Sazuna/UAT_keywords huggingface dataset:
CMZoom: Survey Overview and First Data Release. We present an overview of the CMZoom survey and its first data release. CMZoom is the first blind, high-resolution survey of the Central Molecular Zone (CMZ; the inner 500 pc of the Milky Way) at wavelengths sensitive to the pre-cursors of high-mass stars. CMZoom is a 550 hr Large Program on the Submillimeter Array that mapped at 1.3 mm all of the gas and dust in the CMZ above a molecular hydrogen column density of 1023 cm-2 at a resolution of ∼3″ (0.1 pc). In this paper, we focus on the 1.3 mm dust continuum and its data release, but also describe CMZoom spectral line data which will be released in a forthcoming publication. While CMZoom detected many regions with rich and complex substructure, its key result is an overall deficit in compact substructures on 0.1-2 pc scales (the compact dense gas fraction: CDGF). In comparison with clouds in the Galactic disk, the CDGF in the CMZ is substantially lower, despite having much higher average column densities. CMZ clouds with high CDGFs are well-known sites of active star formation. The inability of most gas in the CMZ to form compact substructures is likely responsible for the dearth of star formation in the CMZ, surprising considering its high density. The factors responsible for the low CDGF are not yet understood but are plausibly due to the extreme environment of the CMZ, having far-reaching ramifications for our understanding of the star formation process across the cosmos.

Keywords: Galactic center, Infrared dark clouds, Star forming regions, Protostars, Molecular clouds, Dense interstellar clouds, Star formation, Submillimeter astronomy, Interferometry
Challenges in Scientific Data Communication from Low-mass Interstellar Probes. An optical downlink for the return of scientific data from space probes at interstellar distances is studied. The context is probes moving at relativistic speed using a terrestrial directed-energy beam for propulsion, necessitating very low mass probes. Achieving simultaneous communication from a swarm of probes launched at regular intervals to a target at the distance of Proxima Centauri is addressed. The analysis focuses on fundamental physical and statistical communication limitations on downlink performance rather than a concrete implementation. Transmission time/distance and probe mass are chosen to achieve the best data latency versus volume trade-off. Challenges in targeting multiple probe trajectories with a single receiver are addressed, including multiplexing, parallax, and target-star proper motion. Constraints on transmit aperture size make a compelling argument in favor of free-space optical communications, and this is the assumed approach for our baseline analysis. Relevant sources of background radiation, including cosmic, atmospheric, and receiver dark count, are identified and estimated. Direct detection enables high photon efficiency and incoherent aperture combining. A novel burst pulse-position modulation (BPPM) beneficially expands the optical bandwidth and ameliorates receiver dark counts. A canonical receive optical collector combines minimum transmit power with constrained swarm-probe coverage. Theoretical limits on reliable data recovery and sensitivity to the various BPPM model parameters are applied, including a wide range of total collector areas. Significant near-term technological obstacles are identified. Enabling innovations include a high peak-to-average power ratio, a large source extinguishing factor, the shortest atmosphere-transparent wavelength to minimize target-star interference, adaptive optics for atmospheric turbulence, very selective bandpass filtering (possibly with multiple passbands), very low dark count single-photon superconducting detectors, and very accurate attitude control and pointing mechanisms.

Keywords: Deep space probes, Space probes, Exoplanets, Exoplanet astronomy, Flyby missions
A Comprehensive Power Spectral Density Analysis of Astronomical Time Series. I. The Fermi-LAT Gamma-Ray Light Curves of Selected Blazars. We present the results of the Fermi-Large Area Telescope 10 yr long light curve (LC) modeling of selected blazars: six flat-spectrum radio quasars (FSRQs) and five BL Lacertae (BL Lacs), examined in 7, 10, and 14 day binning. The LCs and power spectral densities (PSDs) were investigated with various methods: Fourier transform, Lomb-Scargle periodogram (LSP), wavelet scalogram, autoregressive moving average (ARMA) process, continuous-time ARMA (CARMA), Hurst exponent (H), and the ${ \mathcal A }\mbox{--}{ \mathcal T }$ plane. First, with extensive simulations we showed that parametric modeling returns unreliable parameters, with a high dispersion for different realizations of the same stochastic model. Hence, any such analysis should be supported with Monte Carlo simulations. For our blazar sample, we find that the power-law indices β calculated from the Fourier and LSP modeling mostly fall in the range 1 ≲ β ≲ 2. Using the wavelet scalograms, we confirm a quasi-periodic oscillation (QPO) in PKS 2155-304 at a 3σ significance level, but do not detect any QPOs in other objects. The ARMA fits reached higher orders for 7 day binned LCs and lower orders for 10 and 14 day binned LCs for the majority of blazars, suggesting there might exist a characteristic timescale for the perturbations in the jet and/or accretion disk to die out. ARMA and CARMA modeling revealed breaks in their PSDs at timescales of a few hundred days. The estimation of H was performed with several methods. We find that most blazars exhibit H &gt; 0.5, indicating long-term memory. Finally, the FSRQ and BL Lac subclasses are clearly separated in the ${ \mathcal A }\mbox{--}{ \mathcal T }$ plane.

