Sazuna/UAT_keywords huggingface dataset:
Swift J1727.8–1613 Has the Largest Resolved Continuous Jet Ever Seen in an X-Ray Binary. Multiwavelength polarimetry and radio observations of Swift J1727.8–1613 at the beginning of its recent 2023 outburst suggested the presence of a bright compact jet aligned in the north–south direction, which could not be confirmed without high-angular-resolution images. Using the Very Long Baseline Array and the Long Baseline Array, we imaged Swift J1727.8–1613 during the hard/hard-intermediate state, revealing a bright core and a large, two-sided, asymmetrical, resolved jet. The jet extends in the north–south direction, at a position angle of ‑0.60° ± 0.07° east of north. At 8.4 GHz, the entire resolved jet structure is  ∼110(d/2.7kpc)/sini  au long, with the southern approaching jet extending  ∼80(d/2.7kpc)/sini  au from the core, where d is the distance to the source and i is the inclination of the jet axis to the line of sight. These images reveal the most resolved continuous X-ray binary jet, and possibly the most physically extended continuous X-ray binary jet ever observed. Based on the brightness ratio of the approaching and receding jets, we put a lower limit on the intrinsic jet speed of β ≥ 0.27 and an upper limit on the jet inclination of i ≤ 74°. In our first observation we also detected a rapidly fading discrete jet knot 66.89 ± 0.04 mas south of the core, with a proper motion of 0.66 ± 0.05 mas hr‑1, which we interpret as the result of a downstream internal shock or a jet–interstellar medium interaction, as opposed to a transient relativistic jet launched at the beginning of the outburst.

Keywords: Radio jets, Very long baseline interferometry, Relativistic jets, Stellar mass black holes, Transient sources, Low-mass x-ray binary stars
Spectral Variance in a Stochastic Gravitational-wave Background from a Binary Population. A population of compact object binaries emitting gravitational waves that are not individually resolvable will form a stochastic gravitational-wave signal. While the expected spectrum over population realizations is well known from Phinney, its higher-order moments have not been fully studied before or computed in the case of arbitrary binary evolution. We calculate analytic scaling relationships as a function of gravitational-wave frequency for the statistical variance, skewness, and kurtosis of a stochastic gravitational-wave signal over population realizations due to finite source effects. If the time derivative of the binary orbital frequency can be expressed as a power law in frequency, we find that these moment quantities also take the form of power-law relationships. We also develop a numerical population synthesis framework against which we compare our analytic results, finding excellent agreement. These new scaling relationships provide physical context to understanding spectral fluctuations in a gravitational-wave background signal and may provide additional information that can aid in explaining the origin of the nanohertz-frequency signal observed by pulsar timing array campaigns.

Keywords: Neutron stars, Supermassive black holes, Astronomical simulations, Gravitational wave sources, Astrostatistics, Gravitational wave astronomy, General relativity, Gravitational waves, Compact objects, LIGO, Astrophysical black holes
Climatic Effects of Ocean Salinity on M Dwarf Exoplanets. Ocean salinity is known to dramatically affect the climates of Earth-like planets orbiting Sun-like stars, with high salinity leading to less ice and higher surface temperature. However, how ocean composition impacts climate under different conditions, such as around different types of stars or at different positions within the habitable zone, has not been investigated. We used ROCKE-3D, an ocean-atmosphere general circulation model, to simulate how planetary climate responds to ocean salinities for planets with G-star versus M dwarf hosts at several stellar fluxes. We find that increasing ocean salinity from 20 to 100 g kg‑1 in our model results in nonlinear ice reduction and warming on G-star planets, sometimes causing abrupt transitions to different climate states. Conversely, sea ice on M dwarf planets responds more gradually and linearly to increasing salinity. Moreover, reductions in sea ice on M dwarf planets are not accompanied by significant surface warming as on G-star planets. High salinity can modestly bolster the resilience of M dwarf planets against snowball glaciation and allow these planets to retain surface liquid water further from their host star, but the effects are muted compared to G-star planets that experience snowball bifurcation and climate hysteresis due to the ice-albedo feedback.

