Sazuna/UAT_keywords huggingface dataset:
Years-delayed X-Ray Afterglows of TDEs Originated from Wind-Torus Interactions. Tidal disruption events (TDEs) occurring in active galactic nuclei (AGNs) are a special class of sources with outstanding scientific significance. TDEs can generate ultrafast winds, which should almost inevitably collide with the preexisting AGN dusty tori. We perform analytical calculations and simulations on the wind-torus interactions and find such a process can generate considerable X-ray afterglow radiation several years or decades later after the TDE outburst. This provides a new origin for the years delayed X-rays in TDEs. The X-ray luminosity can reach 1041-42 erg s-1, and the light curve characteristics depend on the parameters of winds and tori. We apply the model to two TDE candidates, and provide lower limits on the masses of the disrupted stars, as well as rigorous constraints on the gas densities of tori. Our results suggest that the observations of the time delay, spectral shape, luminosity, and the light curve of the X-ray afterglow can be used to constrain the physical parameters of both TDE winds and tori, including the wind velocity, wind density, cloud density, and cloud size.

Keywords: Supermassive black holes, Hydrodynamical simulations, Active galaxies, X-ray transient sources, Shocks
An X-Ray Spectral Study of the Origin of Reflection Features in Bare Seyfert 1 Galaxy ESO 511-G030. The reprocessed X-ray emission from active galactic nuclei is an important diagnostic tool to study the dynamics and geometry of the matter surrounding supermassive black holes (SMBHs). We present a broadband (optical-UV to hard X-ray) spectral study of the bare Seyfert 1 galaxy, ESO 511-G030, using multi-epoch Suzaku and XMM-Newton data from 2012 and 2007, respectively. The broadband spectra of ESO 511-G030 exhibit a UV bump, a prominent soft excess below $2\,\mathrm{keV}$ , a relatively broad ( $\sigma =0.08\mbox{--}0.14\,\mathrm{keV}$ ) Fe emission line at $6.4\,\mathrm{keV}$ , and a weak Compton hump at $E\gt 10\,\mathrm{keV}$ . The soft X-ray excess in ESO 511-G030 can be described either as the thermal Comptonization of disk seed photons by a warm ( ${0.40}_{-0.02}^{+0.02}\,\mathrm{keV}$ ), optically thick ( $\tau ={12.7}_{-0.4}^{+0.5}$ ), and compact ( $\lt 15{r}_{{\rm{g}}}$ ) corona or as the blurred reflection from an untruncated and moderate to highly ionized accretion disk. However, for the blurred reflection, the model requires some extreme configuration of the disk and corona. Both these models prefer a rapidly spinning black hole ( $a\gt 0.78$ ) and a compact corona, indicating a relativistic origin of the broad Fe emission line. We found an inner disk temperature of $\sim 2\mbox{--}3\,\mathrm{eV}$ that characterizes the UV bump and the SMBH accretes at a sub-Eddington rate ( ${\lambda }_{\mathrm{Edd}}=0.004\mbox{--}0.008$ ).

Keywords: X-ray active galactic nuclei, Active galactic nuclei
An Improved Measurement of the Secondary Cosmic Microwave Background Anisotropies from the SPT-SZ + SPTpol Surveys. We report new measurements of millimeter-wave power spectra in the angular multipole range 2000 ≤ ℓ ≤ 11,000 (angular scales $5^{\prime} \gtrsim \theta \gtrsim 1^{\prime} $ ). By adding 95 and 150 GHz data from the low-noise 500 deg2 SPTpol survey to the SPT-SZ three-frequency 2540 deg2 survey, we substantially reduce the uncertainties in these bands. These power spectra include contributions from the primary cosmic microwave background, cosmic infrared background, radio galaxies, and thermal and kinematic Sunyaev-Zel'dovich (SZ) effects. The data favor a thermal SZ (tSZ) power at 143 GHz of ${D}_{3000}^{\mathrm{tSZ}}=3.42\pm 0.54\,\,\mu {{\rm{K}}}^{2}$ and a kinematic SZ (kSZ) power of ${D}_{3000}^{\mathrm{kSZ}}=3.0\pm 1.0\,\,\mu {{\rm{K}}}^{2}$ . This is the first measurement of kSZ power at ≥3σ. However, different assumptions about the CIB or SZ models can reduce the significance down to 2.4σ in the worst case. We study the implications of the measured kSZ power for the epoch of reionization under the Calabrese et al. model for the kSZ power spectrum and find the duration of reionization to be ${\rm{\Delta }}{z}_{\mathrm{re}}={1.1}_{-0.7}^{+1.6}$ ( ${\rm{\Delta }}{z}_{\mathrm{re}}\lt 4.1$ at 95% confidence), when combined with our previously published tSZ bispectrum measurement. The upper limit tightens to ${\rm{\Delta }}{z}_{\mathrm{re}}\lt 3.2$ if the assumed homogeneous kSZ power is increased by 25% (∼0.5 μK2) and relaxes to ${\rm{\Delta }}{z}_{\mathrm{re}}\lt 5.2$ if the homogeneous kSZ power is decreased by the same amount.

