Sazuna/UAT_keywords huggingface dataset:
Multiple Shock Fronts in RBS 797: The Chandra Window on Shock Heating in Galaxy Clusters. Using ~427 ks of Chandra observations, we present a study of shock heating and intracluster medium (ICM) cooling in the galaxy cluster RBS 797. We discover three nested pairs of weak shocks at roughly 50, 80, and 130 kpc from the center. The total energy associated with the shocks is ~6 × 1061 erg, with the central active galactic nucleus (AGN) driving a pair of weak shocks every 20-30 Myr with a power P sh ≈ 1046 erg s-1. Based on its morphology and age (~30 Myr), the inner cocoon shock is associated with the four equidistant X-ray cavities previously discovered. From the thermodynamic analysis of the inner 30 kpc, we find evidence for ICM condensation into colder gas between and behind the X-ray cavities. The total AGN mechanical power (cavities and shocks) of 3.4 × 1046 erg s-1 can balance the ICM radiative losses, estimated as L cool = 2.3 × 1045 erg s-1. By building plots of P cav versus L cool, P shock versus L cool, and P tot versus L cool for RBS 797 and 14 other galaxy clusters, galaxy groups, and elliptical galaxies where both cavities and shocks are detected, we verify that the most powerful outbursts are found in the strongest cooling systems. Ultimately, we observe that the mechanical power of the AGN exceeds the gas radiative losses by a factor that is different for FR I and FR II radio galaxies, being less than a few tens for FR Is (as RBS 797) and more than roughly 100 for FR IIs.

Keywords: Galaxy clusters, Cooling flows, Radio galaxies, Active galactic nuclei, Fanaroff-Riley radio galaxies, Intracluster medium
A Broad-line Quasar with Unexplained Extreme Velocity Offsets: Post-shock Outflow?. The quasar SDSS 0956 + 5128 exhibits three distinct velocity components with large offsets in emission: the systemic velocity of [O II], [O III], and [Ne III] narrow lines have redshift z = 0.7142; the broad Mg II line is shifted by -1200 km s-1 with respect to the narrow lines; the broad Hα and Hβ lines are at -4100 km s-1. We present new Hubble Space Telescope spectra of Lyα and C IV emission lines and high-resolution images of the quasar. The offsets of these lines are consistent with the velocity component of the Balmer emission, and the photometry in optical and near-infrared wavelengths does not show any signs of recent mergers in the host galaxy or irregularities in the location of the quasar. The data do not confirm predictions of the previous most likely hypotheses involving a special orientation and morphology of the quasar disk, such as in the recoiling black hole scenario, neither it is consistent with accretion disk winds. Instead, based on the cumulative evidence, we propose a new scenario, in which the broad-line region is in the state of outflow caused by a strong shock wave, with a supernova as a possible event for producing the shock ejecta.

Keywords: Shocks, Supernovae, Quasars
Temporal and Latitudinal Variations in Ca-K Plage and Network Area: An Implication for Meridional Flows. The Ca-K spectroheliograms obtained at the Kodaikanal observatory are used to generate a uniform time series using the equal-contrast technique for studying the long- and short-term variations in the solar chromosphere. The percentages of plage, enhanced network, and active and quiet network areas at various latitudes is compared with the activity at 35° latitude and also with the sunspot number for the period of 1907-1984. The values of the phase differences indicate that the activity begins at ~45° latitude and shifts progressively to a lower latitude at a speed of ~9.4 m s-1 . The shift speed slows down gradually and reaches ~3 m s-1 at ~5° latitude. No phase difference between the variations of Ca-K activity at 55°, 65°, and 75° latitude belts implies that changes in the activity are happening simultaneously. The analysis shows that the activity at polar latitude belts is anticorrelated with the sunspot number. This study indicates that a multicell meridional flow pattern could exist in the latitude direction. One type of cell could transport the magnetic elements from mid- to low-latitude belts through meridional flows, and the other cell type could be operating in the polar region.

Keywords: Solar cycle, Solar activity, Plages
Surface Reaction of Methyl Mercaptan (CH<SUB>3</SUB>SH) with Hydrogen Atoms on Amorphous Solid Water. Methyl mercaptan (CH3SH) is one of the S-bearing organic compounds found in the interstellar medium (ISM). In this study, we investigated the surface reactions of solid CH3SH with H atoms on amorphous solid water using experimental and computational methods to examine their physicochemical behavior in the ISM. Consequently, the primary product was discovered to be CH4. As the computational studies show that the dominant reaction pathway is H + CH3SH → CH3 + H2S, the observed CH4 would result from H addition to CH3. As relatively minor routes, the H abstraction processes from the -CH3 and -SH functional groups of CH3SH, giving rise to CH2SH and CH3S radicals, are confirmed. Although these radicals may form CH3SH again by reactions with H atoms, the loss of CH3SH from the ice surface by chemical desorption would be minor.

