Sazuna/UAT_keywords huggingface dataset:
The OTELO Survey: The Star Formation Rate Evolution of Low-mass Galaxies. We present the analysis of a sample of Hα, Hβ, and [O II] emission line galaxies from the OTELO survey, with masses typically below $\mathrm{log}({M}_{* }/{M}_{\odot })\sim 9.4$ and redshifts between z ~ 0.4 and 1.43. We study the star formation rate, star formation rate density, and their number density and evolution with redshift. We obtain a robust estimate of the specific star formation rate-stellar mass relation based on the lowest-mass sample published so far. We also determine a flat trend of the star formation rate density (SFRD) and number density with redshift. Our results suggest a scenario of no evolution of the number density of galaxies, regardless of their masses, up to redshift z ~ 1.4. This implies a gradual change of the relative importance of the star-forming processes, from high-mass galaxies to low-mass galaxies, with decreasing redshift. We also find little or no variation of the SFRD in the redshift range of 0.4 &lt; z &lt; 1.43.

Keywords: Luminosity function, Starburst galaxies, Surveys, Observational cosmology, Star formation
The Outermost Edges of the Milky Way Halo from Galaxy Kinematics. We measure for the first time the outermost edges of the Milky Way (MW) halo in terms of the depletion and turnaround radii. The inner depletion radius, rid, identified at the location of maximum infall velocity, separates a growing halo from the draining environment, while the turnaround radius, rta, marks the outermost edge of infalling material toward the halo, both of which are located well outside the virial radius. Using the motions of nearby dwarf galaxies within 3 Mpc, we obtain a marginal detection of the infall zone around the MW with a maximum velocity of ${v}_{\inf ,\max }=-{46}_{-39}^{+24}\,\mathrm{km}\ {{\rm{s}}}^{-1}$ . This enables us to measure rid = 559 ± 107 kpc and rta = 839 ± 121 kpc. The measured depletion radius is about 1.5 times the MW virial radius (R200m) measured from internal dynamics. Compared with halos in the cosmological simulation Illustris TNG100, the factor 1.5 is consistent with that of halos with similar masses and dynamical environments to the MW but slightly smaller than typical values of Local Group analogs, potentially indicating the unique evolution history of the MW. These measurements of halo edges directly quantify the ongoing evolution of the MW outer halo and provide constraints on the current dynamical state of the MW that are independent from internal dynamics.

Keywords: Local Group, Milky Way dark matter halo, Galaxy dark matter halos, Dark matter distribution, Hydrodynamical simulations, Dwarf galaxies, Milky Way dynamics, Galaxy dynamics
Direct Evidence for Magnetic Reflection of Heavy Ions from High Mach Number Collisionless Shocks. Strong shocks in collisionless plasmas, such as supernovae shocks and shocks driven by coronal mass ejections, are known to be a primary source of energetic particles. Due to their different mass per charge ratio, the interaction of heavy ions with the shock layer differs from that of protons, and injection of these ions into acceleration processes is a challenge. Here we show the first direct observational evidence of magnetic reflection of alpha particles from a high Mach number quasi-perpendicular shock using in situ spacecraft measurements. The intense magnetic amplification at the shock front associated with nonstationarity modulates the trajectory of alpha particles, some of which travel back upstream as they gyrate in the enhanced magnetic field and experience further acceleration in the upstream region. Our results in particular highlight the important role of high magnetic amplification in seeding heavy ions into the energization processes at nonstationary reforming shocks.

