Sazuna/UAT_keywords huggingface dataset:
A Deep-learning Anomaly-detection Method to Identify Gamma-Ray Bursts in the Ratemeters of the AGILE Anticoincidence System. Astro-rivelatore Gamma a Immagini Leggero (AGILE) is a space mission launched in 2007 to study X-ray and gamma-ray astronomy. The AGILE team developed real-time analysis pipelines to detect transient phenomena such as gamma-ray bursts (GRBs) and react to external science alerts received by other facilities. The AGILE anticoincidence system (ACS) comprises five panels surrounding the AGILE detectors to reject background-charged particles. It can also detect hard X-ray photons in the energy range 50-200 keV. The ACS data acquisition produces a time series for each panel. The time series are merged into a single multivariate time series (MTS). We present a new deep-learning model for the detection of GRBs in the ACS data using an anomaly detection technique. The model is implemented with a convolutional neural network autoencoder architecture trained in an unsupervised manner, using a data set of MTSs randomly extracted from the AGILE ACS data. The reconstruction error of the autoencoder is used as the anomaly score to classify the MTS. We calculated the associated p-value distribution, using more than 107 background-only MTSs, to define the statistical significance of the detections. We evaluate the trained model with a list of GRBs reported by the GRBWeb catalog. The results confirm the model's capabilities to detect GRBs in the ACS data. We will implement this method in the AGILE real-time analysis pipeline.

Keywords: Gamma-ray bursts, Gamma-ray detectors, Convolutional neural networks, Gamma-ray astronomy, Time series analysis
Circumstellar Medium Interaction in SN 2018lab, A Low-luminosity Type IIP Supernova Observed with TESS. We present photometric and spectroscopic data of SN 2018lab, a low-luminosity Type IIP supernova (LLSN) with a V-band peak luminosity of -15.1 ± 0.1 mag. SN 2018lab was discovered by the Distance Less Than 40 Mpc (DLT40) SN survey only 0.73 days post-explosion, as determined by observations from the Transiting Exoplanet Survey Satellite (TESS). TESS observations of SN 2018lab yield a densely sampled, fast-rising, early-time light curve likely powered by ejecta-circumstellar medium (CSM) interaction. The blueshifted, broadened flash feature in the earliest spectra (&lt;2 days) of SN 2018lab provides further evidence for ejecta-CSM interaction. The early emission features in the spectra of SN 2018lab are well described by models of a red supergiant progenitor with an extended envelope and a close-in CSM. As one of the few LLSNe with observed flash features, SN 2018lab highlights the need for more early spectra to explain the diversity of the flash feature morphology of Type II SNe.

Keywords: Type II supernovae, Circumstellar matter, Supernovae, Core-collapse supernovae
A Multiwavelength Classification and Study of Red Supergiant Candidates in NGC 6946. We have combined resolved stellar photometry from Hubble Space Telescope (HST), Spitzer, and Gaia to identify red supergiant (RSG) candidates in NGC 6946, based on their colors, proper motions, visual morphologies, and spectral energy distributions. We start with a large sample of 17,865 RSG candidates based solely on HST near-infrared photometry. We then chose a small sample of 385 of these candidates with Spitzer matches for a more detailed study. Using evolutionary models and isochrones, we isolate a space where RSGs would be found in our photometry catalogs. We then visually inspect each candidate and compare them to Gaia catalogs to identify and remove foreground stars. As a result, we classify 95 potential RSGs, with 40 of these being in our highest-quality sample. We fit the photometry of the populations of stars in the regions surrounding the RSGs to infer their ages. Placing our best candidate RSG stars into three age bins between 1 and 30 Myr, we find 27.5% of the candidates falling between 1-10 Myr, 37.5% between 10-20 Myr, and 35% between 20-30 Myr. A comparison of our results to the models of massive star evolution shows some agreement between model luminosities and the luminosities of our candidates for each age. Three of our candidates appear significantly more consistent with binary models than single-star evolution models.

