Solar and Stellar Astrophysics
Evolutionary Links: From Gaia Neutron Star Binaries to Pulsar White Dwarf Endpoints
Debatri Chattopadhyay, Kyle A. Rocha, Seth Gossage et al. (+1 more)
The discovery of wide, eccentric
Gaia neutron stars (NSs) in binaries with still evolving (likely main sequence) companions offers a new probe of mass transfer and
pulsar recycling beyond the compact-binary regime. We model their origins and fates using population synthesis with POSYDON and detailed binary
evolution with MESA, contrasting two limiting prescriptions at Roche-lobe overflow (RLOF): enforced circularization versus explicitly eccentric mass transfer. Our MESA setups include updated treatments of eccentric, non-conservative transfer,
magnetic-braking torques for cool
stars, and
neutron-
star spin evolution with
accretion and dipole spindown. Under optimistic assumptions, isolated
evolution yields
Gaia-like systems at only <1.5% relative rates of NS-evolving companion binaries, yet absolute numbers remain consistent with detections for continuous
star formation. Synthetic populations indicate that many canonical millisecond
pulsar-white
dwarf (WD) binaries arise from unstable mass transfer and common envelope recycling, whereas
Gaia systems typically avoid common envelope and only undergo stable mass transfer. In the case of capping
accretion onto the NS at the Eddington rate, circular RLOF keeps the donor's mass-loss rate hovering around the Eddington limit and sustained over long timescales. Eccentric mass transfer instead produces briefer bursty signatures where the donor's mass-loss rate can climb up to a thousand times higher than in the circular case. The eccentric channel then leaves wide, eccentric NS-helium WD binaries with only mild recycling, whereas the circular channel yields long-lived transfer, circular NS-WD binaries (helium or carbon-oxygen core), and fully recycled millisecond
pulsars.
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All authors Debatri Chattopadhyay, Kyle A. Rocha, Seth Gossage, Vicky Kalogera
Earth and Planetary Astrophysics
Hubble reveals complex multi-scale structure in the edge-on protoplanetary disk IRAS 23077+6707
Kristina Monsch, Joshua B. Lovell, Karl R. Stapelfeldt et al. (+11 more)
We present high-resolution ($\lesssim 0.1''$) Hubble Space
Telescope (HST)/Wide Field Camera 3 (WFC3) imaging of the near edge-on ($i{\sim}80^\circ$) protoplanetary disk IRAS 23077+6707 ("Dracula's Chivito") obtained across six broadband filters spanning $0.4-1.6\,\mu$m. These observations unveil the scattered light from this unusually large disk (${\sim}14''$, or ${\sim}4200\,\mathrm{au}$ at $300\,\mathrm{pc}$) in remarkable detail, revealing a rich tapestry of substructures, including brightness asymmetries and signatures of dynamical activity. Extended filaments are detected extending ${\sim}10''$ from the northern edges of both nebulae, while no comparable southern features are observed. In addition to large-scale asymmetries, the disk exhibits prominent wispy features that extend well above the midplane and are visible in all filters, suggesting a complex, possibly turbulent outer disk atmosphere shaped by infall, dynamical stirring, or gravitational instability. The central dark lane narrows from optical to near-IR wavelengths, and high-resolution millimeter data reveal compact midplane emission. Although our radiative transfer simulations show that the current data cannot yet distinguish between
dust settling and no-settling scenarios, they underscore the need for resolved mid-infrared observations of this unique system. IRAS 23077+6707 thus represents a rare and valuable laboratory for studying the vertical structure, asymmetries, and evolutionary state of protoplanetary disks.
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All authors Kristina Monsch, Joshua B. Lovell, Karl R. Stapelfeldt, Sean M. Andrews, Ammar Bayyari, Alice S. Booth, Adolfo S. Carvalho, John H. Debes, Jeremy J. Drake, Joshua W. J. Earley, Cecilia Garraffo, Garrett K. Keating, Michael L. Sitko, David J. Wilner
Solar and Stellar Astrophysics
Daniel Dalsgaard, Michael Kuffmeier and Troels Haugbølle
The attracting properties of
gravity enable matter present in cores to collapse into
stars with seven orders of magnitude change in space and time making modelling of
star formation a challenging multi-scale process. To circumvent this scale problem
stars are replaced by a sub-grid sink particle at a much larger scale. Sink particles are created above a threshold density and acquire mass and momentum through
accretion. In models where binary
star systems form and migrate to separations of a few
cells, the
accretion flow is unresolved and the relative
accretion rate to the sink particles may become inaccurate. We introduce a new recipe for
accretion onto binary sink particles that have overlapping
accretion regions and implement an
algorithm to track the angular momentum of sink particles as a proxy for the
stellar spin. Our preferential binary
accretion recipe uses a virtual binary sink particle for the purpose of
accretion and redistribute the accreted mass onto the sink particles according to results from models investigating binary
accretion in detail. This solves problems common to current
algorithms in many codes: (i)
accretion is not suppressed due to large velocity differences between gas and
stars, when that velocity is only internal to the binary system, (ii) the
accretion rates are smoother for the unresolved close binaries in eccentric orbits, and (iii) non-physical suppression of
accretion onto the secondary sink particle when the primary dominates the potential is eliminated. We test our implementation by comparing simulations at increasing resolution until the binaries are resolved. While not perfect, it mitigates undesired properties of current
algorithms and in particularly for global models of starforming regions. It may also be applied to other unresolved accreting binaries, such as compact objects in clusters and binary supermassive black holes in cosmological models.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Dynamically generated tilt of isocurvature fluctuations
Saarik Kalia
Light scalar fields acquire isocurvature fluctuations during inflation. While these fluctuations could lead to interesting observable signatures at small scales, they are strongly constrained on large scales by
cosmic microwave background observations. When the mass of the scalar is much lighter than the inflationary Hubble scale, $m\ll H_I$, the spectrum of these fluctuations is flat. Meanwhile, if $m\gg H_I$, the fluctuations are suppressed. A blue-tilted isocurvature spectrum which exhibits enhanced structure on small scales but avoids observational constraints on large scales therefore requires a coincidence of scales $m\sim H_I$ for a free massive scalar. In this work, we show that if a scalar field possesses a nontrivial potential, its inflationary dynamics naturally cause this condition to be satisfied, and so a blue-tilted spectrum is generically expected for a large class of potentials. Specifically, if its potential $V$ exhibits a region which satisfies the slow-roll condition $V''<3H_I^2$, the scalar condensate will spend most of inflation close to the boundary of this region, so that its effective mass is typically close to $H_I$. The resulting blue tilt is inversely proportional to the number of $e$-folds of inflation prior to horizon crossing. If the scalar is long-lived, this mechanism leads to an attractor prediction for its relic abundance, which is insensitive to initial conditions of the scalar. In particular, a scalar field with quartic self-interactions can achieve the correct abundance to constitute all of the dark matter for a wide range of masses. We compute the relationship between the mass and self-coupling of quartic dark matter predicted by this mechanism.
