Sazuna/UAT_keywords huggingface dataset:
Effects of Galaxy Intrinsic Alignment on Weak Lensing Peak Statistics. The galaxy intrinsic alignment (IA) is a dominant source of systematics in weak lensing (WL) studies. In this paper, by employing large simulations with semianalytical galaxy formation, we investigate the IA effects on WL peak statistics. Different simulated source galaxy samples of different redshift distributions are constructed, where both WL shear and IA signals are included. Convergence reconstruction and peak statistics are then performed for these samples. Our results show that the IA effects on peak abundances mainly consist of two aspects. One is the additional contribution from IA to the shape noise. The other is from the satellite IA that can affect the peak signals from their host clusters significantly. The latter depends on the level of inclusion in a shear sample of the satellite galaxies of the clusters that contribute to WL peaks and thus is sensitive to the redshift distribution of source galaxies. We pay particular attention to satellite IA and adjust it artificially in the simulations to analyze the dependence of the satellite IA impacts on its strength. This information can potentially be incorporated into the modeling of WL peak abundances, especially for high peaks physically originated from massive clusters of galaxies, and thus mitigate the IA systematics on the cosmological constraints derived from WL peaks.

Keywords: Weak gravitational lensing
Binary Evolution and Blue Stragglers in Different Regions of the Color-Magnitude Diagrams of Globular Clusters with Different Ages. Blue stragglers (BSs) in different regions (e.g., two sequences) of the color-magnitude diagram (CMD) have been suggested to provide a strong constraint on the origin of BSs in globular clusters (GCs). However, our understanding of the locations of binary-induced BSs is incomplete, e.g., its low-luminosity boundary. By employing Eggleton's stellar evolution code, the locations of mass-transferring (MT) BS binaries and post-mass-transfer (post-MT) BS binaries are investigated in the CMDs of GCs with different ages. The results show that post-MT BS binaries always populate the region of the CMD below the ZAMS+0.75 for GCs older than 10 Gyr and can also populate the region above the ZAMS+0.75 (the region of MT BS binaries). The low-luminosity boundary of the binary-induced BSs is located near the ZAMS in a way that is independent of the age of old GCs. The BS binaries draw a narrow sequence below the ZAMS+0.75 and cover most of the BSs in NGC 362. These results support that binary evolution can explain the appearance of BSs in different regions of the CMDs of GCs with different ages, and at least a fraction of BSs along the blue sequence could be post-MT BSs. However, the theoretical gap does not exactly correspond to the observed gap in NGC 362, and the models predict an excess of BSs below ZAMS+0.75 with respect to the observations in NGC 362. Therefore, more theoretical and observational work is needed to clarify the origin of these discrepancies.

Keywords: Blue straggler stars
Critical Mach Numbers for Magnetohydrodynamic Shocks with Accelerated Particles and Waves. The first critical fast Mach number is defined for a magnetohydrodynamic shock as the Mach number where the shock transitions from subcritical, laminar behavior to supercritical behavior, characterized by incident ion reflection from the shock front. The ensuing upstream waves and turbulence are convected downstream, leading to a turbulent shock structure. Formally, this is the Mach number where plasma resistivity can no longer provide sufficient dissipation to establish a stable shock, and is characterized by the downstream flow speed becoming subsonic. We revisit these calculations, including in the MHD jump conditions terms modeling the plasma energy loss to accelerated particles and the presence of waves associated with these particles. The accelerated particle contributions make an insignificant change, but the associated waves have a more important effect. Upstream waves can be strongly amplified in intensity on passing through the shock, and they represent another means of shock dissipation. The presence of such waves therefore increases the first critical fast Mach number, especially at quasi-parallel shock where wave excitation is strongest. These effects may have significance for the solar regions where shock waves accelerate particles and cause Type II and Type III radio bursts, and they could also contribute to the event-to-event variability of SEP acceleration.