Keywords: Astrobiology, Habitable planets, Planetary climates
TOI-1685 b Is a Hot Rocky Super-Earth: Updates to the Stellar and Planet Parameters of a Popular JWST Cycle 2 Target. We present an updated characterization of the TOI-1685 planetary system, which consists of a P b = 0.69 day ultra-short-period super-Earth planet orbiting a nearby (d = 37.6 pc) M2.5V star (TIC 28900646, 2MASS J04342248+4302148). This planet was previously featured in two contemporaneous discovery papers, but the best-fit planet mass, radius, and bulk density values were discrepant, allowing it to be interpreted either as a hot, bare rock or a 50% H2O/50% MgSiO3 water world. TOI-1685 b will be observed in three independent JWST Cycle 2 programs, two of which assume the planet is a water world, while the third assumes that it is a hot rocky planet. Here we include a refined stellar classification with a focus on addressing the host star's metallicity, an updated planet radius measurement that includes two sectors of TESS data and multicolor photometry from a variety of ground-based facilities, and a more accurate dynamical mass measurement from a combined CARMENES, InfraRed Doppler, and MAROON-X radial velocity data set. We find that the star is very metal-rich ([Fe/H] ≃ +0.3) and that the planet is systematically smaller, lower mass, and higher density than initially reported, with new best-fit parameters of R  pl  = 1.468  −0.051+0.050  R ⊕ and M  pl  =  3.03−0.32+0.33  M ⊕. These results fall in between the previously derived values and suggest that TOI-1685 b is a hot rocky planet with an Earth-like density (ρ  pl  = 5.3 ± 0.8 g cm−3, or 0.96 ρ ⊕), high equilibrium temperature (T eq = 1062 ± 27 K), and negligible volatiles, rather than a water world.

Keywords: Radial velocity, Transit photometry, Super Earths, Exoplanets
VLBA Astrometry of the Fastest-spinning Magnetar Swift J1818.0‑1607: A Large Trigonometric Distance and a Small Transverse Velocity. In addition to being the most magnetic objects in the known Universe, magnetars are the only objects observed to generate fast-radio-burst-like emissions. The formation mechanism of magnetars is still highly debated and may potentially be probed with the magnetar velocity distribution. We carried out a 3 yr long astrometric campaign on Swift J1818.0‑1607, the fastest-spinning magnetar, using the Very Long Baseline Array. After applying the phase-calibrating 1D interpolation strategy, we obtained a small proper motion of 8.5 mas yr‑1 mag and a parallax of 0.12 ± 0.02 mas (uncertainties at 1σ confidence throughout the Letter) for Swift J1818.0‑1607. The latter is the second magnetar parallax and is among the smallest neutron star parallaxes ever determined. From the parallax, we derived the distance  9.4‑1.6+2.0  kpc, which locates Swift J1818.0‑1607 at the far side of the Galactic central region. Combined with the distance, the small proper motion leads to a transverse peculiar velocity  v⊥=48‑16+50  km s‑1—a new lower limit to magnetar v ⊥. Incorporating previous v ⊥ estimates of seven other magnetars, we acquired  v⊥=149‑68+132  km s‑1 for the sample of astrometrically studied magnetars, corresponding to the three-dimensional space velocity  ∼190‑87+168  km s‑1, smaller than the average level of young pulsars. Additionally, we found that the magnetar velocity sample does not follow the unimodal young pulsar velocity distribution reported by Hobbs et al. at &gt;2σ confidence, while loosely agreeing with more recent bimodal young pulsar velocity distributions derived from relatively small samples of quality astrometric determinations.

Keywords: Very long baseline interferometry, Magnetars, Proper motions, Annual parallax, Radio pulsars
Revisiting the Fundamental Metallicity Relation with Observation and Simulation. The gas-phase metallicity of galaxies is regulated by multiple astrophysical processes, which makes it a crucial diagnostic of galaxy formation and evolution. Beyond the fundamental mass–metallicity relation, a debate about the secondary galaxy property to predict the metallicity of galaxies arises. Motivated by this, we systematically examine the relationship between gas-phase metallicity and other galaxy properties, i.e., the star formation rate (SFR) and galaxy size, in addition to stellar mass in both observation and simulation. We utilize the data from the Mapping Nearby Galaxies at Apache Point Observatory survey and the TNG50 simulations. We find that the combination of  M*/Reβ  with β ∼ 0.6–1 is in much stronger correlation to the metallicity than stellar mass alone, regardless of whether the SFR is included or not, in both observation and simulation. This indicates that galaxy size plays a more important role in determining gas-phase metallicity of galaxies than SFR. In addition, The Next Generation simulation predicts that the SFR, although being a subdominant role, becomes increasingly important in the high-z universe. Finally, we speculate that the SFR modulates metallicity on the temporal dimension, synchronized with time-varying gas inflows, and galaxy size regulates metallicity on the spatial dimension by affecting the gravitational potential and the mass-loading factor.

