Sazuna/UAT_keywords huggingface dataset:
From the External to the Internal Dynamics of the Neutron Star: The Exotic Braking Indices of PSR B0540-69. The braking index is of great importance for interpreting the spin-down mechanism of pulsar rotation. The sudden spin-down rate transition of PSR B0540-69, the lowest braking index n = 0.031, and its variations up to 1.2 in its later phases, without glitches or changes in X-ray pulsed flux or shape, are the most enigmatic problem that challenges our understanding of the correlation between pulsar spin-down and magnetospheric emission. Here we discuss the above issue on the external and internal grounds of pulsar dynamics. It is found that the increase of the open field line region of the pulsar magnetosphere would give a plausible explanation for the state transition and the braking index of 0.031 of PSR B0540-69, and changes in the moment of inertia of PSR B0540-69 after the state transition may account for the variable braking indices in its subsequent phases. Results indicate that, on the one hand, a change in the magnetosphere size of a pulsar would influence the external braking torque and have a substantial impact on the observed braking index; and, on the other hand, a sudden change in external torque may trigger the mechanism that could slowly increase the moment of inertia of the pulsar and cause an observable effect on the spin frequency second derivatives. This is hardly explained under the regular glitch hypothesis. In this respect, PSR B0540-69 would be the ideal candidate to study the inside and outside dynamics of a pulsar.

Keywords: Neutron stars, Pulsars
Inferences from Surface Brightness Fluctuations of Zwicky 3146 via the Sunyaev─Zel'dovich Effect and X-Ray Observations. The galaxy cluster Zwicky 3146 is a sloshing cool-core cluster at z = 0.291 that in Sunyaev─Zel'dovich (SZ) imaging does not appear to exhibit significant pressure substructure in the intracluster medium. We perform a surface brightness fluctuation analysis via Fourier amplitude spectra on SZ (MUSTANG-2) and X-ray (XMM-Newton) images of this cluster. These surface brightness fluctuations can be deprojected to infer pressure and density fluctuations from the SZ and X-ray data, respectively. In the central region (Ring 1, r &lt; 100″ = 440 kpc, in our analysis), we find fluctuation spectra that suggest injection scales around 200 kpc (∼140 kpc from pressure fluctuations and ∼250 kpc from density fluctuations). When comparing the pressure and density fluctuations in the central region, we observe a change in the effective thermodynamic state from large to small scales, from isobaric (likely due to the slow sloshing) to adiabatic (due to more vigorous motions). By leveraging scalings from hydrodynamical simulations, we find an average 3D Mach number ≍0.5. We further compare our results to other studies of Zwicky 3146 and, more broadly, to other studies of fluctuations in other clusters.

Keywords: Galaxy clusters, Intracluster medium
Updated Orbital Ephemeris and Detection of Superhump Modulation in X-Ray Band for the Ultra-compact Low Mass X-Ray Binary 4U 1820-30. The 4U 1820-30 is an ultra-compact low-mass X-ray binary (LMXB) near the center of the globular cluster NGC 6624. Its negative orbital period derivative, observed from the phase evolution of its sinusoidal-like orbital variation, contradicts the positive value that was obtained from the theoretical prediction. In this paper, we present the analysis of the 4U 1820-30 orbital modulation from light curves obtained from the Neutron star Interior Composition ExploreR (NICER) observations from 2017 to mid-2022. Combined with historical records, the orbital derivative is measured from the orbital phase evolution between 1976 and 2002 is $\dot{P}/P=(-5.21\pm 0.13)\times {10}^{-8}$ yr-1. No significant second order orbital period derivative is detected with a 2σ upper limit of $| \ddot{P}| \lt 5.48\times {10}^{-22}$ s s-2. We discuss the possible intrinsic orbital period derivative of 4U 1820-30 and suggest that this binary system may have a significant mass outflow similar to some other LMXBs. In addition, a periodic modulation with a period of 691.6 ± 0.7 s, which is consistent with the superhump period discovered in the far-ultraviolet band of the Hubble Space Telescope, was also detected in the X-ray light curves that were collected by NICER. We conclude that this modulation is probably caused by a period of 0.8 ± 0.1 day apsidal precession of the accretion disk, similar to the SU UMa type dwarf novae and some LMXBs. However we cannot exclude the possibility that it is induced by a hierarchical third star that orbits around the binary system.

