Sazuna/UAT_keywords huggingface dataset:
NuSTAR Observations of G11.2-0.3. We present in this paper the hard X-ray view of the pulsar wind nebula in G11.2-0.3 and its central pulsar powered pulsar J1811-1925 as seen by NuSTAR. We complement the data with Chandra for a more complete picture and confirm the existence of a hard, power-law component in the shell with photon index ${\rm{\Gamma }}=2.1\pm 0.1$ , which we attribute to synchrotron emission. Our imaging observations of the shell show a slightly smaller radius at higher energies, consistent with Chandra results, and we find shrinkage as a function of increased energy along the jet direction, indicating that the electron outflow in the PWN may be simpler than that seen in other young PWNe. Combining NuSTAR with INTEGRAL, we find that the pulsar spectrum can be fit by a power law with ${\rm{\Gamma }}=1.32\pm 0.07$ up to 300 keV without evidence of curvature.

Keywords: Supernova remnants, Young disk Cepheid variable stars, Rotation powered pulsars, Single x-ray stars
deepCR: Cosmic Ray Rejection with Deep Learning. Cosmic ray (CR) identification and replacement are critical components of imaging and spectroscopic reduction pipelines involving solid-state detectors. We present deepCR, a deep-learning-based framework for CR identification and subsequent image inpainting based on the predicted CR mask. To demonstrate the effectiveness of this framework, we train and evaluate models on Hubble Space Telescope (HST) ACS/WFC images of sparse extragalactic fields, globular clusters, and resolved galaxies. We demonstrate that at a false-positive rate of 0.5%, deepCR achieves close to 100% detection rates in both extragalactic and globular cluster fields, and 91% in resolved galaxy fields, which is a significant improvement over the current state-of-the-art method LACosmic. Compared with a multicore CPU implementation of LACosmic, deepCR CR mask predictions run up to 6.5 times faster on a CPU and 90 times faster on a single GPU. For image inpainting, the mean squared errors of deepCR predictions are 20 times lower in globular cluster fields, 5 times lower in resolved galaxy fields, and 2.5 times lower in extragalactic fields, compared with the best performing nonneural technique tested. We present our framework and the trained models as an open-source Python project , with a simple-to-use API. To facilitate reproducibility of the results we also provide a benchmarking codebase .

Keywords: Classification, Neural networks, Hubble Space Telescope, Convolutional neural networks, Astronomical detectors, Astronomy data reduction, Cosmic rays
OGLE-ing the Magellanic System: Cepheids in the Bridge. We present a detailed analysis of the Magellanic Bridge Cepheid sample constructed using the Optical Gravitational Lensing Experiment Collection of Variable Stars. Our updated Bridge sample contains 10 classical and 13 anomalous Cepheids. We calculate their individual distances using optical period-Wesenheit relations and construct three-dimensional maps. Classical Cepheid (CC) on-sky locations match very well neutral hydrogen and young stars distributions; thus, they add to the overall young Bridge population. In three dimensions, 8 out of 10 CCs form a bridge-like connection between the Magellanic Clouds. The other two are located slightly farther away and may constitute the Counter Bridge. We estimate ages of our Cepheids to be less than 300 Myr for from 5 up to 8 out of 10, depending on whether the rotation is included. This is in agreement with a scenario where these stars were formed in situ after the last encounter of the Magellanic Clouds. Cepheids' proper motions reveal that they are moving away from both Large and Small Magellanic Clouds. Anomalous Cepheids are more spread than CCs in both two and three dimensions, even though they form a rather smooth connection between the Magellanic Clouds. However, this connection does not seem to be bridge-like, as there are many outliers around both Magellanic Clouds.

