Sazuna/UAT_keywords huggingface dataset:
A Census of Pulsars in Possible Association with Galactic Open Clusters. Among the ∼4000 known pulsars in our Galaxy, ≲10% are found in globular clusters, but none has been confirmed in any open clusters yet, although they outnumber globular clusters by about 20 times. In this work, we make use of the Gaia DR3 catalog of Galactic open clusters and conduct a pulsar census in order to identify pulsars that are either (1) current members of open clusters or (2) escaped from open clusters to the field. Among 164 pulsars with independent distance measurements and 3530 open clusters, we find that 4 pulsars are likely residing in open clusters. In particular, we find compelling evidence that the binary pulsar J1302−6350 (B1259−63) is a member of the open cluster UBC 525; based on Gaia data, we update its distance to be 2.26 ± 0.07 kpc and measure the mass of its companion Be star LS 2883 to be 16.8 M⊙. For 145 pulsars with both distance and proper motion measurements and 2967 open clusters with full kinematic parameters, we trace the past trajectories of both pulsars and open clusters in the Galactic gravitational potential and find pulsars that were within 3 times the radius of a cluster. This results in 19 pulsars that were likely born in open clusters. We discuss implications for the formation history of PSR J1302−6350 and highlight the scientific potential of searching for pulsars in open clusters.

Keywords: Open star clusters, Radio pulsars, Pulsars
LAP1-B is the First Observed System Consistent with Theoretical Predictions for Population III Stars. Recently, Nakajima et al. presented James Webb Space Telescope observations of the z = 6.6 Population III (Pop III) candidate LAP1-B, which is gravitationally lensed by galaxy cluster MACS J0416. We argue that this is the first object to agree with three key theoretical predictions for Pop III stars: (1) formation in extremely low-metallicity halos with virial temperatures ranging from Tvir ∼ 103─104 K, (2) a top-heavy initial mass function, and (3) formation of low-mass clusters with ∼a few ×1000 M⊙ in massive Pop III stars. LAP1-B is consistent with recently formed Pop III stars hosted in a ∼5 × 107 M⊙ dark matter halo, some of which have enriched their surrounding gas either with supernovae or stellar winds. We use the semianalytic model of Visbal et al. to predict the abundance of Pop III clusters observable at the high magnification provided by the foreground galaxy cluster MACS J0416. Using fiducial parameters unmodified from previous work, we expect about one observable Pop III galaxy similar to LAP1-B in the range z = 6─7. At earlier times, the intrinsic abundance is higher, but Pop III systems would not have been detected because of their increased luminosity distance and lower-mass dark matter halos, which would host fewer stars. Thus, we find that LAP1-B was found at the redshift theoretically expected, given current observable limits, despite the fact that most Pop III systems form much earlier.

Keywords: Cosmology, Population III stars
H I Properties of Field Galaxies at z ≍ 0.2─0.6: Insights into Declining Cosmic Star Formation. We report statistically significant detection of H I 21 cm emission from intermediate-redshift (z ≍ 0.2─0.6) galaxies. By leveraging multisightline galaxy survey data from the Cosmic Ultraviolet Baryon Survey and deep radio observations from the MeerKAT Absorption Line Survey, we have established a sample of ≍6000 spectroscopically identified galaxies in 11 distinct fields to constrain the neutral gas content at intermediate redshifts. The galaxies sample a broad range in stellar mass, from  logMstar/M⊙≍8  to  logMstar/M⊙≍11 , with a median of  &lt;logMstar/M⊙&gt;med≍10  and a wide range in redshift from z ≍ 0.24 to z ≍ 0.63 with a median of &lt; z&gt;med = 0.44. While no individual galaxies show detectable H I emission, the emission line signal is detected in the stacked spectra of all subsamples at greater than 4σ significance. The observed total H I 21 cm line flux translates to a H I mass, MH I ≍1010M⊙. We find a high H I-to-stellar-mass ratio of MH I/Mstar ≍ 6 for low-mass galaxies with  &lt;logMstar/M⊙&gt;≍9.3  (&gt;3.7σ). For galaxies with  &lt;logMstar/M⊙&gt;≍10.6 , we find MH I/Mstar ≍ 0.3 (&gt;4.7σ). In addition, the redshift evolution of H I mass, &lt;MH I&gt;, in both low- and high-mass field galaxies, inferred from the stacked emission-line signal, aligns well with the expectation from the cosmic star formation history. This suggests that the overall decline in the cosmic star formation activity across the general galaxy population may be connected to a decreasing supply of neutral hydrogen. Finally, our analysis has revealed significant 21 cm signals at distances greater than 75 kpc from these intermediate-redshift galaxies, indicating a substantial reservoir of H I gas in their extended surroundings.

