Sazuna/UAT_keywords huggingface dataset:
Self-similar Buildup and Inside-out Growth: Tracing the Evolution of Intermediate-to-high-mass Star-forming Galaxies since z = 2. We aim to discern scenarios of structural evolution of intermediate-to-high-mass star-forming galaxies (SFGs) since cosmic noon by comparing their stellar mass profiles with present-day stellar masses of  log(M*,0/M⊙)=10.3‑11 . We addressed discrepancies in the size evolution rates of SFGs, which may be caused by variations in sample selection and methods for size measurements. To check these factors, we traced the evolution of individual galaxies by identifying their progenitors using stellar mass growth histories (SMGHs), integrating along the star-forming main sequence and from the IllustrisTNG simulations. Comparison between the structural parameters estimated from the mass- and light-based profiles shows that mass-weighted size evolves at a slower pace compared to light-based ones, highlighting the need to consider the mass-to-light ratio (M/L) gradients. Additionally, we observed mass-dependent growth in stellar mass profiles: massive galaxies ( log(M*,0/M⊙)≳10.8 ) formed central regions at z ≳ 1.5 and grew faster in outer regions, suggesting inside-out growth, while intermediate-mass and less massive SFGs followed a relatively self-similar mass buildup since z ∼ 2. Moreover, slopes of observed size evolution conflict with the predictions of TNG50 for samples selected using the same SMGHs across our redshift range. To explore the origin of this deviation, we examined changes in angular momentum (AM) retention fraction using the half-mass size evolution and employing a simple disk formation model. Assuming similar dark matter halo parameters, our calculations indicate that the AM inferred from observations halved in the past 10 Gyr while it remained relatively constant in TNG50. This higher AM in simulations may be due to the accretion of high-AM gases into disks.

Keywords: Late-type galaxies, Magnetohydrodynamical simulations, Galaxy structure, Galaxy disks, Galaxy evolution, Galaxies, Galaxy radii
No Evidence for a Dip in the Binary Black Hole Mass Spectrum. Stellar models indicate that the core compactness of a star, which is a common proxy for its explodability in a supernova, does not increase monotonically with the star's mass. Rather, the core compactness dips sharply over a range of carbon–oxygen core masses; this range may be somewhat sensitive to the star's metallicity and evolutionary history. Stars in this compactness dip are expected to experience supernovae leaving behind neutron stars, whereas stars on either side of this range are expected to form black holes. This results in a hypothetical mass range in which black holes should seldom form. Quantitatively, when applied to binary stripped stars, these models predict a dearth of binary black holes with component masses ≈10M ⊙–15M ⊙. The population of gravitational-wave signals indicates potential evidence for a dip in the distribution of chirp masses of merging binary black holes near ≈10M ⊙–12M ⊙. This feature could be linked to the hypothetical component mass gap described above, but this interpretation depends on what assumptions are made of the binaries' mass ratios. Here, we directly probe the distribution of binary black hole component masses to look for evidence of a gap. We find no evidence for this feature using data from the third gravitational-wave transient catalog. If this gap does exist in nature, we find that it is unlikely to be resolvable by the end of the current (fourth) LIGO–Virgo–KAGRA observing run.

Keywords: Gravitational wave astronomy, Gravitational waves, Black holes, Compact objects
Adiabatic Mass Loss in Binary Stars. V. Effects of Metallicity and Nonconservative Mass Transfer—Application in High Mass X-Ray Binaries. Binary stars are responsible for many unusual astrophysical phenomena, including some important explosive cosmic events. The stability criteria for rapid mass transfer and common-envelope evolution are fundamental to binary star evolution. They determine the mass, mass ratio, and orbital distribution of systems such as X-ray binaries and merging gravitational-wave sources. We use our adiabatic mass-loss model to systematically survey metal-poor and solar-metallicity donor thresholds for dynamical timescale mass transfer. The critical mass ratios q ad are systematically explored and the impact of metallicity and nonconservative mass transfer are studied. For metal-poor radiative-envelope donors, q ad are smaller than those for solar-metallicity stars at the same evolutionary stage. However, q ad do the opposite for convective-envelope donors. Nonconservative mass transfer significantly decreases q ad for massive donors. This is because it matters how conservative mass transfer is during the thermal timescale phase immediately preceding a delayed dynamical mass transfer. We apply our theoretical predictions to observed high-mass X-ray binaries that have overfilled their Roche lobes and find a good agreement with their mass ratios. Our results can be applied to study individual binary objects or large samples of binary objects with binary population synthesis codes.