Keywords: Stellar populations, Massive stars, Stellar evolution
On Measuring the 21 cm Global Spectrum of the Cosmic Dawn with an Interferometer Array. We theoretically investigate the recovery of the global spectrum (monopole) from visibilities (cross-correlation only) measured by an interferometer array and the feasibility of extracting the 21 cm signal of the cosmic dawn. In our approach, the global spectrum is obtained by solving the monopole and higher-order components simultaneously from visibilities measured with up to thousands of baselines. Using this algorithm, the monopole of both the foreground and the 21 cm signal can be correctly recovered in a broad range of conditions. We find that a 3D baseline distribution can have much better performance than a 2D (planar) baseline distribution, particularly when there is a lack of shorter baselines. We simulate for ground-based 2D and 3D array configurations, and a cross-shaped space array located at the Sun-Earth L2 point that can form 3D baselines through orbital precession. In all simulations we obtain a good recovered global spectrum, and successfully extract the 21 cm signal from it, with a reasonable number of antennas and observation time.

Keywords: Radio continuum emission, Reionization, Population III stars, Radio interferometers
On the Fine-tuning and Physical Origin of Line-locked Absorption Systems in Active Galaxies. Line locking (LL) of absorption-line systems is a clear signature of the dynamical importance of radiation-pressure force in driving astrophysical flows, with recent findings suggesting that it may be common in quasars exhibiting multiple intrinsic narrow absorption-line (NAL) systems. In this work, we probe the phase space conducive to LL and follow the detailed kinematics of those systems that may lock at the velocity separation of the C IV λ λ1548.19, 1550.77 doublet. We find that a small volume of the phase-phase admits LL, suggesting a high degree of fine-tuning between the physical properties of locked systems. The stability of LL against quasar luminosity variations is quantified with implications for the long-term variability amplitude of quasars and the velocity-separation statistic between multiple NAL systems. The high occurrence of LL by the C IV doublet implies that the hidden extreme-UV emission from quasars is unlikely to be significantly underestimated by current models. Further, the ratio of the LL velocity to the outflow velocity may serve as a powerful constraint on the composition of the accelerating medium. We conclude that LL poses significant challenges to current theories for the formation of nonintervening NAL systems, and speculate that it may be a manifestation of expanding circumstellar shells around asymptotic giant branch stars in the quasar-host bulge.

Keywords: Photoionization, Quasar absorption line spectroscopy, Quasars, Active galactic nuclei, Galaxy winds
A NOEMA Molecular Line Scan of the Hubble Deep Field North: Improved Constraints on the CO Luminosity Functions and Cosmic Density of Molecular Gas. We present measurements of the CO luminosity functions (LFs) and the evolution of the cosmic molecular gas density out to z ~ 6 based on an 8.5 arcmin2 spectral scan survey at 3 mm of the iconic Hubble Deep Field North (HDF-N) observed with the NOrthern Extended Millimeter Array (NOEMA). We use matched filtering to search for line emission from galaxies and determine their redshift probability distributions exploiting the extensive multiwavelength data for the HDF-N. We identify the seven highest-fidelity sources as CO emitters at 1 &lt; z &lt; 6, including the well-known submillimeter galaxy HDF 850.1 at z = 5.18. Four high-fidelity 3 mm continuum sources are found to be radio galaxies at z ≤ 1, plus HDF 850.1. We constrain the CO LFs in the HDF-N out to z ~ 6, including a first measurement of the CO(5-4) LF at &lt;z&gt; = 5.0. The relatively large area and depth of the NOEMA HDF-N survey extends the existing LFs at 1 &lt; z &lt; 4 above the knee, yielding a somewhat lower density by 0.15-0.4 dex at the overlap region for the CO(2-1) and CO(3-2) transitions, attributed to cosmic variance. We perform a joint analysis of the CO LFs in the HDF-N and Hubble Ultra Deep Field from ASPECS, finding that they can be well described by a single Schechter function. The evolution of the cosmic molecular gas density from a joint analysis is in good agreement with earlier determinations. This implies that the impact of cosmic field-to-field variance on the measurements is consistent with previous estimates, adding to the challenges for simulations that model galaxies from first principles.