Keywords: Solar energetic particles, Solar coronal mass ejection shocks, Interplanetary particle acceleration, Alfven waves
Characteristics of Electron Pitch-angle Distribution in the Flapping Magnetotail. The configuration, local motions, and related physics processes of the terrestrial magnetotail have been well studied, playing a key role in magnetotail dynamics. But characteristics of electron pitch-angle distribution (PAD), and the formation mechanisms, at different regions in the flapping magnetotail were not pointed out. Here, we study a current sheet crossing event detected by the Magnetospheric Multiscale Mission inside a magnetotail, and investigate the electron PAD of the event in detail. When the spacecraft are out of the current sheet, low-energy and high-energy electrons present field-aligned PAD and cigar-type PAD, respectively. This difference shows different motions of electrons. We proposed two possible explanation mechanisms: crossing a newly dipolarized magnetotail, or crossing the exhaust region of the reconnection region, and we discussed them in the paper adequately. Based on the dipolarized mechanism, for the first time, we point out that bouncing electrons could be the indicator of a newly dipolarized magnetotail. In addition, four other current sheet crossing cases with similar signatures are observed. Our study improves the understanding of current sheet dynamics and magnetotail configuration physics.

Keywords: Planetary magnetospheres, Magnetic fields, Space plasmas, Plasma physics
Study of Complex Absorption and Reflection in a Unique Intermediate Polar Paloma. We present the broadband (0.3-40.0 keV) X-ray analysis of a unique intermediate polar Paloma using simultaneous data from XMM-Newton and NuSTAR observatories. The X-ray power spectra show strong modulations over orbital period compared to spin period. The orbit-folded light curves show a single broad hump-like structure with strong dips for soft to medium X-rays (0.3-10.0 keV). The energy-dependent dips at ϕ ~ 0.16 and 0.5 arise as a result of a complex intrinsic absorber, strong enough to have an effect around 15 keV. The absorber could potentially be contributed from accretion curtain/accretion stream and absorbing material produced by stream-disk/stream-magnetosphere interactions. We notice significant variation of the absorber with orbital phase, with maximum absorption during orbital phase 0.1-0.22. The absorber requires more than one partial covering absorber component, specifying the necessity to use distribution of column densities for spectral modeling of the source. The isobaric cooling flow component is utilized to model the emission from the multitemperature post-shock region, giving a shock temperature of ${31.7}_{-3.5}^{+3.3}$ keV, which corresponds to a white dwarf mass of ${0.74}_{-0.05}^{+0.04}\,{M}_{\odot }$ . We have used both the neutral absorber and warm absorber models, which statistically give a similarly good fit, but with different physical implications. Among the Fe Kα line complex, the neutral line is the weakest. We probed the Compton reflection and found a minimal statistical contribution in the spectral fitting, suggesting the presence of weak reflection in Paloma.

Keywords: Accretion, Binary stars, White dwarf stars, X-ray point sources, Cataclysmic variable stars
Stellar Distributions around a Supermassive Black Hole: Strong-segregation Regime Revisited. We present a new analytical solution to the steady-state distribution of stars close to a central supermassive black hole of mass M • in the center of a galaxy. Assuming a continuous mass function of the form ${dN}/{dm}\propto {m}^{\gamma }$ , stars with a specific orbital energy x = GM •/r - v 2/2 are scattered primarily by stars of mass m d(x) ∝ x -5/(4γ+10) that dominate the scattering of both lighter and heavier species at that energy. Stars of mass m d(x) are exponentially rare at energies lower than x, and follow a density profile $n(x^{\prime} )\propto x{{\prime} }^{3/2}$ at energies $x^{\prime} \gt x$ . Our solution predicts a negligible flow of stars through energy space for all mass species, similarly to the conclusions of Bahcall &amp; Wolf, but in contrast to the assumptions of Alexander &amp; Hopman. This is the first analytic solution that smoothly transitions between regimes where different stellar masses dominate the scattering.