Keywords: Shocks, Solar wind, Space plasmas
Mapping the Hidden Magnetic Field of the Quiet Sun. The Sun is the only star where we can resolve the intricate magnetism that all convective stars harbor. Yet, more than 99% of its visible surface along the solar cycle (the so-called quiet Sun) is filled with a tangled, unresolved magnetism. These "hidden" fields are thought to store enough magnetic energy to play a role in the heating of the Sun's outer atmosphere, but its field strength is still not constrained. Previous investigations based on the Hanle effect in atomic lines claim a strong magnetization of about 100 G, while the same effect in molecules show a factor of 10 weaker fields. The discrepancy disappears if the magnetic field strength of the hidden field is not homogeneous in the solar surface. In this Letter, we prove using magnetohydrodynamical simulations that it is possible to infer the average field strength of the hidden quiet-Sun magnetic fields using multiline inversions of intensity profiles in the Zeeman regime. Using this technique with 15 spectral lines in the 1.5 μm spectral range, we reveal that the spatial distribution of the hidden field is strongly correlated with convection motions, and that the average magnetization is about 46 G. Reconciling our findings with the Hanle ones is not obvious and will require future work on both sides, since it implies an increase of the field strength with height, something that is physically questionable.

Keywords: Solar photosphere, Spectropolarimetry, Solar magnetic fields
The Architecture of Multiplanet Systems as a Tracer of Their Formation Mechanisms. Exoplanets observed by the Kepler telescope exhibit a bimodal, radius distribution, which is known as the radius gap. We explore an origin of the radius gap, focusing on multiplanet systems. Our simple theoretical argument predicts that type I planetary migration produces different configurations of protoplanets with different masses and such different configurations can result in two distinguishable populations of small-sized multiplanet systems. We then perform an observational analysis to verify this prediction. In the analysis, multiple Kolmogorov-Smirnov tests are applied to the observed systems, using the statistical measures that are devised to systematically characterize the properties of multiplanet systems. We find with 99.5% confidence that the observed, small-sized multiplanet systems are divided into two distinct populations. The distinction likely originates from different spatial distributions of protoplanets, which are determined by type I migration and subsequently trigger giant impact. We also show that these distinct populations are separated around the radius gap when the gas surface density of protoplanetary disks is ~102 g cm-2 in the vicinity of the host stars. This work therefore emphasizes the importance of planetary migration and the inner disk properties.

Keywords: Exoplanet dynamics, Super Earths, Protoplanetary disks, Planetary migration, Mini Neptunes, Planet formation
An Interplanetary Type IIIb Radio Burst Observed by Parker Solar Probe and Its Emission Mechanism. Type IIIb radio bursts were identified as a chain of quasi-periodic striae in dynamic spectra, drifting from high to low frequencies in a manner similar to type III bursts, which fine structures may provide a clue to a better understanding of emission mechanisms. The approaching observation of the Parker Solar Probe (PSP) spacecraft provides a new chance of probing type IIIb bursts in the vicinity of the Sun. In this Letter, combining the in situ measurement of PSP and the empirical model of solar atmospheres in open magnetic field regions, we analyze in detail a typical event of interplanetary (IP) type IIIb bursts observed by PSP, which was first reported by Pulupa et al. Our results show that the electron cyclotron maser (ECM) emission can probably play an important role in the excitation mechanism of the IP type IIIb burst and the formation of the fine striae structure may be attributed to the modulation of Alfvén waves on the growth rate of the ECM instability.

Keywords: Solar radio emission, Interplanetary physics
Phase Transition of Interstellar CO Ice. Among the over 200 molecular species identified in interstellar clouds, many are organic molecules. It has been proposed that some of these molecules survive the star and planet formation process and are eventually delivered to Earth where they can form the molecular basis of the origin of life. It is now well established that one of the most important factories of these molecules are ice mantles that cover the dust grains in star-forming molecular clouds. Simple atoms and molecules such as H, O, N, and CO condense from the gas phase onto the grain surface and then react with each other in the ice to form increasingly complex molecules. At the extremely low temperature (10-15 K) in these clouds, the widely accepted mechanism to bring reactive species together-diffusion-is severely impeded in the ice, raising the question of the mechanism of their formation. In laboratory experiments we find that the top layers of the ice mantle, which are made primarily of CO, transform from a disordered phase to a polycrystalline phase at such a low temperature. During the phase transition, reactive species buried inside may migrate and react without the need to overcome activation energy for diffusion. By quantifying the kinetics of crystallization, we predict that CO ice in interstellar clouds is mostly in the polycrystalline form. The reorganization of CO ice, which occurs below 10 K, may promote mobility of reactive species, and therefore can be a driving force of molecular complexity in molecular clouds.