Keywords: Cepheid variable stars, Magellanic Clouds
Detailed Abundances in the Ultra-faint Magellanic Satellites Carina II and III. We present the first detailed elemental abundances in the ultra-faint Magellanic satellite galaxies Carina II (Car II) and Carina III (Car III). With high-resolution Magellan/MIKE spectroscopy, we determined the abundances of nine stars in Car II, including the first abundances of an RR Lyrae star in an ultra-faint dwarf galaxy (UFD), and two stars in Car III. The chemical abundances demonstrate that both systems are clearly galaxies and not globular clusters. The stars in these galaxies mostly display abundance trends matching those of other similarly faint dwarf galaxies: enhanced but declining [α/Fe] ratios, iron-peak elements matching the stellar halo, and unusually low neutron-capture element abundances. One star displays a low outlying [Sc/Fe] = -1.0. We detect a large Ba scatter in Car II, likely due to inhomogeneous enrichment by low-mass asymptotic giant branch star winds. The most striking abundance trend is for [Mg/Ca] in Car II, which decreases from +0.4 to -0.4 and indicates clear variation in the initial progenitor masses of enriching core-collapse supernovae. So far, the only UFDs displaying a similar [Mg/Ca] trend are likely satellites of the Large Magellanic Cloud. We find two stars with [Fe/H] ≤ -3.5 whose abundances likely trace the first generation of metal-free Population III stars and are well fit by Population III core-collapse supernova yields. An appendix describes our new abundance uncertainty analysis that propagates line-by-line stellar parameter uncertainties.

Keywords: Local Group, Stellar abundances, Dwarf galaxies
Comparison of Kinematics of Solar Eruptive Prominences and Spatial Distribution of the Magnetic Decay Index. Theoretical studies of electric current instability explaining solar prominence eruptions show that the loss of equilibrium may develop in a case when the surrounding magnetic field decreases sufficiently rapidly with height. The magnetic decay index, a parameter indicating whether the external magnetic field has a configuration that may lead to a certain type of electric current instability, is a useful instrument for predicting the behavior of prominences. In our study, we consider three eruptive prominences. We perform potential-field extrapolation to obtain the spatial distribution of the magnetic decay index in the coronal space identified with the prominences. Analysis of time-dependent height profiles of the prominences revealed that eruptions started at heights close to those, where the computed magnetic decay index exceeded a value equal to 1.5. This indicates that the torus instability is a possible mechanism of the considered eruptive events.

Keywords: Solar magnetic fields, Eruptive phenomena, Solar prominences
Three-dimensional Dissipative Pulsar Magnetospheres with Aristotelian Electrodynamics. A good compromise between the resistive model and the particle-in-cell model is Aristotelian electrodynamics, which can include the back-reaction of the radiative photons onto particle motion and allow for a local dissipation where the force-free condition is violated. We study the dissipative pulsar magnetosphere with Aristotelian electrodynamics where particle acceleration is fully balanced by radiation. The expression for the current density is defined by introducing a pair multiplicity. The 3D structure of the pulsar magnetosphere is then presented by solving the time-dependent Maxwell equations using a pseudo-spectral algorithm. It is found that the dissipative magnetosphere approaches the force-free solution and the dissipative region is more restricted to the current sheet outside the light cylinder (LC) as the pair multiplicity increases. The spatial extension of the dissipative region is self-consistently controlled by the pair multiplicity. Our simulations show the high magnetospheric dissipation outside the LC for the low pair multiplicity.

Keywords: Magnetohydrodynamical simulations, Magnetic fields, Pulsars
Two-zone Spatially Dependent Model of the Nonthermal Emission from Plerionic Supernova Remnant G21.5-0.9. Observations of plerionic supernova remnant (SNR) G21.5-0.9 indicate an extended X-ray halo surrounding the bright central pulsar wind nebula (PWN), and that the photon index and the surface brightness of the SNR have been discovered to change with the increase of radial distance in the X-ray band. To explain the observational features of this source, a two-zone spatially dependent model with a slow diffusion in the PWN and a fast diffusion in the extended region is proposed in this paper. In the model, the evolution of electron inside the entire remnant is described with a particle transport equation under the assumption of a spherically symmetric system with dynamical evolution. The observed photon spectral energy distribution of the central PWN, as well as the radial profiles of the photon index and surface brightness observed in the X-ray band of the entire remnant, can be well reproduced in the framework of the model. The modeling results reveal that the X-ray halo of SNR G21.5-0.9 is mainly due to the synchrotron radiation of the accelerated electrons derived from the PWN shock, and the current diffusion coefficient in the extended region has a value of 1.7 × 1028 cm2 s-1 at an electron energy of 1 TeV, which is much larger than the obtained spatial averaged diffusion coefficient of 2.5 × 1025 cm2 s-1 in the central nebula.