Keywords: Analytical mathematics, Supermassive black holes, Galactic center, Stellar dynamics
Probing Patchy Reionization with the Void Probability Function of Lyα Emitters. We probe what constraints for the global ionized hydrogen fraction the void probability function (VPF) clustering can give for the Lyman Alpha Galaxies in the Epoch of Reionization (LAGER) narrowband survey as a function of area. Neutral hydrogen acts like a fog for Lyα emission, and measuring the drop in the luminosity function of Lyα emitters (LAEs) has been used to constrain the ionization fraction in narrowband surveys. However, the clustering of LAEs is independent of the luminosity function's inherent evolution, and can offer additional constraints for reionization under different models. The VPF measures how likely a given circle is to be empty. It is a volume-averaged clustering statistic that traces the behavior of higher-order correlations, and its simplicity offers helpful frameworks for planning surveys. Using the Jensen et al. simulations of LAEs within various amounts of ionized intergalactic medium, we predict the behavior of the VPF in one (301 × 150.5 × 30 Mpc3), four (5.44 × 106 Mpc3), or eight (1.1 × 107 Mpc3) fields of LAGER imaging. We examine the VPF at 5' and 13', corresponding to the minimum scale implied by the LAE density and the separation of the 2D VPF from random, and the maximum scale from the eight-field 15.5 deg2 LAGER area. We find that even a single DECam field of LAGER (2-3 deg2) could discriminate between mostly neutral versus ionized. Additionally, we find four fields allow for the distinction between 30%, 50%, and 95% ionized, and eight fields could even distinguish between 30%, 50%, 73%, and 95% ionized.

Keywords: Large-scale structure of the universe, Clustering, Lyman-alpha galaxies, Reionization, Astronomical simulations
The Solar Cycle Dependence of In Situ Properties of Two Types of Interplanetary CMEs during 1999-2020. Generally, in situ parameters of interplanetary coronal mass ejections (ICMEs) are analyzed as a whole, or ICMEs are classified by speed or whether they are with and without magnetic clouds. Zhai and colleagues found that ICMEs with and without flares can be extracted only by the average charge states of iron (Q Fe). In the present study, the ICMEs are categorized into two types, flare CMEs (FCs) and nonflare CMEs (NFCs) by the Q Fe. We find that the occurrence rates of FCs and NFCs are both decreased from solar maximum to minimum. The occurrence rates and proportions of FCs are both higher in solar cycle 23 than in solar cycle 24. In contrast, the occurrence rates of NFCs are almost the same during the two solar cycles. The durations of FCs are longer than those of NFCs. The fractions of FCs and NFCs that are associated with magnetic clouds (MCs) or magnetic field direction rotation evidence are 73% and 69%, respectively. The speed, Q Fe, O7+/O6+, helium abundance (A He), and first ionization potential bias are all higher for FCs than for NFCs. The above parameters inside NFCs and solar wind are almost the same. The solar cycle dependence of the parameters inside NFCs is more clear than that inside FCs. The statistical results demonstrate that the material sources of FCs are not completely the same as those of NFCs. Part of the material inside FCs should come from the lower atmosphere where the A He is higher. The statistical results indicate that all CMEs are associated with flux ropes on the Sun.

Keywords: Solar abundances, Solar flares, Solar coronal mass ejections
Discovery of Year-scale Time Variability from Thermal X-Ray Emission in Tycho's Supernova Remnant. Mechanisms of particle heating are crucial to understanding the shock physics in supernova remnants (SNRs). However, there has been little information on time variabilities of thermalized particles so far. Here, we present a discovery of a gradually brightening thermal X-ray emission found in the Chandra data of Tycho's SNR obtained during 2000-2015. The emission exhibits a knot-like feature (Knot1) with a diameter of ≃0.04 pc located in the northwestern limb, where we also find localized Hα filaments in an optical image taken with the Hubble Space Telescope in 2008. The model with the solar abundance reproduces the spectra of Knot1, suggesting that Knot1 originates from the interstellar medium; this is the first detection of thermal X-ray emission from swept-up gas found in Tycho's SNR. Our spectral analysis indicates that the electron temperature of Knot1 has increased from ~0.30 to ~0.69 keV within the period between 2000 and 2015. These results lead us to ascribe the time-variable emission to a small dense clump recently heated by the forward shock at the location of Knot1. The electron-to-proton temperature ratio immediately downstream of the shock (β 0 ≡ T  e /T  p ) is constrained to be m  e /m  p  ≤ β 0 ≤ 0.15 to reproduce the data, indicating the collisionless electron heating with efficiency is consistent with previous Hα observations of Tycho and other SNRs with high shock velocities.

