adsabs/SciX_UAT_keywords huggingface dataset:
Extended X-Ray Emission around FR II Radio Galaxies: Hot Spots, Lobes, and Galaxy Clusters

We present a systematic analysis of the extended X-ray emission discovered around 35 FR II radio galaxies from the revised Third Cambridge Catalog (3CR) Chandra Snapshot Survey with redshifts between 0.05 and 0.9. We aimed to (i) test for the presence of extended X-ray emission around FR II radio galaxies, (ii) investigate whether the extended emission origin is due to inverse Compton (IC) scattering of seed photons arising from the cosmic microwave background (CMB) or thermal emission from an intracluster medium (ICM), and (iii) test the impact of this extended emission on hot-spot detection. We investigated the nature of the extended X-ray emission by studying its morphology and compared our results with low-frequency radio observations (i.e., ∼150 MHz) in the TGSS and LOFAR archives, as well as with optical images from Pan-STARRS. In addition, we optimized a search for X-ray counterparts of hot spots in 3CR FR II radio galaxies. We found statistically significant extended emission (>3σ confidence level) along the radio axis of ∼90% and in the perpendicular direction of ∼60% of the galaxies in our sample. We confirmed the detection of seven hot spots in the 0.5-3 keV energy range. In the cases where the emission in the direction perpendicular to the radio axis is comparable to that along the radio axis, we suggest that the underlying radiative process is thermal emission from the ICM. Otherwise, the dominant radiative process is likely nonthermal IC/CMB emission from lobes. We found that nonthermal IC/CMB is the dominant process in ∼70% of the sources in our sample, while thermal emission from the ICM dominates in ∼15% of them.

Keywords: active galactic nuclei; active galaxies; high energy astrophysics; radio hot spots; radio lobes; x-ray active galactic nuclei; radio sources; intracluster medium
The Dense Gas Mass Fraction and the Relationship to Star Formation in M51

Observations of 12CO J = 1 - 0 and HCN J = 1 - 0 emission from NGC 5194 (M51) made with the 50 m Large Millimeter Telescope and the SEQUOIA focal plane array are presented. Using the HCN-to-CO ratio, we examine the dense gas mass fraction over a range of environmental conditions within the galaxy. Within the disk, the dense gas mass fraction varies along the spiral arms but the average value over all spiral arms is comparable to the mean value of interarm regions. We suggest that the near-constant dense gas mass fraction throughout the disk arises from a population of density-stratified, self-gravitating molecular clouds and the required density threshold to detect each spectral line. The measured dense gas fraction significantly increases in the central bulge in response to the effective pressure, P e , from the weight of the stellar and gas components. This pressure modifies the dynamical state of the molecular cloud population and, possibly, the HCN-emitting regions in the central bulge from self-gravitating to diffuse configurations in which P e is greater than the gravitational energy density of individual clouds. Diffuse molecular clouds comprise a significant fraction of the molecular gas mass in the central bulge, which may account for the measured sublinear relationships between the surface densities of the star formation rate and molecular and dense gas.

Keywords: interstellar clouds; dense interstellar clouds; galaxy environments; star forming regions
Solar Evolution Models with a Central Black Hole

Hawking proposed that the Sun may harbor a primordial black hole (BH) whose accretion supplies some of the solar luminosity. Such an object would have formed within the first 1 s after the Big Bang with the mass of a moon or an asteroid. These light BHs are a candidate solution to the dark matter problem, and could grow to become stellar-mass BHs if captured by stars. Here we compute the evolution of stars having such a BH at their center. We find that such objects can be surprisingly long-lived, with the lightest BHs having no influence over stellar evolution, while more massive ones consume the star over time to produce a range of observable consequences. Models of the Sun born about a BH whose mass has since grown to approximately 10-6 M ⊙ are compatible with current observations. In this scenario, the Sun would first dim to half its current luminosity over a span of 100 Myr as the accretion starts to generate enough energy to quench nuclear reactions. The Sun would then expand into a fully convective star, where it would shine luminously for potentially several gigayears with an enriched surface helium abundance, first as a sub-subgiant star, and later as a red straggler, before becoming a subsolar-mass BH. We also present results for a range of stellar masses and metallicities. The unique internal structures of stars harboring BHs may make it possible for asteroseismology to discover them, should they exist. We conclude with a list of open problems and predictions.