Keywords: Metallicity, Galaxy evolution, Galaxy chemical evolution
Outflow Driven by a Protoplanet Embedded in the TW Hya Disk. Gas giant planets are formed by gas accretion onto planetary cores in protoplanetary disks. However, direct evidence of this process is still lacking, limiting our understanding of planetary formation processes. During mass accretion, planet-driven outflows may be launched, which could be observable by shock tracers such as sulfur monoxide (SO). We report the detection of SO gas in the protoplanetary disk around TW Hya in archival Atacama Large Millimeter/submillimeter Array observations. The SO J = 87 ‑ 76 emission line is detected at a 6σ significance and localized to the southeast region of the disk with an arc-like morphology. The line center is redshifted with respect to the systemic velocity by ∼5 km s‑1. The starting point of the SO emission is located at a planet-carved dust gap at 42 au. We attribute this to an outflow driven by an embedded protoplanet. Indeed, the observed morphology is well reproduced by a ballistic outflow model. The outflow velocity suggests that the outflow launching source has a mass of ∼4M ⊕ and the mass-loss rate is 3 × 10‑8–1 × 10‑6 M Jup yr‑1. With the relation of mass-loss and mass-accretion rates established for protostars, we estimated the mass-accretion rate onto the protoplanet to be 3 × 10‑7‑1 × 10‑5 M Jup yr‑1, which matches theoretical predictions for a ∼4M ⊕ planet at this separation. The detection of planet-driven outflow provides us a unique opportunity to directly probe the earliest phase of gas giant planet formation.

Keywords: Protoplanetary disks, Planet formation, Astrochemistry
Glimmers in the Cosmic Dawn: A Census of the Youngest Supermassive Black Holes by Photometric Variability. We report the first results from a deep near-infrared campaign with the Hubble Space Telescope to obtain late-epoch images of the Hubble Ultra Deep Field, 10–15 yr after the first epoch data were obtained. The main objectives are to search for faint active galactic nuclei (AGN) at high redshifts by virtue of their photometric variability and measure (or constrain) the comoving number density of supermassive black holes (SMBHs), n SMBH, at early times. In this Letter, we present an overview of the program and preliminary results concerning eight objects. Three variables are supernovae, two of which are apparently hostless with indeterminable redshifts, although one has previously been recorded as a z ≈ 6 object precisely because of its transient nature. Two further objects are clear AGN at z = 2.0 and 3.2, based on morphology and/or infrared spectroscopy from JWST. Three variable targets are identified at z = 6–7 that are also likely AGN candidates. These sources provide a first measure of n SMBH in the reionization epoch by photometric variability, which places a firm lower limit of 3 × 10‑4 cMpc‑3. After accounting for variability and luminosity incompleteness, we estimate n SMBH ≳ 8 × 10‑3 cMpc‑3, which is the largest value so far reported at these redshifts. This SMBH abundance is also strikingly similar to estimates of n SMBH in the local Universe. We discuss how these results test various theories for SMBH formation. * This research is based on observations made with the NASA/ESA Hubble Space Telescope obtained from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 526555. These observations are associated with programs 11563, 12498, and 17073.

Keywords: Active galactic nuclei, High-redshift galaxies
The Neutron Star Mass, Distance, and Inclination from Precision Timing of the Brilliant Millisecond Pulsar J0437-4715. The observation of neutron stars enables the otherwise impossible study of fundamental physical processes. The timing of binary radio pulsars is particularly powerful, as it enables precise characterization of their (three-dimensional) positions and orbits. PSR J0437–4715 is an important millisecond pulsar for timing array experiments and is also a primary target for the Neutron Star Interior Composition Explorer (NICER). The main aim of the NICER mission is to constrain the neutron star equation of state by inferring the compactness (M  p /R) of the star. Direct measurements of the mass M  p  from pulsar timing therefore substantially improve constraints on the radius R and the equation of state. Here we use observations spanning 26 yr from Murriyang, the 64 m Parkes radio telescope, to improve the timing model for this pulsar. Among the new precise measurements are the pulsar mass M  p  = 1.418 ± 0.044 M ⊙, distance D = 156.96 ± 0.11 pc, and orbital inclination angle i = 137.°506 ± 0.°016, which can be used to inform the X-ray pulse profile models inferred from NICER observations. We demonstrate that these results are consistent between multiple data sets from the Parkes Pulsar Timing Array (PPTA), each modeled with different noise assumptions. Using the longest available PPTA data set, we measure an apparent second derivative of the pulsar spin frequency and discuss how this can be explained either by kinematic effects due to the proper motion and radial velocity of the pulsar or excess low-frequency noise such as a gravitational-wave background.