Keywords: Radio interferometry, Galaxy evolution, Catalogs, H I line emission
Near the Runaway: The Climate and Habitability of Teegarden's Star b. Teegarden's Star b, a nearby terrestrial world receiving an Earth-like instellation, is a prime candidate for next-generation observatories targeting temperate exoplanets in their habitable zones. We employ a suite of three-dimensional global climate model simulations to (1) map the inner boundary of the habitable zone of Teegarden's Star b and (2) characterize its surface climate under the assumption of an Earth-analog atmosphere. Our simulations show that, with its most recently estimated instellation of 1481 W m−2, Teegarden's Star b remains below the runaway greenhouse threshold for both low (αs = 0.07, ocean-dominated) and moderate (αs = 0.30, land-dominated) surface albedos. However, a different estimate of 1565 W m−2 places it beyond the runaway threshold. The result that Teegarden's Star b is habitable under the most recent instellation measurement reinforces its status as one of the most compelling targets for future habitability and biosignature searches. Given the planet's proximity to the runaway threshold, it would benefit from a comparative study done with other models using different parameterizations.

Keywords: Extrasolar rocky planets, Astrobiology, Habitable planets, Exoplanet atmospheres
Masses, Star Formation Efficiencies, and Dynamical Evolution of 18,000 H II Regions. We present measurements of the masses associated with ∼18,000 H II regions across 19 nearby star-forming galaxies by combining data from JWST, Hubble Space Telescope, MUSE, Atacama Large Millimeter/submillimeter Array, Very Large Array, and MeerKAT from the multiwavelength PHANGS survey. We report 10 pc-scale measurements of the mass of young stars, ionized gas, and older disk stars coincident with each H II region, as well as the initial and current mass of molecular gas, atomic gas, and swept-up shell material, estimated from lower-resolution data. We find that the mass of older stars dominates over young stars at ≳10 pc scales, and ionized gas exceeds the stellar mass in most optically bright H II regions. Combining our mass measurements for a statistically large sample of H II regions, we derive 10 pc-scale star formation efficiencies of ≍6%─17% for individual H II regions. Comparing each region's self-gravity with the ambient interstellar medium (ISM) pressure and total pressure from presupernova stellar feedback, we show that most optically bright H II regions are overpressured relative to their own self-gravity and the ambient ISM pressure and that they are hence likely expanding into their surroundings. Larger H II regions in galaxy centers approach dynamical equilibrium. The self-gravity of regions is expected to dominate over presupernova stellar feedback pressure at ≳130 and 60 pc scales in galaxy disks and centers, respectively, but is always subdominant to the ambient ISM pressure on H II region scales. Our measurements have direct implications for the dynamical evolution of star-forming regions and the efficiency of stellar feedback in ionizing and clearing cold gas.

Keywords: Stellar feedback, Star forming regions, Star formation, Interstellar medium, Extragalactic astronomy, H II regions
GW241011 and GW241110: Exploring Binary Formation and Fundamental Physics with Asymmetric, High-spin Black Hole Coalescences. We report the observation of gravitational waves from two binary black hole coalescences during the fourth observing run of the LIGO─Virgo─KAGRA detector network, GW241011 and GW241110. The sources of these two signals are characterized by rapid and precisely measured primary spins, nonnegligible spin─orbit misalignment, and unequal mass ratios between their constituent black holes. These properties are characteristic of binaries in which the more massive object was itself formed from a previous binary black hole merger and suggest that the sources of GW241011 and GW241110 may have formed in dense stellar environments in which repeated mergers can take place. As the third-loudest gravitational-wave event published to date, with a median network signal-to-noise ratio of 36.0, GW241011 furthermore yields stringent constraints on the Kerr nature of black holes, the multipolar structure of gravitational-wave generation, and the existence of ultralight bosons within the mass range 10−13─10−12 eV.