Keywords: stellar evolution; primordial black holes; dark matter
Translators of Galaxy Morphology Indicators between Observation and Simulation

Based on the recent advancements in numerical simulations of galaxy formation, we anticipate the achievement of realistic models of galaxies in the near future. Morphology is the most basic and fundamental property of galaxies, yet observations and simulations still use different methods to determine galaxy morphology, making it difficult to compare them. We hereby perform a test on the recent NEWHORIZON simulation, which has spatial and mass resolutions that are remarkably high for a large-volume simulation, to resolve the situation. We generate mock images for the simulated galaxies using SKIRT, which calculates complex radiative transfer processes in each galaxy. We measure morphological and kinematic indicators using photometric and spectroscopic methods following observers' techniques. We also measure the kinematic disk-to-total ratios using the Gaussian mixture model and assume that they represent the true structural composition of galaxies. We found that spectroscopic indicators such as V/σ and λ R closely trace the kinematic disk-to-total ratios. In contrast, photometric disk-to-total ratios based on the radial profile fitting method often fail to recover the true kinematic structure of galaxies, especially small ones. We provide translating equations between various morphological indicators.

Keywords: galaxy classification systems; galaxy kinematics; galaxy structure
An ALMA Search for High-albedo Objects Among the Midsized Jupiter Trojan Population

We use Atacama Large Millimeter Array (ALMA) measurements of 870 μm thermal emission from a sample of midsized (15-40 km diameter) Jupiter Trojan asteroids to search for high-albedo objects in this population. We calculate the diameters and albedos of each object using a thermal model which also incorporates contemporaneous Zwicky Transient Facility photometry to accurately measure the absolute magnitude at the time of the ALMA observation. We find that while many albedos are lower than reported from WISE, several small Trojans have high albedos independently measured both from ALMA and from WISE. The number of these high-albedo objects is approximately consistent with expectations of the number of objects that recently have undergone large-scale impacts, suggesting that the interiors of freshly-crated Jupiter Trojans could contain high-albedo materials such as ices.

Keywords: jupiter trojans; asteroid surfaces
Seed Population Preconditioning and Acceleration Observed by the Parker Solar Probe

A series of solar energetic particle (SEP) events was observed by the Integrated Science Investigation of the Sun (IS⊙IS) on the Parker Solar Probe (PSP) during the period from 2019 April 18 through 24. The PSP spacecraft was located near 0.48 au from the Sun on Parker spiral field lines that projected out to 1 au within ∼25° of the near-Earth spacecraft. These SEP events, though small compared to historically large SEP events, were among the largest observed thus far in the PSP mission and provide critical information about the space environment inside 1 au during SEP events. During this period, the Sun released multiple coronal mass ejections (CMEs). One of these CMEs observed was initiated on 2019 April 20 at 01:25 UTC, and the interplanetary CME (ICME) propagated out and passed over the PSP spacecraft. Observations by the Electromagnetic Fields Investigation show that the magnetic field structure was mostly radial throughout the passage of the compression region and the plasma that followed, indicating that PSP did not directly observe a flux rope internal to the ICME, consistent with the location of PSP on the ICME flank. Analysis using relativistic electrons observed near Earth by the Electron, Proton and Alpha Monitor on the Advanced Composition Explorer demonstrates the presence of electron seed populations (40-300 keV) during the events observed. The energy spectrum of the IS⊙IS-observed proton seed population below 1 MeV is close to the limit of possible stationary-state plasma distributions out of equilibrium. IS⊙IS observations reveal the enhancement of seed populations during the passage of the ICME, which likely indicates a key part of the preacceleration process that occurs close to the Sun.

Keywords: solar wind; solar energetic particles; solar coronal mass ejections
Sensitivity of 44Ti and 56Ni Production in Core-collapse Supernova Shock-driven Nucleosynthesis to Nuclear Reaction Rate Variations