Keywords: Interstellar molecules, Laboratory astrophysics, Ice formation, Dense interstellar clouds
Measurements of Coronal Magnetic Field Strengths in Solar Active Region Loops. The characteristic electron densities, temperatures, and thermal distributions of 1 MK active region loops are now fairly well established, but their coronal magnetic field strengths remain undetermined. Here we present measurements from a sample of coronal loops observed by the Extreme-ultraviolet Imaging Spectrometer on Hinode. We use a recently developed diagnostic technique that involves atomic radiation modeling of the contribution of a magnetically induced transition to the Fe X 257.262 Å spectral line intensity. We find coronal magnetic field strengths in the range of 60-150 G. We discuss some aspects of these new results in the context of previous measurements using different spectropolarimetric techniques, and their influence on the derived Alfvén speeds and plasma β in coronal loops.

Keywords: Solar active region magnetic fields, Solar physics
Bayesian Evidence for a Nonlinear Damping Model for Coronal Loop Oscillations. Recent observational and theoretical studies indicate that the damping of solar coronal loop oscillations depends on the oscillation amplitude. We consider two mechanisms: linear resonant absorption and a nonlinear damping model. We confront theoretical predictions from these models with observed data in the plane of observables defined by the damping ratio and the oscillation amplitude. The structure of the Bayesian evidence in this plane displays a clear separation between the regions where each model is more plausible relative to the other. There is qualitative agreement between the regions of high marginal likelihood and Bayes factor for the nonlinear damping model and the arrangement of observed data. A quantitative application to 101 loop oscillation cases observed with Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) results in the marginal likelihood for the nonlinear model being larger in the majority of them. The cases with conclusive evidence for the nonlinear damping model outnumber considerably those in favor of linear resonant absorption.

Keywords: Magnetohydrodynamics, Bayesian statistics, Solar coronal loops, Bayes factor, Solar coronal seismology
Energetic Neutral Atom Fluxes from the Heliosheath: Constraints from in situ Measurements and Models. Voyager 2 observations throughout the heliosheath from the termination shock to the heliopause are used to normalize and constrain model pickup ion (PUI) fluxes. Integrating normalized PUI fluxes along the Voyager 2 trajectory through the heliosheath, and combining these integral fluxes with the energy-dependent charge-exchange cross section and the neutral hydrogen density, produces semi-empirical estimates of the energetic neutral atom (ENA) fluxes from the heliosheath. These estimated ENA fluxes are compared with observed ENA fluxes from the Interstellar Boundary Explorer (IBEX) to determine what percentage of the observed fluxes at each IBEX energy are from the heliosheath. These percentages are a maximum of ~10% for most energies and depend strongly on termination shock properties, plasma density, bulk plasma flow characteristics, the shape of the heliopause, and turbulent energy diffusion in the heliosheath.

Keywords: Space plasmas, Astrosphere interstellar medium interactions, Solar wind, Solar wind termination, Pickup ions, Interstellar medium
Discovery of the 5 keV Cyclotron Line Followed by Three Harmonics in Swift J1626.6-5156. We report on observations of the Be/X-ray binary system Swift J1626.6-5156 performed with the Nuclear Spectroscopic Telescope ARray (NuSTAR) during a short outburst in 2021 March, following its detection by the MAXI monitor and Spektrum-Roentgen-Gamma (SRG) observatory. Our analysis of the broadband X-ray spectrum of the source confirms the presence of two absorption-like features at energies E ~ 9 and E ~ 17 keV. These had been previously reported in the literature and interpreted as the fundamental cyclotron resonance scattering feature (CRSF) and its first harmonic (based on Rossi X-ray Timing Explorer (RXTE) data). The better sensitivity and energy resolution of NuSTAR, combined with the low-energy coverage of Neutron star Interior Composition Explorer (NICER), allowed us to detect two additional absorption-like features at E ~ 4.9 keV and E ~ 13 keV. Therefore, we conclude that, in total, four cyclotron lines are observed in the spectrum of Swift J1626.6-5156: the fundamental CRSF at E ~ 4.9 keV and three higher spaced harmonics. This discovery makes Swift J1626.6-5156 the second accreting pulsar, after 4U 0115+63, whose spectrum is characterized by more than three lines of a cyclotronic origin, and implies that the source has the weakest confirmed magnetic field among all X-ray pulsars, B ~ 4 × 1011 G. This discovery makes Swift J1626.6-5156 one of the prime targets for the upcoming X-ray polarimetry missions covering the soft X-ray band, such as Imaging X-ray Polarimetry Explorer (IXPE) and enhanced X-ray Timing and Polarimetry mission (eXTP).

