adsabs/SciX_UAT_keywords huggingface dataset:
Optical Linear Polarization toward the Open Star Cluster Casado Alessi 1

We present B-, V-, R-, and I-band linear polarimetric observations of 73 stars in the direction of open star cluster Casado Alessi 1 (hereafter Alessi 1). We aim to use polarimetry as a tool to investigate the properties and distribution of dust grains toward the direction of the cluster. The polarimetric observations were carried out using the ARIES IMaging POLarimeter mounted at the 104 cm telescope of ARIES, Nainital (India). Using the Gaia photometric data the age and distance of the cluster are estimated to be 0.8 ± 0.1 Gyr and 673 ± 98 pc, respectively. A total of 66 stars with a 26' radius from the cluster are identified as members of the cluster using the astrometric approach. Out of these 66 members, 15 stars were observed polarimetrically and found to have the same value of polarization. The majority of the stars in the region follow the general law of polarization for the interstellar medium, indicating that polarization toward the cluster Alessi 1 is dominated by foreground dust grains. The average values of the maximum polarization (Pmax) and the wavelength corresponding to the maximum polarization (λmax) toward the cluster are found to be 0.83 ± 0.03% and 0.59 ± 0.04 μm, respectively. Also, dust grains toward the cluster appear to be aligned, possibly due to the galactic magnetic field.

Keywords: interstellar medium; interstellar dust; open star clusters; polarimetry; starlight polarization; interstellar dust extinction
The Fermi-GBM Gamma-Ray Burst Spectral Catalog: 10 yr of Data

We present the systematic spectral analyses of gamma-ray bursts (GRBs) detected by the Fermi Gamma-Ray Burst Monitor during its first ten years of operation. This catalog contains two types of spectra: time-integrated spectral fits and spectral fits at the brightest time bin, from 2297 GRBs, resulting in a compendium of over 18,000 spectra. The four different spectral models used for fitting the spectra were selected based on their empirical importance to the shape of many GRBs. We describe in detail our procedure and criteria for the analyses, and present the bulk results in the form of parameter distributions both in the observer frame and in the GRB rest frame. 941 GRBs from the first four years have been refitted using the same methodology as that of the 1356 GRBs in years five through ten. The data files containing the complete results are available from the High-Energy Astrophysics Science Archive Research Center.

Keywords: gamma-ray bursts
Numerical Study of Two Injection Methods for the 2007 November 15 Coronal Mass Ejection in the Inner Heliosphere

In this paper, we use two injection methods, i.e., coronal mass ejection (CME) with and without radial compression, to investigate the propagation of the 2007 November 15 CME in the inner heliosphere with a three-dimensional, time-dependent, numerical magnetohydrodynamic model. In order to reproduce the large-scale interplanetary magnetic field associated with the CME, the spheromak model is used to provide the intrinsic magnetic field structure of the CME. The modeled results also suggest that the CME without radial compression propagates in interplanetary space with a lower velocity and arrives at 1 au later. We interpret these differences as a result of different Lorentz forces acting on the two injection methods, which lead to different CME expansions in the heliosphere. Additionally, the model of a CME without radial compression tends to overestimate the radial extension at 1 au due to an overestimation of the CME radial size in the simulation and the modeled magnetic fields at 1 au are lower compared to the model of a CME with radial compression. The above results are all useful in understanding the dynamic process occurring between the CME and the solar wind.

Keywords: solar coronal mass ejections
Rapidly Declining Hostless Type Ia Supernova KSP-OT-201509b from the KMTNet Supernova Program: Transitional Nature and Constraint on 56Ni Distribution and Progenitor Type