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Solar and Stellar Astrophysics
Probing the wind and evolutionary state of the quiescent luminous blue variable Var$\,$2 in the Galaxy M33: constraints from self-consistent non-LTE modeling
A. Kostenkov, Y. Solovyeva, E. Dedov et al. (+2 more)
Luminous Blue Variables (LBVs) are massive
stars with extreme luminosities, exhibiting significant irregular photometric and spectroscopic variability. This paper is dedicated to the study of dormant LBV Var$\,$2 in the
galaxy M33, which has not shown significant brightness changes for almost century and currently observed as Ofpe/WN9
star. In order to obtain reliable estimates of the fundamental parameters of Var$\,$2, we had calculated self-consistent hydrodynamic models of the extended atmosphere, assuming non-local thermodynamic
equilibrium (non-LTE) and taking into account the balance of radial forces in the wind of the
star. Spectral modeling yields luminosity $L=6.5\times10^{5}\,L_\odot$, current mass $M_* \approx23\,M_\odot$ and hydrogen abundance on the surface ${\rm X}_{\rm H}\approx43\%$. Comparison with evolutionary tracks indicates that these parameters correspond to a
star with the initial mass $M_{\rm init}\approx50\,M_\odot$ and age $t_{\rm age}\approx4.4\,$Myr that is evolving from lower temperatures towards the Wolf-Rayet
stars. A study of dynamic properties of the wind showed that the shape of the wind velocity profile of Var$\,$2 is close to the one of O- and early B-supergiants rather than Wolf-Rayet
stars. In contrast, for the obtained mass-loss rate $\dot{M}=2.1\times10^{-5}\,M_{\odot}\,\text{yr}^{-1}$, the ratio of the wind momentum to the luminosity of Var$\,$2 is in good agreement with the values found for WNL
stars. Given the obtained age estimates, Var$\,$2 could potentially have been ejected from the cluster associated with the nearest large
star-forming region located at a distance of $\sim100\,$pc. However, statistical analysis of the projected distribution of
stars in the vicinity of Var$\,$2 suggests that this LBV could have formed in a local low-populated group.
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All authors A. Kostenkov, Y. Solovyeva, E. Dedov, A. Vinokurov, A. Sarkisyan
Astrophysics of Galaxies
Delayed phase mixing in the self-gravitating Galactic disc
T. Asano and T. Antoja
The
Gaia phase spiral is considered to work as a dynamical clock for dating past perturbations, but some of the previous studies neglected the disc's self-
gravity, potentially biasing estimates of the phase spiral's excitation time. We revisit the impact of self-gravitating effects on the
evolution of vertical phase spirals and quantify the bias introduced in estimating their excitation time when such effects are ignored. We analysed a high-resolution, self-consistent $N$-body simulation of the MW-Sagittarius
dwarf galaxy (Sgr) system, alongside four test particle simulations in potentials constructed from the $N$-body snapshots. In each case, we estimated the winding time of phase spirals by measuring the slope of the density contrast in the vertical angle-frequency space. In the test particle models, the phase spiral begins winding immediately after Sgr's pericentric passage, and the winding time closely tracks the true elapsed time since the Sgr impact. Adding the DM wake yields only a modest (< 100 Myr) reduction of the winding time relative to Sgr alone. By contrast, the self-consistent $N$-body simulation exhibits an initial, coherent vertical oscillation lasting $\gtrsim$ 300 Myr before a clear spiral forms, leading to systematic underestimation of excitation times. An analytical shearing-box model with self-
gravity, developed by Widrow (2023), qualitatively reproduces this delay, supporting its origin in the disc's self-gravitating response. Assuming that self-
gravity affects phase mixing in the MW to the same degree as the $N$-body model, the lag induced by self-
gravity is estimated to be $\sim$ 0.3 Gyr in the
solar neighbourhood. Accounting for this delay revises the inferred age of the MW's observed phase spiral to $\sim$0.6-1.2 Gyr, in better agreement with the Sgr's pericentric passage. (shortened for arXiv)
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Astrophysics of Galaxies
Dwarf diversity in $\Lambda$CDM with baryons
Akaxia Cruz, Alyson Brooks, Mariangela Lisanti et al. (+7 more)
Observed rotation curves of
dwarf galaxies exhibit significant diversity at fixed
halo mass, challenging
galaxy formation within the Cold Dark Matter (CDM) model. Previous cosmological
galaxy formation simulations with baryonic physics fail to reproduce the full diversity of rotation curves, suggesting either that there is a flaw in baryonic feedback models, or that an alternative to CDM must be invoked. In this work, we use the Marvelous Massive
Dwarf zoom-in simulations, a suite of high-resolution
dwarf simulations with $M_{200}~\sim 10^{10}-10^{11}$ ${\rm M}_{\odot}$ and $M_{*}\sim 10^{7}-10^{9}$ ${\rm M}_{\odot}$, designed to target the mass range where
galaxy rotation curve diversity is maximized, i.e., between $V_{\rm max} \sim 70-100~ {\rm km/s}$. We add to this a set of low-mass
galaxies from the Marvel
Dwarf Zoom Volumes to extend the
galaxy mass range to lower values. Our fiducial
star formation and feedback models produce simulated
dwarfs with a broader range of rotation curve shapes, similar to observations. These are the first simulations that can both create dark matter cores via baryonic feedback, reproducing the slower rising rotation curves, while also allowing for compact
galaxies and steeply rising rotation curves. Our simulated
dwarfs also reproduce the observed size$-M_*$ relation, including scatter, producing both extended and compact
dwarfs for the first time in simulated field
dwarfs. We explore
star formation and feedback models and conclude that previous simulations may have had feedback that was too strong to produce compact
dwarfs.
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All authors Akaxia Cruz, Alyson Brooks, Mariangela Lisanti, Annika H. G. Peter, Robel Geda, Thomas Quinn, Michael Tremmel, Ferah Munshi, Ben Keller, James Wadsley
High Energy Astrophysical Phenomena
Eruptive mass loss less than a year before the explosion of superluminous supernovae. II. A systematic search for pre-explosion eruptions with VLT/X-shooter
A. Gkini, C. Fransson, R. Lunnan et al. (+22 more)
We present X-shooter observations of a sample of 21 hydrogen-poor superluminous
supernovae (SLSNe-I), spanning a
redshift range of z=0.13-0.95, aimed at searching for shells of circumstellar material (CSM). Specifically, we focus on identifying broad Mg II absorption features that are blueshifted by several thousand kilometers per second and have previously been interpreted as arising from resonance line scattering of the SLSN continuum by rapidly expanding CSM ejected shortly before explosion. Utilizing high-quality spectra, we model the region around 2800A to characterize the Mg II line profiles, enabling us to either confirm their presence or place constraints on undetected CSM shells. We identify five objects in our sample that show broad Mg II absorption features consistent with the presence of CSM. While SN2018ibb, SN2020xga and SN2022xgc have been previously reported, we identify previously undiscovered CSM shells in DES15S2nr and DES16C3ggu. These shells were likely expelled approximately two and three months, respectively, before the explosion of their associated SNe, timescales consistent with late-stage mass-loss episodes. We do not find any correlations between the shell properties and the SN properties, except for a marginal correlation between the light curve decline time scale and the shell velocities. We further demonstrate that CSM configurations similar to the majority of the detected shells would have been observable in spectra with signal-to-noise >8 per resolution element, and that the lines from a shell are in general detectable except in the cases where the shell is either very geometrically and/or optically thin. Therefore, we conclude that the detection of CSM shells is not a selection effect, but may instead point to the existence of a subclass of SLSNe-I undergoing late-stage shell ejections shortly before explosion.
