Sazuna/UAT_keywords huggingface dataset:
Diversity of Dark Matter Density Profiles in the Galactic Dwarf Spheroidal Satellites. The core-cusp problem is one of the controversial issues in the standard paradigm of Λ cold dark matter (ΛCDM) theory. However, under the assumption of conventional spherical symmetry, the strong degeneracy among model parameters makes it unclear whether dwarf spheroidal (dSph) galaxies indeed have cored dark matter density profiles at their centers. In this work, we revisit this problem using nonspherical mass models, which have the advantage of being able to alleviate the degeneracy. Applying our mass models to the currently available kinematic data of the eight classical dSphs, we find that within finite uncertainties, most of these dSphs favor cusped central profiles rather than cored ones. In particular, Draco has a cusped dark matter halo with high probability even considering a prior bias. We also find the diversity of the inner slopes in their dark matter halos. To clarify the origin of this diversity, we investigate the relation between the inner dark matter density slope and stellar-to-halo mass ratio for the sample dSphs and find that this relation is generally in agreement with the predictions from recent ΛCDM and hydrodynamical simulations. We also find that the simulated subhalos have an anticorrelation between the dark matter density at 150 pc and pericenter distance, which is consistent with the observed one. We estimate their astrophysical factors for dark matter indirect searches and circular velocity profiles associated with huge uncertainties. To more precisely estimate their dark matter profiles, wide-field spectroscopic surveys for the dSphs are essential.

Keywords: Local Group, Galaxy dynamics, Galaxy structure, Galaxy kinematics, Dwarf spheroidal galaxies, Dark matter
Analytical and Numerical Studies of Central Galactic Outflows Powered by Tidal Disruption Events: A Model for the Fermi Bubbles?. Capture and tidal disruption of stars by the supermassive black hole in the Galactic center (GC) should occur regularly. The energy released and dissipated by these processes will affect both the ambient environment of the GC and the Galactic halo. The single star of a super-Eddington eruption generates a subsonic outflow with an energy release of more than 1052 erg, which still is not high enough to push shock heated gas into the halo. Only routine tidal disruption of stars near the GC can provide enough cumulative energy to form and maintain large-scale structures like the Fermi Bubbles. The average rate of disruption events is expected to be 10-4 ∼ 10-5 yr-1, providing the average power of energy release from the GC into the halo of $\dot{W}\sim 3\times {10}^{41}$ erg s-1, which is needed to support the Fermi Bubbles. The GC black hole is surrounded by molecular clouds in the disk, but their overall mass and filling factor are too low to significantly stall the shocks from tidal disruption events. The de facto continuous energy injection on timescales of megayears will lead to the propagation of strong shocks in a density stratified Galactic halo and thus create elongated bubble-like features that are symmetric to the Galactic midplane.

Keywords: Galactic winds, Galactic center, Cosmic rays, Tidal disruption, Interstellar clouds, Gamma-rays, Superbubbles
Zero Net Flux MRI Turbulence in Disks: Sustenance Scheme and Magnetic Prandtl Number Dependence. We investigate sustenance and dependence on magnetic Prandtl number (Pm) for magnetorotational instability (MRI)-driven turbulence in Keplerian disks with zero net magnetic flux using standard shearing box simulations. We focus on the turbulence dynamics in Fourier space, capturing specific/noncanonical anisotropy of nonlinear processes due to disk flow shear. This is a new type of nonlinear redistribution of modes over wavevector orientations in Fourier space—the nonlinear transverse cascade—which is generic to shear flows and fundamentally different from the usual direct/inverse cascade. The zero flux MRI has no exponentially growing modes, so its growth is transient, or nonmodal. Turbulence self-sustenance is governed by constructive cooperation of the transient growth of MRI and the nonlinear transverse cascade. This cooperation takes place at small wavenumbers (on the flow size scales) referred to as the vital area in Fourier space. The direct cascade transfers mode energy from the vital area to larger wavenumbers. At large Pm, the transverse cascade prevails over the direct one, keeping most of modes' energy contained in small wavenumbers. With decreasing Pm, however, the action of the transverse cascade weakens and can no longer oppose the action of the direct cascade, which more efficiently transfers energy to higher wavenumbers, leading to increased resistive dissipation. This undermines the sustenance scheme, resulting in the turbulence decay. Thus, the decay of zero net flux MRI turbulence with decreasing Pm is attributed to the topological rearrangement of the nonlinear processes when the direct cascade begins to prevail over the transverse cascade.

