Sazuna/UAT_keywords huggingface dataset:
A Comparison of Rest-frame Ultraviolet and Optical Emission-line Diagnostics in the Lensed Galaxy SDSS J1723+3411 at Redshift z = 1.3293. For the extremely bright lensed galaxy SDSS J1723+3411 at z = 1.3293, we analyze spatially integrated MMT, Keck, and Hubble Space Telescope spectra that fully cover the rest-frame wavelength range of 1400-7200 Å. We also analyze near-IR spectra from Gemini that cover Hα for a portion of the lensed arc. We report fluxes for 42 detected emission lines, and upper limits for an additional 22. This galaxy has extreme emission-line ratios and high equivalent widths that are characteristic of extreme emission-line galaxies. We compute strong emission-line diagnostics from both the rest-frame optical and rest-frame ultraviolet (UV), to constrain physical conditions and test the spectral diagnostics themselves. We tightly determine the nebular physical conditions using the most reliable diagnostics, and then compare to results from other diagnostics. We find disappointing performance from the UV-only diagnostics: they either are unable to measure the metallicity or dramatically underestimate it; they overestimate the pressure; and the UV diagnostic of ionization parameter has a strong metallicity dependence in this regime. Based on these results, we suggest that upcoming James Webb Space Telescope (JWST) spectroscopic surveys of galaxies in the reionization epoch should invest the additional integration time to capture the optical [O II] and [O III] emission lines, and not rely solely on the rest-frame UV emission lines. We make available the spectra; they represent one of the highest-quality emission-line spectral atlases of star-forming galaxies available beyond the local universe, and will aid the planning of observations with JWST.

Keywords: Starburst galaxies, Emission line galaxies, Atomic spectroscopy, Gravitational lensing, Galaxy evolution, Spectroscopy, Interstellar medium
Spatially Resolved BPT Mapping of Nearby Seyfert 2 Galaxies. We present spatially resolved Baldwin-Phillips-Terlevich (BPT) mapping of the extended narrow-line regions (ENLRs) of seven nearby Seyfert 2 galaxies, using Hubble Space Telescope narrowband filter imaging. We construct the BPT diagrams using ≤0"1 resolution emission line images of [O III] λ5007, Hα, [S II] λλ6717, 6731, and Hβ. By mapping these diagnostic lines according to the BPT classification, we dissect the ENLR into Seyfert, low-ionization nuclear emission-line (LINER), and star-forming regions. The nucleus and ionization cones are dominated by Seyfert-type emission, which can be interpreted as predominantly photoionization by the active galactic nucleus (AGN). The Seyfert nucleus and ionization cones transition to and are surrounded by a LINER cocoon, extending up to ∼250 pc in thickness. The ubiquity of the LINER cocoon in Seyfert 2 galaxies suggests that the circumnuclear regions are not necessarily Seyfert-type, and LINER activity plays an important role in Seyfert 2 galaxies. We demonstrate that spatially resolved diagnostics are crucial to understanding the excitation mechanisms in different regions and the AGN-host galaxy interactions.

Keywords: LINER galaxies, Seyfert galaxies, Active galactic nuclei, Emission line galaxies
The Kiloparsec-scale Fe Ka Emission in the Compton-thin Seyfert 2 Galaxy NGC 4388 Resolved by Chandra. We present imaging and spectral analysis of the combined ∼48 ks Chandra observations of Seyfert 2 galaxy NGC 4388. Compared with previous studies, three prominent extended X-ray structures around the nucleus on a kiloparsec-scale are well imaged, allowing an in-depth spatially resolved study. Both the extended hard continuum (4-6 keV) and the Fe Kα line (6.2-6.7 keV) show similar morphology, consistent with a scenario where the ionizing emission from the nucleus is reprocessed by circumnuclear cold gas, resulting in a weak reflection continuum and an associated neutral Fe Kα line. This has been seen in other Compton-thick active galactic nuclei (AGN), but NGC 4388 is one of the rare cases with a lower column density (NH &lt; 1.25 × 1024 cm-2) along the line of sight. Significant differences in equivalent width of the Fe Kα emission line (up to a factor of 3) are found for the nuclear and extended regions. Such a difference could be ascribed to different column densities or scattering angles with respect to the line of sight, rather than variations in iron abundances. The northeast and west extended structures appear to be aligned with the larger-scale galactic disk and dust lane in the HST V - H color map, and are located at the peak of molecular gas distribution. The morphology of remaining extended features likely traces edges of a known radio jet, indicating that the outflow at the kiloparsec-scale may have compressed the interstellar gas and produced clumps working as the reflector to enhance line emission. In addition, using [O IV] emission as a proxy of the AGN intrinsic luminosity, we find that both of the extended Fe Kα emission and reflection continuum are linearly correlated with the [O IV] luminosity, which indicates a connection between the central AGN and the extended emission.