Keywords: Neutron stars, Neutron star cores, Pulsar timing method, Millisecond pulsars, Pulsars, Binary pulsars, Radio pulsars
Constraining the Dense Matter Equation of State with New NICER Mass–Radius Measurements and New Chiral Effective Field Theory Inputs. Pulse profile modeling of X-ray data from the Neutron Star Interior Composition Explorer is now enabling precision inference of neutron star mass and radius. Combined with nuclear physics constraints from chiral effective field theory (χEFT), and masses and tidal deformabilities inferred from gravitational-wave detections of binary neutron star mergers, this has led to a steady improvement in our understanding of the dense matter equation of state (EOS). Here, we consider the impact of several new results: the radius measurement for the 1.42 M ⊙ pulsar PSR J0437‑4715 presented by Choudhury et al., updates to the masses and radii of PSR J0740+6620 and PSR J0030+0451, and new χEFT results for neutron star matter up to 1.5 times nuclear saturation density. Using two different high-density EOS extensions—a piecewise-polytropic (PP) model and a model based on the speed of sound in a neutron star (CS)—we find the radius of a 1.4 M ⊙ (2.0 M ⊙) neutron star to be constrained to the 95% credible ranges  12.28‑0.76+0.50  km ( 12.33‑1.34+0.70  km) for the PP model and  12.01‑0.75+0.56  km ( 11.55‑1.09+0.94  km) for the CS model. The maximum neutron star mass is predicted to be  2.15‑0.16+0.14  M ⊙ and  2.08‑0.16+0.28  M ⊙ for the PP and CS models, respectively. We explore the sensitivity of our results to different orders and different densities up to which χEFT is used, and show how the astrophysical observations provide constraints for the pressure at intermediate densities. Moreover, we investigate the difference R 2.0 ‑ R 1.4 of the radius of 2 M ⊙ and 1.4 M ⊙ neutron stars within our EOS inference.

Keywords: Neutron stars, Neutron star cores, Gravitational wave sources, Nuclear astrophysics, X-ray sources
A NICER View of the Nearest and Brightest Millisecond Pulsar: PSR J0437─4715. We report Bayesian inference of the mass, radius, and hot X-ray emitting region properties—using data from the Neutron Star Interior Composition ExploreR (NICER)—for the brightest rotation-powered millisecond X-ray pulsar, PSR J0437−4715. Our modeling is conditional on informative tight priors on mass, distance, and binary inclination obtained from radio pulsar timing using the Parkes Pulsar Timing Array (PPTA; Reardon et al.), and we use NICER background models to constrain the nonsource background, cross-checking with data from XMM-Newton. We assume two distinct hot emitting regions and various parameterized hot region geometries that are defined in terms of overlapping circles; while simplified, these capture many of the possibilities suggested by detailed modeling of return current heating. For the preferred model identified by our analysis, we infer a mass of M = 1.418 ± 0.037 M ⊙ (largely informed by the PPTA mass prior) and an equatorial radius of  R=11.36−0.63+0.95  km, each reported as the posterior credible interval bounded by the 16% and 84% quantiles. This radius favors softer dense matter equations of state and is highly consistent with constraints derived from gravitational wave measurements of neutron star binary mergers. The hot regions are inferred to be nonantipodal and hence inconsistent with a pure centered dipole magnetic field.

Keywords: Neutron stars, Neutron star cores, Rotation powered pulsars, Millisecond pulsars, Pulsars, Nuclear astrophysics, Magnetic fields
First Detection of X-Ray Polarization in Galactic Ultraluminous X-Ray Pulsar Swift J0243.6+6124 with IXPE. We report the results of first ever spectropolarimetric analyses of the Galactic ultraluminous X-ray pulsar Swift J0243.6+6124 during the 2023 outburst using quasi-simultaneous IXPE, NICER, and NuSTAR observations. A pulsation of period ∼9.79 s is detected in IXPE and NuSTAR observations with pulse fractions (PFs) ∼18% (2–8 keV) and ∼28% (3–78 keV), respectively. Energy-dependent study of the pulse profiles with NuSTAR indicates an increase in PF from ∼27% (3–10 keV) to ∼50% (40–78 keV). Further, epoch-dependent polarimetric measurements during the decay phase of the outburst confirm the detection of significant polarization, with the polarization degree (PD) and polarization angle ranging between ∼2%–3.1% and ∼8.°6–10.°8, respectively, in the 2–8 keV energy range. We also observe that the PD increases up to ∼4.8% at higher energies (≳5 keV) with dominating bbodyrad flux contribution (1.5 ≲ F BB/F PL ≲ 3.4) in the IXPE spectra. The phase-resolved polarimetric study yields PD as ∼1.7%–3.1% suggesting a marginal correlation with the pulse profiles. Moreover, the broadband (0.6–70 keV) energy spectrum of combined NICER and NuSTAR observations is well described by the combination of bbodyrad and cutoffpl components with seed photon temperature (kT bb) ∼0.86 ± 0.03 keV and photon index (Γ) ∼0.98 ± 0.01. With the above findings, we infer that the observed "low" PD in Swift J0243.6+6124 is attributed possibly due to the "vacuum resonance" effect between the overheated and relatively cooler regions of the neutron star boundary layer.