Keywords: Magnetohydrodynamics, High energy astrophysics, Interplanetary turbulence, Plasma astrophysics, Protoplanetary disks, Stellar accretion disks, Magnetic fields
Robustness of the Pairwise Kinematic Sunyaev-Zeldovich Power Spectrum Shape as a Cosmological Gravity Probe. We prove from the modified gravity (MG) galaxy/halo mock catalogs that the shape of the pairwise kinematic Sunyaev-Zeldovich (kSZ) power spectrum PkSZ has constraining power on discriminating different gravity theories on cosmological scales. By varying the effective optical depth τT as a free parameter, we verify that the τT-f (the linear growth rate) degeneracy in the linear theory of PkSZ is broken down by the nonlinear structure growth and the scale dependence of f in some MG theories. Equivalently speaking, the shape of PkSZ alone could be used to tightly constrain the MG theories on cosmological scales. With good knowledge of galaxy density biases, we verify that a combination of the next-generation galaxy spectroscopic redshift and CMB surveys, e.g., BOSS+CMB-S4 or DESI+CMB-S4, could potentially discriminate f(R) models from the general relativity at the ∼5σ level using the shape of the galaxy pairwise kSZ dipole PkSZ,ℓ = 1 alone, when fR0 = 10-4.

Keywords: Cosmological parameters from large-scale structure, Sunyaev-Zeldovich effect, Dark matter, Dark energy
A New Candidate Transitional Millisecond Pulsar in the Subluminous Disk State: 4FGL J0407.7-5702. We report the discovery of a variable optical and X-ray source within the error ellipse of the previously unassociated Fermi Large Area Telescope γ-ray source 4FGL J0407.7-5702. A 22 ks observation from XMM-Newton/European Photon Imaging Camera (EPIC) shows an X-ray light curve with rapid variability and flaring. The X-ray spectrum is well fit by a hard power law with Γ = 1.7. Optical photometry taken over several epochs is dominated by aperiodic variations of moderate amplitude. Optical spectroscopy with Southern Astrophysical Research (SOAR) and Gemini reveals a blue continuum with broad and double-peaked H and He emission, as expected for an accretion disk around a compact binary. Overall, the optical, X-ray, and γ-ray properties of 4FGL J0407.7-5702 are consistent with a classification as a transitional millisecond pulsar in the subluminous disk state. We also present evidence that this source is more distant than other confirmed or candidate transitional millisecond pulsar binaries, and that the ratio of X-ray to γ-ray flux is a promising tool to help identify such binaries, indicating that a more complete census for these rare systems is becoming possible.

Keywords: Neutron stars, Gamma-rays
SuperBoRG: Exploration of Point Sources at z ∼ 8 in HST Parallel Fields. To extend the search for quasars in the epoch of reionization beyond the tip of the luminosity function, we explore point-source candidates at redshift z ∼ 8 in SuperBoRG, a compilation of ∼0.4 deg2 archival medium-deep (mF160W ∼ 26.5 ABmag, 5σ) parallel infrared (IR) images taken with the Hubble Space Telescope (HST). Initial candidates are selected by using the Lyman-break technique. We then carefully analyze source morphology, and robustly identify three point sources at z ∼ 8. Photometric redshift analysis reveals that they are preferentially fit by extragalactic templates, and we conclude that they are unlikely to be low-z interlopers, including brown dwarfs. A clear IRAC ch2 flux excess is seen in one of the point sources, which is expected if the source has strong Hβ+[O III] emission with a rest-frame equivalent width of ∼3000 Å. Deep spectroscopic data taken with Keck/MOSFIRE, however, do not reveal Lyα emission from the object. In combination with the estimated Hβ+[O III] equivalent width, we place an upper limit on its Lyα escape fraction of ${f}_{\mathrm{esc},\mathrm{Ly}\alpha }\lesssim 2 \% $ . We estimate the number density of these point sources as ∼1 × 10-6 Mpc-3 mag-1 at MUV ∼ -23 mag. The final interpretation of our results remains inconclusive: extrapolation from low-z studies of faint quasars suggests that ≳100× survey volume may be required to find one of this luminosity. The James Webb Space Telescope will be able to conclusively determine the nature of our luminous point-source candidates, while the Roman Space Telescope will probe ∼200 times the area of the sky with the same observing time considered in this HST study. * Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555 (doi:10.17909/t9-m7tx-qb86).