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All authors A. Gkini, C. Fransson, R. Lunnan, S. Schulze, J. Sollerman K. Tsalapatas, N. Sarin, M. Nicholl, C. Angus, U. Burgaz, S. J. Brennan, T.-W. Chen, A. Gal-Yam, A. Gangopadhyay, Y. Hu, M. M. Kasliwal, R. R. Laher, P. J. Pessi, B. Rusholme, E. Russeil, A. Singh, C. Skoglund, R. Smith, B. van Baal, S. L. West, L. Yan
Earth and Planetary Astrophysics
Searching for GEMS: TOI-5916 b & TOI-6158 b are two Saturn-density planets orbiting M2 dwarfs
Shane O'Brien, Amber Wong, Te Han et al. (+20 more)
We confirm the planetary nature of (1) TOI-5916 b and (2) TOI-6158 b, two
Exoplanets Transiting M-
dwarf Stars (GEMS), both discovered by the Transiting
Exoplanet Survey Satellite (TESS). Both systems were confirmed with ground-based photometry (Red Buttes Observatory and Swope, respectively) and radial velocity data from the Habitable-zone
Planet Finder. Their radii are $R_{1}=11.8^{+0.52}_{-0.51}\text{ }R_{\oplus}$ and $R_{2}=10.4^{+2.70}_{-1.11}\text{ }R_{\oplus}$ and masses are $M_{1}=219\pm28\text{ }M_{\oplus}$ and $M_{2}=135^{+19}_{-18}\text{ }M_{\oplus}$. Both
planets have Saturn-like densities ($\rho_{1} = 0.73^{+0.14}_{-0.13}\,\text{g cm}^{-3}$, $\rho_{2} = 0.66^{+0.41}_{-0.23}\,\text{g cm}^{-3}$), which appears to be a growing trend among GEMS systems and, more generally, warm Jupiters. In confirming both of these
exoplanets, we add to the growing evidence for a population of Saturn-density
planets among the GEMS systems. We also find evidence for a preliminary trend in which GEMS exhibit systematically closer orbits compared to FGK
giants.
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All authors Shane O'Brien, Amber Wong, Te Han, Paul Robertson, Shubham Kanodia, Caleb I. Cañas, Arvind F. Gupta, Tera Swaby, Henry A. Kobulnicky, Nidia Morrell, Michael Rodruck, Andrea S.J. Lin, Andrew Monson, William D. Cochran, Chad F. Bender, Scott A. Diddams, Samuel Halverson, Daniel M. Krolikowski, Jessica E. Libby-Roberts, Joe P. Ninan, Arpita Roy, Christian Schwab, Gudmundur Stefansson
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
On the Speed-up of Wave-like Dark Matter Searches with Entangled Qubits
Arushi Bodas, Sohitri Ghosh and Roni Harnik
Qubit-based sensing platforms offer promising new directions for wave-like dark matter searches. Recent proposals demonstrate that entangled
qubits can achieve quadratic scaling of the signal in the number of
qubits. In this work we expand on these proposals to analyze the bandwidth and scan rate performance of entangled
qubit protocols across different error regimes. We find that the phase-based readout of entangled protocols preserves the search bandwidth independent of
qubit number, in contrast to power-based detection schemes, thereby achieving a genuine scan-rate advantage. We derive coherence time and error rate requirements for
qubit systems to realize this advantage. Applying our analysis to dark
photon searches, we find that entangled states of approximately 100
qubits can become competitive with
benchmark photon-counting cavity experiments for masses $\gtrsim 30{-}40~\mu{\rm eV}$, provided sufficiently low error rates are achieved. The advantage increases at higher masses where cavity volume scaling becomes less favorable.
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Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
False Alarm Rates in Detecting Gravitational Wave Lensing from Astrophysical Coincidences: Insights with Model-Independent Technique GLANCE
Aniruddha Chakraborty and Suvodip Mukherjee
Lensing of gravitational waves (GWs) due to intervening massive astrophysical systems between the source and the observer is an inevitable consequence of the general theory of relativity, which can produce multiple GW events with overlapping sky localization error. However, the confirmed detection of such a unique astrophysical phenomenon is challenging due to several sources of contamination, ranging from detector noise to astrophysical uncertainties. Robust model-independent search techniques that can mitigate noise contamination have been developed in the past. In this study, we explore the astrophysical uncertainty associated with incorrectly classifying a pair of unlensed GW events as a lensed pair and the associated false alarm rate (FAR) depending on the GW source properties. To understand the effect of unlensed astrophysical GW sources in producing false
lensing detections, we perform a model-independent test using the pipeline GLANCE on a simulated population of merging binary black holes (BBHs). We find that $\sim$ 0.01% of the pair of events can be falsely classified as lensed with a
lensing threshold signal-to-noise ratio of 1.5, appearing at a time delay between the pair of events of $\sim$ 1000 days or more. We show the FAR distribution for the parameter space of the GW source masses, delay time, and
lensing magnification parameter over which the model-independent technique GLANCE can confidently detect lensed GW pair with the current LIGO detector sensitivity. In the future, this technique will be useful in understanding the
lensing FAR for next-generation GW detectors, which can observe more GW sources.
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Astrophysics of Galaxies
ELPIS: Accelerated metal and dust enrichment in a proto-cluster core at $z\approx8$
Hideki Umehata, Yoichi Tamura, Yoshinobu Fudamoto et al. (+17 more)
We present a study of the metal,
dust, and molecular gas content in
galaxies within the A2744-z7p9OD proto-cluster at z ~ 7.88. We focus on two
galaxy groups, the Quintet and the Chain, which are covered by the ELPIS survey (The Emission-Line Protocluster Imaging Survey of the furthest overdensity beyond Pandora's Cluster Abell 2744). [C II] 158 um emission is detected in five
galaxies, revealing molecular gas reservoirs with log(M_gas/Msun) ~ 9.0-9.6, while
dust continuum at the observed frame of 1.26 mm is detected in three
galaxies, yielding
dust masses of log(M_
dust/Msun) ~ 6.0-6.4, assuming a
dust temperature of T_
dust = 45 (+15, -15) K. The derived properties, including
stellar-to-
dust mass ratios of log(M_
dust/M_
star) ~ -3 to -2 at log(M_
star/Msun) ~ 9, and
dust-to-gas mass ratios of log(M_
dust/M_gas) ~ -4 to -3 at 12+log(O/H) ~ 8, place these
galaxies in an intermediate regime: higher than the very low ratios expected from
supernova-driven
dust production, but still below the levels attained once efficient grain growth dominates. These values indicate a transition phase of
dust mass assembly, likely reflecting the onset of grain growth via metal
accretion under accelerated
evolution in the proto-cluster core.