Keywords: Reionization, Cosmic microwave background radiation, Sunyaev-Zeldovich effect
Multimessenger Parameter Estimation of GW170817: From Jet Structure to the Hubble Constant. The electromagnetic radiation that followed the neutron star merger event GW170817 revealed that gamma-ray burst afterglows from jets misaligned with our line of sight exhibit a light curve with slowly rising flux. The slope of the rising light curve depends sensitively on the angle of the observer with respect to the jet axis, which is likely to be perpendicular to the merger plane of the neutron star binary. Therefore, the afterglow emission can be used to constrain the inclination of the merging system. Here, we calculate the gamma-ray burst afterglow emission based on the realistic jet structure derived from general-relativistic magnetohydrodynamical simulations of a black hole torus system for the central engine of the gamma-ray burst. Combined with gravitational wave parameter estimation, we fit the multi-epoch afterglow emission of GW170817. We show that with such a jet model, the observing angle can be tightly constrained by multimessenger observations. The best fit observing angle of GW170817 is θv = 0.38 ± 0.02 rad. With such a constraint, we can break the degeneracy between inclination angle and luminosity distance in gravitational wave parameter estimation, and substantially increase the precision with which the Hubble constant is constrained by the standard siren method. Our estimation of the distance is DL = 43.4 ± 1 Mpc and the Hubble constant constraint is 69.5 ± 4 km s-1 Mpc-1. As a result, multimessenger observations of short-duration gamma-ray bursts, combined with a good theoretical understanding of the jet structure, can be powerful probes of cosmological parameters.

Keywords: Hubble constant, Gamma-ray bursts, Gravitational waves, Cosmological parameters
Small-scale Bright Blobs Ejected from a Sunspot Light Bridge. Light bridges (LBs) are bright lanes that divide an umbra into multiple parts in some sunspots. Persistent oscillatory bright fronts at a temperature of ∼105 K are commonly observed above LBs in the 1400/1330 Špassbands of the Interface Region Imaging Spectrograph (IRIS). Based on IRIS observations, we report small-scale bright blobs ejected from the oscillating bright front above a light bridge. Some of these blobs reveal a clear acceleration, whereas the others do not. The average speed of these blobs projected onto the plane of sky is 71.7 ± 14.7 km s-1, with an initial acceleration of 1.9 ± 1.3 km s-2. These blobs normally reach a projected distance of 3-7 Mm from their origin sites. They have an average projected area of 0.57 ± 0.37 Mm2. The blobs were also detected in multiple extreme-ultraviolet passbands of the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory, but not in the Hα images taken by the New Vacuum Solar Telescope. The typical temperature and electron density of these blobs are around ${10}^{5.47}$ K and ${10}^{9.7}$ cm-3, respectively. The estimated kinetic and thermal energies are on the order of ${10}^{22.8}$ erg and ${10}^{23.3}$ erg, respectively. These small-scale blobs appear to show three different types of formation processes. They are possibly triggered by induced reconnection or release of enhanced magnetic tension due to interaction of adjacent shocks, local magnetic reconnection between emerging magnetic bipoles on the light bridge and surrounding unipolar umbral fields, and plasma acceleration or instability caused by upward shocks, respectively.