Keywords: Supernova remnants, Interstellar medium, Pulsars
PopSyCLE: A New Population Synthesis Code for Compact Object Microlensing Events. We present a new Milky Way microlensing simulation code, dubbed PopSyCLE (Population Synthesis for Compact object Lensing Events). PopSyCLE is the first resolved microlensing simulation to include a compact object distribution derived from numerical supernova explosion models and both astrometric and photometric microlensing effects. We demonstrate the capabilities of PopSyCLE by investigating the optimal way to find black holes (BHs) with microlensing. Candidate BHs have typically been selected from wide-field photometric microlensing surveys, such as OGLE, by selecting events with long Einstein crossing times (tE &gt; 120 days). These events can be selected at closest approach and monitored astrometrically in order to constrain the mass of each lens; PopSyCLE predicts a BH detection rate of ∼40% for such a program. We find that the detection rate can be enhanced to ∼85% by selecting events with both tE &gt; 120 days and a microlensing parallax of πE &lt; 0.08. Unfortunately, such a selection criterion cannot be applied during the event, as πE requires both pre- and post-peak photometry. However, historical microlensing events from photometric surveys can be revisited using this new selection criterion in order to statistically constrain the abundance of BHs in the Milky Way. The future Wide Field Infrared Survey Telescope (WFIRST) microlensing survey provides both precise photometry and astrometry and will yield individual masses of ${ \mathcal O }(100\mbox{--}1000)$ BHs, which is at least an order of magnitude more than is possible with individual candidate follow-up with current facilities. The resulting sample of BH masses from WFIRST will begin to constrain the shape of the BH present-day mass function, BH multiplicity, and BH kick velocity distributions.

Keywords: Gravitational microlensing, Stellar remnants, Stellar mass black holes
No Significant Evolution of Relations between Black Hole Mass and Galaxy Total Stellar Mass Up to z ∼ 2.5. We investigate the cosmic evolution of the ratio between black hole (BH) mass (MBH) and host galaxy total stellar mass (Mstellar) out to z ∼ 2.5 for a sample of 100 X-ray-selected moderate-luminosity, broad-line active galactic nuclei (AGNs) in the Chandra-COSMOS Legacy Survey. By taking advantage of the deep multiwavelength photometry and spectroscopy in the COSMOS field, we measure in a uniform way the galaxy total stellar mass using an spectral energy distribution decomposition technique and the BH mass based on broad emission line measurements and single-epoch virial estimates. Our sample of AGN host galaxies has total stellar masses of 1010-12M⊙, and BH masses of 107.0-9.5M⊙. Combining our sample with the relatively bright AGN samples from the literature, we find no significant evolution of the MBH-Mstellar relation with the BH-to-host total stellar mass ratio of MBH/Mstellar ∼ 0.3% at all redshifts probed. We conclude that the average BH-to-host stellar mass ratio appears to be consistent with the local value within the uncertainties, suggesting a lack of evolution of the MBH-Mstellar relation up to z ∼ 2.5.

Keywords: AGN host galaxies, Black holes, Active galaxies, Active galactic nuclei, Galaxy evolution, X-ray active galactic nuclei
Population Synthesis of Helium White Dwarf-Red Giant Star Mergers and the Formation of Lithium-rich Giants and Carbon Stars. The formation histories of lithium-rich and carbon-rich red giants are not yet understood. It has been proposed that the merger of a helium-core white dwarf with a red giant branch (RGB) star might provide a solution. We have computed an extended grid of post-merger evolution models and combined these with predictions of binary-star population synthesis. The results strongly support the proposal that the merger of a helium white dwarf with an RGB star can provide the progenitors of both lithium-rich red clump stars and early-R carbon stars. The distribution of post-merger models in Teff, log g, log L, the surface abundances of lithium and carbon, and the predicted space densities agree well with the observed distributions of these parameters for Li-rich and early-R stars in the Galaxy.