Keywords: Neutron stars, High mass x-ray binary stars, Binary stars, Stellar mass black holes
The Linear Mixing Approximation in Silica–Water Mixtures at Planetary Conditions. The linear mixing approximation (LMA) is often used in planetary models for calculating the equations of state (EOS) of mixtures. A commonly assumed planetary composition is a mixture of rock and water. Here we assess the accuracy of the LMA for pressure–temperature conditions relevant to the interiors of Uranus and Neptune. We perform molecular dynamics simulations using ab initio simulations and consider pure water, pure silica, and 1:1 and 1:4 silica–water molecular fractions at a temperature of 3000 K and pressures between 30 and 600 GPa. We find that the LMA is valid within a few percent (&lt; ∼5%) between ∼150 and 600 Gpa, where the sign of the difference in inferred density depends on the specific composition of the mixture. We also show that the presence of rocks delays the transition to superionic water by ∼70 GPa for the 1:4 silica–water mixture. Finally, we note that the choice of electronic theory (functionals) affects the EOS and introduces an uncertainty of the order of 10% in density. Our study demonstrates the complexity of phase diagrams in planetary conditions and the need for a better understanding of rock–water mixtures and their effect on the inferred planetary composition.

Keywords: Planetary interior, Solar system gas giant planets, Uranus
Plausibility of Capture into High-obliquity States for Exoplanets in the M Dwarf Habitable Zone. For temperate exoplanets orbiting M-dwarf hosts, the proximity of the habitable zone to the star necessitates careful consideration of tidal effects. Spin synchronization of the planetary orbital period and rotation period, tidal locking, and the subsequent impact on surface conditions frames common assumptions about M-dwarf planets. We investigate the plausibility of capture into Cassini State 2 (CS2) for a known sample of 280 multiplanet systems orbiting M-dwarf hosts. This resonance of the spin precession and orbital precession frequencies can excite planets into stable nonzero rotational obliquities, breaking tidal locking and inducing a version of "day" and "night." Considering each planetary pair and estimating the spin and orbital precession frequencies, we find that 75% of detected planets orbiting M dwarfs may be plausibly excited to a high obliquity and maintain it through subsequent tidal dissipation over long timescales. We also investigate two possible mechanisms for capture into CS2: quantifying the orbital migration or primordial obliquity necessary for CS2. We find orbital migrations by a factor of ≲2 and an isotropic initial spin distribution can produce high-obliquity planets, aligning with similar findings for planets orbiting close-in to FGK dwarfs. Many of the planets in our sample reside in both CS2 and within their stellar habitable zone. Over half of the planets with T eq &lt; 400 K around host stars with T eff &lt; 3000 K could possess nonzero obliquity due to residence in CS2. This overlap renders the potential capture into Cassini States extremely relevant to understanding the galaxy's most common temperate planets.

Keywords: Exoplanet dynamics, Planetary system evolution, Exoplanet astronomy, Tidal interaction, Habitable zone, Habitable planets
The First Detection of X-Ray Polarization in a Newly Discovered Galactic Transient Swift J151857.0-572147. We study the spectropolarimetric properties of a newly discovered black hole (BH) X-ray binary Swift J151857.0-572147 jointly using Imaging X-ray Polarimetry Explorer (IXPE) and NuSTAR observations during 2024 March. The analysis of IXPE data reports the first detection of X-ray with a polarization degree (PD) of 1.34 ± 0.27 and a polarization angle (PA) of ‑13.°69 ± 5.°85 using a model-independent approach, while the model-dependent analysis gives a PD of 1.18 ± 0.23 and a PA of ‑14.°01 ± 5.°80. The joint spectral analysis of the broadband data and NuSTAR analysis in isolation constrain the mass of the central BH between ∼9.2 ± 1.6 and 10.1 ± 1.7M ⊙ and a moderate spin parameter of ∼0.6 ± 0.1–0.7 ± 0.2 with a disk inclination of ∼35° ± 7°–46° ± 15°. The power-law photon index and cutoff energy are 2.19 ± 0.03–2.47 ± 0.06 and ∼36 ± 4–78 ± 10 keV, suggesting a transition to the soft spectral state. Additionally, a relatively lower corona size of 6 ± 1–9 ± 2r  S , a low mass outflow rate ( &lt;3%ṀEdd ), and the best-fitted halo accretion is less compared to the disk accretion rate further confirm the same state. The low PD detected in the soft state can be due to repeated scattering inside the dense corona, and the dominant emission from the disk agrees with the low spin and low disk inclination. The hydrogen column density obtained from the fit is relatively high at ∼4–5 × 1022 cm‑2.