Keywords: Neutron stars, Binary pulsars
FAST Globular Cluster Pulsar Survey: Twenty-four Pulsars Discovered in 15 Globular Clusters. We present the discovery of 24 pulsars in 15 globular clusters (GCs) using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). These include the first pulsar discoveries in M2, M10, and M14. Most of the new systems are either confirmed or likely members of binary systems. M53C and NGC 6517H and I are the only three pulsars confirmed to be isolated. M14A is a black widow pulsar with an orbital period of 5.5 hr and a minimum companion mass of 0.016 M⊙. M14E is an eclipsing binary pulsar with an orbital period of 20.3 hr. With the other 8 discoveries that have been reported elsewhere, in total 32 GC pulsars have been discovered by FAST so far. In addition, We detected M3A twice. This was enough to determine that it is a black widow pulsar with an orbital period of 3.3 hr and a minimum companion mass of 0.0125 M⊙.

Keywords: Globular star clusters, Radio telescopes, Binary pulsars, Radio pulsars
A Number of nearby Moving Groups May Be Fragments of Dissolving Open Clusters. We propose that 14 co-moving groups of stars uncovered by Kounkel &amp; Covey may be related to known nearby moving groups and bridge those and nearby open clusters with similar ages and space velocities. This indicates that known nearby moving groups may be spatially much more extended than previously thought, and some of them might be parts of tidal tails around the cores of known open clusters, reminiscent of those recently found around the Hyades and a handful of other nearby clusters. For example, we find that both the nearby Carina and Columba associations may be linked to Theia 208 from Kounkel &amp; Covey and together form parts of a large tidal tail around the Platais 8 open cluster. The AB Doradus moving group and Theia 301 may form a trailing tidal tail behind the Pleiades open cluster, with hints of a possible leading tidal tail in Theia 369. Similarly, we find that IC 2391 and its tidal tails identified by Meingast et al. may be extended by the nearby Argus association and are possibly further extended by Theia 115. The nearby Octans and Octans-Near associations, as well as Theia 94 and 95, may form a large tidal tail leading the poorly studied Platais 5 open cluster candidate. While a preliminary analysis of Gaia color-magnitude sequences hint that these structures are plausibly related, more observational evidence is still required to corroborate their consistent ages and space velocities. These observations may change our current understanding of nearby moving groups and the different pathways through which they can form. While some moving groups may have formed loosely in extended star formation events with rich spatial structure, others may in fact correspond to the tidal tails of nearby open clusters.

