baldwin effect, and the logL2500-alpha_ox. We find two CIV EW thresholds: $8.9\pm0.2$Å and $19.3\pm0.3$Å. WLQs (EW(CIV)<$8.9\pm0.2$Å) have enhanced CIV blueshifts, deviate from the Baldwin effect, and include many X-ray weak objects (nearly half). Normal
quasars (EW(CIV)>$19.3\pm0.3$Å) show typical properties, while bridge
quasars (intermediate EW) are transitional. WLQs show a positive correlation between line attenuation and ionization energy: high-ionization lines (e.g., HeII, CIV) are suppressed by ~3-4{\sigma} compared to low-ionization lines (e.g., MgII, OI). This supports the shielding gas model, where a thick inner
accretion disk obscures high-energy
photons, suppressing high-ionization lines, while low-ionization lines are less affected. We suggest that WLQs and normal
quasars correspond to slim and thin disk regimes, respectively, with bridge
quasars as a transitional phase. This work provides a unified criterion for WLQs and highlights the role of
accretion-driven shielding gas in their spectral features.
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High Energy Astrophysical Phenomena · Cross-listed from gr-qc
The influence of the mean anomaly on the dynamical quantities of binary black hole mergers in eccentric orbits
Hao Wang, Bin Liu, Yuan-Chuan Zou et al. (+1 more)
In studies of binary black hole (BBH) mergers in eccentric orbits, the mean anomaly, traditionally regarded as less significant than eccentricity, has been thought to encode only the orbital phase, leading to the assumption that it exerts minimal influence on the dynamics of eccentric mergers. In a previous investigation, we identified consistent oscillations in dynamical quantities peak luminosity $L_{\text{peak}}$, remnant mass $M_{\text{rem}}$,
spin $\alpha_{\text{rem}}$, and
recoil velocity $V_{\text{rem}}$ in relation to the initial eccentricity $e_0$. These oscillations are associated with integer orbital cycles within a phenomenological framework. In this paper, we aim to explore the underlying physical nature of these oscillations through gravitational waveforms. Our examination of remnant mass and
spin reveals that while the initial ADM mass $M_{\mathrm{ADM}}$ and orbital angular momentum $L_0$ exhibit gradual variations with $e_0$, the radiated energy $E_{\text{rad}}$ and angular momentum $L_{\text{rad}}$ display oscillatory patterns akin to those observed in $M_{\text{rem}}$ and $\alpha_{\text{rem}}$. By decomposing the waveforms into three distinct phases inspiral, late inspiral to merger, and ringdown, we demonstrate that these oscillations persist across all phases, suggesting a common origin. Through a comparative analysis of $E_{\text{rad}}$ and $L_{\text{rad}}$ derived from numerical relativity (NR), post-Newtonian (PN) waveforms, and orbital-averaged PN fluxes during the inspiral phase, we identify the initial mean anomaly $l_0$ as the source of the observed oscillations. ...
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All authors Hao Wang, Bin Liu, Yuan-Chuan Zou, Qing-Wen Wu
Solar and Stellar Astrophysics
Probing sulfur chemistry in oxygen-rich AGB stars with ALMA
Prasanta Gorai, Maryam Saberi, Theo Khouri et al. (+1 more)
Sulfur and its isotopic ratios play a crucial role in understanding astrophysical environments, providing insights into nucleosynthesis, ISM processes,
star formation, planetary
evolution, and
galactic chemistry. We investigate the distribution of sulfur bearing species $\rm{SO_2}$, $\rm{^{34}SO_2}$, SO, and $\rm{^{34}SO}$ towards five oxygen rich Asymptotic
Giant Branch (AGB)
stars ($o$ Ceti, R Dor, W Hya, R Leo, and EP Aqr), along with their excitation temperatures, column densities, and isotopic ratios. Using ALMA Band 6,7,8 data and CASSIS, we detect these species and estimate excitation temperature and column density via the rotational diagram and MCMC methods under LTE. Line imaging of various transitions is used to infer spatial distributions. The excitation temperatures of $\rm{SO_2}$ range from $\sim$200-600 K with column densities of $\rm{1-7\times10^{16}\ cm^{-2}}$, while $\rm{^{34}SO_2}$ shows comparable or slightly lower values and about an order of magnitude lower column densities. The $\rm{^{32}S/^{34}S}$ ratios for R Dor and W Hya are near
solar, slightly higher for $o$ Ceti, and lower for EP Aqr and R Leo. Most detected lines exhibit centralized emission: high excitation $\rm{SO_2}$ traces compact hot gas in inner CSEs, whereas low-excitation lines trace more extended structures. Morphological differences, irregular emission in $o$ Ceti, circular in R Leo and W Hya, clumpy in R Dor, and unresolved in EP Aqr may arise from variations in physical conditions, multiplicity,
outflows, rotation, desorption processes, UV or
cosmic ray effects, or observational resolution. Overall, the centralized SO and $\rm{SO_2}$ emissions support previous findings for low mass-loss rate AGB
stars, and the $\rm{^{32}S/^{34}S}$ ratios likely reflect natal cloud composition, with deviations linked to
metallicity or excitation conditions.