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All authors Hideki Umehata, Yoichi Tamura, Yoshinobu Fudamoto, Yurina Nakazato, Daniel Ceverino, Naoki Yoshida, Akio K. Inoue, Ryota Ikeda, Yuma Sugahara, Shutaro Inui, Santiago Arribas, Tom Bakx, Masato Hagimoto, Takuya Hashimoto, Luis Colina, Yi W. Ren, Wataru Osone, Alejandro Crespo Gomez, Ken Mawatari, Javier Alvarez-Marquez
Astrophysics of Galaxies
Connecting Cores and Black Hole Dynamics Across Scales: From Globular Clusters to Massive Ellipticals
Kyle Kremer, Newlin C. Weatherford, Philip F. Hopkins et al. (+2 more)
The centers of massive elliptical
galaxies exhibit a wide range in density profiles, from central cusps to resolved cores with order kiloparsec sizes. The cored ellipticals have been linked to the presence of supermassive black hole binaries that excavate their hosts' central
stellar populations through three-body encounters. This connection between cores and black holes similarly operates in globular clusters, which also exhibit a bimodality in cored and core-collapsed architectures, respectively rich and depleted in
stellar black holes. We report new estimates of the total black hole mass in 25
Galactic globular clusters based on a suite of roughly 150 Monte Carlo $N$-body simulations that fit observed surface brightness and velocity dispersion profiles. We show that both globular clusters and massive elliptical
galaxies individually exhibit strong correlations between total black hole mass ($M_\bullet$) and core radius ($r_c$), and that these individual relations share a common power-law exponent to within $1\sigma$ statistical precision: $M_\bullet \sim r_c^{1.3}$. The individual relations appear to be offset, suggesting swarms of
stellar black holes scour globular cluster cores more efficiently than lone supermassive black holes scour the cores of massive ellipticals. Yet the shared basis of core scouring via black hole binaries hints at a unified $M_{\bullet}-r_c$ connection across over 10 orders of magnitude in $M_\bullet$. Our findings imply core radius measurements may offer a powerful observational constraint on black hole merger rates, from kilohertz sources detectable by LIGO/Virgo/KAGRA formed in globular clusters to millihertz and nanohertz sources formed in massive elliptical
galaxies.
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All authors Kyle Kremer, Newlin C. Weatherford, Philip F. Hopkins, Nicholas Z. Rui, Claire S. Ye
Earth and Planetary Astrophysics
Spin and Obliquity Distributions of Low-mass Planets Shaped by Dynamical Instability
Dieran Wang, Jiaru Li and Dong Lai
Exoplanetary systems hosting multiple low-mass
planets are thought to have experienced dynamical instability, during which
planet-
planet collisions and mergers occur; these collisions can impart substantial amount of angular momentum to the merger remnants, changing the obliquities of the resulting
planets significantly. In this work, we carry out a series of $N$-body experiments to investigate the
spin magnitude $(|\vec{S}|)$ and obliquity $(\theta_{\rm SL})$ distributions of low-mass
exoplanets that have gone through planetary collisions. In our fiducial super-Earth (with $m=3M_{\oplus}$, $R=1.3R_{\oplus}$) and mini-Neptune systems (with $m=9M_{\oplus}$, $R=2.5R_{\oplus}$), the collision products follow a nearly uniform distribution in $\cos{\theta_{\rm SL}}$ and the
spin-magnitude distribution is approximately linear in $|\vec{S}|$. Parameter studies and theoretical analysis show that increasing planetary radii or masses, or decreasing the initial
planet-
planet mutual inclinations, tend to polarize the obliquity distribution toward
alignment or anti-
alignment (i.e., excess probability near $\cos{\theta_{\rm SL}}=\pm1$). Experiments with initially two-
planet and three-
planet systems produce qualitatively similar outcomes, suggesting that the trends in this study may generalize to systems with higher planetary multiplicities.
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High Energy Astrophysical Phenomena · Cross-listed from gr-qc
Quasinormal modes from numerical relativity with Bayesian inference
Richard Dyer and Christopher J. Moore
Numerical relativity (NR) enables the study of physics in strong and dynamical gravitational fields and provides predictions for the gravitational-wave signals produced by merging black holes. Despite the impressive accuracy of modern codes, the resulting waveforms inevitably contain numerical uncertainties. Quantifying these uncertainties is important, especially for studies probing subdominant or nonlinear effects around the merger and ringdown. This paper describes a flexible Gaussian-process model for the numerical uncertainties in all the spherical-harmonic waveform modes across a state-of-the-art catalog of NR waveforms and a highly efficient procedure for sampling the posteriors of quasinormal mode models without the need for expensive Markov chain Monte Carlo. The Gaussian-process model is used to define a likelihood function which allows many
Bayesian data analysis techniques - already widely used in the analysis of experimental gravitational wave data - to be applied to NR waveforms as well. The efficacy of this approach is demonstrated by applying it to the analysis of quasinormal modes in Cauchy-characteristic evolved waveforms.
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High Energy Astrophysical Phenomena · Cross-listed from gr-qc
Black Hole Ringdown Amplitudescopy
Francesco Crescimbeni, Xisco Jimenez-Forteza and Paolo Pani
Black hole ringdowns in extensions of General Relativity (GR) generically exhibit two distinct signatures: (1) theory-dependent shifts in the standard black-hole quasinormal modes, and (2) additional modes arising from extra fundamental fields – such as scalar, vector, or tensor degrees of freedom – that can also contribute to the gravitational-wave signal. As recently argued, in general both effects are present simultaneously, and accurately modeling them is essential for robust tests of GR in the ringdown regime. In this work, we investigate the impact of extra field-induced modes, which are often neglected in standard ringdown analyses, on the interpretation of gravitational-wave signals. To provide some concrete examples, we focus on dynamical Chern-Simons and Einstein-scalar-Gauss-Bonnet theories, well-motivated extensions of GR, characterized respectively by a parity-odd and a parity-even coupling between a dynamical scalar field and quadratic
curvature invariants. We show that including extra field-induced modes improves the bounds on these theories compared to standard spectroscopy and also allows for equally constraining complementary tests not based on quasinormal mode shifts. Our analysis highlights the relevance of incorporating extra field-induced modes in ringdown templates and assesses their potential to either bias or enhance constraints on GR deviations.
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High Energy Astrophysical Phenomena
Violent mergers revisited: The origin of the fastest stars in the Galaxy
Rüdiger Pakmor, Ken J. Shen, Aakash Bhat et al. (+12 more)
Binary systems of two carbon-oxygen white
dwarfs are one of the most promising candidates for the progenitor systems of Type Ia
supernovae. Violent mergers, where the primary white
dwarf ignites when the secondary white
dwarf smashes onto it while being disrupted on its last orbit, were the first proposed double degenerate merger scenario that ignites dynamically. However, violent mergers likely contribute only a few per cent to the total Type Ia
supernova rate and do not yield normal Type Ia
supernova light curves. Here we revisit the scenario, simulating a violent merger with better methods, and in particular a more accurate treatment of the detonation. We find good agreement with previous simulations, with one critical difference. The secondary white
dwarf, being disrupted and accelerated towards the primary white
dwarf, and impacted by its explosion, does not fully burn. Its core survives as a bound object. The explosion leaves behind a $0.16\,\mathrm{M_\odot}$ carbon-oxygen white
dwarf travelling $2800\,\mathrm{km/s}$, making it an excellent (and so far the only) candidate to explain the origin of the fastest observed hyper-velocity white
dwarfs. We also show that before the explosion, $5\times10^{-3}\,\mathrm{M_\odot}$ of material consisting predominantly of helium, carbon, and oxygen has already been ejected at velocities above $1000\,\mathrm{km/s}$. Finally, we argue that if a violent merger made D6-1 and D6-3, and violent mergers require the most massive primary white
dwarfs in binaries of two carbon-oxygen white
dwarfs, there has to be a much larger population of white
dwarf mergers with slightly lower-mass primary white
dwarfs. Because of its size, this population can essentially only give rise to normal Type Ia
supernovae, likely exploding via the quadruple detonation channel and leaving no bound object behind.
