Sazuna/UAT_keywords huggingface dataset:
Diverse Properties of Molecular Gas in the Host Galaxies of Fast Radio Bursts. We report the properties of molecular gas in a sample of six host galaxies of fast radio bursts (FRBs) obtained from CO observations with the Atacama Large Millimeter/submillimeter Array (FRBs 20180924B, 20190102C, and 20190711A), the results of one nondetection in a dwarf galaxy (FRB 20121102A), and two events detected in M81 (FRB 20200120E) and the Milky Way (FRB 20200428A). The CO observations resulted in the detection of CO(3-2) emission in the FRB 20180924B host and nondetections of CO(3-2) and CO(2-1) emission in the hosts of FRB 20190102C and FRB 20190711A, respectively. The derived molecular gas mass and 3σ upper limit is (2.4 ± 0.2) × 109 M ⊙, &lt;3.8 × 108 M ⊙, and &lt;6.7 × 109 M ⊙ for the hosts of FRB 20180924B, FRB 20190102C, and FRB 20190711A, respectively. We found diversity in molecular gas properties (gas mass, gas depletion time, and gas fraction to stellar mass) in the sample. Compared to other star-forming galaxies, the FRB 20180924B host is gas-rich (the larger molecular gas fraction), and the hosts of FRB 20190102C and FRB 20200120E are gas-poor with a shorter depletion time for their stellar mass and star formation rate. Our findings suggest that FRBs arise from multiple progenitors or single progenitors that can exist in a wide range of galaxy environments. Statistical analysis shows a significant difference in the distribution of molecular gas fraction between the FRB hosts and local star-forming galaxies. However, the difference is not substantial when an outlier, the FRB 20200120E host, is excluded, and analysis with a larger sample is needed.

Keywords: Observational astronomy, Molecular gas, Extragalactic radio sources, Radio bursts, Star formation, Interstellar medium, CO line emission, Radio interferometry, Radio astronomy, Galaxies, Radio transient sources
Water and an Escaping Helium Tail Detected in the Hazy and Methane-depleted Atmosphere of HAT-P-18b from JWST NIRISS/SOSS. JWST is here. The early release observation (ERO) program provides us with the first look at the scientific data and the spectral capabilities. One of the targets from the ERO is HAT-P-18b, an inflated Saturn-mass planet with an equilibrium temperature of ~850 K. We present the NIRISS/SOSS transmission spectrum of HAT-P-18b from 0.6 to 2.8 μm and reveal the planet in the infrared beyond 1.6 μm for the first time. From the spectrum, we see clear water and escaping helium tail features in an otherwise very hazy atmosphere. Our free chemistry retrievals with ATMO show moderate Bayesian evidence (3.79) supporting the presence of methane, but the spectrum does not display any clearly identifiable methane absorption features. The retrieved methane abundance is ~2 orders of magnitude lower than that of solar composition. The methane-depleted atmosphere strongly rejects simple equilibrium chemistry forward models with solar metallicity and a C/O ratio and disfavors high metallicity (100 times) and a low C/O ratio (0.3). This calls for additional physical processes such as vertical mixing and photochemistry, which can remove methane from the atmosphere.

Keywords: Exoplanet astronomy, Exoplanet atmospheric composition , Exoplanet atmospheres
Detection of GeV Emission from an Ultralong Gamma-Ray Burst with the Fermi Large Area Telescope. GRB 220627A, detected by Fermi Gamma-ray Burst Monitor (GBM), shows two episodes of gamma-ray emission, which are separated by a ~700 s long quiescent phase. Due to similar temporal shapes and spectra in the two episodes, GRB 220627A is speculated to be a gravitationally lensed gamma-ray burst (GRB). We analyze Fermi Large Area Telescope (LAT) data and find that about 49 gamma-ray photons above 100 MeV come from the GRB during the first episode, while there are no photons above 100 MeV in the second episode. Based on the broadband spectral study of the two episodes, the gravitationally lensing scenario can be ruled out at a high confidence level and we thus conclude that GRB 220627A is an intrinsically ultralong GRB with the prompt burst emission lasting longer than 1000 s. It is then the first case that GeV emission is detected from an ultralong GRB. We find that a short spike seen in the LAT light curve is also present in GBM detectors that see the burst, suggesting a common internal region of emission across the entire Fermi energy range. The detection of a 15.7 GeV photon during the early prompt phase places a lower limit of Γ ≥ 300 on the bulk Lorentz factor of the GRB ejecta. The constraint on the bulk Lorentz factor could shed light on the origin of ultralong GRBs.