Keywords: Pre-biotic astrochemistry, Astrochemistry
Studying Postmerger Outflows from Magnetized-neutrino-cooled Accretion Disks. Neutrino-cooled accretion flow around a spinning black hole, produced by a compact binary merger, is a promising scenario for jet formation and launching magnetically driven outflows. Based on GW170817 gravitational wave detection by LIGO and Virgo observatories, followed by electromagnetic counterparts, this model can explain the central engine of the short-duration gamma-ray bursts and kilonova radiations. Using the open-source general relativistic magnetohydrodynamic HARM-COOL code, we evolved several 2D magnetized accretion disk-black hole models with a realistic equation of state in the fixed curved spacetime background. We applied the particle tracer technique to measure the properties of the outflows. The disk and black hole's initial parameters are chosen in a way to represent different possible postmerger scenarios of the merging compact objects. Our simulations show a strong correlation between the black hole's spin and ejected mass. Generally, mergers producing massive disks and rapidly spinning black holes launch stronger outflows. We observed our models generate winds with moderate velocity (v/c ~ 0.1-0.2) and a broad range of electron fractions. We use these results to estimate the luminosity and light curves of possible radioactively powered transients emitted by such systems. We found that the luminosity peaks within the range of 1040-1042 erg s-1, which agrees with previous studies for disk wind outflows.

Keywords: Accretion
The Evolution and Mass Dependence of Galaxy Cluster Pressure Profiles at 0.05 ≤ z ≤ 0.60 and 4 × 10<SUP>14</SUP> M <SUB>⊙</SUB> ≤ M <SUB>500</SUB> ≤ 30 × 10<SUP>14</SUP> M <SUB>⊙</SUB>. We have combined X-ray observations from Chandra with Sunyaev-Zel'dovich effect data from Planck and Bolocam to measure intracluster medium pressure profiles from 0.03 R 500 ≤ R ≤ 5 R 500 for a sample of 21 low-z galaxy clusters with a median redshift of &lt;z&gt; = 0.08 and a median mass of &lt;M 500&gt; = 6.1 × 1014 M ⊙ and a sample of 19 mid-z galaxy clusters with &lt;z&gt; = 0.50 and &lt;M 500&gt; = 10.6 × 1014 M ⊙. The mean scaled pressure in the low-z sample is lower at small radii and higher at large radii, a trend that is accurately reproduced in similarly selected samples from THE THREE HUNDRED simulations. This difference appears to be primarily due to dynamical state at small radii, evolution at intermediate radii, and a combination of evolution and mass dependence at large radii. Furthermore, the overall flattening of the mean scaled pressure profile in the low-z sample compared to the mid-z sample is consistent with expectations due to differences in the mass accretion rate and the fractional impact of feedback mechanisms. In agreement with previous studies, the fractional scatter about the mean scaled pressure profile reaches a minimum of ≃20% near 0.5 R 500. This scatter is consistent between the low-z and mid-z samples at all radii, suggesting it is not strongly impacted by sample selection, and this general behavior is reproduced in THE THREE HUNDRED simulations. Finally, analytic functions that approximately describe the mass and redshift trends in mean pressure profile shape are provided.

Keywords: Galaxy clusters, Intracluster medium, Sunyaev-Zeldovich effect, X-ray astronomy
Probing Velocity Structures of Protostellar Envelopes: Infalling and Rotating Envelopes within Turbulent Dense Cores. We have observed the three low-mass protostars, IRAS 15398-3359, L1527 IRS, and TMC-1A, with the ALMA 12 m array, the ACA 7 m array, and the IRAM-30 m and APEX telescopes in the C18O J = 2-1 emission. Overall, the C18O emission shows clear velocity gradients at radii of ~100-1000 au, which likely originate from the rotation of envelopes, while velocity gradients are less clear and velocity structures are more perturbed on scales of ~1000-10,000 au. IRAS 15398-3359 and L1527 IRS show a break at radii of ~1200 and ~1700 au in the radial profile of the peak velocity, respectively. The peak velocity is proportional to r -1.38 or r -1.7 within the break radius, which can be interpreted as indicating the rotational motion of the envelope with a degree of contamination by gas motions on larger spatial scales. The peak velocity follows v peak ∝ r 0.68 or v peak ∝ r 0.46 outside the break radius, which is similar to the J/M-R relation of dense cores. TMC-1A exhibits a radial profile of the peak velocity that is not consistent with the rotational motion of the envelope nor the J/M-R relation. The origin of the relation of v peak ∝ r 0.46-r 0.68 is investigated by examining correlations of the velocity deviation (δ v) and the spatial scale (τ) in the two sources. The obtained spatial correlations, δ v ∝ τ ~0.6, are consistent with the scaling law predicted by turbulence models, which may suggest that large-scale velocity structures originate from turbulence.