We report the early discovery and multicolor (BVI) high-cadence light-curve analyses of the rapidly declining sub-Chandrasekhar Type Ia supernova KSP-OT-201509b (= AT 2015cx) from the KMTNet Supernova Program. The Phillips and color stretch parameters of KSP-OT-201509b are ΔMB,15 ≃ 1.62 mag and sBV ≃ 0.54, respectively, at an inferred redshift of 0.072. These, together with other measured parameters (such as the strength of the secondary I-band peak, colors, and luminosity), identify the source to be a rapidly declining Type Ia of a transitional nature that is closer to Branch-normal than 91bg-like. Its early light-curve evolution and bolometric luminosity are consistent with those of homologously expanding ejecta powered by radioactive decay and a Type Ia SN explosion with 0.32 ± 0.01 M⊙ of synthesized 56Ni mass, 0.84 ± 0.12 M⊙ of ejecta mass, and (0.61 ± 0.14) × 1051 erg of ejecta kinetic energy. While its B - V and V - I colors evolve largely synchronously with the changes in the I-band light curve, as found in other supernovae, we also find the presence of an early redward evolution in V - I prior to -10 days since peak. The bolometric light curve of the source is compatible with a stratified 56Ni distribution extended to shallow layers of the exploding progenitor. Comparisons between the observed light curves and those predicted from ejecta-companion interactions clearly disfavor Roche lobe-filling companion stars at large separation distances, thus supporting a double-degenerate scenario for its origin. The lack of any apparent host galaxy in our deep stack images reaching a sensitivity limit of ∼28 mag arcsec-2 makes KSP-OT-201509b a hostless Type Ia supernova and offers new insights into supernova host galaxy environments.

Keywords: type ia supernovae; supernovae
Failures of Minimum Variance Analysis in Diagnosing Planar Structures in Space

Minimum variance analysis of the magnetic field (MVAB), among various techniques of planar structure analysis, is most widely used for its numerical simplicity and loose requirements for data. Through a large number of studies based on MVAB, a global picture of the solar wind intermittency has been established. However, the huge discrepancy between the results from MVAB and other techniques like timing/triangulation implies that the uncertainty of MVAB is a crucial issue that is not fully understood. Utilizing Cluster data, we establish a data set comprised of 6752 discontinuities, whose orientations are precisely determined by timing, as a benchmark for testing MVAB. We find that the scatter of the MVAB normals around the timing normal can be reduced by elevating the threshold for the eigenvalue ratio λ 2/λ 3 and narrowing the data window to which MVAB is applied. The misidentification of discontinuities with $\left|{B}_{N}\right|/| {\boldsymbol{B}}| $ < 0.4, Δ∣ B ∣/∣ B ∣ < 0.2 as rotational discontinuities (RDs, identified by $\left|{B}_{N}\right|/| {\boldsymbol{B}}| $ > 0.4, Δ∣ B ∣/∣ B ∣ < 0.2) is proved to be a major and inherent defect of MVAB, which can occur even when λ 2/λ 3 is large. Such a misidentification process is revealed to be related to a special discontinuity geometry. It also explains the false RD predominance reported by previous studies based on MVAB. Finally, we provide advice for the application of MVAB and discuss the possibility of obtaining the real statistical properties of interplanetary discontinuities by using MVAB.

Keywords: interplanetary discontinuities; astronomy data analysis; interplanetary magnetic fields; solar wind
Optical Spectroscopy of Type Ia Supernovae by the Carnegie Supernova Projects I and II

We present the second and final release of optical spectroscopy of Type Ia supernovae (SNe Ia) obtained during the first and second phases of the Carnegie Supernova Project (CSP-I and CSP-II). The newly released data consist of 148 spectra of 30 SNe Ia observed in the course of CSP-I and 234 spectra of 127 SNe Ia obtained during CSP-II. We also present 216 optical spectra of 46 historical SNe Ia, including 53 spectra of 30 SNe Ia observed by the Calán/Tololo Supernova Survey. We combine these observations with previously published CSP data and publicly available spectra to compile a large sample of measurements of spectroscopic parameters at maximum light, consisting of pseudo-equivalent widths and expansion velocities of selected features for 232 CSP and historical SNe Ia (including more than 1000 spectra). Finally, we review some of the strongest correlations between spectroscopic and photometric properties of SNe Ia. Specifically, we define two samples: one consisting of SNe Ia discovered by targeted searches (most of them CSP-I objects) and the other composed of SNe Ia discovered by untargeted searches, which includes most of the CSP-II objects. The analyzed correlations are similar for both samples. We find a larger incidence of SNe Ia belonging to the cool and broad-line Branch subtypes among the events discovered by targeted searches, shallow-silicon SNe Ia are present with similar frequencies in both samples, while core normal SNe Ia are more frequent in untargeted searches.