Keywords: Gamma-ray bursts, High energy astrophysics
The Giant Low Surface Brightness Galaxy Malin 1: New Constraints for Its Molecular Gas Mass from GBT/ARGUS Observations. We report on results from GBT/ARGUS 12CO(1-0) observations for the giant low surface brightness galaxy Malin 1, which allow us to determine an upper limit for its CO mass, and hence its molecular gas mass and molecular gas mass surface density ${{\rm{\Sigma }}}_{{{\rm{H}}}_{2}}$ . Although we performed very deep observations through 17 hr on-source integration time, reaching a noise level of ~0.2 mK (T ${}_{A}^{* }$ ) with a corresponding extended source CO limit (3σ) of 0.09 K km s-1, 19 times more sensitive than previous works, we do not detect the 12CO(1-0) emission line. However, the observations allow us to estimate an upper limit (3σ) for the CO mass of about 7.4 × 109 M ⊙ for the extended emission, and 1.4 × 108 M ⊙ for the central part of the galaxy. With these figures we conclude that the molecular gas surface density is lower than 0.3 M ⊙ pc-2, and the corresponding molecular to atomic gas mass ratio is lower than 0.13. The evidence suggests quite different physical conditions for the interstellar medium in Malin 1 compared to that of normal, high surface brightness spirals. This, in one way to another, keeps an usual molecular gas tracer as CO hidden from our observations, in spite of the diverse stellar and structural properties of Malin 1 observed by several authors since more than 30 yr.

Keywords: Detection, Molecular gas, Galaxies, Low surface brightness galaxies
Nanoflare Heating of the Solar Corona Observed in X-Rays. The existence of the million-degree corona above the cooler photosphere is an unsolved problem in astrophysics. Detailed study of the quiescent corona that exists regardless of the phase of the solar cycle may provide fruitful hints toward resolving this conundrum. However, the properties of heating mechanisms can be obtained only statistically in these regions due to their unresolved nature. Here, we develop a two-step inversion scheme based on the machine-learning scheme of Upendran &amp; Tripathi (2021a) for the empirical impulsive heating model of Pauluhn &amp; Solanki (2007), and apply it to disk integrated flux measurements of the quiet corona as measured by the X-ray solar monitor on board Chandrayaan-2. We use data in three energy passbands, viz, 1-1.3, 1.3-2.3, and 1-2.3 keV, and estimate the typical impulsive event frequencies, timescales, amplitudes, and the distribution of amplitudes. We find that the impulsive events occur at a frequency of ≈25 events per minute with a typical lifetime of ≈10 minutes. They are characterized by a power-law distribution with a slope α ≤ 2.0. The typical amplitudes of these events lie in an energy range of 1021-1024 erg, with a typical radiative loss of about ≈103 erg cm-2 s-1 in the energy range of 1-2.3 keV. These results provide further constraints on the properties of subpixel impulsive events in maintaining the quiet solar corona.

Keywords: Convolutional neural networks, Solar coronal heating, Quiet solar corona, Solar x-ray emission
A 16 hr Transit of Kepler-167 e Observed by the Ground-based Unistellar Telescope Network. More than 5000 exoplanets have been confirmed and among them almost 4000 were discovered by the transit method. However, few transiting exoplanets have an orbital period greater than 100 days. Here we report a transit detection of Kepler-167 e, a "Jupiter analog" exoplanet orbiting a K4 star with a period of 1071 days, using the Unistellar ground-based telescope network. From 2021 November 18 to 20, citizen astronomers located in nine different countries gathered 43 observations, covering the 16 hr long transit. Using a nested sampling approach to combine and fit the observations, we detected the midtransit time to be UTC 2021 November 19 17:20:51 with a 1σ uncertainty of 9.8 minutes, making it the longest-period planet to ever have its transit detected from the ground. This is the fourth transit detection of Kepler-167 e, but the first made from the ground. This timing measurement refines the orbit and keeps the ephemeris up to date without requiring space telescopes. Observations like this demonstrate the capabilities of coordinated networks of small telescopes to identify and characterize planets with long orbital periods.