Keywords: Millimeter astronomy, Young stellar objects, Star formation, Low mass stars, Interstellar medium, Protostars, Radio astronomy
Compressing the Cosmological Information in One-dimensional Correlations of the Lyman-α Forest. Observations of the Lyman-α forest from spectroscopic surveys such as the Baryon Oscillation Spectroscopic Survey or its extension, eBOSS, or the ongoing Dark Energy Spectroscopic Instrument (DESI) survey offer a unique window to study the growth of structure on megaparsec scales. Interpretation of these measurements is a complicated task, requiring hydrodynamical simulations to model and marginalize over the thermal and ionization state of the intergalactic medium. This complexity has limited the use of Lyα clustering measurements in joint cosmological analyses. In this work we show that the cosmological information content of the one-dimensional power spectrum (P 1D) of the Lyman-α forest can be compressed into a simple two-parameter likelihood without any significant loss of constraining power. We simulate P 1D measurements from DESI using hydrodynamical simulations and show that the compressed likelihood is model independent and lossless, recovering unbiased results even in the presence of massive neutrinos or running of the primordial power spectrum.

Keywords: Cosmology, Large-scale structure of the universe, Astronomy data reduction, Lyman alpha forest
Light Curves and Polarizations of Gravitationally Lensed Kilonovae. Kilonovae are generally believed to originate from the ejecta of binary neutron stars (NSs) or black hole-NS mergers. Free neutrons might be retained in the outermost layer of the ejecta to produce a precursor via β decay. During the propagation of kilonovae to observers, a small percentage of them might be gravitationally lensed by foreground objects. In this paper, three lens models, i.e., the point-mass model, the singular isothermal sphere (SIS) model, and the Chang-Refsdal model, were taken into consideration to explore the light curves and polarizations of gravitationally lensed kilonovae. We found that, if the time delay between two images exceeds the ejecta-heating timescale for the lens mass ~1010 M ⊙ in the SIS model, a tiny bump-like signal will be generated in the light curve, and the total luminosity will be magnified in all cases. The polarization of lensed kilonovae is significantly enhanced in most cases. Future detections of lensed kilonovae will impose constraints on the morphology of the ejecta and aid in the determination of the nature of compact object mergers and the search for strong gravitational lenses.

Keywords: Strong gravitational lensing, Polarimetry, Transient sources
A Comparison of Millisecond Pulsar Populations between Globular Clusters and the Galactic Field. We have performed a systematic study of the rotational, orbital, and X-ray properties of millisecond pulsars (MSPs) in globular clusters (GCs) and compared their nature with those of the MSPs in the Galactic field (GF). We found that GC MSPs generally rotate slower than their counterparts in the GF. Different from the expectation of a simple recycling scenario, no evidence for the correlation between the orbital period and the rotation period can be found in the MSP binaries in GCs. There is also an indication that the surface magnetic field of GC MSPs is stronger than those in the GF. All these suggest dynamical interactions in GCs can alter the evolution of MSPs/their progenitors, which can leave an imprint on their X-ray emission properties. While the MSPs in both GF and GCs have similar distributions of X-ray luminosity and hardness, our sample supports the notion that these two populations follow different relations between the X-ray luminosity and spin-down power. We discuss this in terms of both the pulsar emission model and the observational bias.