Keywords: Interstellar thermal emission, Plasma astrophysics, Supernova remnants, Interstellar medium, X-ray sources
The Effect of Shock-wave Duration on Star Formation and the Initial Condition of Massive Cluster Formation. Stars are born in dense molecular filaments irrespective of their mass. Compression of the interstellar medium by shocks causes filament formation in molecular clouds. Observations show that a massive star cluster formation occurs where the peak of gas column density in a cloud exceeds 1023 cm-2. In this study, we investigate the effect of the shock-compressed layer duration on filament/star formation and how the initial conditions of massive star formation are realized by performing three-dimensional isothermal magnetohydrodynamics simulations with gas inflow duration from the boundaries (i.e., shock-wave duration) as a controlling parameter. Filaments formed behind the shock expand after the duration time for short-shock-duration models, whereas long-duration models lead to star formation by forming massive supercritical filaments. Moreover, when the shock duration is longer than two postshock freefall times, the peak column density of the compressed layer exceeds 1023 cm-2, and the gravitational collapse of the layer causes the number of OB stars expected to be formed in the shock-compressed layer to reach the order of 10 (i.e., massive cluster formation).

Keywords: Magnetohydrodynamics, Star formation, Interstellar clouds, Star clusters
Measurement of High-energy Cosmic-Ray Proton Spectrum from the ISS-CREAM Experiment. The Cosmic Ray Energetics And Mass for the International Space Station (ISS-CREAM) experiment successfully recorded data for 539 days from 2017 August to 2019 February. We report the energy spectrum of cosmic-ray protons from the ISS-CREAM experiment at energies from 1.60 × 103 to 6.55 × 105 GeV. The measured spectrum deviates from a single power law. A smoothly broken power-law fit to the data, including statistical and systematic uncertainties, shows the spectral index change at 9.0 × 103 GeV from 2.57 ± 0.03 to 2.82 ± 0.02 with a significance of greater than 3σ. This bump-like structure is consistent with a spectral softening recently reported by the balloon-borne CREAM, DAMPE, and NUCLEON, but ISS-CREAM extends measurements to higher energies.

Keywords: Galactic cosmic rays
Evolution of Urca Pairs in the Crusts of Highly Magnetized Neutron Stars. We report on the effects of strong magnetic fields on neutrino emission in the modified Urca process. We show that the effect of Landau levels on the various Urca pairs affects the neutrino emission spectrum and leads to an angular asymmetry in the neutrino emission. For low magnetic fields, the Landau levels have almost no effect on the cooling. However, as the field strength increases, the electron chemical potential increases resulting in a lower density at which Urca pairs can exist. For intermediate field strength, there is an interesting interference between the Landau level distribution and the Fermi distribution. For high enough field strength, the entire electron energy spectrum is eventually confined to a single Landau level producing dramatic spikes in the emission spectrum.