Keywords: Binary stars, Red giant clump, Stellar abundances, White dwarf stars, Carbon stars, Stellar evolutionary models, Stellar physics, Red giant stars, Lithium stars, Asteroseismology, Chemically peculiar stars, Stellar evolution
Electron-capture Supernovae of Super-AGB Stars: Sensitivity on Input Physics. Stars of M ∼ 8-10 M⊙ on their main sequence form strongly electron-degenerate oxygen-neon-magnesium (ONeMg) cores and become super-asymptotic giant branch stars. If such an ONeMg core grows to 1.38 M⊙, electron captures on 20Ne(e, νe)20F(e, νe)20O take place and ignite O-Ne deflagration around the center. In this work, we perform two-dimensional hydrodynamical simulations of the propagation of the O-Ne flame to see whether such a flame triggers a thermonuclear explosion or induces a collapse of the ONeMg core due to subsequent electron capture behind the flame. We present a series of models to explore how the outcome depends on model parameters for a central density ranging between 109.80 and 1010.20 g cm-3, flame structures of both centered and off-centered ignition kernels, special and general relativistic effects, turbulent flame speed formulae, and the treatments of laminar burning phase. We obtain bifurcation between the electron-capture induced collapse and thermonuclear explosion depending mainly on the central density. We find that the ONeMg core obtained from stellar evolutionary models has a high tendency to collapse into a neutron star. We discuss the implications of the electron-capture supernovae in chemical evolution and the possible observational signals of this class of supernovae.

Keywords: Neutron stars, Hydrodynamical simulations, Asymptotic giant branch stars, Supernovae
Reconstruction of Plasma Structure with Anisotropic Pressure: Application to Pc5 Compressional Wave. The conventional Grad-Shafranov (GS) method is designed to reconstruct a two-dimensional magnetohydrostatic structure with isotropic pressure. In this work, we developed a new GS solver (GS-like) that includes the effect of pressure anisotropy based on reduced equations from Sonnerup et al. The new GS solver is benchmarked, and the results are compared with two other GS solvers based on the conventional GS method and that from Teh. This solver is applied to reconstruct a Pc5 compressional wave event, which has mirror-like features and includes a significant pressure anisotropy (p⊥/p∥ ~ 1.5, where p⊥ and p∥ are the thermal pressures perpendicular and parallel to the magnetic field), observed by the Magnetospheric Multiscale mission in the duskside outer magnetosphere on 2015 September 19. The recovered maps indicate that, within some model constraints, the wave in the selected time interval consists of two magnetic bottle-like structures, each with an azimuthal size of about 9000 km (wavenumber ~44) and a larger field-aligned size. The spacecraft passed through the bottles at ~1600 km southward of the bottle centers. Further multispacecraft measurements revealed that the Pc5 compressional wave propagates sunward along with the background plasma and retains the bottle-like structures, driven mainly by the ion diamagnetic currents. The reconstructed magnetic topology is similar to that described in previous empirical or theoretical antisymmetric standing wave models. This Pc5 compressional wave is possibly driven by drift-mirror-like instabilities.

Keywords: Planetary magnetospheres, Space plasmas
An Optimized Radio Follow-up Strategy for Stripped-envelope Core-collapse Supernovae. Several ongoing or planned synoptic optical surveys are offering, or will soon be offering, an unprecedented opportunity for discovering larger samples of the rarest types of stripped-envelope core-collapse supernovae, such as those associated with relativistic jets, mildly relativistic ejecta, or strong interaction with the circumstellar medium. Observations at radio wavelengths are a useful tool to probe the fastest moving ejecta, as well as denser circumstellar environments, and can thus help us identify the rarest type of core-collapse explosions. Here, we discuss how to set up an efficient radio follow-up program to detect and correctly identify radio-emitting stripped-envelope core-collapse explosions. We use a method similar to the one described in Carbone &amp; Corsi, and determine the optimal timing of GHz radio observations assuming a sensitivity comparable to that of the Karl G. Jansky Very Large Array. The optimization is done so as to ensure that the collected radio observations can identify the type of explosion powering the radio counterpart by using the smallest possible amount of telescope time. We also present a previously unpublished upper limit on the late-time radio emission from supernova iPTF 17cw. Finally, we conclude by discussing implications for follow-up in the X-rays.