Keywords: Neutron stars, Accretion, X-ray binary stars, Magnetic fields
The Negative Baryon Acoustic Oscillation Shift in the Lyα Forest from Cosmological Simulations. We present the first measurement of the Lyα forest baryon acoustic oscillations (BAO) shift parameter from cosmological simulations. In particular, we generate a suite of 1000 accurate effective field-level bias-based Lyα forest simulations of volume  V=(1h‑1Gpc)3  at z = 2, both in real and redshift space, calibrated upon two fixed-and-paired cosmological hydrodynamic simulations. To measure the BAO, we stack the 3D power spectra of the 1000 different realizations, compute the average, and use a model accounting for a proper smooth-peak component decomposition of the power spectrum, to fit it via an efficient Markov Chain Monte Carlo scheme estimating the covariance matrices directly from the simulations. We report the BAO shift parameters to be  α=0.9969‑0.0014+0.0014  and  α=0.9905‑0.0027+0.0027  in real and redshift space, respectively. We also measure the bias b lya and the BAO broadening parameter Σnl, finding  blya=‑0.1786‑0.0001+0.0001  and  Σnl=3.87‑0.20+0.20  in real space, and  blya=‑0.073‑0.004+0.005  and  Σnl=6.55‑0.22+0.23  in redshift space. Moreover, we measure the linear Kaiser factor  βlya=1.39‑0.18+0.24  from the isotropic redshift space fit. Overall, we find evidence for a negative shift of the BAO peak at the ∼2.2σ and ∼3.5σ levels in real and redshift space, respectively. This work sets new important theoretical constraints on the Lyα forest BAO scale and offers a potential solution to the tension emerging from previous observational analysis, in light of ongoing and upcoming Lyα forest spectroscopic surveys, such as DESI, the Prime Focus Spectrograph Survey, and WEAVE-QSO.

Keywords: Cosmology, Hydrodynamical simulations, Cosmological perturbation theory, Large-scale structure of the universe, Astrostatistics, Dark energy
Polarization Substructure in the Spiral-dominated HH 111 Disk: Evidence for Grain Growth. The HH 111 protostellar disk has recently been found to host a pair of spiral arms. Here we report the dust polarization results in the disk as well as the inner envelope around it, obtained with the Atacama Large Millimeter/submillimeter Array in continuum at λ ∼ 870 μm and ∼0.″05 resolution. In the inner envelope, polarization is detected with a polarization degree of ∼6% and an orientation almost everywhere parallel to the minor axis of the disk and thus likely to be due to the dust grains magnetically aligned mainly by toroidal fields. In the disk, the polarization orientation is roughly azimuthal on the far side and becomes parallel to the minor axis on the near side, with a polarization gap in between on the far side near the central protostar. The disk polarization degree is ∼2%. The polarized intensity is higher on the near side than the far side, showing a near–far side asymmetry. More importantly, the polarized intensity and thus polarization degree are lower in the spiral arms but higher in between the arms, showing an anticorrelation of the polarized intensity with the spiral arms. Our modeling results indicate that this anticorrelation is useful for constraining the polarization mechanism and is consistent with the dust self-scattering by the grains that have grown to a size of ∼150 μm. The interarms are sandwiched and illuminated by two brighter spiral arms and thus have higher polarized intensity. Our dust self-scattering model can also reproduce the observed polarization orientation parallel to the minor axis on the near side and the observed azimuthal polarization orientation at the two disk edges in the major axis. Further modeling work is needed to study how to reproduce the observed near–far side asymmetry in the polarized intensity and the observed azimuthal polarization orientation on the far side.

Keywords: Stellar accretion disks, Magnetic fields, Star formation, Polarimetry