Keywords: Galaxy formation, Lyman-break galaxies, Galaxy evolution, Quasars
Testing the Strong Equivalence Principle: Detection of the External Field Effect in Rotationally Supported Galaxies. The strong equivalence principle (SEP) distinguishes general relativity (GR) from other viable theories of gravity. The SEP demands that the internal dynamics of a self-gravitating system under freefall in an external gravitational field should not depend on the external field strength. We test the SEP by investigating the external field effect (EFE) in Milgromian dynamics (MOND), proposed as an alternative to dark matter in interpreting galactic kinematics. We report a detection of this EFE using galaxies from the Spitzer Photometry and Accurate Rotation Curves (SPARC) sample together with estimates of the large-scale external gravitational field from an all-sky galaxy catalog. Our detection is threefold: (1) the EFE is individually detected at 8σ to 11σ in "golden" galaxies subjected to exceptionally strong external fields, while it is not detected in exceptionally isolated galaxies, (2) the EFE is statistically detected at more than 4σ from a blind test of 153 SPARC rotating galaxies, giving a mean value of the external field consistent with an independent estimate from the galaxies' environments, and (3) we detect a systematic downward trend in the weak gravity part of the radial acceleration relation at the right acceleration predicted by the EFE of the MOND modified gravity. Tidal effects from neighboring galaxies in the Λ cold dark matter (CDM) context are not strong enough to explain these phenomena. They are not predicted by existing ΛCDM models of galaxy formation and evolution, adding a new small-scale challenge to the ΛCDM paradigm. Our results point to a breakdown of the SEP, supporting modified gravity theories beyond GR.

Keywords: Gravitation, Non-standard theories of gravity, Modified Newtonian dynamics, Disk galaxies
The Distant, Galaxy Cluster Environment of the Short GRB 161104A at z ∼ 0.8 and a Comparison to the Short GRB Host Population. We present optical observations of the Swift short-duration gamma-ray burst (GRB) GRB 161104A and its host galaxy at z = 0.793 ± 0.003. We model the multiband photometry and spectroscopy with the stellar population inference code Prospector and explore the posterior using nested sampling. We find a mass-weighted age of tm = 2.12+0.23-0.21 Gyr, stellar mass of $\mathrm{log}(M/{M}_{\odot })=10.21\pm 0.04$ , metallicity of $\mathrm{log}(Z/{Z}_{\odot })={0.08}_{-0.06}^{+0.05}$ , dust extinction of AV = 0.08+0.08-0.05, and low star formation rate of 9.9 × 10-2 M☉ yr-1. These properties, along with a prominent 4000 Å break and optical absorption lines, classify this host as an early-type, quiescent galaxy. Using Dark Energy Survey galaxy catalogs, we demonstrate that the host of GRB 161104A resides on the outskirts of a galaxy cluster at z ≍ 0.8, situated ≍1 Mpc from the likely brightest cluster galaxy. We also present new modeling for 20 additional short GRB hosts (≍33% of which are early-type galaxies), finding population medians of $\mathrm{log}(M/{M}_{\odot })={9.94}_{-0.98}^{+0.88}$ and tm = 1.07+1.98-0.67 Gyr (68% confidence). We further find that the host of GRB 161104A is more distant, less massive, and younger than the four other short GRB hosts known to be associated with galaxy clusters. Cluster short GRBs have faint afterglows, in the lower ≍11% (≍30%) of observed X-ray (optical) luminosities. We place a lower limit on the fraction of short GRBs in galaxy clusters versus those in the field of ≍5%-13%, consistent with the fraction of stellar mass of ≍10%-20% in galaxy clusters at redshifts 0.1 ≤ z ≤ 0.8. Future studies that take advantage of wider-field and deeper cluster surveys are needed to understand the true rate of short GRBs in clusters and their effect on heavy-element enrichment in the intracluster medium.