Keywords: Low-mass x-ray binary stars, Stellar accretion disks, Close binary stars
HALO7D. III. Chemical Abundances of Milky Way Halo Stars from Medium-resolution Spectra. The Halo Assembly in Lambda Cold Dark Matter: Observations in 7 Dimensions (HALO7D) survey measures the kinematics and chemical properties of stars in the Milky Way (MW) stellar halo to learn about the formation of our Galaxy. HALO7D consists of Keck II/DEIMOS spectroscopy and Hubble Space Telescope-measured proper motions of MW halo main-sequence turnoff stars in the four Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey fields. HALO7D consists of deep pencil beams, making it complementary to other contemporary wide-field surveys. We present the [Fe/H] and [α/Fe] abundances for 113 HALO7D stars in the Galactocentric radial range of ~10-40 kpc along four separate pointings. Using the full 7D chemodynamical data (3D positions, 3D velocities, and abundances) of HALO7D, we measure the velocity anisotropy, β, of the halo velocity ellipsoid for each field and for different metallicity-binned subsamples. We find that two of the four fields have stars on very radial orbits, while the remaining two have stars on more isotropic orbits. Separating the stars into high-, mid-, and low-[Fe/H] bins at -2.2 and -1.1 dex for each field separately, we find differences in the anisotropies between the fields and between the bins; some fields appear dominated by radial orbits in all bins, while other fields show variation between the [Fe/H] bins. These chemodynamical differences are evidence that the HALO7D fields have different fractional contributions from the progenitors that built up the MW stellar halo. Our results highlight the additional information available on smaller spatial scales compared to results from a spherical average of the stellar halo.

Keywords: Stellar abundances, Milky Way stellar halo, Milky Way Galaxy, Astrostatistics
HAZMAT. IX. An Analysis of the UV and X-Ray Evolution of Low-mass Stars in the Era of Gaia. Low-mass stars (≤1 M ⊙) are some of the best candidates for hosting planets with detectable life because of these stars' long lifetimes and relative ratios of planet to star mass and radius. An important aspect of these stars to consider is the amount of ultraviolet (UV) and X-ray radiation incident on planets in the habitable zones due to the ability of UV and X-ray radiation to alter the chemistry and evolution of planetary atmospheres. In this work, we build on the results of the HAZMAT I and HAZMAT III M-star studies to determine the intrinsic UV and X-ray flux evolution with age for M stars using Gaia parallactic distances. We then compare these results to the intrinsic fluxes of K stars adapted from HAZMAT V. We find that although the intrinsic M-star UV flux is 10-100 times lower than that of K stars, the UV fluxes in their respective habitable zone are similar. However, the habitable zone X-ray flux evolutions are slightly more distinguishable with a factor of 3-15 times larger X-ray flux for late M stars than for K stars. These results suggest that there may not be a K-dwarf advantage compared to M stars in the UV, but one may still exist in the X-ray.

Keywords: Ultraviolet astronomy, X-ray astronomy, Low mass stars, Stellar evolution
Constraints on Populations of Neutrino Sources from Searches in the Directions of IceCube Neutrino Alerts. Beginning in 2016, the IceCube Neutrino Observatory has sent out alerts in real time containing the information of high-energy (E ≳ 100 TeV) neutrino candidate events with moderate to high (≳30%) probability of astrophysical origin. In this work, we use a recent catalog of such alert events, which, in addition to events announced in real time, includes events that were identified retroactively and covers the time period of 2011-2020. We also search for additional, lower-energy neutrinos from the arrival directions of these IceCube alerts. We show how performing such an analysis can constrain the contribution of rare populations of cosmic neutrino sources to the diffuse astrophysical neutrino flux. After searching for neutrino emission coincident with these alert events on various timescales, we find no significant evidence of either minute-scale or day-scale transient neutrino emission or of steady neutrino emission in the direction of these alert events. This study also shows how numerous a population of neutrino sources has to be to account for the complete astrophysical neutrino flux. Assuming that sources have the same luminosity, an E -2.5 neutrino spectrum, and number densities that follow star formation rates, the population of sources has to be more numerous than 7 × 10-9 Mpc-3. This number changes to 3 × 10-7 Mpc-3 if number densities instead have no cosmic evolution.