Keywords: Solar activity, Solar physics, Sunspots, Solar magnetic fields
Low-energy Measurement of the <SUP>96</SUP>Zr(α,n)<SUP>99</SUP>Mo Reaction Cross Section and Its Impact on Weak r-process Nucleosynthesis. Lighter heavy elements beyond iron and up to around silver can form in neutrino-driven ejecta in core-collapse supernovae and neutron star mergers. Slightly neutron-rich conditions favor a weak r-process that follows a path close to stability. Therefore, the beta decays are slow compared to the expansion timescales, and (α,n) reactions become critical to move matter toward heavier nuclei. The rates of these reactions are calculated with the statistical model and their main uncertainty, at energies relevant for the weak r-process, is the α+nucleus optical potential. There are several sets of parameters to calculate the α+nucleus optical potential leading to large deviations for the reaction rates, exceeding even one order of magnitude. Recently the 96Zr(α,n)99Mo reaction has been identified as a key reaction that impacts the production of elements from Ru to Cd. Here, we present the first cross section measurement of this reaction at energies (6.22 MeV ≤ Ec.m. ≤ 12.47 MeV) relevant for the weak r-process. The new data provide a stringent test of various model predictions which is necessary to improve the precision of the weak r-process network calculations. The strongly reduced reaction rate uncertainty leads to very well-constrained nucleosynthesis yields for Z = 44-48 isotopes under different neutrino-driven wind conditions.

Keywords: R-process, Explosive nucleosynthesis, Nuclear reaction cross sections, Nuclear physics
Acceleration of Ring Current Protons Driven by Magnetosonic Waves: Comparisons of Test Particle Simulations with Quasilinear Calculations. Wave-particle interactions play important roles in local acceleration and pitch angle scattering loss of charged particle dynamics in astrophysics and space physics, and energy transfer between plasma waves and particles is a key problem in plasma physics. Using full relativistic test particle simulations, we quantitatively evaluate the magnetosonic wave-driven acceleration of Earth's ring current protons both inside and outside the plasmapause at L = 4.5. Analysis of resonance conditions indicates that the broadband magnetosonic waves can affect protons by multiple harmonic cyclotron resonances. With a representative amplitude ∼200 pT, magnetosonic waves can produce energy diffusion coefficients, obtained from test particle simulations, at rates of ∼10-4 s-1 for protons ∼1-3 keV inside the plasmapause and ∼3-30 keV outside the plasmapause, both at equatorial pitch angles ∼75°-90°. Compared with the quasilinear theory calculations, the test particle diffusion coefficients exhibit a difference due to the nonresonant transit time effect outside the plasmapause. Subsequent 2D Fokker-Planck simulations indicate that on a timescale of ∼2 days, magnetosonic waves can effectively enhance the phase space density of the ring current protons ∼10 keV inside the plasmapause and ∼100 keV outside the plasmapause at equatorial pitch angles ∼60°-90°, thereby leading to the evolvement of the ring current proton distribution from a Kappa-type to a 90°-peaked profile. Our results demonstrate that the local acceleration of the ring current protons by magnetosonic waves is an important process of energy transfer between different populations of magnetospheric protons and hence contributes to the dynamic evolution of Earth's ring current.

Keywords: Van Allen radiation belts, Planetary magnetospheres, Space plasmas
Approximate Bayesian Uncertainties on Deep Learning Dynamical Mass Estimates of Galaxy Clusters. We study methods for reconstructing Bayesian uncertainties on dynamical mass estimates of galaxy clusters using convolutional neural networks (CNNs). We discuss the statistical background of approximate Bayesian neural networks and demonstrate how variational inference techniques can be used to perform computationally tractable posterior estimation for a variety of deep neural architectures. We explore how various model designs and statistical assumptions impact prediction accuracy and uncertainty reconstruction in the context of cluster mass estimation. We measure the quality of our model posterior recovery using a mock cluster observation catalog derived from the MultiDark simulation and UniverseMachine catalog. We show that approximate Bayesian CNNs produce highly accurate dynamical cluster mass posteriors. These model posteriors are log-normal in cluster mass and recover 68% and 90% confidence intervals to within 1% of their measured value. We note how this rigorous modeling of dynamical mass posteriors is necessary for using cluster abundance measurements to constrain cosmological parameters.