Keywords: BL Lacertae objects, High energy astrophysics, Quasars, Blazars, Light curves, Active galactic nuclei, Time series analysis
The Quijote Simulations. The QUIJOTE simulations are a set of 44,100 full N-body simulations spanning more than 7000 cosmological models in the $\{{{\rm{\Omega }}}_{{\rm{m}}},{{\rm{\Omega }}}_{{\rm{b}}},h,{n}_{s},{\sigma }_{8},{M}_{\nu },w\}$ hyperplane. At a single redshift, the simulations contain more than 8.5 trillion particles over a combined volume of 44,100 ${\left({h}^{-1}\mathrm{Gpc}\right)}^{3};$ each simulation follows the evolution of 2563, 5123, or 10243 particles in a box of 1 h-1 Gpc length. Billions of dark matter halos and cosmic voids have been identified in the simulations, whose runs required more than 35 million core hours. The QUIJOTE simulations have been designed for two main purposes: (1) to quantify the information content on cosmological observables and (2) to provide enough data to train machine-learning algorithms. In this paper, we describe the simulations and show a few of their applications. We also release the petabyte of data generated, comprising hundreds of thousands of simulation snapshots at multiple redshifts; halo and void catalogs; and millions of summary statistics, such as power spectra, bispectra, correlation functions, marked power spectra, and estimated probability density functions.

Keywords: Large-scale structure of the universe, Cosmological parameters, Astrostatistics, Cosmological neutrinos, N-body simulations
The Variable Mg II Narrow Absorption Line Systems. Compared to high ionization C IV absorption lines, variable Mg II absorption lines are rare. Using spectra from the Sloan Digital Sky Survey, we investigate the variations in Mg II narrow absorption lines (NALs) for quasars with multi-epoch observations. We have compiled 8958 Mg II NALs in the spectral regions from the red wings of C IV emission lines to the red wings of Mg II emission lines. Among these 8958 Mg II NALs, 22 variable NALs are detected with $| {\rm{\Delta }}{W}_{r}^{\lambda 2796}| \geqslant 3{\sigma }_{W}$ and with velocity offsets ranging from ${\upsilon }_{r}=522$ to 145,513 $\mathrm{km}\,{{\rm{s}}}^{-1}$ . We find that: (1) the detected frequency of Mg II NALs with ${\upsilon }_{r}\leqslant {\rm{10,000}}$ $\mathrm{km}\,{{\rm{s}}}^{-1}$ is significantly larger than the uniformly random value expected for the Mg II NALs with ${\upsilon }_{r}\gt {\rm{10,000}}$ $\mathrm{km}\,{{\rm{s}}}^{-1}$ , (2) the incidence rates of the variable Mg II NALs with ${\upsilon }_{r}\leqslant {\rm{10,000}}$ $\mathrm{km}\,{{\rm{s}}}^{-1}$ are much larger than those with ${\upsilon }_{r}\gt {\rm{10,000}}$ $\mathrm{km}\,{{\rm{s}}}^{-1}$ , (3) the velocity offsets of variable Mg II NALs with ${\upsilon }_{r}\leqslant {\rm{10,000}}$ $\mathrm{km}\,{{\rm{s}}}^{-1}$ are much smaller than the maximum velocities expected from radiation-driven outflows, and (4) the variations of variable Mg II NALs with ${\upsilon }_{r}\leqslant {\rm{10,000}}$ $\mathrm{km}\,{{\rm{s}}}^{-1}$ are obviously correlated with the changes in the quasar radiative output. Therefore, the 16 variable Mg II NALs, whose velocities are smaller than the maximum velocities expected from radiation-driven outflows, are likely related to quasar outflows, while the 6 variable Mg II NALs, whose velocities are much larger than the maximum velocities expected from radiation-driven outflows, possibly originated in intervening gas. We also find that both the variations and fractional variations in absorption strengths are not related to the velocity offsets of Mg II NALs and the time intervals between the two epochs of observations. Also, the fractional variations in absorption strengths are inversely correlated with absorption strengths. In addition, both the associated and intervening Mg II NALs can significantly vary on a timescale of days.