Keywords: supernovae; spectroscopy
Photometry and Polarimetry of 2010 XC15: Observational Confirmation of E-type Near-Earth Asteroid Pair

Asteroid systems such as binaries and pairs are indicative of the physical properties and dynamical histories of small solar system bodies. Although numerous observational and theoretical studies have been carried out, the formation mechanism of asteroid pairs is still unclear, especially for near-Earth asteroid (NEA) pairs. We conducted a series of optical photometric and polarimetric observations of a small NEA 2010 XC15 in 2022 December to investigate its surface properties. The rotation period of 2010 XC15 is possibly a few to several dozen hours and the color indices of 2010 XC15 are derived as g - r = 0.435 ± 0.008, r - i = 0.158 ± 0.017, and r - z = 0.186 ± 0.009 in the Pan-STARRS system. The linear polarization degrees of 2010 XC15 are a few percent at the phase angle range of 58°-114°. We found that 2010 XC15 is a rare E-type NEA on the basis of its photometric and polarimetric properties. Taking the similarity of not only physical properties but also dynamical integrals and the rarity of E-type NEAs into account, we suppose that 2010 XC15 and 1998 WT24 are of common origin (i.e., an asteroid pair). These two NEAs are the sixth NEA pair and first E-type NEA pair ever confirmed, possibly formed by rotational fission. We conjecture that the parent body of 2010 XC15 and 1998 WT24 was transported from the main belt through the ν 6 resonance or Hungaria region.

Keywords: asteroids; near-earth objects; photometry; multi-color photometry; light curves; polarimetry
The Improved Amati Correlations from Gaussian Copula

In this paper, we present two improved Amati correlations of gamma-ray burst (GRB) data via a powerful statistical tool called copula. After calibrating with the low-redshift GRB data, the improved Amati correlations based on a fiducial Λ cold dark matter (ΛCDM) model with Ωm0 = 0.3 and H 0 = 70 km s-1 Mpc-1, and extrapolating the results to the high-redshift GRB data, we obtain the Hubble diagram of GRB data points. Applying these GRB data to constrain the ΛCDM model, we find that the improved Amati correlation from copula can give a result well consistent with Ωm0 = 0.3, while the standard Amati and extended Amati correlations do not. This results suggest that when the improved Amati correlation from copula is used in the low-redshift calibration method, the GRB data can be regarded as a viable cosmological explorer. However, the Bayesian information criterion indicates that the standard Amati correlation remains to be favored mildly since it has the least model parameters. Furthermore, once the simultaneous fitting method rather than the low-redshift calibration one is used, there is no apparent evidence that the improved Amati correlation is better than the standard one. Thus, more work needs to be done in the future in order to compare different Amati correlations.

Keywords: gamma-ray bursts; cosmology
Kelvin-Helmholtz versus Tearing Instability: What Drives Turbulence in Stochastic Reconnection?

Over the last few years it became clear that turbulent magnetic reconnection and magnetized turbulence are inseparable. It was not only shown that reconnection is responsible for violating the frozen-in condition in turbulence, but also that stochastic reconnection in 3D generates turbulence by itself. The actual mechanism responsible for this driving is still unknown. Processes such as the tearing mode or Kelvin-Helmholtz, among other plasma instabilities, could generate turbulence from irregular current sheets. We address the nature of the driving mechanism for this process and consider the relative role of tearing and Kelvin-Helmholtz instabilities for the process of turbulence generation. In particular, we analyze the conditions for development of these two instabilities within 3D reconnection regions. We show that both instabilities can excite turbulence fluctuations in reconnection regions. However, the tearing mode has a relatively slow growth rate, and at later times it becomes partially suppressed by a component of the magnetic field that runs transversely to the current sheet, which is generated during the growth of turbulent fluctuations. In contrast, the Kelvin-Helmholtz instability quickly establishes itself in the outflow region, and at later times, it dominates the turbulence generation compared to the contribution from the tearing mode. Our results demonstrate that the tearing instability is subdominant to the the Kelvin-Helmholtz instability in terms of generation of turbulence in the 3D reconnection layers, and therefore the self-driven reconnection is turbulent reconnection, and the tearing instability is only important at the initial stage of the reconnection.