Keywords: Neutrino astronomy, Transient sources, High energy astrophysics
Rotation in Event Horizon Telescope Movies. The Event Horizon Telescope (EHT) has produced images of M87* and Sagittarius A*, and will soon produce time sequences of images, or movies. In anticipation of this, we describe a technique to measure the rotation rate, or pattern speed Ω p , from movies using an autocorrelation technique. We validate the technique on Gaussian random field models with a known rotation rate and apply it to a library of synthetic images of Sgr A* based on general relativistic magnetohydrodynamics simulations. We predict that EHT movies will have Ω p  ≈ 1° per GMc -3, which is of order 15% of the Keplerian orbital frequency in the emitting region. We can plausibly attribute the slow rotation seen in our models to the pattern speed of inward-propagating spiral shocks. We also find that Ω p  depends strongly on inclination. Application of this technique will enable us to compare future EHT movies with the clockwise rotation of Sgr A* seen in near-infrared flares by GRAVITY. Pattern speed analysis of future EHT observations of M87* and Sgr A* may also provide novel constraints on black hole inclination and spin, as well as an independent measurement of black hole mass.

Keywords: Black holes, Magnetohydrodynamical simulations
Planar Magnetic Structures Downstream of Coronal Mass Ejection-driven Shocks in the Inner Heliosphere. Planar magnetic structures (PMSs), characterized by interplanetary magnetic field vectors remaining parallel to a specific plane, are commonly observed in the solar wind, especially in the sheath region of interplanetary coronal mass ejections (ICMEs). In this study, PMS events in the 2 hr regions downstream of ICME-driven shocks were investigated to reveal the relationship between PMS formation and shock environment using data collected by the Parker Solar Probe, Solar Orbiter, and Venus Express spacecraft in the inner heliosphere. PMS events are identified in the majority (around 93%) of the postshock 2 hr regions, with transit times ranging from 10 to 120 minutes, which demonstrates their common occurrence associated with ICME-driven shocks. About 33% of the detected PMS events cover the whole 2 hr intervals, called full PMS events. Most of the full PMS events are observed in the downstream region of quasi-perpendicular shocks. In addition, statistical results show that full PMS events occurring in the downstream region of quasi-perpendicular shocks are generally associated with higher magnetic compression ratios, which implies that full PMS events are more likely to be formed in the downstream region of strong quasi-perpendicular shocks.

Keywords: Interplanetary physics, Solar wind, Interplanetary shocks, Interplanetary magnetic fields
Dust Properties of 870 μm-selected Galaxies in GOODS-S. We analyze the dust properties of 57 870 μm-selected dusty star-forming galaxies in GOODS-S using new deep Atacama Large Millimeter/Submillimeter Array 1.2, 2, and 3 mm continuum imaging together with other far-infrared through millimeter data. We fit the spectral energy distributions (SEDs) with optically thin modified blackbodies to constrain the emissivity indices and effective dust temperatures, finding a median emissivity index of $\beta ={1.78}_{-0.25}^{+0.43}$ and a median temperature of ${T}_{d}={33.6}_{-5.4}^{+12.1}$ K. We observe a negative correlation between β and T  d . By testing several SED models, we determine that the derived emissivity indices can be influenced by opacity assumptions. Our temperature measurements are consistent with no evolution in dust temperature with redshift.

