Sazuna/UAT_keywords huggingface dataset:
A Radial Limit on Polar Circumbinary Orbits from General Relativity. A particle orbiting a misaligned eccentric orbit binary undergoes nodal precession either around the binary angular momentum vector (a circulating orbit) or around a stationary inclination (a librating orbit). In the absence of general relativity (GR), the stationary inclination is inclined by 90° to the binary angular momentum vector (aligned with the binary eccentricity vector) and does not depend on the particle semimajor axis. GR causes apsidal precession of the binary orbit. Close to the binary, the behavior of the particle is not significantly affected, and a librating particle precesses with the binary. However, we find that the stationary inclination and the minimum inclination required for libration both increase with the particle semimajor axis. There is a critical radius beyond which there are no librating orbits, only circulating orbits, and therefore there is a maximum orbital radius for a stationary polar-orbiting body. The critical radius is within planet-forming regions around binaries with a semimajor axis ≲1 au. This has implications for the search for misaligned circumbinary planets and the radial extent of polar circumbinary disks.

Keywords: Celestial mechanics, Binary stars, Planet formation
Anisotropy of Magnetic Field Spectra at Kinetic Scales of Solar Wind Turbulence as Revealed by the Parker Solar Probe in the Inner Heliosphere. Using the Parker Solar Probe data taken in the inner heliosphere, we investigate the power and spatial anisotropy of magnetic field spectra at kinetic scales (i.e., around sub-ion scales) in solar wind turbulence in the inner heliosphere. We find that strong anisotropy of the magnetic spectra occurs at kinetic scales with the strongest power in the perpendicular direction with respect to the local magnetic field (forming an angle θ B with the mean flow velocity). The spectral index of the magnetic spectra varies from -3.2 to -5.8 when the angle θ B changes from 90° to 180° (or 0°), indicating that strong anisotropy of the spectral indices occurs at kinetic scales in the solar wind turbulence. Using a diagnosis based on the magnetic helicity, we show that the anisotropy of the spectral indices can be explained by the nature of the plasma modes that carry the cascade at kinetic scales. We discuss our findings in light of existing theories and current development in the field.

Keywords: Interplanetary turbulence, Space plasmas, Solar wind, Heliosphere
A BL Lacertae Object at a Cosmic Age of 800 Myr. We report the discovery of the BL Lacertae object FIRST J233153.20+112952.11 at redshift &gt;6 using near-infrared spectroscopy and broadband observations in the infrared, submillimeter, and radio wavelengths. The detection of the continuum break at ~0.92 μm in the near-infrared spectrum of FIRST J233153.20+112952.11 provides an approximate redshift of 6.57, corresponding to an age of the universe of ~800 Myr. The rest-frame UV/optical spectrum of FIRST J233153.20+112952.11 shows no emission lines detected with equivalent width &gt;1.5 Å. The nondetection of the C IV λ1549 broad emission line constrains the luminosity of the accretion disk to be ≲1045 erg s-1, which corresponds to the radiatively inefficient accretion regime of BL Lacertae objects. The spectral index of the rest-frame UV/optical continuum, α  ν,opt = 1.43 ± 0.23, is consistent with the expected spectral index of the synchrotron emission spectrum of the relativistic jet. The flat radio continuum (α  ν,r  ≍ 0) in a rest-frame frequency interval of 7-23 GHz is similar to that of the typical BL Lacertae objects and also consistent with originating from the synchrotron jet emission. The rest-frame UV/optical and radio fluxes of FIRST J233153.20+112952.11 show significant (15%-40%) variations. The shortest recorded rest-frame timescale of these variations is ~8 days. Assuming the local scaling relation between the radio luminosity and black hole mass, the 5 GHz radio luminosity of FIRST J233153.20+112952.11, 1.6 × 1033 erg s-1 Hz-1, suggests a billion solar mass central supermassive black hole.