Recent observational advances have enabled high resolution mapping of 44Ti in core-collapse supernova (CCSN) remnants. Comparisons between observations and models provide stringent constraints on the CCSN mechanism. However, past work has identified several uncertain nuclear reaction rates that influence 44Ti and 56Ni production in postprocessing model calculations. We evolved one-dimensional models of 15 M⊙, 18 M⊙, 22 M⊙, and 25 M⊙ stars from zero age main sequence through CCSN using Modules for Experiments in Stellar Astrophysics and investigated the previously identified reaction rate sensitivities of 44Ti and 56Ni production. We tested the robustness of our results by making various assumptions about the CCSN explosion energy and mass cut. We found a number of reactions that have a significant impact on the nucleosynthesis of 44Ti and 56Ni, particularly for lower progenitor masses. Notably, the reaction rates ${}^{13}{\rm{N}}{(\alpha ,p)}^{16}{\rm{O}}$ , ${}^{17}{\rm{F}}{(\alpha ,p)}^{20}\mathrm{Ne}$ , ${}^{52}\mathrm{Fe}{(\alpha ,p)}^{55}\mathrm{Co}$ , ${}^{56}\mathrm{Ni}{(\alpha ,p)}^{59}\mathrm{Cu}$ , ${}^{57}\mathrm{Ni}{(n,p)}^{57}\mathrm{Co}$ , ${}^{56}\mathrm{Co}{(p,n)}^{56}\mathrm{Ni}$ , ${}^{39}{\rm{K}}{(p,\gamma )}^{40}\mathrm{Ca}$ , ${}^{47}{\rm{V}}{(p,\gamma )}^{48}\mathrm{Cr}$ , ${}^{52}\mathrm{Mn}{(p,\gamma )}^{53}\mathrm{Fe}$ , ${}^{57}\mathrm{Co}{(p,\gamma )}^{58}\mathrm{Ni}$ , and ${}^{39}{\rm{K}}{(p,\alpha )}^{36}\mathrm{Ar}$ are influential for a large number of model conditions. Furthermore, we found the list of influential reactions identified by previous postprocessing studies of CCSN shock-driven nucleosynthesis is likely incomplete, motivating future larger-scale sensitivity studies.

Keywords: astrophysical explosive burning; explosive nucleosynthesis; core-collapse supernovae
Gas-phase Metallicity Profiles of Star-forming Galaxies in the Modified Accretion Disk Framework

Simulations indicate that the inflow of gas of star-forming galaxies is almost coplanar and corotating with the gas disk, and that the outflow of gas driven by stellar winds and/or supernova explosions is preferentially perpendicular to the disk. This indicates that the galactic gas disk can be treated as a modified accretion disk. In this work, we focus on the metal enhancement in galactic disks in this scenario of gas accretion. Assuming that the star formation rate surface density (ΣSFR) is of exponential form, we obtain the analytic solution of gas-phase metallicity with only three free parameters: the scale length of ΣSFR (h R), the metallicity of the inflowing gas, and the mass-loading factor defined as the wind-driven outflow rate surface density per ΣSFR. According to this simple model, the negative gradient of gas-phase metallicity is a natural consequence of the radial inflow of cold gas that is continuously enriched by in situ star formation as it moves toward the disk center. We fit the model to the observed metallicity profiles for six nearby galaxies chosen to have well-measured metallicity profiles extending to very large radii. Our model can well characterize the overall features of the observed metallicity profiles. The observed profiles usually show a floor at the outer regions of the disk, corresponding to the metallicity of inflow gas. Furthermore, we find the h R of ΣSFR inferred from these fits agree well with independent estimates from ΣSFR profiles, supporting the basic model.

Keywords: galaxies; metallicity; galaxy chemical evolution
OGLE-ing the Magellanic System: Optical Reddening Maps of the Large and Small Magellanic Clouds from Red Clump Stars

We present the most extensive and detailed reddening maps of the Magellanic Clouds (MCs) derived from the color properties of Red Clump (RC) stars. The analysis is based on the deep photometric maps from the fourth phase of the Optical Gravitational Lensing Experiment (OGLE-IV), covering approximately 670 deg2 of the sky in the Magellanic System region. The resulting maps provide reddening information for 180 deg2 in the Large Magellanic Cloud (LMC) and 75 deg2 in the Small Magellanic Cloud (SMC), with a resolution of 1'7 × 1'7 in the central parts of the MCs, decreasing to approximately 27' × 27' in the outskirts. The mean reddening is E(V - I) = 0.100 ± 0.043 mag in the LMC and E(V - I) = 0.047 ± 0.025 mag in the SMC. We refine methods of calculating the RC color to obtain the highest possible accuracy of reddening maps based on RC stars. Using spectroscopy of red giants, we find the metallicity gradient in both MCs, which causes a slight decrease of the intrinsic RC color with distance from the galaxy center of ∼0.002 mag/deg in the LMC and between 0.003 and 0.009 mag/deg in the SMC. The central values of the intrinsic RC color are 0.886 and 0.877 mag in the LMC and SMC, respectively. The reddening map of the MCs is available both in downloadable form and as an interactive interface.