Keywords: Submillimeter astronomy, High-redshift galaxies, Galaxy evolution
ALMA 1.1 mm Observations of a Conservative Sample of High-redshift Massive Quiescent Galaxies in SHELA. We present a sample of 30 massive (log(M */M ⊙) &gt; 11) z = 3-5 quiescent galaxies selected from the Spitzer-HETDEX Exploratory Large Area (SHELA) Survey and observed at 1.1 mm with Atacama Large Millimeter/submillimeter Array (ALMA) Band 6 observations. These ALMA observations would detect even modest levels of dust-obscured star formation, on the order of ~20 M ⊙ yr-1 at z ~ 4 at the 1σ level, allowing us to quantify the amount of contamination from dusty star-forming sources in our quiescent sample. Starting with a parent sample of candidate massive quiescent galaxies from the Stevans et al. v1 SHELA catalog, we use the Bayesian BAGPIPES spectral energy distribution fitting code to derive robust stellar masses (M *) and star formation rates (SFRs) for these sources, and select a conservative sample of 36 candidate massive (M * &gt; 1011  M ⊙) quiescent galaxies, with specific SFRs &gt;2σ below the Salmon et al. star-forming main sequence at z ~ 4. Based on the ALMA imaging, six of these candidate quiescent galaxies show the presence of significant dust-obscured star formation, and thus were removed from our final sample. This implies a ~17% contamination rate from dusty star-forming galaxies with our selection criteria using the v1 SHELA catalog. This conservatively selected quiescent galaxy sample at z = 3-5 will provide excellent targets for future observations to constrain better how massive galaxies can both grow and shut down their star formation in a relatively short period.

Keywords: Submillimeter astronomy, Quenched galaxies, Galaxy evolution, Galaxies
Probing the Circumgalactic Medium with Cosmic Microwave Background Polarization Statistical Anisotropy. As cosmic microwave background (CMB) photons traverse the universe, anisotropies can be induced via Thomson scattering (proportional to the electron density; optical depth) and inverse Compton scattering (proportional to the electron pressure; thermal Sunyaev-Zel'dovich effect). Measurements of anisotropy in optical depth τ and Compton y parameters are imprinted by the galaxies and galaxy clusters and are thus sensitive to the thermodynamic properties of the circumgalactic medium and intergalactic medium. We use an analytic halo model to predict the power spectrum of the optical depth (τ τ), the cross-correlation between the optical depth and the Compton y parameter (τ y), and the cross-correlation between the optical depth and galaxy clustering (τ g), and compare this model to cosmological simulations. We constrain the optical depths of halos at z ≲ 3 using a technique originally devised to constrain patchy reionization at a higher redshift range. The forecasted signal-to-noise ratio is 2.6, 8.5, and 13, respectively, for a CMB-S4-like experiment and a Vera C. Rubin Observatory-like optical survey. We show that a joint analysis of these probes can constrain the amplitude of the density profiles of halos to 6.5% and the pressure profiles to 13%. These constraints translate to astrophysical parameters, such as the gas mass fraction, f g, which can be constrained to 5.3% uncertainty at z ~ 0. The cross-correlations presented here are complementary to other CMB and galaxy cross-correlations since they do not require spectroscopic galaxy redshifts and are another example of how such correlations are a powerful probe of the astrophysics of galaxy evolution.

Keywords: Galaxy cluster counts, Cosmic microwave background radiation, Observational cosmology, Sunyaev-Zeldovich effect, Circumgalactic medium
A New Sample of Transient Ultraluminous X-Ray Sources Serendipitously Discovered by Swift/XRT. Ultraluminous X-ray sources (ULXs) are our best laboratories for studying extreme super-Eddington accretion. Most studies of these objects are of relatively persistent sources; however, there is growing evidence to suggest a large fraction of these sources are transient. Here we present a sample of five newly reported transient ULXs in the galaxies NGC 4945, NGC 7793, and M81 serendipitously discovered in Swift/XRT observations. Swift monitoring of these sources have provided well-sampled lightcurves, allowing for us to model the lightcurves with the disk-instability model of Hameury &amp; Lasota, which implies durations of 60-400 days and that the mass-accretion rate through the disk is close to or greater than the Eddington rate. Of the three source regions with prior Hubble Space Telescope imaging, color-magnitude diagrams of the potential stellar counterparts show varying ages of the possible stellar counterparts. Our estimation of the rates of these sources in these three galaxies is 0.4-1.3 yr-1. We find that, while persistent ULXs dominate the high end of galaxy luminosity functions, the number of systems that produce ULX luminosities are likely dominated by transient sources.