Keywords: AGN host galaxies, X-ray active galactic nuclei
Directional Association of TeV to PeV Astrophysical Neutrinos with Radio Blazars. Recently we have shown that high-energy neutrinos above 200 TeV detected by IceCube are produced within several parsecs in the central regions of radio-bright blazars, that is active galactic nuclei with jets pointing toward us. To independently test this result and extend the analysis to a wider energy range, we use public data for all neutrino energies from seven years of IceCube observations. The IceCube point-source likelihood map is analyzed against the positions of blazars from a statistically complete sample selected according to their compact radio flux density. The latter analysis delivers a 3.0σ significance, with the combined post-trial significance of both studies being 4.1σ. The correlation is driven by a large number of blazars. Together with fainter but physically similar sources not included in the sample, they may explain the entire IceCube astrophysical neutrino flux as derived from muon-track analyses. The neutrinos can be produced in interactions of relativistic protons with X-ray self-Compton photons in parsec-scale blazar jets.

Keywords: Quasars, Neutrino astronomy, Active galaxies, Galaxy jets, Radio continuum emission
PSR J0437-4715: The Argentine Institute of Radioastronomy 2019-2020 Observational Campaign. We present the first-year data set of high-cadence, long-duration observations of the bright millisecond pulsar J0437-4715 obtained in the Argentine Institute of Radioastronomy (IAR). Using two single-dish 30 m radio antennas, we gather more than 700 hr of good-quality data with timing precision better than 1 μs. We characterize the white and red timing noise in IAR's observations, we quantify the effects of scintillation, and we perform single-pulsar searches of continuous gravitational waves, setting constraints in the nHz-μHz frequency range. We demonstrate IAR's potential for performing pulsar monitoring in the 1.4 GHz radio band for long periods of time with a daily cadence. In particular, we conclude that the ongoing observational campaign of the millisecond pulsar J0437-4715 can contribute to increase the sensitivity of the existing pulsar-timing arrays.

Keywords: Radio pulsars, Pulsar timing method, Millisecond pulsars
Observational Evidence for Rotational Desorption of Complex Molecules by Radiative Torques from Orion BN/KL. Complex organic molecules (COMs) are believed to form in the ice mantle of dust grains and are released to the gas by thermal sublimation when grain mantles are heated to temperatures of ${T}_{{\rm{d}}}\gtrsim 100\,{\rm{K}}$ . However, some COMs are detected in regions with temperatures below 100 K. Recently, a new mechanism of rotational desorption due to centrifugal stress induced by radiative torques (RATs) was proposed by Hoang &amp; Tram (2020) that can desorb COMs at low temperatures. In this paper, we report observational evidence for rotational desorption of COMs toward the nearest massive star-forming region, Orion BN/KL. We compare the abundance of three representative COMs that have very high binding energy computed by the rotational desorption mechanism with observations by ALMA, and demonstrate that the rotational desorption mechanism can explain the existence of such COMs. We also analyze the polarization data from SOFIA/HAWC+ and JCMT/SCUBA-2 and find that the polarization degree at far-infrared/submillimeter decreases with increasing the grain temperature for ${T}_{{\rm{d}}}\gtrsim 71\,{\rm{K}}$ . This is consistent with the theoretical prediction using the RAT alignment theory and Radiative Torque Disruption mechanism. Such an anticorrelation between dust polarization and dust temperature supports the rotational disruption as well as rotational desorption mechanism of COMs induced by RATs.