Keywords: Luminosity function, Molecular gas, Galaxy evolution, Interstellar medium, CO line emission, Spectroscopy, High-redshift galaxies
A High-resolution Optical Survey of Upper Sco: Evidence for Coevolution of Accretion and Disk Winds. Magnetohydrodynamic (MHD) and photoevaporative winds are thought to play an important role in the evolution and dispersal of planet-forming disks. Here, we analyze high-resolution (Δv ~ 7 km s-1) optical spectra from a sample of 115 T Tauri stars in the ~5-10 Myr Upper Sco association and focus on the [O I] λ6300 and Hα lines to trace disk winds and accretion, respectively. Our sample covers a large range of spectral types and we divide it into warm (G0-M3) and cool (later than M3) to facilitate comparison with younger regions. We detect the [O I] λ6300 line in 45 out of 87 Upper Sco sources with protoplanetary disks and 32 out of 45 are accreting based on Hα profiles and equivalent widths. All [O I] λ6300 Upper Sco profiles have low-velocity (centroid &lt; -30 km s-1; low-velocity component (LVC)) emission and most (36/45) can be fit by a single Gaussian (SC). The single-component (SC) distribution of centroid velocities and FWHMs is consistent with MHD disk winds. We also find that the Upper Sco sample follows the same accretion luminosity-LVC [O I] λ6300 relation and the same anticorrelation between SC FWHM and Wide-field Infrared Survey Explorer W3-W4 spectral indices as the younger samples. These results indicate that accretion and disk winds coevolve and that, as inner disks clear out, wind emission arises further away from the star. Finally, our large spectral range coverage reveals that cool stars have larger FWHMs normalized by stellar mass than warm stars indicating that [O I] λ6300 emission arises closer in toward lower-mass/lower luminosity stars.

Keywords: Stellar accretion disks, Magnetohydrodynamics, Pre-main sequence stars, Protoplanetary disks
Origin of Quasi-periodic Pulsation at the Base of a Kink-unstable Jet. We studied a blowout jet that occurred at the west limb of the Sun on 2014 August 29 using high-resolution imaging/spectroscopic observations provided by the Solar Dynamics Observatory/Atmospheric Imaging Assembly and the Interface Region Imaging Spectrograph. An inverse γ-shaped flux rope appeared before the jet-morphological indication of the onset of kink instability. The twisted field lines of the kink-unstable flux rope reconnected at its bright knot and launched the blowout jet at ≈06:30:43 UT with an average speed of 234 km s-1. Just after the launch, the northern leg of the flux rope erupted completely. The time-distance diagrams show multiple spikes or bright dots, which is the result of periodic fluctuations, i.e., quasi-periodic fluctuations (QPPs). The wavelet analysis confirms that QPPs have a dominant period of ≈3 minutes. IRIS spectra (Si IV, C II, and Mg II) may also indicate the occurrence of magnetic reconnection through the existence of broad and complex profiles and bidirectional flows in the jet. Further, we found that line broadening is periodic with a period of ≈3 minutes, and plasma upflow always occurs when the line width is high, i.e., multiple reconnection may produce periodic line broadening. The emission measure (EM) curves also show the same period of ≈3 minutes in different temperature bins. The images and EM show that this jet spire is mainly cool (chromospheric/transition region) rather than hot (coronal) material. Further, line broadening, intensity, and EM curves have a period of ≈3 minutes, which strongly supports the fact that multiple magnetic reconnection triggers QPPs in the blowout jet.

Keywords: Solar ultraviolet emission, Solar magnetic reconnection, Spectroscopy, Solar transition region
Examining the Rotation Period Distribution of the 40 Myr Tucana-Horologium Association with TESS. The Tucana-Horologium association (Tuc-Hor) is a 40 Myr old moving group in the southern sky. In this work, we measure the rotation periods of 313 Tuc-Hor objects with TESS light curves derived from TESS full-frame images and membership lists driven by Gaia EDR3 kinematics and known youth indicators. We recover a period for 81.4% of the sample and report 255 rotation periods for Tuc-Hor objects. From these objects we identify 11 candidate binaries based on multiple periodic signals or outlier Gaia DR2 and EDR3 renormalized unit weight error values. We also identify three new complex rotators (rapidly rotating M dwarf objects with intricate light-curve morphology) within our sample. Along with the six previously known complex rotators that belong to Tuc-Hor, we compare their light-curve morphology between TESS Cycle 1 and Cycle 3 and find that they change substantially. Furthermore, we provide context for the entire Tuc-Hor rotation sample by describing the rotation period distributions alongside other youth indicators such as Hα and Li equivalent width, as well as near-ultraviolet and X-ray flux. We find that measuring rotation periods with TESS is a fast and effective means to confirm members in young moving groups.