Keywords: Neutron stars, Urca process, Nuclear astrophysics, Magnetars, Cosmic magnetic fields theory
Preemergence Signatures of Horizontal Divergent Flows in Solar Active Regions. Solar active regions (ARs) play a fundamental role in driving many of the geoeffective eruptions, which propagate into the solar system. However, we are still unable to consistently predict where and when ARs will occur across the solar disk by identifying preemergence signatures in observables such as the Doppler velocity (without using helioseismic methods). Here we aim to determine the earliest time at which preemergence signatures, the horizontal divergent flow (HDF) in particular, can be confidently detected using data from the Solar Dynamics Observatory's Helioseismic and Magnetic Imager. Initially, we follow previous studies using the thresholding method, which searches for significant increases in the number of pixels that display a specific line-of-sight velocity. We expand this method to more velocity windows and conduct a basic parameter study investigating the effect of cadence on the inferred results. Our findings agree with previous studies with 37.5% of ARs displaying an HDF, with average lead times between the HDF and flux emergence of 58 minutes. We present a new potential signature of flux emergence, which manifests as cadence-independent transient disruptions to the amplitudes of multiple velocity windows and recover potential preemergence signatures for 10 of the 16 ARs studied, with lead times of 60-156 minutes. Several effects can influence both the estimated times of both HDF and flux emergence suggesting that one may need to combine Doppler and magnetic field data to get a reliable indicator of continued flux emergence.

Keywords: Solar active region velocity fields, Solar active region magnetic fields, Solar active regions, Solar magnetic flux emergence
Simulation for Distributions of Several Geometric Parameters in Nulling Pulsars. We investigate the distributions of the obliquity angle and impact parameters of nulling pulsars of different duty cycles based on the simulation of more than 600,000 samples. We adopt a purely geometric approach for pulsar visibility, in which visible emission is emitted tangentially to the magnetic field line and parallel to the line-of-sight direction. The geometry is incorporated with the model for pulsar magnetospheres of multiple emission states, in which the plasma charge density is dependent on the emission state. We assume that an emission state can only exist between two limiting conditions described by the vacuum and corotation models, respectively. In this model, pulse nulling corresponds to emission switching to a state in which the plasma charge density is zero. The event is detectable only if the switching occurs at source points that lie on a trajectory, whose locus defines the locations of visible emission, within an open-field region. Our results show that detectable nulling is dependent on all three parameters, such that nulling pulsars prefer a small obliquity angle and duty cycle, and tend to have positive impact parameters. We find that the total population of nulling pulsars in our samples is around 23%, of which about 47% possess a duty cycle of 0.1 or smaller. The former implies that there are more nulling pulsars than currently known. Our model predicts that the number of nulling pulsars increases as the obliquity angle decreases, which also implies that the occurrence of nulling in a pulsar should evolve over time.

Keywords: Radio pulsars
X-Ray and Radio Observations of Central Black Holes in Nearby Low-mass Early-type Galaxies: Preliminary Evidence for Low Eddington Fractions. We present new radio and X-ray observations of two nearby (&lt;4 Mpc) low-mass early-type galaxies with dynamically confirmed central black holes: NGC 5102 and NGC 205. NGC 5102 shows a weak nuclear X-ray source and has no core radio emission. However, for the first time we demonstrate that it shows luminous extended radio continuum emission in low-resolution, low-frequency (&lt;3 GHz) data, consistent with jet lobes on scales ≳100 pc formed from past accretion and jet activity. By contrast, in new, extremely deep, strictly simultaneous Very Large Array and Chandra observations, no radio or X-ray emission is detected from the black hole in NGC 205. We consider these measurements and upper limits in the context of the few other low-mass early-type galaxies with dynamically confirmed black holes, and show that the mean ratio of bolometric to Eddington luminosity in this sample is only $\mathrm{log}\,({L}_{\mathrm{bol}}/{L}_{\mathrm{Edd}})=-6.57\pm 0.50$ . These Eddington ratios are lower than typical in a comparison sample of more massive early-type galaxies, though this conclusion is quite tentative due to our small sample of low-mass galaxies and potential biases in the comparison sample. This preliminary result is in mild tension with previous work using less sensitive observations of more distant galaxies, which predict higher X-ray luminosities than we observe for low-mass galaxies. If it is confirmed that central black holes in low-mass galaxies typically have low Eddington ratios, this presents a challenge to measuring the occupation fraction of central black holes with standard optical emission line, X-ray, or radio surveys.

Keywords: Radio active galactic nuclei, X-ray active galactic nuclei, Early-type galaxies