Keywords: Interstellar dust, Interstellar dust extinction, Astrochemistry, Starlight polarization, Interstellar clouds, Star formation
Hydrodynamic Properties of the Sun's Giant Cellular Flows. Measurements of the large cellular flows on the Sun were made by local correlation tracking of features (supergranules) seen in full-disk Doppler images obtained by the Helioseismic and Magnetic Imager (HMI) instrument on the NASA Solar Dynamics Observatory (SDO) satellite. Several improvements made to the local correlation tracking method allowed for more precise measurements of these flows. Measurements were made hourly over the nearly ten years of the mission-to-date. A four-hour time-lag between images was determined to give the best results as a compromise between increased feature displacement and decreased feature evolution. The hourly measurements were averaged over the 34 days that it takes to observe all longitudes at all latitudes to produce daily maps of the latitudinal and longitudinal velocities. Analyses of these flow maps reveal many interesting characteristics of these large cellular flows. While flows at all latitudes are largely in the form of vortices with left-handed helicity in the north and right-handed helicity in the south, there are key distinctions between the low-latitude and high-latitude cells. The low-latitude cells have roughly circular shapes, lifetimes of about one month, rotate nearly rigidly, do not drift in latitude, and do not exhibit any correlation between longitudinal and latitudinal flow. The high-latitude cells have long extensions that spiral inward toward the poles and can wrap nearly completely around the Sun. They have lifetimes of several months, rotate differentially with latitude, drift poleward at speeds approaching 2 m s-1, and have a strong correlation between prograde and equatorward flows. Spherical harmonic spectral analyses of maps of the divergence and curl of the flows confirm that the flows are dominated by the curl component with rms velocities of about 12 m s-1 at wavenumber ℓ = 10. Fourier transforms in time over 1024 daily records of the spherical harmonic spectra indicate two notable components—an m = ±ℓ feature representing the low-latitude component and an m = ±1 feature representing the high-latitude component. The dispersion relation for the low-latitude component is well represented by that derived for Rossby waves or r-modes. The high-latitude component has a constant temporal frequency for all ℓ indicating features advected by differential rotation at rates representative of the base of the convection zone high latitudes. The poleward motions of these features further suggest that the high-latitude meridional flow at the base of the convection zone is poleward—not equatorward.

Keywords: Solar convective zone, Solar meridional circulation, Solar differential rotation, Solar interior
Constraining the Metallicities of Damped Lyα Systems Using Extinction Curves. In this paper, we present a new method to constrain the metallicities of high-redshift damped Lyα (DLA) absorbers using observed extinction curves. This is the first time such an approach is employed to constrain the metallicities of extragalactic absorbers. To demonstrate our method, we use the spectra of 13 quasars and one gamma-ray burst (GRB) with DLA absorbers detected along their sightlines. By using the Kramers-Kronig (KK) relation, which relates the wavelength-integrated extinction to the total volume occupied by dust per hydrogen nucleon, we set some robust lower limits on the metallicity of the DLAs. The resulting lower limits are all consistent with the DLA metallicities from the literature. The GRB extinction curve exhibits a very strong 2175 Å extinction bump. We try to constrain the metallicity of the GRB DLA by modeling the GRB extinction curve using dust models with two (graphite and silicates) and three (polycyclic aromatic hydrocarbon, hydrogenated amorphous carbon, and silicates) dust components. The two-component model results in a metallicity of Z ∼ -0.45, while the three-component model gives Z ∼ -0.50. However, the lower limit from the KK approach for this DLA is Z ≥ -0.60. Modeling a large sample of extinction curves with a 2175 Å extinction bump and measured DLA metallicities would allow a thorough comparison between the KK and the model-dependent approach. In cases where the precise measurement of the metallicity of a DLA is not possible (e.g., due to the saturation of important absorption lines), the approach presented in this paper can be used to constrain the metallicity.