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All authors Prasanta Gorai, Maryam Saberi, Theo Khouri, Taïssa Danilovich
Solar and Stellar Astrophysics
Physical Properties of 29 March 2006 Solar Corona
Hikmet Çakmak
On 29 March 2006, a total
solar eclipse was observed in the Manavgat district of Antalya, Turkey. During the event, the
solar corona was observed using an 8-inch mirrored
telescope. White-light polarization observations were carried out at three distinct angles using a polarizing filter placed in front of the camera system. To calibrate the intensity of the roll film, photographs of the eclipse and the
solar disk were taken with a traditional 35mm manual camera. Using the
solar disk images obtained during the eclipse, an intensity calibration curve for the roll film was created. This curve was then used to calculate various physical properties of the
solar corona, including intensity, degree of polarization, electron density, and mean temperature. The results of these calculations were compared with the corona models developed by \cite{VDH1950} and \cite{SK1970}, as well as with findings from other researchers. Except for the degree of polarization, the measured physical parameters closely match the values given in the literature.
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Astrophysics of Galaxies
Observation of CH$_{3}$$^{17}$OH and CH$_{3}$$^{18}$OH in Orion KL: A New Tool to Study Star-Formation History
Yoshimasa Watanabe, Takahiro Oyama, Akemi Tamanai et al. (+2 more)
Methanol is a seed species of complex organic molecules that is of fundamental importance in astrochemistry. Although various isotopologues of CH$_3$OH have been detected in the interstellar medium (ISM), CH$_{3}$$^{17}$OH is only tentatively detected in Sgr~B2. To confirm the presence of CH$_{3}$$^{17}$OH in the ISM and to investigate its abundance, we search for its emission lines in the Orion~KL region. We have obtained image cubes covering the frequency ranges 236.40~GHz-236.65~GHz and 231.68~GHz-231.88~GHz using ALMA archival data observed toward the Orion~KL region. The column densities of CH$_3$$^{17}$OH and CH$_3$$^{18}$OH are estimated under the assumption of local thermodynamic
equilibrium condition with fixed excitation temperatures at the two CH$_3$$^{18}$OH peaks, MeOH1 and MeOH2,. We have identified six emission lines of CH$_{3}$$^{17}$OH in MeOH1 and MeOH2 and confirmed that the line profiles and spatial distributions are consistent with those of CH$_3$$^{18}$OH. The abundance ratios of CH$_3$$^{18}$OH/CH$_3$$^{17}$OH are evaluated to be $\sim 3.4-3.5$ and are similar to the canonical value of $^{18}$O/$^{17}$O $\sim 3-4$ derived from CO observations in the Orion~KL region. We have compared the results with the previous study of CH$_3$OH and evaluated CH$_3$$^{16}$OH/CH$_3$$^{17}$OH ratios to be $\sim 2300-2500$ at a resolution of $\sim 4$~arcsec. The ratios are close to the $^{16}$O/$^{17}$O ratio in the local ISM. This result indicates that the CH$_3$OH isotopologues can serve as new tracers of oxygen isotope ratios in
star-forming regions because the opacity of CH$_3$OH can be evaluated using transition lines spanning a wide range of line intensities. Moreover, this method enables us to study the
star-formation history of our
Galaxy with the aid of the
Galactic chemical
evolution models.
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All authors Yoshimasa Watanabe, Takahiro Oyama, Akemi Tamanai, Shaoshan Zeng, Nami Sakai
High Energy Astrophysical Phenomena
Acceleration of Ultrahigh Energy Particles from Fast Radio Bursts
Lin Yu, Tianxing Hu, Zhiyu Lei et al. (+6 more)
Two extreme events in the universe, fast
radio bursts (FRBs) and
cosmic rays (CRs), could be correlated, where FRBs with extreme field strength near their sources may contribute to CRs. This study investigates localized particle acceleration driven by FRB-like ultra-relativistic electromagnetic pulses in an electron–positron–ion
plasma system. It is found ultra-high energy neutral
plasma sheets form constantly via the front erosion of an FRB pulse. There are two regimes of ion acceleration depending upon the field strength and the
plasma density: the piston regime driven by the Lorentz force of the pulse, and the wakefield regime dominated by charge separation field. The predicted energy scalings align well with particle-in-
cell simulations. A power-law energy spectrum with an index close to the CRs naturally emerges during FRBs expansion outward. Detecting high-energy particles possibly produced by FRBs enables deeper insights into their origins and promotes the development of multi-messenger astronomy.