Keywords: X-ray astronomy, Globular star clusters, X-ray binary stars, Millisecond pulsars, Pulsars, X-ray sources, Binary pulsars, X-ray stars
Near-infrared Polarimetry and H<SUB>2</SUB> Emission toward Massive Young Stars: Discovery of a Bipolar Outflow Associated to S235 e2s3. We present a near-infrared H-band polarimetric study toward the S235 e2s3 protostar, obtained using the POLICAN instrument on the 2.1 m OAGH telescope. The images reveal a bipolar outflow with a total length of about 0.5 pc. The outflow nebulosity presents a high degree of linear polarization (~80%) and reveals a centrosymmetric pattern with the polarization position angles. The polarization characteristics suggest their origin to be single scattering associated with dust in the outflow. Using multiwavelength archival data, we performed spectral energy distribution (SED) fitting based on radiative transfer models of turbulent core accretion theory. The best-fit SED model indicated that the protostar has a mass of 6.8 ± 1.2 M ⊙, with a disk accretion rate of 3.6 ± 1.2 × 10-4 M ⊙ yr-1 and a total bolometric luminosity of 9.63 ± 2.1 × 103 L ⊙. Narrowband H2 (2.12 μm) observations show shocked emission along the bipolar lobes tracing the jet's interaction with the surrounding medium. The estimated H2 luminosity of the outflow is ${2.3}_{-1.3}^{+3.5}\,{L}_{\odot }$ , which matched the known power-law correlation with the source bolometric luminosity, similar to other high-mass outflows. The orientation of the bipolar outflow was found to be parallel to the local magnetic field direction. The overall results assert the fact that the S235 e2s3 source is a massive young star driving a highly collimated bipolar outflow through disk accretion.

Keywords: Massive stars, Stellar jets, Star formation, Spectral energy distribution, Protostars, Polarimetry
Does Turbulence along the Coronal Current Sheet Drive Ion Cyclotron Waves?. Evidence for the presence of ion cyclotron waves (ICWs), driven by turbulence, at the boundaries of the current sheet is reported in this paper. By exploiting the full potential of the joint observations performed by Parker Solar Probe and the Metis coronagraph on board Solar Orbiter, local measurements of the solar wind can be linked with the large-scale structures of the solar corona. The results suggest that the dynamics of the current sheet layers generates turbulence, which in turn creates a sufficiently strong temperature anisotropy to make the solar-wind plasma unstable to anisotropy-driven instabilities such as the Alfvén ion cyclotron, mirror-mode, and firehose instabilities. The study of the polarization state of high-frequency magnetic fluctuations reveals that ICWs are indeed present along the current sheet, thus linking the magnetic topology of the remotely imaged coronal source regions with the wave bursts observed in situ. The present results may allow improvement of state-of-the-art models based on the ion cyclotron mechanism, providing new insights into the processes involved in coronal heating.

Keywords: Space plasmas, Magnetohydrodynamics, Heliosphere, Interplanetary turbulence, Solar coronal heating, Solar wind, Coronagraphic imaging, Alfven waves, Solar corona
Structure and Kinematics of Sh2-138-A Distant Hub-filament System in the Outer Galactic Plane. We present a molecular line study of the Sh2-138 (IRAS 22308+5812) hub-filament system with the aim of investigating its structure and kinematics. Archival CO molecular line data from the Canadian Galactic Plane Survey (CO(J = 1-0)) for the wider region (~50' × 50') and the James Clerk Maxwell Telescope (CO(3-2), 13CO(3-2), and C18O(3-2)) for the central portion (~5' × 5') have been utilized. Analysis of the CO(1-0) spectra for the extended region in conjunction with the identification of the hub and filament using a column density map and the getsf tool, respectively, reveals a complex structure with the spectral extraction for the central position displaying multiple velocity components. Based on the Herschel 70 μm warm dust emission, one of the filaments in the extended region was inferred to be associated with active star formation, and is host to a Bolocam 1.1 mm clump of ~1606 M ☉. An integrated intensity map of 13CO(3-2) emission, constructed from clumps detected at above 5σ in position-position-velocity space, reveals three filamentary structures (labeled the western filament (W-f), southwestern filament (SW-f), and southeast filament (SE-f)) in the central portion. Velocity gradients observed in 13CO(3-2) position-velocity slices point to longitudinal gas flow along the filaments into the central region. Filaments W-f, SW-f, and SE-f were calculated to have observed line masses of ~32, 33.5, and 50 M ☉ pc-1, respectively. The cloud was found to be dominated by supersonic and nonthermal motions, with high Mach numbers (≳3) and a low thermal-to-nonthermal pressure ratio (~0.01-0.1).