Keywords: Quasar absorption line spectroscopy, Quasars, Active galaxies, Astronomy data analysis, Galaxies
Identifying and Tracking Solar Magnetic Flux Elements with Deep Learning. Deep learning has drawn significant interest in recent years due to its effectiveness in processing big and complex observational data gathered from diverse instruments. Here we propose a new deep learning method, called SolarUnet, to identify and track solar magnetic flux elements or features in observed vector magnetograms based on the Southwest Automatic Magnetic Identification Suite (SWAMIS). Our method consists of a data preprocessing component that prepares training data from the SWAMIS tool, a deep learning model implemented as a U-shaped convolutional neural network for fast and accurate image segmentation, and a postprocessing component that prepares tracking results. SolarUnet is applied to data from the 1.6 m Goode Solar Telescope at the Big Bear Solar Observatory. When compared to the widely used SWAMIS tool, SolarUnet is faster while agreeing mostly with SWAMIS on feature size and flux distributions and complementing SWAMIS in tracking long-lifetime features. Thus, the proposed physics-guided deep learning-based tool can be considered as an alternative method for solar magnetic tracking.

Keywords: Solar photosphere, Convolutional neural networks, Solar magnetic fields
Comprehensive Analysis of the Tidal Effect in Gravitational Waves and Implication for Cosmology. Detection of gravitational waves (GWs) produced by coalescence of compact binaries provides a novel way to measure the luminosity distance of GW events. Combining their redshift, they can act as standard sirens to constrain cosmological parameters. For various GW detector networks in second-generation (2G), 2.5G, and 3G, we comprehensively analyze the method to constrain the equation-of-state (EOS) of binary neutron stars (BNSs) and extract their redshifts through the imprints of tidal effects in GW waveforms. We find for these events that the observations of electromagnetic counterparts in the low-redshift range z &lt; 0.1 are important for constraining the tidal effects. Considering 17 different EOSs of NSs or quark stars, we find GW observations have strong capability to determine the EOS. Applying the events as standard sirens, and considering the constraints of NS's EOS derived from low-redshift observations as prior, we can constrain the dark energy EOS parameters w0 and wa. In the 3G era, the potential constraints are Δw0 ∈ (0.0006,0.004) and Δwa ∈ (0.004,0.02), which are 1-3 orders smaller than those from traditional methods, including Type Ia supernovae (SNe Ia) and baryon acoustic oscillations. The constraints are also made 1 order smaller than the method of GW standard siren by fixing the redshifts through short-hard γ-ray bursts, due to more available GW events in this method. Therefore, GW standard sirens, based on the tidal effect measurement, provide a realizable and much more powerful tool in cosmology.

Keywords: Neutron stars, Gravitational wave detectors, Gravitational waves, Dark energy
Completing the 3CR Chandra Snapshot Survey: Extragalactic Radio Sources at High Redshift. We present the analysis of nine radio sources belonging to the Third Cambridge Revised catalog (3CR) observed with Chandra during Cycle 20 in the redshift range between 1.5 and 2.5. This study completes the 3CR Chandra Snapshot Survey thus guaranteeing the X-ray coverage of all 3CR sources identified to date. This sample lists two compact steep spectrum sources, four radio galaxies, and three quasars. We detected X-ray emission from all nuclei, with the only exception of 3C 326.1 and 3C 454.1 and from radio lobes in six out of nine sources at a level of confidence larger than ∼5σ. We measured X-ray fluxes and luminosities for all nuclei and lobes in the soft (0.5-1 keV), medium (1-2 keV), and hard (2-7 keV) X-ray bands. Since the discovered X-ray extended emission is spatially coincident with the radio structure in all cases, its origin could be due to inverse Compton (IC) scattering of the cosmic microwave background (CMB) occurring in radio lobes.