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All authors Lin Yu, Tianxing Hu, Zhiyu Lei, Xiangyan An, Dong Wu, Suming Weng, Min Chen, Jie Zhang, Zhengming Sheng
Cosmology and Nongalactic Astrophysics
On the contribution of galaxies to the magnetic field in cosmic voids
Károly Seller and Günter Sigl
Astrophysical processes can contribute to
magnetic fields within
cosmic voids either through magnetized
outflows from the astrophysical large-scale structure or through superposition of dipolar contributions from individual
galaxies. Such astrophysical
magnetic fields represent a foreground to possible space-filling
primordial magnetic fields seeded in the early Universe. In this paper, we provide a qualitative description of the screening of
magnetic fields by intergalactic
plasmas. We find that contributions from superposition of static dipoles are highly suppressed and cannot explain indications for lower bounds based on observations of $\gamma$-ray cascades from high energy sources such as blazars.
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Earth and Planetary Astrophysics
From gas to ice giants: A unified mechanism for equatorial jets
Keren Duer-Milner, Nimrod Gavriel, Eli Galanti et al. (+2 more)
The equatorial jets dominating the dynamics of the Jovian
planets exhibit two distinct types of zonal flows: strongly eastward in the gas
giants (superrotation) and strongly westward in the ice
giants (subrotation). Existing theories propose different mechanisms for these patterns, but no single mechanism has successfully explained both. However, the planetary parameters of the four
Solar System
giant planets suggest that a fundamentally different mechanism is unlikely. In this study, we show that convection-driven columnar structures can account for both eastward and westward equatorial jets, framing the phenomenon as a bifurcation. Consequently, both superrotation and subrotation emerge as stable branches of the same mechanistic solution. Our analysis of these solutions uncovers similarities in the properties of equatorial waves and the leading-order momentum balance. This study suggests that the fundamental dynamics governing equatorial jet formation may be more broadly applicable across the Jovian
planets than previously believed, offering a unified explanation for their two distinct zonal wind patterns.
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All authors Keren Duer-Milner, Nimrod Gavriel, Eli Galanti, Eli Tziperman, Yohai Kaspi
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Atomic Observables Induced by Cosmic Fields
Sebastian Lahs, Daniel Comparat, Fiona Kirk et al. (+1 more)
The existence of
cosmic fields made from yet unknown light
bosons is predicted in many extensions to the Standard Model. They are especially of interest as possible constituents of dark matter. To detect such light and weakly interacting fields, atomic precision measurements offer one of the most sensitive platforms. In this work, we derive which atomic observables are sensitive to what kind of
cosmic field couplings. For this we consider fields that couple either through scalar, pseudoscalar, vector, axial vector, or tensor couplings. We derive the corresponding non relativistic atomic potentials. Based on their
symmetry properties, these can induce direct energy shifts or induce atomic electric dipole,
magnetic dipole, electric quadrupole as well as
nuclear Schiff and anapole moments.
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All authors Sebastian Lahs, Daniel Comparat, Fiona Kirk, Benjamin Roberts
Astrophysics of Galaxies
CHILES X: Molecular and atomic gas at intermediate redshift
Kelley M. Hess, John Hibbard, Jennifer Donovan Meyer et al. (+10 more)
We present ALMA CO observations of 14 HI-detected
galaxies from the CHILES survey found in a
cosmic over-density at z~0.12. This is the largest collection of spatially resolved CO + HI observations beyond the local Universe (z>0.05) to date. While the HI-detected parent sample spans a range of
stellar masses,
star formation rates (SFR), and environments, we only directly detect CO in the highest
stellar mass
galaxies, log(M_*/M_Sun)>10.0, with SFRs greater than ~2 M_Sun/yr. The detected CO has the kinematic signature of a rotating disk, consistent with the HI. We stack the CO non-detections and find a mean H_2 mass of log(M_H2/M_Sun) = 8.46 in
galaxies with a mean
stellar mass of log(M_*/M_Sun) = 9.35. In addition to high
stellar masses and SFRs, the systems detected in CO are spatially larger, have redder overall colors, and exhibit broader (stacked) line widths. The CO emission is spatially coincident with both the highest
stellar mass surface density and
star forming region of the
galaxies, as revealed by the 1.4 GHz continuum emission. We interpret the redder colors as the molecular gas being coincident with dusty regions of obscured
star formation. The 14 HI detections show a range of morphologies, but the HI reservoir is always more extended than the CO. Finally, we compare with samples in the literature and find mild evidence for
evolution in the molecular gas reservoir and H_2-to-HI gas ratio with
redshift in HI flux-limited samples. We show that the scatter in the HI, and HI-to-
stellar mass ratio is too great to conclusively measure
evolution below z=0.2, and is even extremely difficult below z=0.4. Detections from CHILES are likely to be the only individual
galaxies detected in HI between 0.1<z<0.23 for the foreseeable future due to the severity of satellite
radio frequency interference, and its preferential impact on short baselines which dominate contemporary HI surveys.