Keywords: High energy astrophysics, Radio astronomy, Core-collapse supernovae, Astronomical simulations
The Dearth of Differences between Central and Satellite Galaxies. III. Environmental Dependencies of Mass-Size and Mass-Structure Relations. As demonstrated in Paper I, the quenching properties of central and satellite galaxies are quite similar as long as both stellar mass and halo mass are controlled. Here, we extend the analysis to the size and bulge-to-total light ratio (B/T) of galaxies. In general, central galaxies have size-stellar mass and B/T-stellar mass relations different from satellites. However, the differences are eliminated when halo mass is controlled. We also study the dependence of size and B/T on halo-centric distance and find a transitional stellar mass ( ${M}_{* ,{\rm{t}}}$ ) at given halo mass (Mh), which is about one-fifth of the mass of the central galaxies in halos of mass Mh. The transitional stellar masses for size, B/T and quenched fraction are similar over the whole halo mass range, suggesting a connection between the quenching of star formation and the structural evolution of galaxies. Our analysis further suggests that the classification based on the transitional stellar mass is more fundamental than the central-satellite dichotomy, and provides a more reliable way to understand the environmental effects on galaxy properties. We compare the observational results with the hydrodynamical simulation, EAGLE, and the semianalytic model, L-GALAXIES. The EAGLE simulation successfully reproduces the similarities of size for centrals, satellites, and even ${M}_{* ,{\rm{t}}}$ , while L-GALAXIES fails to recover the observational results.

Keywords: Galaxy clusters, Galaxy environments, Galaxy bulges, Galaxy structure, Galaxies
The NANOGrav 11 yr Data Set: Limits on Gravitational Wave Memory. The mergers of supermassive black hole binaries (SMBHBs) promise to be incredible sources of gravitational waves (GWs). While the oscillatory part of the merger gravitational waveform will be outside the frequency sensitivity range of pulsar timing arrays, the nonoscillatory GW memory effect is detectable. Further, any burst of GWs will produce GW memory, making memory a useful probe of unmodeled exotic sources and new physics. We searched the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) 11 yr data set for GW memory. This data set is sensitive to very low-frequency GWs of ∼3 to 400 nHz (periods of ∼11 yr-1 month). Finding no evidence for GWs, we placed limits on the strain amplitude of GW memory events during the observation period. We then used the strain upper limits to place limits on the rate of GW memory causing events. At a strain of 2.5 × 10-14, corresponding to the median upper limit as a function of source sky position, we set a limit on the rate of GW memory events at &lt;0.4 yr-1. That strain corresponds to an SMBHB merger with reduced mass of ηM ∼ 2 × 1010 ${M}_{\odot }$ and inclination of ι = π/3 at a distance of 1 Gpc. As a test of our analysis, we analyzed the NANOGrav 9 yr data set as well. This analysis found an anomolous signal, which does not appear in the 11 yr data set. This signal is not a GW, and its origin remains unknown.

Keywords: Astronomy data analysis, Gravitational waves, Millisecond pulsars
A New Implementation of the Schwarzchild Method for Constructing Observationally Driven Dynamical Models of Galaxies of All Morphological Types. We present Forstand, a new code for constructing dynamical models of galaxies with the Schwarzschild orbit-superposition method. These models are constrained by line-of-sight kinematic observations and applicable to galaxies of all morphological types, including disks and triaxial rotating bars. Our implementation has several novel and improved features, is computationally efficient, and has been made publicly available. Using mock data sets taken from N-body simulations, we demonstrate that the pattern speed of a bar can be recovered with an accuracy of 10-20%, regardless of orientation, if the 3D shape of the galaxy is known or inferred correctly.

Keywords: Galaxy structure, Galaxy dynamics