Keywords: X-ray astronomy, Shocks, Jets, Hydrodynamics
Surface Flux Transport Modeling Using Physics-informed Neural Networks. Studying the magnetic field properties on the solar surface is crucial for understanding the solar and heliospheric activities, which in turn shape space weather in the solar system. Surface flux transport (SFT) modeling helps us to simulate and analyze the transport and evolution of magnetic flux on the solar surface, providing valuable insights into the mechanisms responsible for solar activity. In this work, we demonstrate the use of machine learning techniques in solving magnetic flux transport, making it accurate. We have developed a novel physics-informed neural network (PINN)-based model to study the evolution of bipolar magnetic regions using SFT in one-dimensional azimuthally averaged and also in two dimensions. We demonstrate the efficiency and computational feasibility of our PINN-based model by comparing its performance and accuracy with that of a numerical model implemented using the Runge–Kutta implicit–explicit scheme. The mesh-independent PINN method can be used to reproduce the observed polar magnetic field with better flux conservation. This advancement is important for accurately reproducing observed polar magnetic fields, thereby providing insights into the strength of future solar cycles. This work paves the way for more efficient and accurate simulations of solar magnetic flux transport and showcases the applicability of PINNs in solving advection–diffusion equations with a particular focus on heliophysics.

Keywords: Solar surface, Solar physics, Solar active regions, Solar magnetic fields
Impact of Current Uncertainties in the <SUP>12</SUP>C+<SUP>12</SUP>C Nuclear Reaction Rate on Intermediate-mass Stars and Massive White Dwarfs. Recent determinations of the total rate of the 12C+12C nuclear reaction show non-negligible differences with the reference reaction rate commonly used in previous stellar simulations. In addition, the current uncertainties in determining each exit channel constitute one of the main uncertainties in shaping the inner structure of super asymptotic giant branch stars that could have a measurable impact on the properties of pulsating ultramassive white dwarfs (WDs). We explore how new determinations of the nuclear reaction rate and its branching ratios affect the evolution of WD progenitors. We show that the current uncertainties in the branching ratios constitute the main uncertainty factor in determining the inner composition of ultramassive WDs and their progenitors. We found that the use of extreme branching ratios leads to differences in the central abundances of 20Ne of at most 17%, which are translated into differences of at most 1.3% and 0.8% in the cooling times and size of the crystallized core, respectively. However, the impact on the pulsation properties is small, less than 1 s for the asymptotic period spacing. We found that the carbon burns partially in the interior of ultramassive WD progenitors within a particular range of masses, leaving a hybrid CONe-core composition in their cores. The evolution of these new kinds of predicted objects differs substantially from the evolution of objects with pure CO cores. Differences in the size of the crystallized core and cooling times of up to 15% and 6%, respectively, lead to distinct patterns in the period spacing distribution.

Keywords: Nuclear abundances, DA stars, Stellar evolution
The Twisting of Radio Waves in a Randomly Inhomogeneous Plasma. Polarization of electromagnetic waves carries a large amount of information about their astrophysical emitters and the media they passed through, and hence is crucial in various aspects of astronomy. Here we demonstrate an important but long-overlooked depolarization mechanism in astrophysics: when the polarization vector of light travels along a nonplanar curve, it experiences an additional rotation, in particular for radio waves. The process leads to depolarization, which we call "geometric" depolarization (GDP). We give a concise theoretical analysis of the GDP effect on the transport of radio waves in a randomly inhomogeneous plasma under the geometrical optics approximation. In the case of isotropic scattering in the coronal plasma, we show that the GDP of the angle of arrival of the linearly polarized radio waves propagating through the turbulent plasma cannot be ignored. The GDP effect of linearly polarized radio waves can be generalized to astrophysical phenomena, such as fast radio bursts and stellar radio bursts, etc. Our findings may have a profound impact on the analysis of astrophysical depolarization phenomena.