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All authors Kelley M. Hess, John Hibbard, Jennifer Donovan Meyer, Hansung B. Gim, Nicholas M. Luber, Min S. Yun, Julia Blue Bird, Richard Dodson, Aeree Chung, Danielle Lucero, Emmanuel Momjian, D.J. Pisano, J.H. van Gorkom
High Energy Astrophysical Phenomena
Spin-Orbit Misalignments of Eccentric Black Hole Mergers in AGN Disks
Gaia Fabj, Christopher Tiede, Connar Rowan et al. (+2 more)
The disks of active
galactic nuclei (AGNs) provide a natural environment where
stellar-mass black holes (BHs) can dynamically pair, undergo repeated interactions, and eventually merge. It is commonly assumed that gas
accretion will both efficiently
spin up disk-embedded black holes and align the orbits of embedded binaries with the disk plane, leading to mergers with preferentially positive effective
spin parameters ($\chi_{\mathrm{eff}}$). Such predictions have motivated the use of $\chi_{\mathrm{eff}}$ as a diagnostic for identifying candidate AGN-embedded mergers in the LIGO-Virgo-KAGRA gravitational-wave catalog. In this work, we perform post-Newtonian $N$-body simulations of nearly planar binary-single encounters and apply an empirically motivated, gas-driven
alignment prescription to characterize the expected $\chi_{\mathrm{eff}}$-eccentricity correlations of AGN-embedded mergers. By comparing the
alignment and gravitational-wave inspiral timescales, we identify the regions of parameter space, across both disk location and binary properties, where full disk-
spin-orbit
alignment is effective and where it is not. We find that quasi-circular binaries typically align by the time they merge, supporting the standard picture of
spin-orbit aligned orientations. By contrast, eccentric binaries (with in-band eccentricity $e_{10\mathrm{Hz}}\gtrsim 0.1$) typically inspiral too quickly for gas torques to act, preserving the post-encounter
spin-orbit misalignments and yielding more isotropic $\chi_{\mathrm{eff}}$ distributions when disk densities and torque efficiencies are modest. This interplay naturally establishes a correlation between binary eccentricity and $\chi_{\mathrm{eff}}$ in AGN disks, highlighting a new key observable of the AGN channel and a potential explanation for massive events such as GW190521 and GW231123.
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All authors Gaia Fabj, Christopher Tiede, Connar Rowan, Martin Pessah, Johan Samsing
Astrophysics of Galaxies
Evidence for inefficient dust production in a massive, metal-rich galaxy at $z=7.13$ uncovered by JWST and ALMA
Kasper E. Heintz, Darach Watson, Francesco Valentino et al. (+17 more)
Recent observations have revealed a remarkably rapid buildup of
cosmic dust in the interstellar medium (ISM) of high
redshift galaxies, with complex
dust compositions and large abundances already appearing at
redshifts $z>6$. Here we present a comprehensive, joint analysis of observations taken with the James Webb Space
Telescope (\jwst) and the Atacama Large Millimetre/submillimetre Array (ALMA) of the highly magnified ($\mu = 9.6$), dusty `normal'
galaxy, A1689-zD1 at $z=7.13$. We perform detailed spectro-photometric modeling of the rest-frame UV to far-infrared spectral energy distribution (SED) based on archival photometry of the source and report new rest-frame optical strong-line measurements and
metallicity estimates from recent \jwst/NIRSpec IFU data. We find that despite its substantial
dust mass, $M_{\rm dust}\sim 1.5\times 10^{7}\,M_\odot$, A1689-zD1 has remarkably low
dust-to-gas and
dust-to-metal mass ratios, ${\rm DTG} = (5.5^{+3.5}_{-1.2})\times 10^{-4}$ and ${\rm DTM} = (6.2^{+4.2}_{-2.6})\times 10^{-2}$, respectively, due to its high
metallicity $12+\log({\rm O/H}) = 8.36\pm 0.10$ and substantial gas mass, $M_{\rm gas} = (2.8^{+0.2}_{-1.7})\times 10^{10}\,M_\odot$ inferred from the [\cii] luminosity and bounded by its dynamics. The DTG and DTM mass ratios are an order of magnitude lower than expected for
galaxies in the local universe with similar chemical enrichment. These low relative measurements are also consistent with the deficit observed in the $A_V/N_{\rm HI}$ ratio of A1689-zD1 in the line-of-sight. We find that this deviation in the DTG and DTM mass ratios appears to be ubiquitous in other metal-rich
galaxies at similar
redshifts, $z\gtrsim 6$. This suggests that the processes that form and destroy
dust at later times, or the
dust emissivity itself, are likely different for
galaxies in the early Universe.