Keywords: Gravitational wave detectors, Compact binary stars, Gravitational wave astronomy, General relativity, Astrophysical black holes
Black Hole Collisions with Thin Accretion Disks: OJ 287 and Small Mass Ratio Supermassive Black Hole Binary Candidates. OJ 287 is the best-known supermassive black hole binary candidate in the nanohertz gravitational-wave band. It exhibits periodic flares every ∼12 yr, likely caused by collisions of a lower-mass secondary with the accretion disk surrounding a higher-mass primary. It is therefore an important benchmark for understanding black hole binary accretion in the approaching era of space-based gravitational-wave detectors and large electromagnetic surveys. Because the electromagnetic emission of the system is determined by a complex interplay of plasma, accretion, and radiation physics in strong gravity, numerical simulations are required for realistic modeling. We present the first global, three-dimensional, general relativistic magnetohydrodynamic simulations of OJ 287─like systems, namely lower-mass secondaries colliding with a radiatively cooled (thin) disk surrounding a higher-mass primary. We focus on disks with scale heights that are 10% of the distance from the primary and binary mass ratios of q = 0.1, 0.05, and 0.025 using an optically thin cooling prescription. We confirm the basic paradigm that impacts of the secondary on the disk can generate enough power to outshine the quiescent emission. The secondary also causes spiral shocks to form in the disk, enhanced accretion events, overall heating of the flow, and stochastic tilting of the disk, though these effects are small for q &lt; 0.05. Our results can be extrapolated to the parameters of OJ 287 and similar systems, an important step on the path toward fully realistic simulations of accretion onto small mass ratio black hole binaries and predicting electromagnetic counterparts to low-frequency gravitational-wave detections.

Keywords: Accretion, Black hole physics, Optical bursts, BL Lacertae objects, Radio jets, Relativistic jets, Computational methods, General relativity, Active galactic nuclei, Relativistic fluid dynamics, Magnetohydrodynamical simulations
Onset of CN Emission in 3I/ATLAS: Evidence for Strong Carbon-chain Depletion. Interstellar objects provide a direct window into the environmental conditions around stars other than the Sun. The recent discovery of 3I/ATLAS, a new interstellar comet, offers a unique opportunity to investigate the physical and chemical properties of interstellar objects and to compare them with those of comets in our own solar system. In this Letter we present the results of a 10 night spectroscopic and photometric monitoring campaign with the 2.4 m Hiltner and 1.3 m McGraw─Hill telescopes at the MDM Observatory. The campaign was conducted between August 8 and 17 while 3I/ATLAS was inbound at heliocentric distances of 3.2─2.9 au. Our observations captured the onset of optical gas activity. Nightly spectra reveal a weak CN emission feature in the coma of 3I/ATLAS, absent during the first nights but steadily strengthening thereafter. We measure a CN production rate of Q(CN) ∼ 6 × 1024 s−1, toward the lower end of activity observed in solar system comets. Simultaneous photometry also indicates a small but measurable increase in the coma's radial profile and increasing r-band Afρ with values in the order of ∼300 cm. We derived a gas-to-dust production ratio of  logQ(CN)/Afρ∼22.4 . Our upper limit on the C2-to-CN ratio ( logQ(C2)/Q(CN)≲−0.8 ) indicates that 3I/ATLAS is a strongly carbon-chain-depleted comet. Further observations of 3I/ATLAS are required to verify the apparent carbon-chain depletion and to explore whether such composition represents a recurring trait of the interstellar comet population.

Keywords: Comets, Interstellar objects
The First Proper Motion Measurement of the Acceleration Regions in the Large-scale Jets of SS 433 Powering the W50 Nebula. We report on new Chandra ACIS-I observations of the X-ray knots located in the western and eastern lobes of W50 associated with the parsec-scale jets of the Galactic microquasar SS 433. These knots are likely counterparts of the recently detected very-high-energy (E &gt; 100 GeV) gamma-ray emission by HAWC and HESS. These findings, together with the ultrahigh-energy signal recently reported by the LHAASO Collaboration, have established the SS 433/W50 system as a unique jet-driven PeVatron candidate. Combining new and archival Chandra data, we perform the first proper motion search of the X-ray knot structures over a time interval spanning approximately 20 yr. We found no statistically significant motion of these knots at the 3σ confidence level, and place an upper limit of &lt;0.019─0.033c (5800─9800 km s−1) for the speed of the innermost knots at an assumed distance d = 5.5 kpc. Combined with the velocities reported in the literature, the upstream speed in the shock rest frame would reach several 104 km s−1, suggesting that highly efficient particle acceleration, approaching the Bohm limit, is occurring. The absence of significant motion of the knots suggests the presence of a standing recollimation shock, formed by the balance between the jet pressure and the external pressure. This interpretation is consistent with the expected occurrence of such shocks at 20─30 pc from SS 433, matching the location of the observed knots.