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All authors Rüdiger Pakmor, Ken J. Shen, Aakash Bhat, Abinaya Swaruba Rajamuthukumar, Christine E. Collins, Cillian O'Donnell, Evan B. Bauer, Fionntan P. Callan, Friedrich K. Röpke, Joshua M. Pollin, Kate Maguire, Lindsey A. Kwok, Ravi Seth, Stefan Taubenberger, Stephen Justham
Astrophysics of Galaxies
Cross-correlation of Luminous Red Galaxies with ML-selected AGN in HSC-SSP III: HOD Parameters for Type I and Type II Quasars
Rodrigo Córdova Rosado, Andy D. Goulding, Jenny E. Greene et al. (+4 more)
Understanding the dark matter (DM)
halo environment in which
galaxies that host active
galactic nuclei (AGN) reside is a window into the nature of supermassive black hole (SMBH)
accretion. We apply
halo occupation distribution (HOD) modeling tools to interpret the angular cross-correlation functions between $1.5\times10^6$ luminous red
galaxies (LRGs) and our $\sim28,500$ Hyper Suprime-Cam + Wide-field Infrared Survey Explorer-selected (and $L_{6 \mu m}$-limited) AGN to infer the
halo properties of distinct
quasar samples at physical scales $s>0.1\,{\rm Mpc}$, for $z\in0.7-1.0$. We find that Type I (unobscured) and Type II (obscured) AGN cluster differently, both on small and large physical scales. The derived HODs imply that Type I AGN reside, on average, in substantially ($\sim3\times$) more massive
halos ($M_h \sim 10^{13.4} M_\odot$) than Type II AGN ($M_h \sim 10^{12.9} M_\odot$) at $>5\sigma$ significance. While Type II AGN show one-
halo correlations similar to that of
galaxies of their average
halo mass, the Type I AGN intra-
halo clustering signal is significantly shallower. We interpret this observation with HOD methods and find Type I AGN are significantly less likely ($f_{sat}\sim0.05^{+1}_{-0.05}\%$) to be found in satellite
galaxies than Type II AGN. We find reddened + obscured AGN to have typical satellite fractions for their inferred average
halo mass ($\sim10^{13} M_\odot$), with $f_{sat} \sim 20^{+10}_{-5}\%$. Taken together, these results pose a significant challenge to the strict unified AGN morphological model, and instead suggest that a
quasar's spectral class is strongly correlated with its host
galaxy's dark matter
halo environment. These intriguing results have provided a more complex picture of the SMBH – DM
halo connection, and motivate future analyses of the intrinsic
galaxy and
accretion properties of AGN.
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All authors Rodrigo Córdova Rosado, Andy D. Goulding, Jenny E. Greene, Nickolas Kokron, Andrina Nicola, Michael A. Strauss, Ryan C. Hickox
Earth and Planetary Astrophysics
Spatial Profiles of 3I/ATLAS CN and Ni Outgassing from Keck/KCWI Integral Field Spectroscopy
W. B. Hoogendam, B. J. Shappee, J. J. Wray et al. (+11 more)
Cometary activity from interstellar objects provides a unique window into the environs of other
stellar systems. We report blue-sensitive integral field unit spectroscopy of the interstellar object 3I/ATLAS from the Keck-II-mounted Keck
Cosmic Web Imager on August 24, 2025 UT. We confirm previously reported CN and Ni outgassing, and present, for the first time, the radial profiles of Ni and CN emission in 3I/ATLAS. We find a characteristic $e$-folding radius of $593.7\pm14.8$ km for Ni and $841.0\pm15.4$ km for CN; this suggests that the Ni emission is more centrally concentrated in the
nucleus of the comet and favors hypotheses involving easily dissociated species such as metal carbonyls or metal-polycyclic-aromatic-hydrocarbon molecules. Additional integral field spectroscopy after perihelion will offer a continued opportunity to determine the
evolution of the radial distributions of species in interstellar comet 3I/ATLAS.
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All authors W. B. Hoogendam, B. J. Shappee, J. J. Wray, B. Yang, K. J. Meech, C. Ashall, D. D. Desai, K. Hart, J. T. Hinkle, A. Hoffman, E. M. Hu, D. O. Jones, K. Medler, C. Pfeffer
Astrophysics of Galaxies
The PHANGS-MUSE/HST-Halpha Nebulae Catalogue
A. T. Barnes, R. Chandar, K. Kreckel et al. (+38 more)
We present the PHANGS-MUSE/HST-Halpha nebulae catalogue, comprising 5177 spatially resolved nebulae across 19 nearby
star-forming
galaxies (< 20 Mpc), based on high-resolution Halpha imaging from HST, homogenised to a fixed 10 pc resolution and sensitivity. Combined with MUSE spectroscopy, this enables robust classification of 4882 H II regions and separation of planetary nebulae and
supernova remnants. Electron densities for 2544 H II regions are derived using [S II] diagnostics, and nebular sizes measured via circularised radii and second moments yield a median of 20 pc, extending to sub-parsec scales. A structural complexity score traces substructure, showing that about a third of regions are H II complexes, with a higher fraction in
galaxy centres. A luminosity-size relation calibrated from the HST sample is applied to 30,790 MUSE nebulae, recovering sizes down to 1 pc. Observed sizes exceed classical Stromgren radii, implying typical volume filling factors of 0.22. We associate 3349 H II regions with
stellar populations from PHANGS-HST, finding median ages of 3 Myr and masses of 4-5 log(Msun). The
dataset provides a detailed, spatially resolved link between nebular structure and ionising sources, serving as a
benchmark for future studies of feedback, diffuse ionised gas, and
star formation regulation in the interstellar medium. The full catalogue is made publicly available in machine-readable format.
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All authors A. T. Barnes, R. Chandar, K. Kreckel, F. Belfiore, D. Pathak, D. Thilker, A. K. Leroy, B. Groves, S. C. O. Glover, R. McClain, A. Amiri, Z. Bazzi, M. Boquien, E. Congiu, D. A. Dale, O. V. Egorov, E. Emsellem, K. Grasha, J. Gonzalez Lobos, K. Henny, H. He, R. Indebetouw, J. C. Lee, J. Li, F.-H. Liang, K. Larson, D. Maschmann, S. E. Meidt, J. E. Méndez-Delgado, J. Neumann, H.-A. Pan, M. Querejeta, E. Rosolowsky, S. K. Sarbadhicary, F. Scheuermann, L. Úbeda, T. G. Williams, T. D. Weinbeck, B. Whitmore, A. Wofford, the PHANGS collaboration
Astrophysics of Galaxies
The Blue Jay Survey: Deep JWST Spectroscopy for a Representative Sample of Galaxies at Cosmic Noon
Sirio Belli, Letizia Bugiani, Minjung Park et al. (+17 more)
We present the Blue Jay survey, a cycle 1 JWST program aimed at studying the
stellar and gas content of
galaxies at
cosmic noon. The survey consists of deep spectroscopy for 153 targets observed over two pointings in the COSMOS field using the NIRSpec micro-shutter assembly (MSA). We employed the three medium-resolution gratings, G140M, G235M, and G395M, with exposure times of 13 hours, 3.2 hours, and 1.6 hours, respectively. We thus obtained full coverage of the 1 - 5 um range, corresponding to the entire rest-frame optical wavelength range, with a spectral resolution R~1000. Parallel observations provided deep multiband NIRCam imaging, which partially overlaps with the spectroscopic observations. The sample was carefully selected to provide a census of
galaxies over the
redshift range 1.7 < z < 3.5 without strong biases in color,
star formation rate, or other properties. Since the standard A-B nod subtraction leads to flux self-subtraction for large
galaxies, we constructed a master background from empty shutters and subtracted it from each of the science spectra. In order to obtain self-consistent fits of spectroscopic and photometric data, we measured multiband photometry using space-based observations from the exact area in the sky where the NIRSpec 1D spectrum is extracted. The spectra contain a wealth of emission and absorption lines, including hydrogen lines, helium lines, metal emission lines from ionized gas, metal
stellar absorption lines, and resonant absorption lines. Spectroscopic
redshifts are unambiguously measured for 93% of the sample. The Blue Jay
dataset, which we publicly release, represents the ideal sample for studying the
stellar populations, neutral gas, and ionized gas in
cosmic noon
galaxies, including
star formation histories, quenching,
outflows,
metallicity, and
dust attenuation.