Keywords: Cosmology, Galaxy clusters, Galaxy dynamics, Astrostatistics
In the Trenches of the Solar-Stellar Connection. II. Extreme Ultraviolet Flux-Flux Correlations across Solar Cycle 24. Solar extreme-ultraviolet (EUV: 100-1100 Å) radiation rises in the 104 K upper chromosphere and hotter layers extending into the million-degree corona. Much of the EUV normally is not visible in other stars owing to interstellar H I absorption. The present study derived power-law scaling relations for EUV species based on irradiance spectra from the Extreme Ultraviolet Variability Experiment on board the Solar Dynamics Observatory, over the rise and fall of recent sunspot Cycle 24. These relations not only can test solar models, but also allow "invisible" stellar EUV emissions to be reconstructed from more accessible ultraviolet (UV: 1100-3000 Å) proxies, with implications for heating, ionization, and erosion of exoplanet atmospheres by Sun-like hosts. Hot EUV coronal tracers like Si XII 520 Å (8 MK) show strongly curved power laws relative to chromospheric H I 1025 Å Lyβ, as was seen in Paper I for 0.2-2 keV soft X-rays versus Mg II 2800 Å. The brightest EUV feature, He II 303 Å, exhibits a nearly 1:1 correlation with Lyβ (and H I 1215 Lyα, but slightly steeper than 1:1 relative to Mg II). The second brightest, C III 977 Å, has a shallower power-law slope of ∼0.5. Correlations for low first ionization potential species, such as Mg, Si, and Fe, might be affected by cycle-dependent chemical fractionation. Parameterized flux-flux relations are presented for most of the strong EUV (and selected UV) features, together with fluxes of individual lines and broad EUV wavelength bands at the highs and lows of Cycle 24.

Keywords: Solar cycle, Solar ultraviolet emission, Stellar chromospheres, Stellar activity, Stellar coronae
A New Cosmic-Ray-driven Instability. Cosmic-ray-driven (CR-driven) instabilities play a decisive role during particle acceleration at shocks and CR propagation in galaxies and galaxy clusters. These instabilities amplify magnetic fields and modulate CR transport so that the intrinsically collisionless CR population is tightly coupled to the thermal plasma and provides dynamical feedback. Here, we show that CRs with a finite pitch angle drive electromagnetic waves (along the background magnetic field) unstable on intermediate scales between the gyroradii of CR ions and electrons as long as CRs are drifting with a velocity less than half of the Alfvén speed of electrons. By solving the linear dispersion relation, we show that this new instability typically grows faster by more than an order of magnitude in comparison to the commonly discussed resonant instability at the ion gyroscale. We find the growth rate for this intermediate-scale instability and identify the growing modes as background ion-cyclotron modes in the frame that is comoving with the CRs. We confirm the theoretical growth rate with a particle-in-cell simulation and study the nonlinear saturation of this instability. We identify three important astrophysical applications of this intermediate-scale instability, which is expected to (1) modulate CR transport and strengthen CR feedback in galaxies and galaxy clusters, (2) enable electron injection into the diffusive shock acceleration process, and (3) decelerate CR escape from the sites of particle acceleration, which would generate gamma-ray halos surrounding CR sources such as supernova remnants.

Keywords: Galactic cosmic rays, Supernova remnants, Interstellar medium
Nearly 30,000 Late-type Main-sequence Stars with Stellar Age from LAMOST DR5. We construct a sample of nearly 30,000 main-sequence stars with 4500 K &lt; Teff &lt; 5000 K and stellar ages estimated by the chromospheric activity-age relation. This sample is used to determine the age distribution in the R-Z plane of the Galaxy, where R is the projected Galactocentric distance in the disk midplane and Z is the height above the disk midplane. As ∣Z∣ increases, the percentage of old stars becomes larger. It is known that scale-height of Galactic disk increases as R increases, which is called a flare. A mild flare from R ∼ 8.0 to 9.0 kpc in stellar age distribution is found. We also find that the velocity dispersion increases with age as confirmed by previous studies. Finally we present spiral-shaped structures in Z-υZ phase space in three stellar age bins. The spiral is clearly seen in the age bin of [0, 1] Gyr, which suggests that a vertical perturbation to the disk probably took place within the last ∼1.0 Gyr.