Keywords: Gamma-ray sources, X-ray binary stars, Non-thermal radiation sources, Stellar mass black holes
GW231123: A Binary Black Hole Merger with Total Mass 190─265 M<SUB>⊙</SUB>. On 2023 November 23, the two LIGO observatories both detected GW231123, a gravitational-wave signal consistent with the merger of two black holes with masses  137−18+23M⊙  and  101−50+22M⊙  (90% credible intervals), at a luminosity distance of 0.7─4.1 Gpc, a redshift of  0.40−0.25+0.27 , and with a network signal-to-noise ratio of ∼20.7. Both black holes exhibit high spins— 0.90−0.19+0.10  and  0.80−0.52+0.20 , respectively. A massive black hole remnant is supported by an independent ringdown analysis. Some properties of GW231123 are subject to large systematic uncertainties, as indicated by differences in the inferred parameters between signal models. The primary black hole lies within or above the theorized mass gap where black holes between 60─130 M⊙ should be rare, due to pair-instability mechanisms, while the secondary spans the gap. The observation of GW231123 therefore suggests the formation of black holes from channels beyond standard stellar collapse and that intermediate-mass black holes of mass ∼200 M⊙ form through gravitational-wave-driven mergers.

Keywords: LIGO, Intermediate-mass black holes, Gravitational waves, Astrophysical black holes
Monitoring of the Spectral and Timing Properties of the Ultraluminous X-Ray Pulsar NGC 7793 P13. We present the long-term spectral and timing evolution of the ultraluminous X-ray pulsar NGC 7793 P13 from 2011 to 2024 based on archival data from XMM-Newton, Chandra, NICER, and NuSTAR, including unpublished data after 2020. This data set enables us to investigate the observational properties across a long modulation of ∼10 yr. Although previous studies suggested an increasing trend in flux in 2020, we find that the pulsar decreased its flux to  2.6−0.7+0.7×10−14ergcm−2s−1  in 2021, and rebrightened to  3.9−0.1+0.1×10−12ergcm−2s−1  by 2024. Moreover, in the last two years, the spin-up rate was twice as large as that before 2020. However, the pulsed fraction was roughly as expected from an anticorrelation with the flux confirmed before 2020. Furthermore, we perform systematic phase-resolved spectroscopy to investigate the spectral evolution. The results show that, during the flux-decaying epoch, spectral hardness in the off-pulse phase softened while that in its on-pulse phase remained almost unchanged. This softening was not observable in the rebrightening epoch. Our results could provide new insights into the accretion geometry of neutron stars in supercritical accretion systems.

Keywords: Neutron stars, X-ray transient sources, Ultraluminous x-ray sources, High mass x-ray binary stars
A Correlation between Fast Radio Burst Dispersion Measure and Foreground Large-scale Structure. The distribution of baryons in the Universe remains a fundamental open question in astronomy, and the dispersion measure (DM) of fast radio bursts (FRBs) serves as a valuable tool for probing this cosmic gas. We investigate the impact of the foreground cosmic web on FRB DMs, using 61 localized FRBs and public galaxy catalogs. We test for the large-scale structure's impact on the cosmological DM using two methods. First, we searched for a correlation between the galaxy number density along the line of sight and the extragalactic DM and found a statistically significant positive correlation (p = 1.76 × 10−5). The shape of this correlation contains information about the cosmic baryon distribution and can also be used to better constrain the host galaxy DM, by providing an estimate of the cosmic contribution on a per-source basis. We observe similar correlations in a mock FRB survey based on the IllustrisTNG cosmological simulation, where the DM is dominated by filaments in the intergalactic medium (IGM) and not by halos. Next, we performed a stacking analysis that measures the average excess DM as a function of the impact parameter of foreground galaxies to obtain spatial information about how ionized gas is distributed around galaxy halos. We report excess DM in the stacked signal for impact parameters up to megaparsec scales (∼3σ). Finally, we identified FRBs that do not appear to intersect intervening halos within r200, allowing us to estimate the fraction of baryons that reside in the IGM. We find fIGM ≥ 0.69 at 95 % confidence, indicating significant astrophysical feedback.