Keywords: plasma astrophysics; solar magnetic reconnection; interplanetary turbulence
Star-Gas Misalignment in Galaxies. I. The Properties of Galaxies from the Horizon-AGN Simulation and Comparisons to SAMI

Recent integral field spectroscopy observations have found that about 11% of galaxies show star-gas misalignment. The misalignment possibly results from external effects such as gas accretion, interaction with other objects, and other environmental effects, hence providing clues to these effects. We explore the properties of misaligned galaxies using Horizon-AGN, a large-volume cosmological simulation, and compare the results with those of the Sydney-AAO Multi-object integral field spectrograph (SAMI) Galaxy Survey. Horizon-AGN can match the overall misalignment fraction and reproduces the distribution of misalignment angles found by observations surprisingly closely. The misalignment fraction is found to be highly correlated with galaxy morphology both in observations and in the simulation: early-type galaxies are substantially more frequently misaligned than late-type galaxies. The gas fraction is another important factor associated with misalignment in the sense that misalignment increases with decreasing gas fraction. However, there is a significant discrepancy between the SAMI and Horizon-AGN data in the misalignment fraction for the galaxies in dense (cluster) environments. We discuss possible origins of misalignment and disagreement.

Keywords: galaxies; galaxy evolution; galaxy kinematics
Prospects for kSZ2-Galaxy Cross-correlations during Reionization

We explore a new approach for extracting reionization-era contributions to the kinetic Sunyaev-Zel'dovich (kSZ) effect. Our method utilizes the cross-power spectrum between filtered and squared maps of the cosmic microwave background (CMB) and photometric galaxy surveys during the Epoch of Reionization (EoR). This kSZ2-galaxy cross-power spectrum statistic has been successfully detected at lower redshifts (z ≲ 1.5). Here we extend this method to z ≳ 6 as a potential means to extract signatures of patchy reionization. We model the expected signal across multiple photometric redshift bins using seminumeric simulations of the reionization process. In principle, the cross-correlation statistic robustly extracts reionization-era contributions to the kSZ signal, while its redshift evolution yields valuable information regarding the timing of reionization. Specifically, the model cross-correlation signal near ℓ ~ 1000 peaks during the early stages of the EoR, when about 20% of the volume of the universe is ionized. Detectable ℓ modes mainly reflect squeezed-triangle configurations of the related bispectrum, quantifying correlations between the galaxy overdensity field on large scales and the smaller-scale kSZ power. We forecast the prospects for detecting this signal using future wide-field samples of Lyman-break galaxies from the Roman Space Telescope and next-generation CMB surveys including the Simons Observatory, CMB-S4, and CMB-HD. We find that a roughly 13σ detection is possible for CMB-HD and Roman after summing over all ℓ modes. We discuss the possibilities for improving this approach and related statistics, with the aim of moving beyond simple detections to measure the scale and redshift dependence of the cross-correlation signals.

Keywords: cosmic microwave background radiation; cosmology; reionization; sunyaev-zeldovich effect
Spectral Templates Optimal for Selecting Galaxies at z > 8 with the JWST

The selection of high-redshift galaxies often involves spectral energy distribution (SED) fitting to photometric data, an expectation for contamination levels, and measurement of sample completeness-all vetted through comparison to spectroscopic redshift measurements of a sub-sample. The first JWST data are now being taken over several extragalactic fields to different depths and across various areas, which will be ideal for the discovery and classification of galaxies out to distances previously uncharted. As spectroscopic redshift measurements for sources in this epoch will not be initially available to compare with the first photometric measurements of z > 8 galaxies, robust photometric redshifts are of the utmost importance. Galaxies at z > 8 are expected to have bluer rest-frame ultraviolet (UV) colors than typically used model SED templates, which could lead to catastrophic photometric redshift failures. We use a combination of BPASS and CLOUDY models to create a supporting set of templates that match the predicted rest-UV colors of z > 8 simulated galaxies. We test these new templates by fitting simulated galaxies in a mock catalog, Yung et al., which mimic expected field depths and areas of the JWST Cosmic Evolution Early Release Science Survey (m 5σ ~ 28.6 over ~100 arcmin2). We use EAZY to highlight the improvements in redshift recovery with the inclusion of our new template set and suggest criteria for selecting galaxies at 8 < z < 10 with the JWST, providing an important test case for observers venturing into this new era of astronomy.