Keywords: Stellar kinematics, Late-type dwarf stars, Stellar ages, Stellar activity
Ancient Very Metal-poor Stars Associated with the Galactic Disk in the H3 Survey. Ancient, very metal-poor (VMP) stars offer a window into the earliest epochs of galaxy formation and assembly. We combine data from the H3 Spectroscopic Survey and Gaia to measure metallicities, abundances of α elements, stellar ages, and orbital properties of a sample of 482 VMP ([Fe/H] &lt; -2) stars in order to constrain their origins. This sample is confined to 1 ≲ ∣Z∣ ≲ 3 kpc from the Galactic plane. We find that &gt;70% of VMP stars near the disk are on prograde orbits and this fraction increases toward lower metallicities. This result is unexpected if metal-poor stars are predominantly accreted from many small systems with no preferred orientation, as such a scenario would imply a mostly isotropic distribution. Furthermore, we find there is some evidence for higher fractions of prograde orbits among stars with lower [α/Fe]. Isochrone-based ages for main-sequence turn-off stars reveal that these VMP stars are uniformly old (≈12 Gyr) irrespective of the α abundance and metallicity, suggesting that the metal-poor population was not born from the same well-mixed gas disk. We speculate that the VMP population has a heterogeneous origin, including both in situ formation in the ancient disk and accretion from a satellite with the same direction of rotation as the ancient disk at early times. Our precisely measured ages for these VMP stars on prograde orbits show that the Galaxy has had a relatively quiescent merging history over most of cosmic time, and implies the angular momentum alignment of the Galaxy has been in place for at least 12 Gyr.

Keywords: Milky Way formation, Milky Way dynamics, Milky Way disk, Milky Way evolution, Metallicity, Milky Way Galaxy
The Extreme Space Weather Event in 1941 February/March. Given the infrequency of extreme geomagnetic storms, it is significant to note the concentration of three extreme geomagnetic storms in 1941, whose intensities ranked fourth, twelfth, and fifth within the aa index between 1868-2010. Among them, the geomagnetic storm on 1941 March 1 was so intense that three of the four Dst station magnetograms went off scale. Herein, we reconstruct its time series and measure the storm intensity with an alternative Dst estimate (Dst*). The source solar eruption at 09:29-09:38 GMT on February 28 was located at RGO AR 13814 and its significant intensity is confirmed by large magnetic crochets of ∣35∣ nT measured at Abinger. This solar eruption most likely released a fast interplanetary coronal mass ejection with estimated speed 2260 km s-1. After its impact at 03:57-03:59 GMT on March 1, an extreme magnetic storm was recorded worldwide. Comparative analyses on the contemporary magnetograms show the storm peak intensity of minimum Dst* ≤ -464 nT at 16 GMT, comparable to the most and the second most extreme magnetic storms within the standard Dst index since 1957. This storm triggered significant low-latitude aurorae in the East Asian sector and their equatorward boundary has been reconstructed as 38°5 in invariant latitude. This result agrees with British magnetograms, which indicate an auroral oval moving above Abinger at 53°0 in magnetic latitude. The storm amplitude was even more enhanced in equatorial stations and consequently casts caveats on their usage for measurements of the storm intensity in Dst estimates.

Keywords: Geomagnetic fields, Solar flares, Sunspots, Solar active regions, Solar coronal mass ejections, Solar-terrestrial interactions
Determining the Variations of Ca-K Index and Features Using Century-long Equal-contrast Images from Kodaikanal Observatory. In an earlier analysis of Ca-K spectroheliograms obtained at the Kodaikanal Observatory, the "Good" images were used to investigate variations in the chromosphere. However, the contrast of the images varied on a day-to-day basis. We have developed a new methodology to generate images to form a uniform time series. We adjusted each image's contrast until the FWHM of the normalized intensity distribution attained a value between 0.10 and 0.11. This "equal-contrast technique" is expected to compensate for the change of emulsion, development, and contrast of the images due to centering of the Ca-K line on the exit slit and sky transparency. In addition, this procedure will correct variations in density-to-intensity conversion for different images. We find that the correlation between sunspot and Ca-K line data improves to a large extent. For example, the correlation coefficient (CC) between monthly averaged sunspots and Ca-K plage areas for the equal-contrast data reaches 0.9 compared to 0.75 for the "Good" data with unequal contrast. The CC for equal-contrast images improves to ∼0.78 from ∼0.46 for the "Okay" data with unequal contrast. Even the CC between the plage area and the daily sunspot number is 0.85 for 100 years of data. This methodology also permits us, for the first time, to study the variations in enhanced, active, and quiet networks with time with high accuracy over about a century. Further, this procedure can be used to combine data from different observatories to make a long time series.

Keywords: Solar cycle, Quiet sun, Active sun