Keywords: M dwarf stars, Light curves, Young star clusters, Young stellar objects, Stellar rotation
Resolving the Emission Regions of the Crab Pulsar's Giant Pulses. II. Evidence for Relativistic Motion. The Crab Pulsar is the prime example of an emitter of giant pulses. These short, very bright pulses are thought to originate near the light cylinder, at ~1600 km from the pulsar. The pulsar's location inside the Crab Nebula offers an unusual opportunity to resolve the emission regions, using the nebula, which scatters radio waves, as a lens. We attempt to do this using a sample of 61,998 giant pulses found in coherently combined European VLBI network observations at 18 cm. These were taken at times of relatively strong scattering and hence good effective resolution. From correlations between pulse spectra, we show that the giant pulse emission regions are indeed resolved. We infer apparent diameters of ~2000 and ~2400 km for the main and interpulse components, respectively, and show that with these sizes the correlation amplitudes and decorrelation timescales and bandwidths can be understood quantitatively, both in our observations and in previous ones. Using pulse-spectra statistics and correlations between polarizations, we also show that the nebula resolves the nanoshots that comprise individual giant pulses. The implied diameters of ~1100 km far exceed light-travel-time estimates, suggesting the emitting plasma is moving relativistically, with γ ≃ 104, as inferred previously from drifting bands during the scattering tail of a giant pulse. If so, the emission happens over a region extended along the line of sight by ~107 km. We conclude that relativistic motion likely is important for producing giant pulses, and may be similarly for other sources of short, bright radio emission, such as fast radio bursts.

Keywords: Very long baseline interferometry, Pulsars, Supernova remnants, Radio bursts, Interstellar scintillation
Tracking Nonradial Outflows in Extreme Ultraviolet and White Light Solar Images. Understanding the solar corona requires knowledge of its dynamics through its various layers and subsequent connectivity to the heliosphere. This requires understanding the nature of the outflows and the physical transitions through the middle corona (~1.5-6.0 R  s ). While this region is still inaccessible to in situ measurements, remote sensing observations are available, but their interpretation can be controversial due to line-of-sight effects and the nonradial motion of outflowing structures close to the Sun (≤3.0 R  s ). In this work, we describe a method to mitigate these challenges by generating nonradial height-time profiles of outflows by using advanced image processing techniques. The northern and southern boundaries of a large equatorial streamer during the 2008 solar minimum were identified in STEREO/SECCHI solar images, using two different methodologies based on thresholds of brightness and piecewise polynomial function fitting. To address line-of-sight issues, we used tomographic reconstruction of the 3D distribution of the coronal electron density based on SECCHI/COR2 images. Spectral analysis of the time series of the position angle of the streamer boundary revealed its oscillatory nature at some heights at 36-48 and 10.5-14.6 hr. Dividing the distance between the northern and southern streamer boundaries in equal parts at each height, we obtained nonradial height-time paths from which we generated nonradial profiles of corona/solar wind plasma outflow. We tracked outflows as they moved uninterruptedly from the Sun in EUVI, through COR1 and into COR2. Finally, we discuss the preliminary results of nonradial plane-of-sky velocities for a coronal mass ejection and two small-scale features.