Keywords: Observational astronomy, Supermassive black holes, BL Lacertae objects, Radio jets, Blazars, Active galaxies, Active galactic nuclei, Galaxy evolution, High-redshift galaxies, Galaxies
First Census of Gas-phase Metallicity Gradients of Star-forming Galaxies in Overdense Environments at Cosmic Noon. We report the first spatially resolved measurements of gas-phase metallicity radial gradients in star-forming galaxies in overdense environments at z ≳ 2. The spectroscopic data are acquired by the MAMMOTH-Grism survey, a Hubble Space Telescope (HST) cycle 28 medium program. This program is obtaining 45 orbits of WFC3/IR grism spectroscopy in the density peak regions of three massive galaxy protoclusters (BOSS 1244, BOSS 1542, and BOSS 1441) at z = 2-3. Our sample in the BOSS 1244 field consists of 20 galaxies with stellar mass ranging from 109.0 to 1010.3 M ⊙, star formation rate (SFR) from 10 to 240 M ⊙ yr-1, and global gas-phase metallicity ( $12+\mathrm{log}({\rm{O}}/{\rm{H}})$ ) from 8.2 to 8.6. At 1σ confidence level, 2/20 galaxies in our sample show positive (inverted) gradients-the relative abundance of oxygen increasing with galactocentric radius, opposite the usual trend. Furthermore, 1/20 shows negative gradients, and 17/20 are consistent with flat gradients. This high fraction of flat/inverted gradients is uncommon in simulations and previous observations conducted in blank fields at similar redshifts. To understand this, we investigate the correlations among various observed properties of our sample galaxies. We find an anticorrelation between metallicity gradient and global metallicity of our galaxies residing in extreme overdensities, and a marked deficiency of metallicity in our massive galaxies as compared to their coeval field counterparts. We conclude that the cold-mode gas accretion plays an active role in shaping the chemical evolution of galaxies in the protocluster environments, diluting their central chemical abundance, and flattening/inverting their metallicity gradients.

Keywords: Galaxy formation, Protoclusters, Chemical abundances, Galaxy evolution, High-redshift galaxies, Galaxies
The Archival Discovery of a Strong Lyα and [C II] Emitter at z = 7.677. We report the archival discovery of Lyα emission from the bright ultraviolet galaxy Y002 at z = 7.677, spectroscopically confirmed by its ionized carbon [C II] 158 μm emission line. The Lyα line is spatially associated with the rest-frame UV stellar emission (M UV ~ -22, 2× brighter than ${M}_{\mathrm{UV}}^{\star }$ ), and it appears offset from the peak of the extended [C II] emission at the current ~1″ spatial resolution. We derive an estimate of the unobscured SFRUV = (22 ± 1) M ☉ yr-1 and set an upper limit of SFRIR &lt; 15 M ☉ yr-1 from the far-infrared (FIR) wavelength range, which globally places Y002 on the SFR(UV+IR)-L [C II] correlation observed at lower redshifts. In terms of velocity, the peak of the Lyα emission is redshifted by ∆v Lyα  ~ 500 km s-1 from the systemic redshift set by [C II] and a high-velocity tail extends up to ~1000 km s-1. The velocity offset is up to ~3.5× higher than the average estimate for similarly UV-bright emitters at z ~ 6-7, which might suggest that we are witnessing the merging of two clumps. A combination of strong outflows and the possible presence of an extended ionized bubble surrounding Y002 would likely facilitate the escape of copious Lyα light, as indicated by the large equivalent width EW0(Lyα) $\,=\,{24}_{-6}^{+5}$ Å. Assuming that [C II] traces the neutral hydrogen, we estimate a H I gas fraction of M H I/M ⋆ ≳ 8 for Y002 as a system and speculate that patches of high H I column densities could contribute to explaining the observed spatial offsets between Lyα- and [C II]-emitting regions. The low dust content, implied by the nondetection of the FIR continuum emission at rest frame ~160 μm, would be sufficient to absorb any potential Lyα photons produced within the [C II] clump as a result of large H I column densities.

Keywords: Galaxy evolution, Interstellar medium, Lyman-alpha galaxies, Reionization, Lyman-break galaxies, High-redshift galaxies
Magnetic Switchback Occurrence Rates in the Inner Heliosphere: Parker Solar Probe and 1 au. The subject of switchbacks, defined either as large angular deflections or polarity reversals of the magnetic field, has generated substantial interest in the space physics community since the launch of the Parker Solar Probe (PSP) in 2018. Previous studies have characterized switchbacks in several different ways and have been restricted to data available from the first few orbits. Here, we analyze the frequency of occurrence of switchbacks per unit distance for the first full eight orbits of PSP. In this work, events that reverse the sign of the magnetic field relative to a regional average are considered switchbacks. A significant finding is that the rate of occurrence falls off sharply approaching the Sun near 0.2 au (40 R ⊙) and rises gently from 0.2 au outward. The analysis is varied for different magnetic field cadences and for different local averages of the ambient field, confirming the robustness of the results. We discuss implications for the mechanisms of switchback generation. A publicly available database has been created with the identified reversals.