Keywords: Observational astronomy, Astronomy data modeling, Transits, Exoplanets, Observatories, Astronomy education, Light curves, Amateur astronomers, Astronomy data analysis, Optical telescopes, Exoplanet detection methods, Transit photometry
Directly Tracing Cool Filamentary Accretion over &gt;100 kpc into the Interstellar Medium of a Quasar Host at z = 1. We report the discovery of giant (50-100 kpc) [O II] emitting nebulae with MUSE in the field of TXS 0206-048, a luminous quasar at z = 1.13. "Down-the-barrel" UV spectra of the quasar show absorption at velocities coincident with those of the extended nebulae, enabling new insights into inflows and outflows around the quasar host. One nebula exhibits a filamentary morphology extending over 120 kpc from the halo toward the quasar and intersecting with another nebula surrounding the quasar host with a radius of 50 kpc. This is the longest cool filament observed to date and arises at higher redshift and in a less massive system than those in cool-core clusters. The filamentary nebula has line-of-sight velocities &gt;300 km s-1 from nearby galaxies but matches that of the nebula surrounding the quasar host where they intersect, consistent with accretion of cool intergalactic or circumgalactic medium or cooling hot halo gas. The kinematics of the nebulae surrounding the quasar host are unusual and complex, with redshifted and blueshifted spiral-like structures. The emission velocities at 5-10 kpc from the quasar match those of inflowing absorbing gas observed in UV spectra of the quasar. Together, the extended nebulae and associated redshifted absorption represent a compelling case of cool, filamentary gas accretion from halo scales into the extended interstellar medium and toward the nucleus of a massive quasar host. The inflow rate implied by the combined emission and absorption constraints is well below levels required to sustain the quasar's radiative luminosity, suggesting anisotropic or variable accretion.

Keywords: Quasars, Circumgalactic medium, Galaxy groups, Intergalactic filaments
Galactic Contribution to the High-energy Neutrino Flux Found in Track-like IceCube Events. Astrophysical sources of neutrinos detected by large-scale neutrino telescopes remain uncertain. While there exist statistically significant observational indications that a part of the neutrino flux is produced by blazars, numerous theoretical studies suggest also the presence of potential Galactic point sources. Some of them have been observed in gamma rays above 100 TeV. Moreover, cosmic-ray interactions in the Galactic disk guarantee a diffuse neutrino flux. However, these Galactic neutrinos have not been unambiguously detected so far. Here we examine whether such a Galactic component is present among the observed neutrinos of the highest energies. We analyze public track-like IceCube events with estimated neutrino energies above 200 TeV. We examine the distribution of arrival directions of these neutrinos in the Galactic latitude b with the help of a simple unbinned, nonparametric test statistics, the median ∣b∣ over the sample. This distribution deviates from that implied by the null hypothesis of the neutrino flux isotropy, and is shifted toward lower ∣b∣ with the p-value of 4 × 10-5, corresponding to the statistical significance of 4.1σ. There exists a significant component of the high-energy neutrino flux of Galactic origin, matching well the multimessenger expectations from Tibet-ASγ observations of diffuse Galactic gamma rays at hundreds of TeV. Together with the previously established extragalactic associations, the Galactic component we report here implies that the neutrino sky is rich and is composed of contributions from various classes of sources.

Keywords: Neutrino astronomy, Milky Way disk, Particle astrophysics
Laboratory and Astronomical Discovery of Magnesium Dicarbide, MgC<SUB>2</SUB>. We report the detection of magnesium dicarbide, MgC2, in the laboratory at centimeter wavelengths and assign 24MgC2, 25MgC2, and 26MgC2 to 14 unidentified lines in the radio spectrum of the circumstellar envelope of the evolved carbon star IRC+10216. The structure of MgC2 is found to be T-shaped with a highly ionic bond between the metal atom and the C2 unit, analogous to other dicarbides containing electropositive elements. A two-temperature excitation model of the MgC2 emission lines observed in IRC+10216 yields a very low rotational temperature of 6 ± 1 K, a kinetic temperature of 22 ± 13 K, and a column density of (1.0 ± 0.3) × 1012 cm-2. The abundance of MgC2 relative to the magnesium-carbon chains MgCCH, MgC4H, and MgC6H is 1:2:22:20 and provides a new constraint on the sequential radiative association-dissociative recombination mechanisms implicated in the production of metal-bearing molecules in circumstellar environments.