Keywords: High energy astrophysics, Active galaxies, X-ray active galactic nuclei, Active galactic nuclei, Radio active galactic nuclei, Radio sources
The Sloan Digital Sky Survey Quasar Catalog: Sixteenth Data Release. We present the final Sloan Digital Sky Survey IV (SDSS-IV) quasar catalog from Data Release 16 of the extended Baryon Oscillation Spectroscopic Survey (eBOSS). This catalog comprises the largest selection of spectroscopically confirmed quasars to date. The full catalog includes two subcatalogs (the current versions are DR16Q_v4 and DR16Q_Superset_v3 at https://data.sdss.org/sas/dr16/eboss/qso/DR16Q/): a "superset" of all SDSS-IV/eBOSS objects targeted as quasars containing 1,440,615 observations and a quasar-only catalog containing 750,414 quasars, including 225,082 new quasars appearing in an SDSS data release for the first time, as well as known quasars from SDSS-I/II/III. We present automated identification and redshift information for these quasars alongside data from visual inspections for 320,161 spectra. The quasar-only catalog is estimated to be 99.8% complete with 0.3%-1.3% contamination. Automated and visual inspection redshifts are supplemented by redshifts derived via principal component analysis and emission lines. We include emission-line redshifts for Hα, Hβ, Mg II, C III], C IV, and Lyα. Identification and key characteristics generated by automated algorithms are presented for 99,856 broad absorption-line quasars and 35,686 damped Lyman alpha quasars. In addition to SDSS photometric data, we also present multiwavelength data for quasars from the Galaxy Evolution Explorer, UKIDSS, the Wide-field Infrared Survey Explorer, FIRST, ROSAT/2RXS, XMM-Newton, and Gaia. Calibrated digital optical spectra for these quasars can be obtained from the SDSS Science Archive Server.

Keywords: Cosmology, Large-scale structure of the universe, Surveys, Quasars, Observational cosmology, Catalogs
Lyα Radiative Transfer: Monte Carlo Simulation of the Wouthuysen-Field Effect. A three-dimensional Monte Carlo Lyα radiative transfer (RT) code, named LaRT, is developed to study the Lyα RT and the Wouthuysen-Field (WF) effect. Using the code, we calculate the line profile of Lyα radiation within the multiphase interstellar medium (ISM), with a particular emphasis on gas at low densities. We show that the WF effect is in action: the central portion of the line profile tends to approach a small slice of the Planck function with a color temperature equal to the kinetic temperature of the gas, even in a system with an optical thickness as low as τ0 ≈ 100-500. We also investigate the effects of the turbulent motion of the ISM on the emergent Lyα spectrum and color temperature. The turbulent motion broadens the emergent spectrum, as generally expected, but the color temperature is not affected by the turbulent motion in typical astrophysical environments. We utilize two multiphase ISM models, appropriate for the vicinity of the Sun, to calculate the 21 cm spin temperature of neutral hydrogen, including excitation via the Lyα resonant scattering. The first ISM model is a simple clumpy model, while the second is a self-consistent magnetohydrodynamics simulation model using the TIGRESS framework. Lyα photons originating from both H II regions and the collisionally cooling gas are taken into account. We find that the Lyα radiation field is, in general, likely to be strong enough to bring the 21 cm spin temperature of the warm neutral medium close to the kinetic temperature. The escape fraction of Lyα in our ISM models is estimated to be ≈7%-20%.

Keywords: H I line emission, Radiative transfer, Interstellar medium, Warm neutral medium, Lyman-alpha galaxies, Radiative transfer simulations
MANTRA: A Machine-learning Reference Light-curve Data Set for Astronomical Transient Event Recognition. We introduce Many ANnotated TRAnsients (MANTRA), an annotated data set of 4869 transient and 71207 non-transient object light curves built from the Catalina Real-time Transient Survey. We provide public access to this data set as a plain text file to facilitate standardized quantitative comparison of astronomical transient event recognition algorithms. Some of the classes included in the data set are: supernovae, cataclysmic variables, active galactic nuclei, high proper motion stars, blazars, and flares. As an example of the tasks that can be performed on the data set we experiment with multiple data preprocessing methods, feature selection techniques, and popular machine-learning algorithms (support vector machines, random forests, and neural networks). We assess quantitative performance in two classification tasks: binary (transient/non-transient) and eight-class classification. The best-performing algorithm in both tasks is the random forest classifier. It achieves an F1 score of 96.25% in the binary classification and 52.79% in the eight-class classification. For the eight-class classification, non-transients (96.83%) is the class with the highest F1 score, while the lowest corresponds to high proper motion stars (16.79%); for supernovae it achieves a value of 54.57%, close to the average across classes. The next release of MANTRA includes images and benchmarks with deep learning models.