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All authors Kasper E. Heintz, Darach Watson, Francesco Valentino, Rashmi Gottumukkala, Desika Narayanan, Robert M. Yates, Chamilla Terp, Negin Nezhad, John R. Weaver, Joris Witstok, Gabriel Brammer, Anja C. Andersen, Albert Sneppen, Clara L. Pollock, Hiddo Algera, Lucie E. Rowland, Pascal A. Oesch, Georgios Magdis, Giorgos Nikopoulos, Kirsten K. Knudsen
Cosmology and Nongalactic Astrophysics
Probing Anisotropic Cosmic Birefringence with Foreground-Marginalised SPT B-mode Likelihoods
L. Balkenhol, A. Coerver, C. L. Reichardt et al. (+1 more)
In this work, we construct foreground-marginalised versions of the SPT-3G D1 and SPTpol
cosmic microwave background (CMB) B-mode polarisation likelihoods. The compression is performed using the CMB-lite framework and we use the resulting data sets to constrain anisotropic
cosmic birefringence, parametrised by the amplitude of a scale-invariant anisotropic birefringence spectrum, $A_{\rm CB}$. Using the new SPT-3G data we report a $95\%$ upper limit on $A_{\rm CB}$ of $ 1.2\times 10^{-4}$, which tightens to $0.53\times 10^{-4}$ when imposing a prior on the amplitude of gravitational
lensing based on CMB
lensing reconstruction analyses. These are the tightest constraints on anisotropic birefringence from BB power spectrum measurements to-date, demonstrating the constraining power of the South Pole
Telescope. The likelihoods used in this work are made publicly available at https://github.com/lbalkenhol/candl_data
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All authors L. Balkenhol, A. Coerver, C. L. Reichardt, J. A. Zebrowski
Astrophysics of Galaxies · Cross-listed from quant-ph
Measuring gravitational lensing time delays with quantum information processing
Zhenning Liu, William DeRocco, Shiming Gu et al. (+6 more)
The gravitational fields of astrophysical bodies bend the light around them, creating multiple paths along which light from a distant source can arrive at Earth. Measuring the difference in
photon arrival time along these different paths provides a means of determining the mass of the
lensing system, which is otherwise difficult to constrain. This is particularly challenging in the case of microlensing, where the images produced by
lensing cannot be individually resolved; existing proposals for detecting time delays in microlensed systems are significantly constrained due to the need for large
photon flux and the loss of signal coherence when the angular diameter of the light source becomes too large. In this work, we propose a novel approach to measuring astrophysical time delays. Our method uses exponentially fewer
photons than previous schemes, enabling observations that would otherwise be impossible. Our approach, which combines a
quantum-inspired
algorithm and
quantum information processing technologies, saturates a provable lower bound on the number of
photons required to find the time delay. Our scheme has multiple applications: we explore its use both in calibrating optical interferometric
telescopes and in making direct mass measurements of ongoing microlensing events. To demonstrate the latter, we present a fiducial example of microlensed
stellar flares sources in the
Galactic Bulge. Though the number of
photons produced by such events is small, we show that our
photon-efficient scheme opens the possibility of directly measuring microlensing time delays using existing and near-future ground-based
telescopes.
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All authors Zhenning Liu, William DeRocco, Shiming Gu, Emil T. Khabiboulline, Soonwon Choi, Andrew M. Childs, Anson Hook, Alexey V. Gorshkov, Daniel Gottesman
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Emission of Nambu-Goldstone bosons from the semilocal string network
Yukihiro Kanda and Naoya Kitajima
Semilocal
cosmic string is a line-like non-topological
soliton associated with the breakdown of the $SU(2)_{\rm global} \times U(1)_{\rm gauge}$
symmetry to the $U(1)_{\rm global}$
symmetry. The broken phase has two massless Nambu-Goldstone (NG) modes as dynamical fields, and they can be emitted by semilocal strings. In this paper, we numerically show that such NG
bosons are copiously produced with the
evolution of the semilocal string network in the early universe. Our numerical analysis shows that the spectrum of produced particles has a peak at low momenta corresponding to the horizon scale. If the emitted NG
bosons acquire mass due to soft-breaking terms, they can take the role of dark matter. This scenario typically predicts very light pseudo NG
boson dark matter.
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Instrumentation and Methods for Astrophysics
FlowLensing: Simulating Gravitational Lensing with Flow Matching
Hamees Sayed, Pranath Reddy, Michael W. Toomey et al. (+1 more)
Gravitational
lensing is one of the most powerful probes of dark matter, yet creating high-fidelity lensed images at scale remains a bottleneck. Existing tools rely on ray-tracing or forward-modeling pipelines that, while precise, are prohibitively slow. We introduce FlowLensing, a
Diffusion Transformer-based compact and efficient flow-matching model for strong gravitational
lensing simulation. FlowLensing operates in both discrete and continuous regimes, handling classes such as different dark matter models as well as continuous model parameters ensuring physical consistency. By enabling scalable simulations, our model can advance dark matter studies, specifically for probing dark matter substructure in cosmological surveys. We find that our model achieves a speedup of over 200$\times$ compared to classical simulators for intensive dark matter models, with high fidelity and low inference latency. FlowLensing enables rapid, scalable, and physically consistent image synthesis, offering a practical alternative to traditional forward-modeling pipelines.