Keywords: Interplanetary medium, Interplanetary magnetic fields, Interplanetary turbulence
Precursors of the RNA World in Space: Detection of (Z)-1,2-ethenediol in the Interstellar Medium, a Key Intermediate in Sugar Formation. We present the first detection of (Z)-1,2-ethenediol, (CHOH)2, the enol form of glycolaldehyde, in the interstellar medium toward the G+0.693-0.027 molecular cloud located in the Galactic Center. We have derived a column density of (1.8 ± 0.1) × 1013 cm-2, which translates into a molecular abundance with respect to molecular hydrogen of 1.3 × 10-10. The abundance ratio between glycolaldehyde and (Z)-1,2-ethenediol is ~5.2. We discuss several viable formation routes through chemical reactions from precursors such as HCO, H2CO, CHOH, or CH2CHOH. We also propose that this species might be an important precursor in the formation of glyceraldehyde (HOCH2CHOHCHO) in the interstellar medium through combination with the hydroxymethylene (CHOH) radical.

Keywords: Interstellar molecules, Galactic center, Molecular clouds, Astrochemistry, Interstellar medium, Pre-biotic astrochemistry
Hubble Space Telescope Detection of the Nucleus of Comet C/2014 UN<SUB>271</SUB> (Bernardinelli-Bernstein). We present a high-resolution observation of the distant comet C/2014 UN271 (Bernardinelli-Bernstein) using the Hubble Space Telescope on 2022 January 8. The signal of the nucleus was successfully isolated by means of a nucleus extraction technique, with an apparent V-band magnitude measured to be 21.65 ± 0.11, corresponding to an absolute magnitude of 8.63 ± 0.11. The product of the visual geometric albedo with the effective radius squared is ${p}_{V}{R}_{{\rm{n}}}^{2}=157\pm 16$ km2. If the ALMA observation by Lellouch et al. refers to a bare nucleus, we derived a visual geometric albedo of 0.033 ± 0.009. If dust contamination of the ALMA signal is present at the maximum allowed level (24%), we found an albedo of 0.044 ± 0.012 for the nucleus having an effective diameter of 119 ± 15 km. In either case, we confirm that C/2014 UN271 is the largest long-period comet ever detected. Judging from the measured surface brightness profile of the coma, whose logarithmic gradient varies azimuthally between ~1.0 and 1.7 as a consequence of solar radiation pressure, the mass production is consistent with steady-state production but not with impulsive ejection, as would be produced by an outburst. Using aperture photometry, we estimated an enormous (albeit uncertain) mass-loss rate of ~103 kg s-1 at a heliocentric distance of ~20 au.

Keywords: Comet nuclei, Comets, Long period comets
Resolving Massive Black Hole Binary Evolution via Adaptive Particle Splitting. The study of the interaction of a massive black hole binary with its gaseous environment is crucial in order to be able to predict merger rates and possible electromagnetic counterparts of gravitational-wave signals. The evolution of the binary semimajor axis resulting from this interaction has been recently debated, and a clear consensus is still missing because of several numerical limitations, i.e., fixed orbit binaries or lack of resolution inside the cavity carved by the binary in its circumbinary disk. Using on-the-fly particle splitting in the 3D meshless code GIZMO, we achieve hyper-Lagrangian resolution, which allows us to properly resolve the dynamics inside the cavity-in particular, for the first time, the disks that form around the two components of a live binary surrounded by a locally isothermal gaseous circumbinary disk. We show that the binary orbit decays with time for very cold and very warm disks and that the result of the interaction in the intermediate regime is strongly influenced by the disk viscosity, as this essentially regulates the fraction of mass contained in the disks around the binary components, as well as the fraction that is accreted by the binary. We find the balance between these two quantities to determine whether the binary semimajor axis decreases with time.

Keywords: Accretion, Hydrodynamical simulations, Binary stars, Black holes, Stellar accretion disks
Discovery of Nine Super Li-rich Unevolved Stars from the LAMOST Survey. Based on the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) medium-resolution spectroscopic survey (MRS), we report the discovery of nine super Li-rich unevolved stars with A(Li) &gt; 3.8 dex. These objects show unusually high levels of lithium abundances, up to three times higher than the meteoritic value of 3.3 dex, which indicates that they must have experienced a history of lithium enrichment. It is found that seven of our program stars are fast rotators with v sin i &gt; 9 km s-1, which suggests that the accretion of circumstellar matter may be the main contributor to the lithium enhancement of these unevolved stars; however, other sources cannot be excluded.