Keywords: Gamma-ray bursts, Quasar absorption line spectroscopy, Extinction, Ultraviolet extinction, Galaxies
Deciphering the 3D Orion Nebula. III. Structure on the NE Boundary of the Orion-S Embedded Molecular Cloud. We have extended the work of Papers I and II of this series to determine at a higher spatial resolution the properties of the embedded Orion-S Molecular Cloud that lies within the ionized cavity of the Orion Nebula and of the thin ionized layer that lies between the Cloud and the observer. This was done using existing and new [N II] (658.3 nm) and [O III] (500.7 nm) spectra that map the central region of the Orion Nebula (the Huygens region). Although our observations show that the surface brightness of the ionized layer on the Orion-S Molecular Cloud and that of the nearer foreground ionized layer are linked, the process by which this is done is unclear. It is shown that the Cloud modifies the outer parts of the Huygens region in the direction of the extended hot X-ray gas.

Keywords: H II regions
Extremely Low Molecular Gas Content in the Vicinity of a Red Nugget Galaxy at z = 1.91. We present Atacama Large Millimeter/submillimeter Array Band 5 observations of a galaxy at z = 1.91, GDS24569, in search of molecular gas in its vicinity via the [C I] 3P1-3P0 line. GDS24569 is a massive ( $\mathrm{log}{M}_{* }/{M}_{\odot }=11$ ), passively evolving galaxy, characterized by compact morphology with an effective radius of ∼0.5 kpc. We apply two blind detection algorithms to the spectral data cubes and find no promising detection in or around GDS24569 out to a projected distance of ∼320 kpc, while a narrow tentative line (4.1σ) is identified at +1200 km s-1 by one of the algorithms. From the nondetection of [C I], we place a 3σ upper limit on molecular hydrogen mass, ∼ 7.1 × 109 M⊙, which converts to an extremely low gas-to-stellar mass fraction of ≲ 5%. We conduct a spectral energy distribution modeling by including optical to far-infrared data and find a considerably high ( ∼ 0.1%) dust-to-stellar mass ratio, i.e., ∼10-100× higher than those of local early-type galaxies. In combination with a previous result of an insufficient number of surrounding satellite galaxies, it is suggested that GDS24569 is unlikely to experience significant size evolution via satellite mergers. We discuss possible physical mechanisms that quenched GDS24569.

Keywords: Galaxy quenching, Galaxies, Circumgalactic medium
Nitrogen Dioxide Pollution as a Signature of Extraterrestrial Technology. Nitrogen dioxide (NO2) on Earth today has biogenic and anthropogenic sources. During the Covid-19 pandemic, observations of global NO2 emissions have shown a significant decrease in urban areas. Drawing upon this example of NO2 as an industrial byproduct, we use a one-dimensional photochemical model and synthetic spectral generator to assess the detectability of NO2 as an atmospheric technosignature on exoplanets. We consider cases of an Earth-like planet around Sun-like, K-dwarf, and M-dwarf stars. We find that NO2 concentrations increase on planets around cooler stars because there are fewer short-wavelength photons that can photolyze NO2. In cloud-free results, present Earth-level NO2 on an Earth-like planet around a Sun-like star at 10 pc can be detected with signal-to-noise ratio ∼5 within ∼400 hr with a 15 m LUVOIR-like telescope when observed in the 0.2-0.7 μm range where NO2 has a strong absorption. However, clouds and aerosols can reduce the detectability and could mimic the NO2 feature. Historically, global NO2 levels were 3× higher, indicating the capability of detecting a civilization at the stage where Earth's civilization was 40 yr ago. Transit and direct imaging observations to detect infrared spectral signatures of NO2 on habitable planets around M-dwarfs would need several hundred hours of observation time, both due to weaker NO2 absorption in this region and because of masking features by dominant H2O and CO2 bands in the infrared part of the spectrum. Non-detection at these levels could be used to place upper limits on the prevalence of NO2 as a technosignature.