Keywords: Radio transient sources, Extragalactic astronomy, Intergalactic medium, Large-scale structure of the universe
Azimuthal Misalignments in Stellar Warp Structure as Dynamical Tracers of Mergers in Milky Way─like Galaxies. We investigate the origin of warps in stellar disks using high-resolution Milky Way analogs from the IllustrisTNG50 simulation. Focusing on galaxies that experienced a major merger, we identify a characteristic azimuthal misalignment between the warp structures of stellar populations formed before and after the merger. This misalignment persists even after correcting for differential rotation, suggesting it is a dynamical imprint of the merger rather than a consequence of internal kinematics. In contrast, galaxies without significant merger events show no such offset between stellar populations of different ages. These findings support the scenario in which mergers can induce long-lived warps and leave detectable structural signatures in stellar disks. Applied to the Milky Way, this approach offers a potential way to test whether the Gaia-Sausage-Enceladus merger contributed to the formation of the Galactic warp. It may also provide an independent means to constrain the timing of such merger events by examining the phase offsets in the stellar warp as a function of stellar age.

Keywords: Galaxy dynamics, Galaxy mergers
TESS Discovers a Second System of Transiting Exocomets in the Extreme Debris Disk of RZ Psc. We present the Transiting Exoplanet Survey Satellite (TESS) discovery of only the second system of transiting exocomets with a sufficient number of events to measure the size distribution in the RZ Psc system, enabling comparisons with the β Pictoris and solar system size distributions. Twenty-four transits with absorption depths (ADs) of 1%─20% were observed across three TESS sectors of the 20─50 Myr K0V star, detected as part of our TESS survey of extreme debris disks identified by their IR excess. We discover that the ADs (and hence exocomet radii) follow a broken power-law cumulative frequency distribution not previously seen in extrasolar contexts but similar to that observed in solar system Kuiper Belt object sizes, with power-law slopes above and below the break of γAD&gt;break = 2.32 ± 0.12 and γAD&lt;break = 0.11 ± 0.04, respectively. We derive size distributions of 1─7 km from two independent lines of evidence. We use the RZ Psc exocomet rate to predict exocomet yields for the Early eVolution Explorer (EVE) NASA astrophysics Small Explorer mission concept to obtain simultaneous photometry of 104 young stars in near-ultraviolet, optical, and near-infrared bands. Assuming occurrence rates scaled from RZ Psc, EVE would detect 590 exocomets from ≍70 young systems in the optical band, with ≍120 simultaneous 5σ detections in all three bands. These data would enable grain sizes of 200─700 nm and graphite─olivine compositions of dozens of events to be distinguished at 2.5σ─3σ, as well as a 4σ determination of the accuracy of the Herschel-derived M debris disk fraction.

Keywords: Observational astronomy, Interstellar objects, Exocomets, Debris disks, Planet formation
On the Formation of GW231123 in Population III Star Clusters. GW231123 is a binary black hole (BBH) merger whose primary component lies within or above the pair-instability mass gap, while the secondary component falls within this gap. The standard theory of stellar evolution is significantly challenged by this event. We investigate the formation of candidate progenitors of GW231123 in Population III (Pop III) star clusters. We find that they could form through stellar mergers, BBH mergers, and mixed mergers. The mass distribution of these candidate progenitors covers the component masses of GW231123. Under our model assumptions, their predicted merger rate density spans the range of 0.001−0.26 Gpc−3 yr−1, encompassing that of GW231123. These findings suggest that GW231123 may originate from Pop III star clusters. Furthermore, such candidate progenitors are expected to be detectable by future gravitational-wave detectors LISA/Taiji/TianQin/DECIGO/Cosmic Explorer/Einstein Telescope, which would provide valuable insights into the formation scenarios of events like GW231123.

Keywords: Gravitational wave astronomy, Population III stars, N-body simulations, Astrophysical black holes