Keywords: Carbon stars, Circumstellar envelopes, Laboratory astrophysics, Metal-containing molecules
Testing Velocity Kinks as a Planet Detection Method: Do Velocity Kinks in Surface Gas Emission Trace Planetary Spiral Wakes in the Midplane Continuum?. Spiral density waves generated by an embedded planet are understood to cause "kinks" in observed velocity channel maps of CO surface emission by perturbing the gas motion within the spiral arms. If velocity kinks are a reliable probe of embedded planets, we should expect to see the planet-driven spiral arms in other observational tracers. We test this prediction by searching the dust continuum for the midplane counterparts of the spirals responsible for all of the velocity kink planet candidates reported to date whose orbits lie inside the dust continuum disk. We find no clear detection of any spiral structure in current continuum observations for six of the 10 velocity kink planet candidates in our sample (DoAr 25, GW Lup, Sz 129, HD 163296 #2, P94, and HD 143006), despite the high planet masses inferred from the kink amplitude. The remaining four cases include three clear detections of two-armed dust spirals (Elias 27, IM Lup, and WaOph 6) wherein neither spiral arm aligns with a wake originating from a reported planet location, suggesting that under the planetary-origin hypothesis, an accurate method for inferring the location of the planet in the midplane may need to encompass vertical effects. The 10th case, HD 97048, is inconclusive with current knowledge of the disk geometry.

Keywords: Planetary-disk interactions, Protoplanetary disks, Exoplanet detection methods, Exoplanet formation, Planet formation
Interacting Kilonovae: Long-lasting Electromagnetic Counterparts to Binary Mergers in the Accretion Disks of Active Galactic Nuclei. We investigate the dynamics and electromagnetic (EM) signatures of neutron star-neutron star (NS-NS) or neutron star-black hole (NS-BH) merger ejecta that occur in the accretion disk of an active galactic nucleus (AGN). We find that the interaction between ejecta and disk gas leads to important effects on the dynamics and radiation. We show five stages of the ejecta dynamics: gravitational slowing down, coasting, Sedov-Taylor deceleration in the disk, reacceleration after the breakout from the disk surface, and momentum-conserved snowplow phase. Meanwhile, the radiation from the ejecta is so bright that its typical peak luminosity reaches a few times 1043-1044 erg s-1. Since most of the radiation energy has converted from the kinetic energy of merger ejecta, we call such an explosive phenomenon an interacting kilonova (IKN). It should be emphasized that IKNe are very promising, bright EM counterparts to NS-NS/BH-NS merger events in AGN disks. The bright peak luminosity and long rising time (i.e., 10 to 20 days in UV bands, 30 to 50 days in optical bands, and 100 days to hundreds of days in IR bands) allow most survey telescopes to have ample time to detect an IKN. However, the peak brightness, peak time, and evolution pattern of the light curve of an IKN are similar to a superluminous supernova in a galactic nucleus and a tidal disruption event making it difficult to distinguish between them. But it also suggests that IKNe might have been present in recorded AGN transients.

Keywords: Neutron stars, Gamma-ray bursts, High energy astrophysics, Gravitational wave sources, Active galactic nuclei
CME-related Large Decreases in the Differential Phase Delay of Tianwen-1 DOR Signals. Differential phase delay is calculated for the differential one-way range (DOR) signals transmitted by Tianwen-1, the first Chinese Mars spacecraft that entered into the Mars orbit on 2021 February 10. Large decreases in the differential phase delay are identified in the DOR signals received by ground stations on 2021 March 23 and June 18. The decreases indicate sizable increases of the total electron content (TEC) along the DOR signal path between Tianwen-1 and the ground stations. The TEC increases are estimated to be 85 and 175 TEC units on 2021 March 23 and June 18, respectively. Evidence shows that they are caused by the sheath regions ahead of the coronal mass ejections (CMEs) that traversed the signal path on both days. The results represent the first observations of CME-related structures by the DOR signals and demonstrate the potential of DOR signals in remote sensing the interplanetary plasma structures in the solar wind.