Keywords: Interstellar molecules, Interstellar filaments, Millimeter astronomy, Massive stars, Star formation, Interstellar medium, H II regions
Near-infrared Polarization Charateristics of the Zodiacal Light Observed with DIRBE/COBE. We report near-infrared polarization of the zodiacal light (ZL) measured from space by the Diffuse Infrared Background Experiment (DIRBE) on board the Cosmic Background Explorer in photometric bands centered at 1.25, 2.2, and 3.5 μm. To constrain the physical properties of interplanetary dust, we use DIRBE Weekly Sky Maps to investigate the solar elongation (ϵ), ecliptic latitude (β), and wavelength (λ) dependence of ZL polarization. We find that the polarization of the ZL varies as a function of ϵ and β, consistent with observed polarization at λ = 550 nm. While the polarization dependence on wavelength at (ϵ, β) = (90°, 0°) is modest (increasing from 17.7% ± 0.2% at 1.25% μm to 21.0% ± 0.3% at 3.5 μm), the variation is more pronounced at the north ecliptic pole (23.1% ± 1.6%, 35.1% ± 2.0%, and 39.3% ± 2.1% at 1.25, 2.2, and 3.5 μm, respectively). The variation in ZL polarization with wavelength is not explained by either Rayleigh scattering or absorptive particles larger than 10 μm.

Keywords: Infrared Astronomical Satellite, Zodiacal cloud, Interplanetary dust, Polarimetry, Near infrared astronomy
A Unified Model for Bipolar Outflows from Young Stars: Kinematic Signatures of Jets, Winds, and Their Magnetic Interplay with the Ambient Toroids. Kinematic signatures of the jet, winds, multicavities, and episodic shells arising in the unified model of bipolar outflows developed in Shang et al. (Paper I), in which an outflow forms by radially directed, wide-angle toroidally magnetized winds interacting with magnetized isothermal toroids, are extracted in the form of position-velocity diagrams. Elongated outflow lobes, driven by magnetized winds and their interplay with the environment, are dominated by extended bubble structures with mixing layers beyond the conventional thin-shell models. The axial cylindrically stratified density jet carries a broad profile near the base, across the projected velocity of the wide-angle wind, and narrows down along the axis with the collimated flow. The reverse shock encloses the magnetized free wind, forms an innermost cavity, and deflects the flow pattern. Shear, Kelvin-Helmholtz instabilities, and pseudopulses add fine and distinctive features between the jet-shell components, and the fluctuating jet velocities. The broad webbed velocity features connect the extremely high and the low velocities across the multicavities, mimicking nested outflowing slower-wind components. Rings and ovals in the perpendicular cuts trace multicavities at different heights, and the compressed ambient gap regions enrich the low-velocity features with protruding spikes. Our kinematic signatures capture the observed systematics of the high-, intermediate-, and low-velocity components from Class 0 to II jet-outflow systems in molecular and atomic lines. The nested shells observed in HH 212, HH 30, and DG Tau B are naturally explained. Outflows as bubbles are ubiquitous and form an inevitable integrative outcome of the interaction between wind and ambient media.

Keywords: Interstellar line emission, Stellar wind bubbles, Magnetohydrodynamical simulations, Stellar jets, Young stellar objects, Stellar winds, Star formation, Protostars, Collapsing clouds
X3: A High-mass Young Stellar Object Close to the Supermassive Black Hole Sgr A*. To date, the proposed observation of young stellar objects (YSOs) in the Galactic center still raises the question of where and how these objects could have formed due to the violent vicinity of Sgr A*. Here, we report the multiwavelength detection of a highly dynamic YSO close to Sgr A* that might be a member of the IRS 13 cluster. We observe the beforehand known coreless bow-shock source X3 in the near- and mid-infrared (NIR/MIR) with SINFONI (VLT), NACO (VLT), ISAAC (VLT), VISIR (VLT), SHARP (NTT), and NIRCAM2 (KECK). In the radio domain, we use CO continuum and H30α ALMA observations to identify system components at different temperatures and locations concerning the central stellar source. It is suggested that these radio/submillimeter observations in combination with the NIR Brγ line can be associated with a protoplanetary disk of the YSO, which is consistent with manifold VISIR observations that reveal complex molecules and elements such as PAH, S IV, Ne II, and Ar III in a dense and compact region. Based on the photometric multiwavelength analysis, we infer the mass of ${15}_{-5}^{+10}{M}_{\odot }$ for the YSO with a related age of a few 104 yr. Due to this age estimate and the required relaxation timescales for high-mass stars, this finding is an indication of ongoing star formation in the inner parsec. The proper motion and 3D distance imply a relation between X3 and IRS 13. We argue that IRS 13 may serve as a birthplace for young stars that are ejected due to the evaporation of the cluster.

Keywords: Supermassive black holes, Galactic center, Massive stars, Young massive clusters, Stellar bow shocks, Young stellar objects, Star formation