Keywords: Exoplanet atmospheric composition , Exoplanet atmospheres
SDSS-IV/MaNGA: Can Impulsive Gaseous Inflows Explain Steep Oxygen Abundance Profiles and Anomalously Low-Metallicity Regions?. Gaseous inflows are necessary suppliers of galaxies' star-forming fuel, but are difficult to characterize at the survey scale. We use integral-field spectroscopic measurements of gas-phase metallicity and single-dish radio measurements of total atomic gas mass to estimate the magnitude and frequency of gaseous inflows incident on star-forming galaxies. We reveal a mutual correlation between steep oxygen abundance profiles between 0.25 and 1.5 Re, increased variability of metallicity between 1.25 and 1.75 Re, and elevated H I content at fixed total galaxy stellar mass. Employing a simple but intuitive inflow model, we find that galaxies with total stellar mass less than 1010.1 M⊙ have local oxygen abundance profiles consistent with reinvigoration by inflows. Approximately 10%-25% of low-mass galaxies possess signatures of recent accretion, with estimated typical enhancements of approximately 10%-90% in local gas mass surface density. Higher-mass galaxies have limited evidence for such inflows. The large diversity of H I mass implies that inflow-associated gas ought to reside far from the star-forming disk. We therefore propose that a combination of high H I mass, steep metallicity profile between 0.25 and 1.5 Re, and wide metallicity distribution function between 1.25 and 1.75 Re be employed to target possible hosts of inflowing gas for high-resolution radio follow-up.

Keywords: Galaxy chemical evolution, Disk galaxies, Neutral hydrogen clouds, Galactic and extragalactic astronomy, Chemical enrichment, Galaxy evolution, Galaxies
Far-Infrared Line Diagnostics: Improving N/O Abundance Estimates for Dusty Galaxies. The nitrogen-to-oxygen (N/O) abundance ratio is an important diagnostic of galaxy evolution because the ratio is closely tied to the growth of metallicity and the star formation history in galaxies. Estimates for the N/O are traditionally made with optical lines that could suffer from extinction and excitation effects, so the N/O is arguably measured better through far-infrared (far-IR) fine-structure lines. Here we show that the [N III]57 μm/[O III]52 μm line ratio, denoted N3O3, is a physically robust probe of N/O. This parameter is insensitive to gas temperature and only weakly dependent on electron density. Although it has a dependence on the hardness of the ionizing radiation field, we show that it is well corrected when the [Ne III]15.5 μm/[Ne II]12.8 μm line ratio is included. We verify the method, and characterize its intrinsic uncertainties by comparing the results to photoionization models. We then apply our method to a sample of nearby galaxies using new observations obtained with SOFIA/FIFI-LS in combination with available Herschel/PACS data, and the results are compared with optical N/O estimates. We find evidence for a systematic offset between the far-IR and optically derived N/O. We argue that the likely reason is that our far-IR method is biased toward younger and denser H II regions, while the optical methods are biased toward older H II regions as well as diffuse ionized gas. This work provides a local template for studies of the abundance of interstellar medium in the early Universe.

Keywords: Abundance ratios, Galaxy evolution, Chemical abundances, Far infrared astronomy
An Ab Initio Approach to Antiproton Modulation in the Inner Heliosphere. Recent advances in the detection of cosmic-ray (CR) antiproton intensities at Earth have the potential to provide valuable new insights in the search for dark matter. As such, a fuller understanding of the modulation of these particles due to the influence of the Sun is of vital importance. Valuable insights can be gained through the study of galactic CR protons, as the transport parameters for these particles are theoretically expected to be the same as those for antiprotons, barring drift effects. As such, the present study develops a data-driven, 3D time-dependent ab initio model for the modulation of galactic CR protons in the region of the heliosphere dominated by the supersonic solar wind, which yields results in good agreement with spacecraft observations over several solar cycles when an observationally motivated expression for the differential intensity spectrum of these particles at the heliospheric termination shock is employed. This model is then applied to the study of solar-cycle-dependent antiproton modulation using two current estimates for the local interstellar differential intensities of these particles. This approach yields estimates of antiproton intensities at the heliospheric termination shock that are considerably lower than the proposed interstellar spectra, with the implication that a significant amount of antiproton modulation is expected to occur in the heliosheath.

Keywords: Galactic cosmic rays, Solar cycle, Heliosphere