Keywords: Radio transient sources, Radio astronomy, Plasma astrophysics, Radio bursts
Discovery of a Dense Association of Stars in the Vicinity of the Supermassive Black Hole Sgr A*. We focus on a sample of 42 sources in the vicinity of the bow-shock source IRS 1W (N-source region), located at a distance of 6.″05 northeast of the supermassive black hole Sagittarius A* (Sgr A*), within the radius of 1.″35. We present the first proper-motion measurements of N sources and find that a larger subset of N sources (28 sources) exhibit a north─west (NW) flying angle. These sources can be bound by an intermediate-mass black hole (IMBH) or the concentration that we observe is due to a disk-like distribution projection along the line of sight. We detect the N sources in the H, K  s , and  L'  bands. The NW-ward flying sources could be a bound collection of stars. We discuss the tentative existence of an IMBH or an inclined disk distribution to explain the significant overdensity of stars. The first scenario of having an IMBH implies the lower limit of ∼104 M ⊙ for the putative IMBH. Our measurements for the first time reveal that the dense association of stars containing IRS 1W is a comoving group of massive, young stars. This stellar association might be the remnant core of a massive stellar cluster that is currently being tidally stripped as it inspirals toward Sgr A*. The second scenario suggests that the appearance of the N sources might be influenced by the projection of a disk-like distribution of younger He-stars and/or dust-enshrouded stars.

Keywords: Intermediate-mass black holes, Galactic center, Stellar motion, Astrophysical black holes, Stellar kinematics, Infrared photometry, Young star clusters, Infrared astronomy, Infrared excess, Proper motions, Stellar associations, Star clusters
Embedded Young Stellar Objects near H72.97-69.39: A Forming Super Star Cluster in N79. We present 102 embedded young stellar object (YSO) candidates associated with the H72.97-69.39 super star cluster (SSC) in the Large Magellanic Cloud (LMC). With the use of the James Webb Space Telescope Mid-Infrared Instrument (MIRI) imaging mode, we utilize an F770W – F1000W versus F1000W color–magnitude diagram to select 70 YSO candidates. An additional 27 YSO candidates are selected based on model fitting using the four MIRI imaging filters employed for this study (F770W, F1000W, F1500W, and F2100W). The central region of H72.97-69.39 is saturated in MIRI imaging, however it is covered by observations made with the Medium Resolution Spectrometer (MRS), leading to the identification of five additional massive YSOs. The total star formation rate inferred based on the 102 YSO candidates is 0.02 M ⊙ yr‑1, similar to other high-mass star-forming regions in the LMC which have undergone several generations of starburst events. Due to its young age, however, H72.97-69.39's stellar production rate is expected to increase. The central five YSOs identified with MRS have masses ranging from 21.1 to 40.3 M ⊙ and total luminosity over 106 L ⊙, making H72.97-69.39 a very compact and luminous star-forming region similar to other known SSCs. We theorize that the central five massive YSOs were formed via filamentary collision, while other YSO candidates of varying masses were triggered by wind, radiation, and expanding H II shells based on their spatial distribution.

Keywords: Young stellar objects
The Outflowing [O II] Nebulae of Compact Starburst Galaxies at z ∼ 0.5. High-velocity outflows are ubiquitous in compact, massive (M * ∼ 1011 M ⊙), z ∼ 0.5 galaxies with extreme star formation surface densities (ΣSFR ∼ 2000 M ⊙ yr‑1 kpc‑2). We have previously detected and characterized these outflows using Mg II absorption lines. To probe their full extent, we present Keck/KCWI integral field spectroscopy of the [O II] and Mg II emission nebulae surrounding all of the 12 galaxies in this study. We find that [O II] is more effective than Mg II in tracing low surface brightness, extended emission in these galaxies. The [O II] nebulae are spatially extended beyond the stars, with radial extent R 90 between 10 and 40 kpc. The nebulae exhibit nongravitational motions, indicating galactic outflows with maximum blueshifted velocities ranging from ‑335 to ‑1920 km s‑1. The outflow kinematics correlate with the bursty star formation histories of these galaxies. Galaxies with the most recent bursts of star formation (within the last &lt;3 Myr) exhibit the highest central velocity dispersions (σ ≳ 400 km s‑1), while the oldest bursts have the lowest-velocity outflows. Many galaxies exhibit both high-velocity cores and more extended, slower-moving gas indicative of multiple outflow episodes. The slower, larger outflows occurred earlier and have decelerated as they propagate into the circumgalactic medium and mix on timescales ≳50 Myr.