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All authors Sirio Belli, Letizia Bugiani, Minjung Park, J. Trevor Mendel, Rebecca L. Davies, Amir H. Khoram, Benjamin D. Johnson, Joel Leja, Sandro Tacchella, Vanessa Brown, Charlie Conroy, Razieh Emami, Yijia Li, Caterina Liboni, Gabriel Maheson, Elijah P. Mathews, Rohan P. Naidu, Erica J. Nelson, Bryan A. Terrazas, Rainer Weinberger
High Energy Astrophysical Phenomena
MESA-QUEST: Tracing the formation of direct collapse black hole seeds via quasi-stars
Andrew D. Santarelli, Claire B. Campbell, Ebraheem Farag et al. (+3 more)
The origin of the first supermassive black holes (SMBHs) observed at
redshifts $z\geq 9$ remains one of the most challenging open questions in astrophysics. Their rapid emergence suggests that massive “heavy seeds” must have formed early, possibly through the direct collapse of pristine gas clouds in the first
galaxies. We present MESA-QUEST, a new framework built upon the Modules for Experiments in
Stellar Astrophysics (MESA) code, designed to model the structure and
evolution of quasi-
stars – massive, radiation-supported envelopes hosting accreting black holes at their cores – believed to be the progenitors of direct-collapse black hole (DCBH) seeds. Our implementation introduces flexible boundary conditions representing both Bondi
accretion and saturated-convection regimes, and explores the impact of several
stellar wind and mass-loss prescriptions, including Reimers, Dutch, and super-Eddington radiation-driven winds. We find that quasi-
stars can grow central black holes to $\geq 10^3\,M_{\odot}$ under favorable conditions, with saturated-convection models yielding BH-to-total mass ratios up to 0.55$M_*$ – five times higher than Bondi-limited cases. However, strong radiation-driven winds can dramatically curtail growth, potentially quenching heavy-seed formation unless balanced by sustained envelope
accretion. Our results delineate the physical limits under which quasi-
stars can remain stable and produce heavy seeds capable of evolving into the earliest SMBHs detected by JWST and Chandra. Future extensions will incorporate rotation,
magnetic fields, and GR-radiation hydrodynamics to refine
accretion physics and constrain the viability of the quasi-
star pathway for early SMBH formation.
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All authors Andrew D. Santarelli, Claire B. Campbell, Ebraheem Farag, Earl P. Bellinger, Priyamvada Natarajan, Matthew E. Caplan
Astrophysics of Galaxies
Early massive galaxy formation in the core of a galaxy protocluster 650 million years after the Big Bang
Yoshinobu Fudamoto, Yurina Nakazato, Daniel Ceverino et al. (+24 more)
Rest-frame optical observations with the James Webb Space
Telescope (JWST) have uncovered a population of massive
galaxies, exceeding $10^{10}$
solar masses, present less than a billion years after the Big Bang. The large
stellar masses of these
galaxies require an efficient conversion of
baryons into
stars, which may exceed theoretical expectations. However, the formation process of massive
galaxies so early in the Universe's history is perplexing, as observations provide limited information to constrain their evolutionary pathways. Here, we present multi-wavelength observations of a
galaxy complex consisting of at least five
galaxies within a $\sim10\,{\rm kpc}$ region, referred to as the \quintet, using JWST and the Atacama Large Millimeter/submillimeter Array. This system, located in the core of a
galaxy protocluster at approximately 650 million years after the Big Bang, reveals the detailed physical processes involved in the formation of massive
galaxies. These processes include a dynamic cycles of merger induced gas stripping, leading the temporal termination of
star formation, and recycling of the stripped gas, with subsequent enhancement of
star formation in other
galaxies of the system, which is expected to evolve into massive
galaxies that host more than $10^{10}$
solar masses of
stars. The new observations represent the first comprehensive evidence of a massive
galaxy formation through gas-rich, multiple-
galaxy mergers induced by a dense protocluster environment in the $650\,{\rm Myrs}$ after the Big Bang. Our results suggest that the protocluster core is indeed one of the main drivers of efficient
galaxy formation and rapid
evolution in the early Universe, as predicted by theoretical studies.
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All authors Yoshinobu Fudamoto, Yurina Nakazato, Daniel Ceverino, Luis Colina, Takuya Hashimoto, Akio K. Inoue, Yoichi Tamura, Naoki Yoshida, Yongda Zhu, Yuma Sugahara, Santiago Arribas, Javier 'Arvarez-M'arquez, Tom Bakx, Carmen Blanco Prieto, Luca Costantin, Alejandro Crespo G'omez, Masato Hagimoto, Takeshi Hashigaya, Hiroshi Matsuo, Rui Marques-Chaves, Ken Mawatari, Ikki Mitsuhashi, Wataru Osone, Miguel Pereira-Santaella, Hideki Umehata, Callum Witten, Yi W. Ren
Cosmology and Nongalactic Astrophysics
BayeSN-TD: Time Delay and $H_0$ Estimation for Lensed SN H0pe
M. Grayling, S. Thorp, K. S. Mandel et al. (+6 more)
We present BayeSN-TD, an enhanced implementation of the probabilistic type Ia
supernova (SN Ia) BayeSN SED model, designed for fitting multiply-imaged, gravitationally lensed type Ia
supernovae (glSNe Ia). BayeSN-TD fits for magnifications and time-delays across multiple images while marginalising over an achromatic, Gaussian process-based treatment of microlensing, to allow for time-dependent deviations from a typical SN Ia SED caused by gravitational
lensing by
stars in the
lensing system. BayeSN-TD is able to robustly infer time delays and produce well-calibrated uncertainties, even when applied to simulations based on a different SED model and incorporating chromatic microlensing, strongly validating its suitability for time-delay cosmography. We then apply BayeSN-TD to publicly available photometry of the glSN Ia SN H0pe, inferring time delays between images BA and BC of $\Delta T_{BA}=121.9^{+9.5}_{-7.5}$ days and $\Delta T_{BC}=63.2^{+3.2}_{-3.3}$ days along with absolute magnifications $\beta$ for each image, $\beta_A = 2.38^{+0.72}_{-0.54}$, $\beta_B=5.27^{+1.25}_{-1.02}$ and $\beta_C=3.93^{+1.00}_{-0.75}$. Combining our constraints on time-delays and magnifications with existing lens models of this system, we infer $H_0=69.3^{+12.6}_{-7.8}$ km s$^{-1}$ Mpc$^{-1}$, consistent with previous analysis of this system; incorporating additional constraints based on spectroscopy yields $H_0=66.8^{+13.4}_{-5.4}$ km s$^{-1}$ Mpc$^{-1}$. While this is not yet precise enough to draw a meaningful conclusion with regard to the `Hubble tension', upcoming analysis of SN H0pe with more accurate photometry enabled by template images, and other glSNe, will provide stronger constraints on $H_0$; BayeSN-TD will be a valuable tool for these analyses.