Keywords: Galaxy clusters, Gamma-ray bursts, High energy astrophysics, Galaxy environments
Revealing the Spectroscopic Variations of FU Orionis Object V960 Mon with High-resolution Spectroscopy. We present the results of the high-resolution spectroscopy of the FU Orionis-type star V960 Mon. The brightness of V960 Mon decreased continuously after the outburst was detected in 2014 November. During this dimming event, we carried out medium-resolution spectroscopic monitoring observations and found that the equivalent width of the absorption features showed variations. To further investigate the spectroscopic variations, we conducted a high-resolution spectroscopic observation of V960 Mon with the Subaru Telescope and the High Dispersion Spectrograph on 2018 January 8 and 2020 February 1. By comparing this spectrum with the archival data of the Keck Observatory and the High Resolution Echelle Spectrometer taken between 2014 and 2017, we found that the absorption profiles changed as V960 Mon faded. The line profile of absorption lines such as Fe I and Ca I can be explained by a sum of the spectra of the disk atmosphere and the central star. The model spectrum created to explain the variations of the line profiles suggests that the effective temperature of the central star is ∼5500 K, which is comparable to that of the pre-outburst phase with a distance of 1.6 kpc with Gaia. The spectrum also shows that the effective temperature of the disk atmosphere decreased as V960 Mon faded. The variations of the Hα and Ca II lines (8498.0, 8542.1 Å) also show that the V960 Mon spectrum became central-star dominant.

Keywords: Pre-main sequence stars, Star formation, Protoplanetary disks
An Analysis of the North Polar Spur Using HaloSat. We present HaloSat X-ray observations of the entirety of the bright X-ray emitting feature known as the North Polar Spur (NPS). The large field of view of HaloSat enabled coverage of the entire bright NPS in only 14 fields, which were each observed for ≍30,000 s. We find that the NPS fields are distinct in both brightness and spectral shape from the surrounding halo fields. We fit the NPS as two thermal components in ionization equilibrium with temperatures ${\text{}}{{kT}}_{\mathrm{cool}}\approx 0.087\,{keV}$ and ${\text{}}{{kT}}_{\mathrm{hot}}\approx 0.28\,{keV}$ . We note a temperature gradient in the NPS hot component with an inner arc temperature warmer than the outer arc. The emission measures we find for the cool component of the NPS is a factor of 3-5 greater than that of the hot component, which suggests that the bulk of the NPS material is in the ≍0.1 keV component. We evaluate distance estimates of 0.4 and 8.0 kpc for the NPS. Our findings suggest a preference for a distant NPS with an energy of ≍ 6 × 1054 erg, an age of ≍ 10 Myr, and pressures consistent with a 10μG magnetic field associated with the Fermi bubbles. The electron density ≍10 × 10-3 cm-3 is consistent with estimates for the shock region surrounding a Galactic-scale event.

Keywords: X-ray astronomy, Superbubbles, Interstellar medium, Diffuse x-ray background
An Investigation of Fragmentation in the Disk Instability Model for Giant Planet Formation. We investigate a few issues regarding fragmentation in the disk instability model for giant planet formation—specifically, initial clump mass (Mp), fragmentation region, and fragmentation starting time, ending time, and duration. By running calculations over a wide parameter space and using an evolutionary model of protoplanetary disks, we study dependence on properties of the parent cloud core of the protostar+disk system. We investigate evolution of Mp-R relationship for clumps forming at different times during the disk evolution. We find that, in general, for the same radius, Mp changes slightly with time, first decreasing and then increasing. In different disks, for the same radius, Mp does not change significantly with ω, decreases with MMCC, and increases with TMCC, where ω, MMCC, and TMCC are angular velocity, mass, and temperature of a parent core. Fragmentation might occur most probably at 20-200 au, at 200-450 au with less probability, and at &gt;450 au with small probability. Mp might be most probably between 3-35MJ, between 35-80MJ with less probability, and &gt;80MJ with small probability. The ranges of the fragmentation starting time, ending time, and duration are (1-3) × 105 yr, $(2\mbox{--}25)\times {10}^{5}\,\mathrm{yr}$ , and $(0.1\mbox{--}25)\times {10}^{5}\,\mathrm{yr}$ , respectively. We derive an analytical formula that shows dependence of ${M}_{{\rm{p}}}$ on disk properties and can be used to understand numerical calculations. We tentatively use our calculations to understand exoplanet observations.