Keywords: Astrostatistics tools, Transient detection, Astronomy databases
Artificial Intelligence-Assisted Inversion (AIAI) of Synthetic Type Ia Supernova Spectra. We generate ∼100,000 model spectra of Type 1a supernovae (SNe Ia) to form a spectral library for the purpose of building an artificial intelligence-assisted inversion (AIAI) algorithm for theoretical models. As a first attempt, we restrict our studies to the time around B-band maximum and compute theoretical spectra with a broad spectral wavelength coverage from 2000 to 10000 Å using the code TARDIS. Based on the library of theoretically calculated spectra, we construct the AIAI algorithm with a multiresidual convolutional neural network to retrieve the contributions of different ionic species to the heavily blended spectral profiles of the theoretical spectra. The AIAI is found to be very powerful in distinguishing spectral patterns due to coupled atomic transitions and has the capacity to quantitatively measure the contributions from different ionic species. By applying the AIAI algorithm to a set of well-observed SN Ia spectra, we demonstrate that the model can yield powerful constraints on the chemical structures of these SNe Ia. Using the chemical structures deduced from AIAI, we successfully reconstructed the observed data, thus confirming the validity of the method. We show that the light-curve decline rate of SNe Ia is correlated with the amount of 56Ni above the photosphere in the ejecta. We detect a clear decrease of 56Ni mass with time that can be attributed to its radioactive decay. Our code and model spectra are available on the website https://github.com/GeronimoChen/AIAI-Supernova.

Keywords: Convolutional neural networks, Type Ia supernovae
Makemake + Sedna: A Continuum Radiation Transport and Photoionization Framework for Astrophysical Newtonian Fluid Dynamics. Astrophysical fluid flow studies often encompass a wide range of physical processes to account for the complexity of the system under consideration. In addition to gravity, a proper treatment of thermodynamic processes via continuum radiation transport and/or photoionization is becoming the state of the art. We present a major update of our continuum radiation transport module, Makemake, and a newly developed module for photoionization, Sedna, coupled to the magnetohydrodynamics code PLUTO. These extensions are currently not publicly available; access can be granted on a case-by-case basis. We explain the theoretical background of the equations solved, elaborate on the numerical layout, and present a comprehensive test suite for radiation-ionization hydrodynamics. The grid-based radiation and ionization modules support static one-dimensional, two-dimensional, and three-dimensional grids in Cartesian, cylindrical, and spherical coordinates. Each module splits the radiation field into two components, one originating directly from a point source—solved using a ray-tracing scheme—and a diffuse component—solved with a three-dimensional flux-limited diffusion (FLD) solver. The FLD solver for the continuum radiation transport makes use of either the equilibrium one-temperature approach or the linearization two-temperature approach. The FLD solver for the photoionization module enables accounting for the temporal evolution of the radiation field from direct recombination of free electrons into hydrogen's ground state as an alternative to on-the-spot approximation. A brief overview of completed and ongoing scientific studies is given to explicitly illustrate the multipurpose nature of the numerical framework presented.

Keywords: Magnetohydrodynamics, Radiative magnetohydrodynamics, Stellar feedback, Astronomy software, Hydrodynamics, Circumstellar matter, Computational methods, Star formation, Radiative transfer, Stellar accretion, Stellar accretion disks, H II regions
Solar Wind Turbulence from 1 to 45 au. V. Data Intervals from the Voyager Observations. We have surveyed the Voyager 1 and 2 spacecraft magnetic field data from launch in 1977 through 1990 using daily spectrograms to find suitably long data intervals and to eliminate times near transients or strong gradients that might not represent homogeneous turbulence intervals. In the process, we have also omitted times when waves due to suprathermal particle populations such as interstellar pickup ions can be seen. Our goal was to construct a database of interplanetary magnetic field spectra that could be used in our companion papers to study the properties of the inertial and dissipation range of interplanetary turbulence. Here, we list those data intervals along with their heliocentric distance, latitude, and longitude as well as the angle between the mean magnetic field and the radial direction. Furthermore, we show the mean plasma parameters for the intervals listed. We invite others to use these listings in their associated studies.

Keywords: Magnetohydrodynamics, Solar wind, Heliosphere