Keywords: Lithium stars, Circumstellar matter, Stellar rotation, Chemically peculiar stars
The Candidate Progenitor Companion Star of the Type Ib/c SN 2013ge. This Letter presents the detection of a source at the position of the Type Ib/c supernova (SN) 2013ge more than four years after the radioactive component is expected to have faded. This source could mark the first post-SN direct detection of a surviving companion to a stripped-envelope Type Ib/c explosion. We test this hypothesis and find the shape of the source's spectral energy distribution is most consistent with that of a B5 I supergiant. While binary models tend to predict OB-type stars for stripped-envelope companions, the location of the source on a color-magnitude diagram places it redward of its more likely position on the main sequence (MS). The source may be temporarily out of thermal equilibrium, or a cool and inflated non-MS companion, which is similar to the suggested companion of Type Ib SN 2019yvr that was constrained from pre-SN imaging. We also consider other possible physical scenarios for the source, including a fading SN, circumstellar shock interaction, line-of-sight coincidence, and an unresolved host star cluster, all of which will require future observations to more definitively rule out. Ultimately, the fraction of surviving companions ("binary fraction") will provide necessary constraints on binary evolution models and the underlying physics.

Keywords: Type Ic supernovae, Core-collapse supernovae, Close binary stars, Type Ib supernovae, Massive stars
New Constraint on Early Dark Energy from Planck and BOSS Data Using the Profile Likelihood. A dark energy-like component in the early universe, known as early dark energy (EDE), is a proposed solution to the Hubble tension. Currently, there is no consensus in the literature as to whether EDE can simultaneously solve the Hubble tension and provide an adequate fit to the data from the cosmic microwave background (CMB) and large-scale structure of the universe. In this work, we deconstruct the current constraints from the Planck CMB and the full-shape clustering data of the Baryon Oscillation Spectroscopic Survey to understand the origin of different conclusions in the literature. We use two different analyses, a grid sampling and a profile likelihood, to investigate whether the current constraints suffer from volume effects upon marginalization and are biased toward some values of the EDE fraction, f EDE. We find that the f EDE allowed by the data strongly depends on the particular choice of the other parameters of the model, and that several choices of these parameters prefer larger values of f EDE than in the Markov Chain Monte Carlo analysis. This suggests that volume effects are the reason behind the disagreement in the literature. Motivated by this, we use a profile likelihood to analyze the EDE model and compute a confidence interval for f EDE, finding f EDE = 0.072 ± 0.036 (68% C.L.). Our approach gives a confidence interval that is not subject to volume effects and provides a powerful tool to understand whether EDE is a possible solution to the Hubble tension.

Keywords: Hubble constant, Dark energy, Cosmology, Cosmological parameters
Limiting the Abundance of LIGO/Virgo Black Holes with Microlensing Observations of Quasars of Finite Size. We present a simple but general argument that strongly limits the abundance of primordial black holes (PBHs) (or other unknown population of compact objects) with masses similar to those determined by LIGO/Virgo from BH binary mergers. We show that quasar microlensing can be very sensitive to the mass of the lenses, and that it is able to distinguish between stars and BHs of high mass, when the finite size of the source is taken into account. A significant presence of massive BHs would produce frequent high-flux magnifications (except for unrealistically large sources), which have been very rarely observed. On the contrary, a typical stellar population would induce flux magnifications consistent with the observations. This result excludes PBHs (or any type of compact object) in the mass range determined by LIGO/Virgo as the main dark matter constituents in the lens galaxies.

Keywords: Cosmology, Astrophysical black holes, Gravitational lensing, Quasar microlensing, Dark matter, Primordial black holes
Slow Star Formation in the Milky Way: Theory Meets Observations. The observed star formation rate of the Milky Way can be explained by applying a metallicity-dependent factor to convert CO luminosity to molecular gas mass and a star formation efficiency per freefall time that depends on the virial parameter of a molecular cloud. These procedures also predict the trend of star formation rate surface density with Galactocentric radius. The efficiency per freefall time variation with virial parameter plays a major role in bringing theory into agreement with observations for the total star formation rate, while the metallicity dependence of the CO luminosity-to-mass conversion is most notable in the variation with Galactocentric radius. Application of these changes resolves a factor of over 100 discrepancy between observed and theoretical star formation rates that has been known for nearly 50 yr.