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All authors Hamees Sayed, Pranath Reddy, Michael W. Toomey, Sergei Gleyzer
High Energy Astrophysical Phenomena
GPU-Accelerated X-ray Pulse Profile Modeling
Tianzhe Zhou and Chun Huang
Pulse-profile modeling (PPM) of thermal X-ray emission from rotation-powered millisecond
pulsars enables simultaneous constraints on the mass $M$, radius $R$, and hence the equation of state of cold, dense matter. However,
Bayesian PPM has faced a hard accuracy-speed bottleneck: current production resolutions used to keep inference tractable can under-resolve extreme hotspot geometries and bias the waveform computation, whereas the higher resolutions that remove this bias push forward models to minutes per evaluation, making inference impractical. We break this trade-off with, to our knowledge, the first public GPU-accelerated X-ray PPM framework that matches established
benchmarks to within $\sim10^{-3}$ relative accuracy even for extreme geometries, while collapsing minutes-long high-fidelity computations to $2$–$5$ ms on an RTX 4080 ($10^{3}$–$10^{4}\times$ speedups), enabling posterior exploration at resolutions and complexities previously out of reach. We further uncover a bias near the interpolation boundaries of atmosphere lookup tables, demonstrate it with two diagnostic tests, and counter it with a mixed-order interpolator. Together, these advances enlarge the feasible hotspot model space and reduce key systematics in PPM, strengthening inferences for current and future X-ray missions.
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High Energy Astrophysical Phenomena
Two Possible Optical–X-Ray Anti-Correlations of PSR J1023+0038
Ka-Yui Au, Kwan-Lok Li, Albert K. H. Kong et al. (+3 more)
X-ray emission is generally believed to be one of the major heating sources for the optical modulation in redback
pulsar binaries as we have seen similar phenomena in many low mass X-ray binaries (LMXBs). While, e.g., MeV/GeV gamma-rays from the
neutron stars are also possible heating sources, X-ray observations are currently much more sensitive, and therefore, joint optical–X-ray data are observationally unique on the irradiation mechanism investigation. Using 18 X-ray/B-band simultaneous XMM-Newton observations (717 ks in total) of the redback system PSR J1023+0038 taken during the LMXB state, we find a general trend that the amplitude of the B-band orbital modulation was lower when the observed X-ray flux was higher. Depending on the analysis method adopted, the statistical significance of the anti-correlation can be from 1.7sigma to 3.1sigma. We also extended the analysis to the GeV gamma-ray band using the
Fermi-LAT data, but the result is insignificant to claim any relations. Moreover, another X-ray/optical correlation regarding the low modes of the system was found in some of the XMM-Newton observations, and the astrophysical reason behind is currently unclear yet. These anti-correlations likely suggest that the irradiation is generally stronger when the X-ray flux is in a fainter state, indicating that there is a more dominant irradiation source than the X-ray emission.
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All authors Ka-Yui Au, Kwan-Lok Li, Albert K. H. Kong, Jumpei Takata, Chung-Yue Hui, Lupin C. C. Lin
Instrumentation and Methods for Astrophysics
Introducing SESHAT: A Tool for Object Classification from JWST Catalogs
B. L. Crompvoets, H. Kirk, R. Gutermuth et al. (+1 more)
JWST's exquisite data have opened the doors to new possibilities in detecting broad classes of astronomical objects, but also to new challenges in classifying those objects. In this work, we introduce SESHAT, the
Stellar Evolutionary Stage Heuristic Assessment Tool for the identification of Young
Stellar Objects, field
stars (main sequence through asymptotic
giant branch), brown
dwarfs, white
dwarfs, and
galaxies, from any JWST photometry. This identification is done using the machine learning method XGBoost to analyze thousands of rows of synthetic photometry, modified at run-time to match the filters available in the data to be classified. We validate this tool on real data of both
star-forming regions and cosmological fields, and find we are able to reproduce the observed classes of objects to a minimum of 85% recall across every class, with all available data, without additional information on the ellipticity or spatial distribution of the objects. Furthermore, this tool can be used to test the filter choices for JWST proposals by verifying whether the chosen filters are sufficient to identify the desired class of objects. SESHAT is released as a Python package to the community for general use.