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All authors M. Grayling, S. Thorp, K. S. Mandel, M. Pascale, J. D. R. Pierel, E. E. Hayes, C. Larison, A. Agrawal, G. Narayan
Earth and Planetary Astrophysics
TOI-3288 b and TOI-4666 b: two gas giants transiting low-mass stars characterised by NIRPS
Yolanda G. C. Frensch, François Bouchy, Gaspare Lo Curto et al. (+62 more)
Gas
giant planets orbiting low-mass
stars are uncommon outcomes of
planet formation. Increasing the sample of well-characterised
giants around early M
dwarfs will enable population-level studies of their properties, offering valuable insights into their formation and evolutionary histories. We aim to characterise
giant exoplanets transiting M
dwarfs identified by TESS. High-resolution spectroscopic data are obtained in the optical and nIR, combining HARPS and NIRPS. We derive RVs via the cross-correlation function and implement a novel post-processing procedure to further mitigate telluric contamination in the nIR. The resulting RVs are jointly fit with TESS and ground-based photometry to derive the orbital and physical parameters of the systems. We confirm two gas
giants transiting the low-mass
stars TOI-3288 A (K9V) and TOI-4666 (M2.5V). TOI-3288 A hosts a Hot Jupiter with a mass of $2.11\pm0.08~M_{\rm Jup}$ and a radius of $1.00 \pm 0.03~R_{\rm Jup}$, with an orbital period of 1.43 days ($T_{\rm eq} = 1059 \pm 20~{\rm K}$). TOI-4666 hosts a $0.70_{-0.06}^{+0.05}~M_{\rm Jup}$ warm Jupiter ($T_{\rm eq} = 713 \pm 14~{\rm K}$) with a radius of $1.11 \pm 0.04~R_{\rm Jup}$, and an orbital period of 2.91 days. We identify a decrease in planetary mass with spectral type, where late M
dwarfs host less massive
giant planets than early M
dwarfs. More massive gas
giants that deviate from this trend are preferentially hosted by more metal-rich
stars. Furthermore, we find an increased binarity fraction among low-mass
stars hosting gas
giants, which may play a role in enhancing
giant planet formation around low-mass
stars. The observed population trends agree with theoretical expectations, where higher
metallicity can compensate for lower disk masses, and wide binary systems may influence
planet formation and migration through Kozai-Lidov cycles or disk instabilities.
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All authors Yolanda G. C. Frensch, François Bouchy, Gaspare Lo Curto, Alexandrine L'Heureux, Roseane de Lima Gomes, João Faria, Xavier Dumusque, Lison Malo, Marion Cointepas, Avidaan Srivastava, Xavier Bonfils, Elisa Delgado-Mena, Nicola Nari, Khaled Al Moulla, Romain Allart, Jose M. Almenara, Étienne Artigau, Khalid Barkaoui, Frédérique Baron, Susana C. C. Barros, Björn Benneke, Marta Bryan, Charles Cadieux, Bruno L. Canto Martins, Izan de Castro Leão, Amadeo Castro-González, Ryan Cloutier, Karen A. Collins, Nicolas B. Cowan, Eduardo Cristo, Jose R. De Medeiros, Xavier Delfosse, René Doyon, David Ehrenreich, Sergio B. Fajardo-Acosta, Thierry Forveille, Tianjun Gan, João Gomes da Silva, Jonay I. González Hernández, Nolan Grieves, Steve Howell, David Lafrenière, Christophe Lovis, Claudio Melo, Lina Messamah, Lucile Mignon, Christoph Mordasini, Louise D. Nielsen, Ares Osborn, Léna Parc, Francesco Pepe, Caroline Piaulet-Ghorayeb, Rafael Rebolo, Jason Rowe, Nuno C. Santos, Damien Ségransan, Keivan G. Stassun, Stephanie Striegel, Alejandro Suárez Mascareño, Stéphane Udry, Solène Ulmer-Moll, Diana Valencia, Valentina Vaulato, Gregg Wade, Cristilyn N. Watkins
Astrophysics of Galaxies
The Sunburst Arc with JWST. IV. The importance of interaction, turbulence, and feedback for Lyman-continuum escape
T. Emil Rivera-Thorsen, Brian Welch, Taylor Hutchison et al. (+13 more)
At present, the best opportunity for detailed Lyman Continuum escape studies is in gravitationally lensed
galaxies at z >~ 2. Only one such
galaxy currently exists in the literature with sufficient spatial magnification: The Sunburst Arc at
redshift z = 2.37. Here, we present rest-frame optical JWST NIRSpec integral field observations of the Sunburst Arc that cover a large fraction of the source plane. From this
dataset, we generate precise maps of ISM kinematics,
dust geometry, ionization, and chemical enrichment. We extract a stacked spectrum of five gravitationally lensed images of the Lyman-Continuum leaking cluster, as well as an magnification-corrected, integrated spectrum of most of the
galaxy, enabling a direct comparison to other LyC leakers in the literature. We find that the
galaxy rotates but also shows strong, possibly dominant, signatures of
turbulence, which are indicative of recent or ongoing major interaction. The cluster that leaks ionizing
photons shows little variation in kinematics or
dust coverage, but dramatically elevated ionization, indicating that photoionization is the predominant mechanism that creates paths for LyC escape. We
conjecture that
tidal stripping of H I gas due to an interaction could have removed a large portion of the neutral ISM around the LyC emitting cluster, making it easier for the cluster to completely ionize the rest.
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All authors T. Emil Rivera-Thorsen, Brian Welch, Taylor Hutchison, Matthew J. Hayes, Jane R. Rigby, Keunho Kim, Suhyeon Choe, Michael Florian, Matthew B. Bayliss, Gourav Khullar, Keren Sharon, Håkon Dahle, John Chisholm, Erik Solhaug, M. Riley Owens, Michael D. Gladders
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Revisiting the limits on dark matter annihilation cross-section and decay lifetime in light of electron and positron fluxes
Nagisa Hiroshima, Kazunori Kohri, Partha Kumar Paul et al. (+1 more)
We revisit the upper bound on the annihilation cross-section, $\langle\sigma v\rangle$ of a stable dark matter (DM) of mass $500-10^{14}$ GeV by considering five different channels: $W^+W^-$, $b\bar{b}$, $\mu^+\mu^-$, $\tau^+\tau^-$, and $e^+e^-$. We use the observed electron and positron fluxes from CALET, DAMPE, HESS, positron flux from AMS-02, and gamma-ray flux from HAWC, GRAPES-3, CASA-MIA to constrain the annihilation cross-section. We also consider unstable DM of mass $10^3-10^{16}$~GeV decaying to $W^+W^-$, $b\bar{b}$, $\mu^+\mu^-$, $\tau^+\tau^-$, and $e^+e^-$ and derive the corresponding lower bound on the DM lifetime, $\tau_{\rm DM}$. We find that the latest AMS-02 data provide the most stringent constraints on $\langle\sigma v\rangle$ for DM masses below 2 TeV, while HESS yields the strongest limits for $M_{\rm DM}\gtrsim2$ TeV. The HESS gives a much more stringent limit on the DM lifetime, excluding $\tau_{\rm DM\rightarrow\mu^+\mu^-}\lesssim\mathcal{O}(10^{30})$ s for a 10 TeV mass of DM. The limits on $\langle\sigma v\rangle$ derived from the $e^+e^-$ flux are competitive with those from $\gamma$-ray and
neutrino observations for DM masses in the range $10^5$–$10^{11}$ GeV, and become the most stringent beyond this range. For decaying DM, the $e^+e^-$ flux provides the strongest constraints on the DM lifetime over the mass range $10^3$–$10^9$ GeV.