Keywords: Stellar kinematics, Open star clusters, Stellar associations
Zero-metallicity Hypernova Uncovered by an Ultra-metal-poor Star in the Sculptor Dwarf Spheroidal Galaxy. Although true metal-free "Population III" stars have so far escaped discovery, their nature, and that of their supernovae, is revealed in the chemical products left behind in the next generations of stars. Here we report the detection of an ultra-metal-poor star in the Sculptor dwarf spheroidal galaxy AS0039. With [Fe/H]LTE = -4.11, it is the most metal-poor star discovered in any external galaxy thus far. Contrary to the majority of Milky Way stars at this metallicity, AS0039 is clearly not enhanced in carbon, with [C/Fe]LTE = -0.75, and A(C) = +3.60, making it the lowest detected carbon abundance in any star to date. Furthermore, it lacks α-element uniformity, having extremely low [Mg/Ca]NLTE = -0.60 and [Mg/Ti]NLTE = -0.86, in stark contrast with the near solar ratios observed in C-normal stars within the Milky Way halo. The unique abundance pattern indicates that AS0039 formed out of material that was predominantly enriched by a ~20 M☉ progenitor star with an unusually high explosion energy E = 10 × 1051 erg. Therefore, star AS0039 represents some of the first observational evidence for zero-metallicity hypernovae and provides a unique opportunity to investigate the diverse nature of Population III stars. * Based on observations made with ESO VLT/X-SHOOTER at the La Silla Paranal observatory under program ID 0102.B-0786.

Keywords: Population III stars, Chemically peculiar giant stars, Hypernovae, Galactic archaeology, Population II stars, Chemically peculiar stars, Sculptor dwarf elliptical galaxy
Selection of Three (Extreme)Ultraviolet Channels for Solar Satellite Missions by Deep Learning. We address the question of which combination of channels can best translate other channels in ultraviolet (UV) and extreme UV (EUV) observations. For this, we compare the image translations among the nine channels of the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) using a deep-learning (DL) model based on conditional generative adversarial networks. In this study, we develop 170 DL models: 72 models for single-channel input, 56 models for double-channel input, and 42 models for triple-channel input. All models have a single-channel output. Then we evaluate the model results by pixel-to-pixel correlation coefficients (CCs) within the solar disk. Major results from this study are as follows. First, the model with 131 Å shows the best performance (average CC = 0.84) among single-channel models. Second, the model with 131 and 1600 Å shows the best translation (average CC = 0.95) among double-channel models. Third, among the triple-channel models with the highest average CC (0.97), the model with 131, 1600, and 304 Å is suggested in that the minimum CC (0.96) is the highest. Interestingly, they represent coronal, upper photospheric, and chromospheric channels, respectively. Our results may be used as a secondary perspective in addition to primary scientific purposes in selecting a few channels of an UV/EUV imaging instrument for future solar satellite missions.

Keywords: Solar ultraviolet emission, Solar extreme ultraviolet emission, The Sun, Convolutional neural networks, Solar instruments
Dependencies of Mantle Shock Heating in Pairwise Accretion. The final assembly of planets involves mutual collisions of large similar-sized protoplanets ("giant impacts"), setting the stage for modern geologic and atmospheric processes. However, thermodynamic consequences of impacts in diverse (exo)planetary systems/models are poorly understood. Impact velocity in "self-stirred" systems is proportional to the mass of the colliding bodies (vimp ∝ M1/3), providing a predictable transition to supersonic collisions in roughly Mars-sized bodies. In contrast, nearby larger planets, or migrating gas giants, stir impact velocities, producing supersonic collisions between smaller protoplanets and shifting outcomes to disruption and nonaccretion. Our particle hydrocode simulations suggest that thermodynamic processing can be enhanced in merging collisions more common to calmer dynamical systems due to post-impact processes that scale with the mass of the accreting remnant. Thus, impact heating can involve some contribution from energy scaling, a departure from pure velocity-scaling in cratering scenarios. Consequently, planetary thermal history depends intimately on the initial mass distribution assumptions and dynamical conditions of formation scenarios. In even the gentlest pairwise accretions, sufficiently large bodies feature debris fields dominated by melt and vapor. This likely plays a critical role in the observed diversity of exoplanet systems and certain debris disks. Furthermore, we suggest solar system formation models that involve self-stirred dynamics or only one to a few giant impacts between larger-than-Mars-sized bodies (e.g., "pebble accretion") are more congruent with the "missing mantle problem" for the main belt, as we demonstrate debris would be predominantly vapor and thus less efficiently retained due to solar radiation pressure effects.

Keywords: Impact phenomena, Hydrodynamical simulations, Exoplanet atmospheres, Shocks, Exoplanet formation, Planet formation