Keywords: X-ray transient sources, Ultraluminous x-ray sources, Transient sources, X-ray sources
Dwarfs in Void Environments (DIVE): The Stellar Kinematics of Void Dwarf Galaxies Using the Keck Cosmic Web Imager. Dwarf galaxies located in extremely underdense cosmic voids are excellent test beds for disentangling the effects of large-scale environments on galaxy formation and evolution. We present the first results of the Dwarfs in Void Environments Survey, which has obtained integral field spectroscopy for low-mass galaxies (M ⋆ = 107-109 M ⊙) located inside (N = 21) and outside (N = 9) cosmic voids using the Keck Cosmic Web Imager. Using measurements of stellar line-of-sight rotational velocity v rot and velocity dispersion σ ⋆, we test the tidal stirring hypothesis, which posits that dwarf spheroidal galaxies are formed through tidal interactions with more massive host galaxies. We measure low values of v rot/σ ⋆ ≲ 2 for our sample of isolated dwarf galaxies, and we find no trend between v rot/σ ⋆ and the distance from a massive galaxy ${d}_{{L}^{\star }}$ out to ${d}_{{L}^{\star }}\sim 10$ Mpc. These suggest that dwarf galaxies can become dispersion-supported, "puffy" systems even in the absence of environmental effects like tidal interactions. We also find indications of an upward trend between v rot/σ ⋆ and galaxy stellar mass, perhaps implying that stellar disk formation depends on mass rather than environment. Although some of our conclusions may be slightly modified by systematic effects, our main result still holds: that isolated low-mass galaxies may form and remain as puffy systems rather than the dynamically cold disks predicted by classical galaxy formation theory.

Keywords: Stellar kinematics, Dwarf galaxies, Galaxy kinematics, Galaxy environments
Kinetic Alfvén Waves Excited by Multiple Free Energy Sources in the Magnetotail. The generation of kinetic Alfvén waves (KAWs) is investigated through a three-component theoretical model incorporating ion beam and velocity shear as the sources of free energy in a non-Maxwellian κ-distributed plasmas. The model considers Maxwellian distributed background ions, drifting-Maxwellian beam ions, and κ-electrons as its constituent species. It is found that the combination of either positive velocity shear with counter-streaming beam ions or parallel streaming beam ions with negative velocity shear favors the excitation of KAWs. The effect of the κ-parameter on the excitation of KAWs under the combined energy sources is explored. The effect of plasma parameters such as number density, propagation angle, and temperature of plasma species on the real frequency and the growth rate of KAWs are examined. For the plasma parameters pertinent to the magnetotail region of Earth's magnetosphere, the model is able to produce KAWs in the frequency range of ≈(5-67) mHz, which matches well with the recent 'Time History of Events and Macroscale Interactions during Substorms (THEMIS)' observations in the near-Earth magnetotail region.

Keywords: Space plasmas, Solar wind, Alfven waves
Magnetic Field Extrapolation in Active Region Well Comparable to Observations in Multiple Layers. Magnetic field extrapolation is a fundamental tool to reconstruct the three-dimensional magnetic field above the solar photosphere. However, the prevalently used force-free field model might not be applicable in the lower atmosphere with non-negligible plasma β, where the crucial process of flux rope formation and evolution could happen. In this work, we perform extrapolation in active region 12158, based on a recently developed magnetohydrostatic (MHS) method that takes plasma forces into account. By comparing the results with those from the force-free field extrapolation methods, we find that the overall properties, which are characterized by the magnetic free energy and helicity, are roughly the same. The major differences lie in the magnetic configuration and the twist number of the magnetic flux rope (MFR). Unlike previous works either obtained sheared arcades or one coherent flux rope, the MHS method derives two sets of MFR, which are highly twisted and slightly coupled. Specifically, the result in the present work is more comparable to the high-resolution observations from the chromosphere, through the transition region to the corona, such as the filament fibrils, pre-eruptive braiding characteristics, and the eruptive double-J-shaped hot channel. Overall, our work shows that the newly developed MHS method is more promising to reproduce the magnetic fine structures that can well match the observations at multiple layers, and future data-driven simulation based on such extrapolation will benefit in understanding the critical and precise dynamics of flux rope before eruption.

Keywords: Solar photosphere, Solar extreme ultraviolet emission, Solar active regions, Solar corona, Solar magnetic fields, Solar chromosphere