Keywords: interstellar dust extinction; magellanic clouds; red giant clump
Tracking Downflows from the Chromosphere to the Photosphere in a Solar Arch Filament System

We study the dynamics of plasma along the legs of an arch filament system (AFS) from the chromosphere to the photosphere, observed with high-cadence spectroscopic data from two ground-based solar telescopes: the GREGOR telescope (Tenerife) using the GREGOR Infrared Spectrograph in the He I 10830 Å range and the Swedish Solar Telescope (La Palma) using the CRisp Imaging Spectro-Polarimeter to observe the Ca II 8542 Å and Fe I 6173 Å spectral lines. The temporal evolution of the draining of the plasma was followed along the legs of a single arch filament from the chromosphere to the photosphere. The average Doppler velocities inferred at the upper chromosphere from the He I 10830 Å triplet reach velocities up to 20-24 km s-1, and in the lower chromosphere and upper photosphere the Doppler velocities reach up to 11 km s-1 and 1.5 km s-1 in the case of the Ca II 8542 Å and Si I 10827 Å spectral lines, respectively. The evolution of the Doppler velocities at different layers of the solar atmosphere (chromosphere and upper photosphere) shows that they follow the same line-of-sight (LOS) velocity pattern, which confirms the observational evidence that the plasma drains toward the photosphere as proposed in models of AFSs. The Doppler velocity maps inferred from the lower photospheric Ca I 10839 Å or Fe I 6173 Å spectral lines do not show the same LOS velocity pattern. Thus, there is no evidence that the plasma reaches the lower photosphere. The observations and the nonlinear force-free field (NLFFF) extrapolations demonstrate that the magnetic field loops of the AFS rise with time. We found flow asymmetries at different footpoints of the AFS. The NLFFF values of the magnetic field strength help us to explain these flow asymmetries.

Keywords: solar chromosphere; solar photosphere; observational astronomy; astronomy data analysis; high resolution spectroscopy
A Study of the Pulsation Properties of 57 Non-Blazhko Ab-type RR Lyrae Stars with Homogeneous Metallicities from the LAMOST-Kepler/K2 Survey

Homogeneous metallicities and continuous high-precision light curves play key roles in studying the pulsation properties of RR Lyrae stars. By cross matching LAMOST DR6 with the Kepler and K2 fields, we have determined seven and 50 non-Blazhko RRab stars, respectively, that have homogeneous metallicities determined from low-resolution spectra of the LAMOST-Kepler/K2 survey. The Fourier decomposition method is applied to the light curves of these stars provided by the Kepler space-based telescope to determine the fundamental pulsation periods and parameters. The calculated amplitude ratios of R 21, R 31 and the phase differences of ϕ 21, ϕ 31 are consistent with the parameters of RRab stars in both globular clusters and the Large Magellanic Cloud. We find a linear relationship between the phase differences ϕ 21 and ϕ 31, which is in good agreement with the results in the literature. As far as the amplitude, we find that the amplitude of primary frequency A 1 and the total amplitude A tot follow either a cubic or linear relationship. For the rise time, we do not find its relevance with the period of the fundamental pulsation mode P1, or A tot and ϕ 21. However, it might follow a linear relationship with R 31. Based on the homogeneous metallicities, we have derived a new calibration formula for the period-ϕ 31-[Fe/H] relation, which agrees well with previous studies.