Keywords: Exoplanet formation, Solar system formation, Exoplanet systems, Planet formation
Stars Stripped in Binaries: The Living Gravitational-wave Sources. Binary interaction can cause stellar envelopes to be stripped, which significantly reduces the radius of the star. The orbit of a binary composed of a stripped star and a compact object can therefore be so tight that the gravitational radiation the system produces reaches frequencies accessible to the Laser Interferometer Space Antenna (LISA). Two such stripped stars in tight orbits with white dwarfs are known so far (ZTF J2130+4420 and CD-30°11223), but many more are expected to exist. These binaries provide important constraints for binary evolution models and may be used as LISA verification sources. We develop a Monte Carlo code that uses detailed evolutionary models to simulate the Galactic population of stripped stars in tight orbits with either neutron star or white dwarf companions. We predict 0-100 stripped star + white dwarf binaries and 0-4 stripped star + neutron star binaries with a signal-to-noise ratio &gt;5 after 10 yr of observations with LISA. More than 90% of these binaries are expected to show large radial velocity shifts of ≳200 $\,\mathrm{km}\,{{\rm{s}}}^{-1}$ , which are spectroscopically detectable. Photometric variability due to tidal deformation of the stripped star is also expected and has been observed in ZTF J2130+4420 and CD-30°11223. In addition, the stripped star + neutron star binaries are expected to be X-ray bright with LX ≳ 1033-1036 $\,\mathrm{erg}\,{{\rm{s}}}^{-1}$ . Our results show that stripped star binaries are promising multimessenger sources for the upcoming electromagnetic and gravitational wave facilities.

Keywords: X-ray binary stars, Compact binary stars, Interacting binary stars, Gravitational wave sources, Ellipsoidal variable stars, Radial velocity, Common envelope binary stars
Two Candidate High-redshift X-Ray Jets without Coincident Radio Jets. We report the detection of extended X-ray emission from two high-redshift radio quasars. These quasars, J1405+0415 at z = 3.208 and J1610+1811 at z = 3.118, were observed in a Chandra snapshot survey selected from a complete sample of the radio-brightest quasars in the overlap area of the VLA-FIRST radio survey and the Sloan Digital Sky Survey. The extended X-ray emission is located along the line connecting the core to a radio knot or hotspot, favoring the interpretation of X-ray jets. The inferred rest-frame jet X-ray luminosities from 2 to 30 keV would be of order 1045 erg s-1 if emitted isotropically and without relativistic beaming. In the scenario of inverse Compton scattering of the cosmic microwave background (CMB), X-ray jets without a coincident radio counterpart may be common, and should be readily detectable to redshifts even beyond 3.2 due to the (1+z)4 increase of the CMB energy density compensating for the (1+z)-4 cosmological diminution of surface brightness. If these can be X-ray confirmed, they would be the second and third examples of quasar X-ray jets without detection of underlying continuous radio jets.

Keywords: Galaxy jets, Radio loud quasars, X-ray quasars, X-ray active galactic nuclei, Non-thermal radiation sources
The Effect of Supernovae on the Turbulence and Dispersal of Molecular Clouds. We study the impact of supernovae on individual molecular clouds, using a high-resolution magnetohydrodynamic simulation of a 250 pc region where we resolve the formation of individual massive stars. The supernova feedback is implemented with real supernovae, meaning supernovae that are the natural evolution of the resolved massive stars, so their position and timing are self-consistent. We select a large sample of molecular clouds from the simulation to investigate the supernova energy injection and the resulting properties of molecular clouds. We find that molecular clouds have a lifetime of a few dynamical times, less than half of them contract to the point of becoming gravitationally bound, and the dispersal time of bound clouds of order one dynamical time is a factor of 2 shorter than that of unbound clouds. We stress the importance of internal supernovae, that is, massive stars that explode inside their parent cloud, in setting the cloud dispersal time, and their huge overdensity compared to models where the supernovae are randomly distributed. We also quantify the energy injection efficiency of supernovae as a function of supernova distance to the clouds. We conclude that intermittent driving by supernovae can maintain molecular cloud turbulence and may be the main process for cloud dispersal and that the full role of supernovae in the evolution of molecular clouds cannot be fully accounted for without a self-consistent implementation of the supernova feedback.

Keywords: Magnetohydrodynamics, Molecular clouds, Supernova remnants, Giant molecular clouds, Computational methods