Keywords: Star formation, Molecular clouds
Constraints on r-modes and Mountains on Millisecond Neutron Stars in Binary Systems. Continuous gravitational waves are nearly monochromatic signals emitted by asymmetries in rotating neutron stars. These signals have not yet been detected. Deep all-sky searches for continuous gravitational waves from isolated neutron stars require significant computational expense. Deep searches for neutron stars in binary systems are even more expensive, but these targets are potentially more promising emitters, especially in the hundreds of Hertz region, where ground-based gravitational-wave detectors are most sensitive. We present here an all-sky search for continuous signals with frequency between 300 and 500 Hz, from neutron stars in binary systems with orbital periods between 15 and 60 days and projected semimajor axes between 10 and 40 lt-s. This is the only binary search on Advanced LIGO data that probes this frequency range. Compared to previous results, our search is over an order of magnitude more sensitive. We do not detect any signals, but our results exclude plausible and unexplored neutron star configurations, for example, neutron stars with relative deformations greater than 3 × 10-6 within 1 kpc from Earth and r-mode emission at the level of α ~ a few 10-4 within the same distance.

Keywords: Neutron stars, Gravitational waves
Using the Hills Mechanism to Generate Repeating Partial Tidal Disruption Events and ASASSN-14ko. Periodic nuclear transients have been detected with increasing frequency, with one such system-ASASSN-14ko-exhibiting highly regular outbursts on a timescale of 114 ± 1 days. It has been postulated that the outbursts from this source are generated by the repeated partial disruption of a star, but how the star was placed onto such a tightly bound orbit about the supermassive black hole remains unclear. Here we use analytic arguments and three-body integrations to demonstrate that the Hills mechanism, where a binary system is destroyed by the tides of the black hole, can lead to the capture of a star on a ~114 days orbit and with a pericenter distance that is comparable to the tidal radius of one of the stars within the binary. Thus, Hills capture can produce stars on tightly bound orbits that undergo repeated partial disruption, leading to a viable mechanism for generating not only the outbursts detected from ASASSN-14ko but periodic nuclear transients in general. We also show that the rate of change of the period of the captured star due to gravitational-wave emission is likely too small to produce the observed value for ASASSN-14ko, indicating that in this system there must be additional effects that contribute to the decay of the orbit. In general, however, gravitational-wave emission can be important for limiting the lifetimes of these systems and could produce observable period decay rates in future events.

Keywords: Black hole physics, Supermassive black holes, Binary stars, Tidal disruption, Astrophysical black holes
Deep Very Large Telescope Photometry of the Faint Stellar System in the Large Magellanic Cloud Periphery YMCA-1. We present FORS2@VLT follow-up photometry of YMCA-1, a recently discovered stellar system located 13° from the Large Magellanic Cloud (LMC) center. The deep color-magnitude diagram (CMD) reveals a well-defined main sequence (MS) and a handful of stars in the post-MS evolutionary phases. We analyze the YMCA-1 CMD by means of the automated isochrone-matching package ASteCA and model its radial density profile with a Plummer function. We find that YMCA-1 is an old ( ${11.7}_{-1.3}^{+1.7}$ Gyr), metal-intermediate ([Fe/H] $\simeq -{1.12}_{-0.13}^{+0.21}$ dex), compact (r h = 3.5 ± 0.5 pc), low-mass (M = 102.45±0.02 M ☉), and low-luminosity (M  V  = -0.47 ± 0.57 mag) stellar system. The estimated distance modulus ( ${\mu }_{0}={18.72}_{-0.17}^{+0.15}$ mag), corresponding to about 55 kpc, suggests that YMCA-1 is associated with the LMC, but we cannot discard the scenario in which it is a Milky Way satellite. The structural parameters of YMCA-1 are remarkably different compared with those of the 15 known old LMC globular clusters. In particular, it resides in a transition region of the M  V -r  h  plane, in between the ultrafaint dwarf galaxies and the classical old clusters, and close to SMASH-1, another faint stellar system recently discovered in the LMC surroundings.

Keywords: Broad band photometry, Galaxy interactions, Large Magellanic Cloud, Milky Way stellar halo, Hertzsprung Russell diagram, Star clusters