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All authors B. L. Crompvoets, H. Kirk, R. Gutermuth, J. Di Francesco
Solar and Stellar Astrophysics
A New Algol-type Binary with an Accretion disk
Tongyu He, Jiao Li, Xiaobin Zhang et al. (+10 more)
We present a comprehensive photometric and spectroscopic analysis of the Algol-type binary
Gaia DR3 1892576067672499328. We identified the system as a spectroscopic binary based on medium-resolution LAMOST spectra. Combined with TESS photometry, we determine an orbital period of \( P = 2.47757 (1) \) days, a low mass ratio of \( q = 0.098 \pm 0.002 \), and an orbital inclination of \( i = 46.934^{+2.613}_{-1.11} \) degrees. The orbit is consistent with being circular (\( e = 0 \)). The binary comprises a \( M_1 = 1.817 ^{ +0.106}_{-0.202} \,M_\odot \), \( R_1 = 1.265^{+0.121}_{-0.160}\,R_\odot \) A-type primary and a Roche-lobe-filling secondary of \( M_2 = 0.179 ^{ +0.011}_{-0.020} \,M_\odot \), \( R_2 = 1.994 ^{ +0.041}_{-0.077} \,R_\odot \). The double-peak H$\alpha$ emission line indicates the possible existence of a Keplerian
accretion disc. We established a simple standard
accretion disc model and modeled the
geometric and dynamical properties of the
accretion disc. The obtained outer disc radius $R_{\mathrm{out}} \approx 3.36 \pm 0.43\,R_\odot$ is consistent with the values inferred from the emission velocity of H$\alpha$. Systemic velocity variations observed over time suggest the possible presence of a tertiary companion, with a minimum mass of $M_3 > 0.369 \pm 0.024 \,M_\odot$. Given the low mass ratio, the secondary may evolve into a proto-helium white
dwarf, forming an \text{EL CVn}-type system in the future. This system offers valuable insights into
accretion dynamics and the formation of binaries.
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All authors Tongyu He, Jiao Li, Xiaobin Zhang, Mikhail Kovalev, Zhibin Dai, Zhenwei Li, Hongwei Ge, Shunyi Lan, Jiangdan Li, Dengkai Jiang, Jianping Xiong, Xuefei Chen, Zhanwen Han
Solar and Stellar Astrophysics
Classification for 969 double-mode RR Lyrae stars from Zwicky Transient Facility
Jianxing Zhang, Xiaodian Chen, Shu Wang et al. (+2 more)
RR Lyrae (RRL) variable
stars are cornerstone distance indicators. In particular, double-mode RR Lyrae (RRd)
stars enable period–luminosity relations (PLRs) that are less sensitive to
metallicity, reducing systematic biases in distance measurements. However, their utility has been limited by a global sample of only $\sim$3,000 objects. We develop an automated RRd-screening pipeline and apply it to a cross-matched sample between the
Gaia DR3 RRL catalog and ZTF DR22 time-series photometry. The workflow combines Lomb–Scargle period searches, iterative pre-whitening, period-ratio constraints that suppress $\sim$1-day sampling aliases, and amplitude-based quality cuts, enabling large-scale RRd
star screening. We produce two ZTF-based catalogs: (i) 39,322 reliable single-mode RRL (40.5% of the cross-matched set) and (ii) 969 RRd
stars. Among the RRd
stars, 614 objects are newly identified, substantially enlarging this previously scarce sample; the catalog achieves an estimated completeness of 47.7%. The PLR derived from the newly discovered RRd
stars agrees with the LMC-based relation, though with larger uncertainties. Incorporating these
stars will help tighten the RRd PLR and improve distance measurements. Looking ahead, systematic RRd searches with upcoming surveys such as the Legacy Survey of Space and Time (LSST) and the China Space Station
Telescope (CSST) should further extend high-accuracy distances across the Local Group and strengthen their cosmological applications.
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All authors Jianxing Zhang, Xiaodian Chen, Shu Wang, Jiyu Wang, Licai Deng
Astrophysics of Galaxies
Multi-modal Foundation Model for Cosmological Simulation Data
Bin Xia, Nesar Ramachandra, Azton I. Wells et al. (+2 more)
We present a multi-modal foundation model for astrophysical
galaxy data, designed to map between simulation- and observation-based
galactic features. Our encoder-only
transformer flexibly ingests scalar quantities (e.g.,
redshifts,
galaxy masses) and vectors (e.g.,
star formation histories, spectra), supporting multi-task training that includes within-modality reconstruction and cross-modality prediction. With a dynamic masking strategy, the model can query arbitrary
galaxy properties from partial inputs – including predicting spectra from
redshift and mass, or estimating photometric
redshifts from broadband magnitudes – while also recovering missing segments within a modality. Trained on 185,000 simulated
galaxies from a gigaparsec-scale Cosmology simulation, the model yields a 50% improvement in
redshift estimation when combining LSST and SPHEREx photometry over LSST photometry alone, and a 63% improvement in
stellar mass inference when combining late-time SFH with LSST photometry over early-time SFH with LSST photometry. The model demonstrates strong generalization across multi-modal tasks and lays the groundwork for future integration of higher-dimensional and structured data such as images, merger trees, and 3D fields. This approach provides a unified framework for connecting simulations and observations, advancing the development of generalizable astrophysical foundation models.