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All authors Nagisa Hiroshima, Kazunori Kohri, Partha Kumar Paul, Narendra Sahu
High Energy Astrophysical Phenomena
Gamma-ray Orbital Modulation in Spider Pulsars: Three Discoveries and a Universal Modulated Fraction
Maksat Satybaldiev, Manuel Linares and Vittoria Vecchiotti
Compact binary millisecond
pulsars (also known as spiders) allow us to probe
pulsar winds in their innermost regions, between the light cylinder (radius $\sim10^{7}$ cm) and the companion
star (at $\sim10^{11}$ cm). Their flux is known to vary along the orbit, from
radio to X-rays. During the past decade, gamma-ray orbital modulation (GOM) has been discovered in a handful of spiders, but its origin remains largely unknown. We present the results of a systematic search for GOM among 43 systems, selecting pulsed 0.1-1 GeV
photons and using
spin and orbital ephemeris from
Fermi's Third
Pulsar Catalog. We discover GOM from three spiders - PSR J1124-3653, PSR J1946-5403 and PSR J2215+5135 - and confirm four previous detections. In all seven cases so far, the GOM peaks near the
pulsar's superior conjunction. The X-ray orbital light curves are usually in antiphase, peaking when the
pulsar is at inferior conjunction, but we find one case where both gamma-rays and X-rays peak around superior conjunction: PSR J1946-5403. We measure the modulated fractions of the GOM and find consistent values for all seven spiders, with an average $22.0\pm2.6\%$. Including eclipsing systems seen edge-on, we find no clear dependence of the modulated fraction on the orbital inclination (within $\simeq$45-90$^\circ$). Our results challenge previous models proposed to explain GOM in spiders, based on inverse Compton and synchrotron emission close to the companion, since these predict a clear dependence on orbital inclination (stronger modulation at high inclinations). We nearly double the number of GOM detections in spiders, showing that it is more common than previously thought.
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Astrophysics of Galaxies
Ultra-Faint Milky Way Satellites Discovered in Carina, Phoenix, and Telescopium with DELVE Data Release 3
C. Y. Tan, W. Cerny, A. B. Pace et al. (+76 more)
We report the discovery of three Milky Way satellite candidates: Carina IV, Phoenix III, and DELVE 7, in the third data release of the DECam Local Volume Exploration survey (DELVE). The candidate systems were identified by cross-matching results from two independent search
algorithms. All three are extremely faint systems composed of old, metal-poor
stellar populations ($\tau \gtrsim 10$ Gyr, [Fe/H] $ \lesssim -1.4$). Carina IV ($M_V = -2.8;\ r_{1/2} = 40 {\rm pc}$) and Phoenix III ($M_V = -1.2;\ r_{1/2} = 19 {\rm pc}$) have half-light radii that are consistent with the known population of
dwarf galaxies, while DELVE 7 ($M_V = 1.2;\ r_{1/2} = 2 {\rm pc}$) is very compact and seems more likely to be a
star cluster, though its nature remains ambiguous without spectroscopic followup. The
Gaia proper motions of
stars in Carina IV ($M_* = 2250^{+1180}_{-830} {\rm M_\odot}$) indicate that it is unlikely to be associated with the LMC, while DECam CaHK photometry confirms that its member
stars are metal-poor. Phoenix III ($M_* = 520^{+660}_{-290} {\rm M_\odot}$) is the faintest known satellite in the extreme outer
stellar halo ($D_{\rm GC} > 100$ kpc), while DELVE 7 ($M_* = 60^{+120}_{-40} {\rm M_\odot}$) is the faintest known satellite with $D_{\rm GC} > 20$ kpc.
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All authors C. Y. Tan, W. Cerny, A. B. Pace, J. A. Sharp, K. Overdeck, A. Drlica-Wagner, J. D. Simon, B. Mutlu-Pakdil, D. J. Sand, A. M. Senkevich, D. Erkal, P. S. Ferguson, F. Sobreira, K. R. Atzberger, J. L. Carlin, A. Chiti, D. Crnojević, A. P. Ji, L. C. Johnson, T. S. Li, G. Limberg, C. E. Martínez-Vázquez, G. E. Medina, V. M. Placco, A. H. Riley, E. J. Tollerud, A. K. Vivas, T. M. C. Abbott, M. Aguena, O. Alves, D. Bacon, S. Bocquet, D. Brooks, D. L. Burke, R. Camilleri, J. A. Carballo-Bello, A. Carnero Rosell, J. Carretero, T.-Y. Cheng, Y. Choi, L. N. da Costa, M. E. da Silva Pereira, T. M. Davis, J. De Vicente, S. Desai, P. Doel, S. Everett, B. Flaugher, J. Frieman, J. García-Bellido, D. Gruen, G. Gutierrez, S. R. Hinton, D. L. Hollowood, D. J. James, K. Kuehn, S. Lee, J. L. Marshall, J. Mena-Fernández, F. Menanteau, R. Miquel, J. Myles, M. Navabi, D. L. Nidever, N. E. D. Noël, R. L. C. Ogando, A. A. Plazas Malagón, A. Porredon, S. Samuroff, E. Sanchez, D. Sanchez Cid, I. Sevilla-Noarbe, M. Smith, G. S. Stringfellow, E. Suchyta, M. E. C. Swanson, V. Vikram, A. R. Walker, A. Zenteno
High Energy Astrophysical Phenomena · Cross-listed from hep-ph
Hints of Dark Matter Spikes in Low-mass X-ray Binaries: a critical assessment
Francesca Scarcella and Bradley J. Kavanagh
Three black-hole low-mass X-ray binaries (LMXBs) in the Milky Way show rates of period decay which cannot be easily explained by standard mechanisms. Recently, it has been claimed that the anomalous period decays in two of these systems may be explained by dynamical friction due to very high dark matter (DM) densities around the black holes. We critically assess these claims by performing $N$-body simulations of binaries embedded in dense DM “spikes". We simulate the previously-studied systems XTE J1118+480 and A0620–00, as well as studying the third binary Nova Muscae 1991 for the first time in this context. These simulations show that feedback on the DM distribution plays a crucial role and we rule out previously-claimed shallow DM spikes. We set lower limits on the steepness $\gamma$ of DM density profiles required to explain the period decay in these LMXBs, requiring $\gamma \gtrsim 2.15-2.20$ in XTE J1118+480 and A0620–00 and $\gamma \gtrsim 2.3$ in Nova Muscae 1991. Improved modeling of the long-term
evolution of binaries embedded in DM spikes may allow us to exclude even larger densities in future.
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