Keywords: Starburst galaxies, Galactic winds, Stellar feedback, Circumgalactic medium
The COS CGM Compendium. V. The Dichotomy of O VI Associated with Low- and High-metallicity Cool Gas at z &lt; 1. We analyze the O VI content and kinematics for 126 H I-selected absorbers at 0.14 ≲ z ≲ 0.73 for which the metallicities of their cool photoionized phase have been determined. We separate the absorbers into 100 strong Lyα forest systems (SLFSs with 15 ≲ log N(H I) &lt; 16.2) and 26 partial Lyman Limit systems (pLLSs with 16.2 ≤ log N(H I) ≤ 17.2). The sample is drawn from the COS CGM Compendium (CCC) and has O VI coverage in signal-to-noise ratio ≥ 8 Hubble Space Telescope/COS G130M/G160M QSO spectra, yielding a 2σ completeness level of  logN (O VI) ≥ 13.6. The O VI detection rates differ substantially between low-metallicity (LM; [X/H] ≤ ‑1.4) and high-metallicity (HM; [X/H] &gt; ‑1.4) SLFSs, with 20% and 60% detection rates, respectively. The O VI detection frequency for the HM and LM pLLSs is, however, similar at ∼60%. The SLFSs and pLLSs without detected O VI are consistent with the absorbing gas being in a single phase, while those with O VI trace multiphase gas. We show that the O VI velocity widths and column densities have different distributions in LM and HM gas. We find a strong correlation between O VI column density and metallicity. The strongest ( logN (O VI) ≳ 14) and broadest O VI absorbers are nearly always associated with HM absorbers, while weaker O VI absorbers are found in both LM and HM absorbers. From comparisons with galaxy-selected and blind O VI surveys, we conclude absorbers with  logN (O VI) ≳ 14 most likely arise in the CGM of star-forming galaxies. Absorbers with weak O VI likely trace the extended CGM or intergalactic medium, while those without O VI likely originate in the intergalactic medium.

Keywords: Galaxies, Quasar absorption line spectroscopy, Circumgalactic medium
Dual Active Galactic Nuclei: Precursors of Binary Supermassive Black Hole Formation and Mergers. The presence of dual active galactic nuclei (AGNs) on scales of a few tens of kiloparsecs can be used to study merger-induced accretion on supermassive black holes (SMBHs) and offer insights about SMBH mergers, using dual AGNs as merger precursors. This study uses the ROMULUS25 cosmological simulation to investigate the properties and evolution of dual AGNs. We first analyze the properties of AGNs (L bol &gt; 1043 erg s‑1) and their neighboring SMBHs (any SMBHs closer than 30 pkpc to an AGN) at z ≤ 2. This is our underlying population. We then applied the luminosity threshold of L bol &gt; 1043 erg s‑1 to the neighboring SMBHs thereby identifying dual and multiple AGNs. Our findings indicate an increase in the number of both single and dual AGNs from lower to higher redshifts. We also find that the number of dual AGNs with separations of 0.5–4 kpc is twice the number of duals with separations of 4–30 kpc. All dual AGNs in our sample resulted from major mergers. Compared to single AGNs, duals have a lower black hole-to-halo mass ratio. We found that the properties of dual AGN host halos, including halo mass, stellar mass, star formation rate, and gas mass, are generally consistent with those of single AGN halos, albeit tending toward the higher end of their respective property ranges. Our analysis uncovered a diverse array of evolutionary patterns among dual AGNs, including rapidly evolving systems, slower ones, and instances where SMBH mergers are ineffective.

Keywords: Black hole physics, Computational methods, Active galaxies, Active galactic nuclei