Keywords: Astronomical techniques, Quiet sun, Solar wind, Solar corona
Spatially Resolved Stellar Populations of 0.3 &lt; z &lt; 6.0 Galaxies in WHL 0137-08 and MACS 0647+70 Clusters as Revealed by JWST: How Do Galaxies Grow and Quench over Cosmic Time?. We study the spatially resolved stellar populations of 444 galaxies at 0.3 &lt; z &lt; 6.0 in two clusters (WHL 0137-08 and MACS 0647+70) and a blank field, combining imaging data from the Hubble Space Telescope and JWST to perform spatially resolved spectral energy distribution (SED) modeling using PIXEDFIT. The high spatial resolution of the imaging data combined with magnification from gravitational lensing in the cluster fields allows us to resolve a large fraction of our galaxies (109) to subkiloparsec scales. At redshifts around cosmic noon and higher (2.5 ≲ z ≲ 6.0), we find mass-doubling times to be independent of radius, inferred from flat specific star formation rate (sSFR) radial profiles and similarities between the half-mass and half-SFR radii. At lower redshifts (1.5 ≲ z ≲ 2.5), a significant fraction of our star-forming galaxies shows evidence for nuclear starbursts, inferred from a centrally elevated sSFR and a much smaller half-SFR radius compared to the half-mass radius. At later epochs, we find more galaxies suppress star formation in their centers but are still actively forming stars in the disk. Overall, these trends point toward a picture of inside-out galaxy growth consistent with theoretical models and simulations. We also observe a tight relationship between the central mass surface density and global stellar mass with ~0.38 dex scatter. Our analysis demonstrates the potential of spatially resolved SED analysis with JWST data. Future analysis with larger samples will be able to further explore the assembly of galaxy mass and the growth of their structures.

Keywords: Galaxy clusters, Galaxy quenching, Galaxy formation, Galaxy evolution
Prospects of Detecting Nonthermal Protons in Solar Flares via Lyman Line Spectroscopy: Revisiting the Orrall-Zirker Effect. Solar flares are efficient particle accelerators, with a substantial fraction of the energy released manifesting as nonthermal particles. While the role that nonthermal electrons play in transporting flare energy is well studied, the properties and importance of nonthermal protons are rather less well understood. This is in large part due to the paucity of diagnostics, particularly at the lower-energy (deka-keV) range of nonthermal proton distributions in flares. One means to identify the presence of deka-keV protons is by an effect originally described by Orrall &amp; Zirker. In the Orrall-Zirker effect, nonthermal protons interact with ambient neutral hydrogen, and via charge exchange produce a population of energetic neutral atoms (ENAs) in the chromosphere. These ENAs subsequently produce an extremely redshifted photon in the red wings of hydrogen spectral lines. We revisit predictions of the strength of this effect using modern interaction cross sections, and numerical models capable of self-consistently simulating the flaring nonequilibrium ionization stratification, and the nonthermal proton distribution (and, crucially, their feedback on each other). We synthesize both the thermal and nonthermal emission from Ly α and Ly β, the most promising lines that may exhibit a detectable signal. These new predictions are weaker and more transient than prior estimates, but the effects should be detectable in fortuitous circumstances. We degrade the Ly β emission to the resolution of the Spectral Imaging of the Coronal Environment (SPICE) instrument on board Solar Orbiter, demonstrating that though likely difficult, it should be possible to detect the presence of nonthermal protons in flares observed by SPICE.

Keywords: Hydrodynamical simulations, Solar flares, Solar ultraviolet emission, Charge transfer, Solar flare spectra, Non-thermal radiation sources, Radiative transfer, Radiative processes, Radiative transfer simulations, Solar chromosphere
The Oceanus Moving Group: A New 500 Myr Old Host for the Nearest Brown Dwarf. We report the discovery of the Oceanus moving group, a ≈500 Myr old group with 50 members and candidate members at distances 2-50 pc from the Sun, using an unsupervised clustering analysis of nearby stars with Gaia DR3 data. This new moving group includes the nearest brown dwarf WISE J104915.57-531906.1 AB (Luhman 16 AB) at a distance of 2 pc, which was previously suspected to be young (600-800 Myr) based on a comparison of its dynamical mass measurements with brown dwarf evolutionary models. We use empirical color-magnitude sequences, stellar activity, and gyrochronology to determine that this new group is roughly coeval with the Coma Ber open cluster, with an isochronal age of 510 ± 95 Myr. This newly discovered group will be useful to refine the age and chemical composition of Luhman 16 AB, which is already one of the best substellar benchmarks known to date. Furthermore, the Oceanus moving group is one of the nearest young moving groups identified to date, making it a valuable laboratory for the study of exoplanets and substellar members, with eight brown dwarf candidate members already identified here.

Keywords: Stellar kinematics, Open star clusters, Brown dwarfs, Stellar associations