Keywords: Deep space probes, Solar wind, Remote sensing, Solar coronal mass ejections, Radio astronomy
Testing the Galaxy-collision-induced Formation Scenario for the Trail of Dark-matter-deficient Galaxies with the Susceptibility of Globular Clusters to the Tidal Force. It has been suggested that a trail of diffuse galaxies, including two dark-matter-deficient galaxies (DMDGs), in the vicinity of NGC 1052 formed because of a high-speed collision between two gas-rich dwarf galaxies, one bound to NGC 1052 and the other one on an unbound orbit. The collision compresses the gas reservoirs of the colliding galaxies, which in turn triggers a burst of star formation. In contrast, the dark matter and preexisting stars in the progenitor galaxies pass through it. Since the high pressures in the compressed gas are conducive to the formation of massive globular clusters (GCs), this scenario can explain the formation of DMDGs with large populations of massive GCs, consistent with the observations of NGC 1052-DF2 (DF2) and NGC 1052-DF4. A potential difficulty with this "mini bullet cluster" scenario is that the observed spatial distributions of GCs in DMDGs are extended. GCs experience dynamical friction causing their orbits to decay with time. Consequently, their distribution at formation should have been even more extended than that observed at present. Using a semianalytic model, we show that the observed positions and velocities of the GCs in DF2 imply that they must have formed at a radial distance of 5-10 kpc from the center of DF2. However, as we demonstrate, the scenario is difficult to reconcile with the fact that the strong tidal forces from NGC 1052 strip the extendedly distributed GCs from DF2, requiring 33-59 massive GCs to form at the collision to explain observations.

Keywords: Galaxy formation, Galaxy interactions, Galaxy evolution, Dark matter, Low surface brightness galaxies
Large Ion-neutral Drift Velocities and Plasma Heating in Partially Ionized Coronal Rain Blobs. In this paper we present a numerical study of the dynamics of partially ionized coronal rain blobs. We use a two-fluid model to perform a high-resolution 2D simulation that takes into account the collisional interaction between the charged and neutral particles contained in the plasma. We follow the evolution of a cold plasma condensation as it falls through an isothermal vertically stratified atmosphere that represents the much hotter and lighter solar corona. We study the consequences of the different degrees of collisional coupling that are present in the system. On the one hand, we find that at the dense core of the blob there is a very strong coupling and the charged and neutral components of the plasma behave as a single fluid, with negligible drift velocities (of a few cm s-1). On the other hand, at the edges of the blob the coupling is much weaker and larger drift velocities (of the order of 1 km s-1) appear. In addition, frictional heating causes large increases of temperature at the transition layers between the blob and the corona. For the first time we show that such large drift velocities and temperature enhancements can develop as a consequence of ion-neutral decoupling associated to coronal rain dynamics. This can lead to enhanced emission coming from the plasma at the coronal rain-corona boundary, which possesses transition region temperature.

Keywords: Solar physics, Plasma astrophysics, Solar corona, Magnetohydrodynamical simulations
Discovery of a Binary-origin Classical Cepheid in a Binary System with a 59 day Orbital Period. We report the discovery of a surprising binary configuration of the double-mode Cepheid OGLE-LMC-CEP-1347 pulsating in the first (P 1 = 0.690 days) and second-overtone (P 2 = 0.556 days) modes. The orbital period (P orb = 59 days) of the system is five times shorter than the shortest known to date (310 days) for a binary Cepheid. The Cepheid itself is also the shortest-period one ever found in a binary system and the first double-mode Cepheid in a spectroscopically double-lined binary. OGLE-LMC-CEP-1347 is most probably on its first crossing through the instability strip, as inferred from both its short period and fast period increase, consistent with evolutionary models, and from the short orbital period (not expected for binary Cepheids whose components have passed through the red giant phase). Our evolutionary analysis yielded a first-crossing Cepheid with a mass in a range of 2.9-3.4 M ☉ (lower than any measured Cepheid mass), consistent with observations. The companion is a stable star, at least two times fainter and less massive than the Cepheid (preliminary mass ratio q = 0.55), while also redder and thus at the subgiant or more advanced evolutionary stage. To match these characteristics, the Cepheid has to be a product of binary interaction, most likely a merger of two less massive stars, which makes it the second known classical Cepheid of binary origin. Moreover, further evolution of the components may lead to another binary interaction. *Based on observations collected at the European Southern Observatory, Chile. †This Letter includes data gathered with the 6.5 m Magellan Clay Telescope at Las Campanas Observatory, Chile.

Keywords: Spectroscopic binary stars, Double-mode Cepheid variable stars, Cepheid variable stars, Late-type stars