Keywords: galaxies; spectral energy distribution; astronomical simulations
Deep X-Ray and Radio Observations of the First Outburst of the Young Magnetar Swift J1818.0-1607

Swift J1818.0-1607 is a radio-loud magnetar with a spin period of 1.36 s and a dipolar magnetic field strength of B ~ 3 × 1014 G, which is very young compared to the Galactic pulsar population. We report here on the long-term X-ray monitoring campaign of this young magnetar using XMM-Newton, NuSTAR, and Swift from the activation of its first outburst in 2020 March until 2021 October, as well as INTEGRAL upper limits on its hard X-ray emission. The 1-10 keV magnetar spectrum is well modeled by an absorbed blackbody with a temperature of kT BB ~ 1.1 keV and apparent reduction in the radius of the emitting region from ~0.6 to ~0.2 km. We also confirm the bright diffuse X-ray emission around the source extending between ~50″ and ~110″. A timing analysis revealed large torque variability, with an average spin-down rate $\dot{\nu }\,\sim $ -2.3 × 10-11 Hz2 that appears to decrease in magnitude over time. We also observed Swift J1818.0-1607 with the Karl G. Jansky Very Large Array on 2021 March 22. We detected the radio counterpart to Swift J1818 measuring a flux density of S v = 4.38 ± 0.05 mJy at 3 GHz and a half-ringlike structure of bright diffuse radio emission located at ~90″ to the west of the magnetar. We tentatively suggest that the diffuse X-ray emission is due to a dust-scattering halo and that the radio structure may be associated with the supernova remnant of this young pulsar, based on its morphology.

Keywords: neutron stars; magnetars
Pseudo-redshifts of Gamma-Ray Bursts Derived from the L-T-E Correlation

The X-ray afterglow of many gamma-ray bursts (GRBs) exhibits a plateau phase before the normal power-law decay stage, which may be related to continued activities of the central engine. Tang et al. collected 174 such GRBs and confirmed the so-called L-T-E correlation which involves three key parameters, i.e., the isotropic γ-ray energy E γ,iso of the prompt phase, the end time T a of the plateau phase, and the corresponding X-ray luminosity L X. In this study, the L-T-E correlation is confirmed and updated as ${L}_{{\rm{X}}}\propto {T}_{{\rm{a}}}^{-0.99}{E}_{\gamma ,\mathrm{iso}}^{0.86}$ with a large sample consisting of 210 plateau GRBs with known redshifts. The tight correlation is then applied to derive the pseudo-redshift of other 130 plateau GRBs whose redshifts are not directly measured. Statistical analysis is also carried out on this pseudo-redshift sample.

Keywords: gamma-ray bursts; magnetars; neutron stars; markov chain monte carlo
Effects of External Flow on Resonant Absorption of Coronal Loop Kink Oscillations Driven by an External Fast Wave: Selective Excitation Problem

Resonant absorption is considered to be a crucial mechanism for the damping of the coronal loop oscillations and plasma heating. We study resonant absorption of the coronal loop kink oscillations excited by such external drivers as flares, assuming that there is an intermediate shear flow region surrounding the loop. We find that for long coronal loops resonant absorption can be highly enhanced or reduced depending sensitively on the magnitude and direction of the flow and the spatial extent of the flow region when the transitional layer is thin. For short coronal loops, high flow speed and a thick transitional layer are needed to have a substantial resonant absorption. We provide a potential picture to explain the results where the external Alfvén speed and phase speed of the wave are important parameters. These results imply that the transport of the external wave energy into the loop is significantly changed by the shear flow region, which may cause the selective excitation of the coronal loop oscillations.

Keywords: solar coronal loops; magnetohydrodynamics