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All authors Bin Xia, Nesar Ramachandra, Azton I. Wells, Salman Habib, John Wise
Cosmology and Nongalactic Astrophysics
Detection of supernova magnitude fluctuations induced by large-scale structure
A. Nguyen, C. Blake, R. J. Turner et al. (+56 more)
The peculiar velocities of
supernovae and their host
galaxies are correlated with the large-scale structure of the Universe, and can be used to constrain the growth rate of structure and test the cosmological model. In this work, we measure the correlation statistics of the large-scale structure traced by the Dark Energy Spectroscopic Instrument Bright
Galaxy Survey Data Release 1 sample, and magnitude fluctuations of type Ia
supernova from the Pantheon+ compilation across
redshifts $z < 0.1$. We find a detection of the cross-correlation signal between
galaxies and type Ia
supernova magnitudes. Fitting the normalised growth rate of structure $f \sigma_8$ to the auto- and cross-correlation function measurements we find $f \sigma_8 = 0.384^{+0.094}_{-0.157}$ at $z = 0.03$, which is consistent with the Planck $\Lambda$CDM model prediction, and indicates that the
supernova magnitude fluctuations are induced by peculiar velocities. Using a large ensemble of N-body simulations, we validate our methodology, calibrate the covariance of the measurements, and demonstrate that our results are insensitive to
supernova selection effects. We highlight the potential of this methodology for measuring the growth rate of structure, and forecast that the next generation of type Ia
supernova surveys will improve $f \sigma_8$ constraints by a further order of magnitude.
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All authors A. Nguyen, C. Blake, R. J. Turner, V. Aronica, J. Bautista, J. Aguilar, S. Ahlen, S. BenZvi, D. Bianchi, D. Brooks, A. Carr, T. Claybaugh, A. Cuceu, A. de la Macorra, B. Dey, P. Doel, K. Douglass, S. Ferraro, J. E. Forero-Romero, E. Gaztañaga, S. Gontcho A Gontcho, G. Gutierrez, J. Guy, K. Honscheid, C. Howlett, D. Huterer, M. Ishak, R. Joyce, R. Kehoe, A. G. Kim, A. Kremin, O. Lahav, M. Landriau, L. Le Guillou, A. Leauthaud, M. E. Levi, M. Manera, P. Martini, A. Meisner, R. Miquel, E. Mueller, S. Nadathur, N. Palanque-Delabrouille, W. J. Percival, C. Poppett, F. Prada, F. Qin, A. J. Ross, C. Ross, G. Rossi, E. Sanchez, D. Schlegel, M. Schubnell, D. Sprayberry, G. Tarlé, B. A. Weaver, P. Zarrouk, R. Zhou, H. Zou
Cosmology and Nongalactic Astrophysics
Testing Lens Models of PLCK G165.7+67.0 Using Lensed SN H0pe
Aadya Agrawal, J. D. R. Pierel, Gautham Narayan et al. (+9 more)
Supernova H0pe is a multiply-imaged Type Ia
supernova (SN~Ia) and the second lensed SN to yield a measurement of the Hubble constant by the time-delay cosmography method, finding $H_0 = 75.4^{+8.1}_{-5.5} \text{km s}^{-1} \text{Mpc}^{-1}$ (Pascale et. al 2025). We investigate the seven lens modeling approaches used to derive $H_0$, assessing their agreement with $\Lambda \text{CDM}$ constraints from SN~Ia surveys through a purely observational comparison. We test each lens model by combining its predicted magnifications with the observed time delays to reconstruct the intrinsic SN~Ia luminosity and corresponding distance modulus. While photometrically derived magnifications yield distance
moduli in line with $\Lambda \text{CDM}$ expectations, our comparison reveals that lens model predictions, even the most precise ones, \textbf{consistently overestimate the magnification, with an offset $> 1$~mag}. This known bias, already appreciated by modeling teams, is independently confirmed through our analysis and highlights the value of lensed SNe as a tool to test model accuracy. If unaccounted for, such magnification biases can propagate into uncertainties in derived cosmological parameters, including $H_0$, a critical challenge for precision cosmology using strongly lensed transients.
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All authors Aadya Agrawal, J. D. R. Pierel, Gautham Narayan, B. L. Frye, Jose M. Diego, Nikhil Garuda, Matthew Grayling, Anton M. Koekemoer, Kaisey S. Mandel, M. Pascale, David Vizgan, Rogier A. Windhorst