Keywords: rrab variable stars
MOSEL Survey: Tracking the Growth of Massive Galaxies at 2 < z < 4 Using Kinematics and the IllustrisTNG Simulation

We use K-band spectroscopic data from the Multi-Object Spectroscopic Emission Line survey to analyze the kinematic properties of galaxies at z > 3. Our sample consists of 34 galaxies at 3.0 < zspec < 3.8 between 9.0 < $\mathrm{log}({M}_{* }/{M}_{\odot })$ < 11.0. We find that galaxies with $\mathrm{log}({M}_{* }/{M}_{\odot })$ > 10.2 at z > 3 have 56 ± 21 km s-1 lower integrated velocity dispersion compared to galaxies at z ≃ 2 of similar stellar mass. Massive galaxies at z > 3 have either a flat or declining star formation history (SFH), whereas similar stellar mass galaxies at z ∼ 2.0 exhibit a slight peak in the past 500 Myr. Comparing with the IllustrisTNG cosmological simulation, we find that (I) the dynamical mass of massive galaxies in simulations ( $\mathrm{log}({M}_{* }/{M}_{\odot })$ > 10.0) increases by ∼0.1 dex at a fixed stellar mass between z = 2.0-3.0, and (II) dynamical mass growth is coupled with a rapid rise in the ex situ stellar mass fraction (stars accreted from other galaxies) for massive galaxies at z < 3.5. We speculate that the rising contribution of ex situ stellar mass to the total stellar mass growth of massive galaxies is driving the higher integrated velocity dispersion and rising SFHs of massive galaxies at z ∼ 2.0 compared to galaxies of similar stellar masses at z > 3.

Keywords: high-redshift galaxies; galaxy evolution; galaxy kinematics; spectroscopy
Turbulence Spectra of Electron Density and Magnetic Field Fluctuations in the Local Interstellar Medium

We present the turbulence spectra of magnetic and electron density fluctuations in situ measured by Voyager 1 in the local interstellar medium from 2012 to 2019. The magnetic spectrum shows a Kolmogorov power law with a one-dimensional power-law index -5/3 at mk ≤ 10-8.8, where k is a wavenumber and m is the unit meter. A bulge of enhanced magnetic power is found at mk = 10-8.8-10-8.2. Meanwhile, the electron density spectrum also shows a Kolmogorov power law with a one-dimensional power-law index -5/3 in the inertial range. A bulge of enhanced power is found around the kinetic scales of mk ≈ 10-5-10-1. Based on the observational data, the relationships between the outer scale of the turbulent system and the powers of electron density and magnetic fluctuations are obtained. We then calculate the spectra locally for six individual time periods, within which the electron density and magnetic fluctuations are simultaneously observed. It is found that the power of perpendicular magnetic fluctuations is usually higher than that of parallel magnetic fluctuations, which indicates the dominance of Alfvén waves in turbulence spectrum. Part of the observed turbulence spectra reveal that the normalized parallel magnetic power exhibits a much higher intensity than the normalized electron density power in the local interstellar medium of low to moderate plasma beta (β = 0.1-0.8). This dominance in the parallel magnetic power cannot be explained by the linear magnetohydrodynamic modes alone and may be associated with the arc/spherically polarized Alfvén mode.

Keywords: interstellar magnetic fields; magnetohydrodynamics; interstellar medium; interplanetary turbulence
MEGASIM: Lifetimes and Resonances of Earth Trojan Asteroids-The Death of Primordial ETAs?

We present an analysis of lifetimes and resonances of Earth Trojan Asteroids (ETAs) in the MEGASIM data set. Trojan asteroids co-orbit the Sun with a planet, but remain bound to the Lagrange points, L4 (60° leading the planet) or L5 (60° trailing). In the circular three-body approximation, the stability of a Trojan asteroid depends on the ratio of the host planet mass and the central mass. For the inner planets, the range of stability becomes increasingly small, so perturbations from the planets have made primordial Trojans rare. To date, there have been just two ETAs (2010 TK7 and 2020 XL5), several Mars Trojans, and a Venus Trojan discovered. The estimated lifetimes of the known inner system Trojans are shorter than a million years, suggesting they are interlopers rather than members of a stable and long-lasting population. With the largest ETA n-body simulation to date, we are able to track their survival across a wide initialized parameter space. We find that the remaining fraction of ETAs over time is well fit with a stretched exponential function that, when extrapolated beyond our simulation run time, predicts zero ETAs by 2.33 Gyr. We also show correlations between ETA ejections and the periods of the Milankovitch cycles. Though Earth's orbital dynamics dominate the instabilities of ETAs, we provide evidence that ETA ejections are linked to resonances found in the variation of the orbital elements of many if not all of the planets.

Keywords: trojan asteroids; earth trojans; n-body simulations; asteroid dynamics; orbital resonances; orbital evolution; lagrangian points