Sazuna/UAT_keywords huggingface dataset:
Neutral Hydrogen (H I) 21 cm as a Probe: Investigating Spatial Variations in Interstellar Turbulent Properties. Interstellar turbulence shapes the H I distribution in the Milky Way (MW). How this affects large-scale statistical properties of H I column density across the MW remains largely unconstrained. We use the ~13,000 deg2 GALFA-H I survey to map statistical fluctuations of H I over the ±40 km s-1 velocity range. We calculate the spatial power spectrum (SPS) of the H I column density image by running a 3° kernel and measuring the SPS slope over a range of angular scales from 16' to 20°. Due to GALFA's complex observing and calibration strategy, we construct detailed estimates of the noise contribution and account for GALFA beam effects on the SPS. This allows us to systematically analyze H I images that trace a wide range of interstellar environments. We find that the SPS slope varies between ~ -2.6 at high Galactic latitudes and ~ -3.2 close to the Galactic plane. The range of SPS slope values becomes tighter when we consider H I optical depth and line-of-sight length caused by the plane-parallel geometry of the H I disk. This relatively uniform, large-scale distribution of the SPS slope is suggestive of large-scale turbulent driving being a dominant mechanism for shaping H I structures in the MW and/or the stellar feedback turbulence being efficiently dissipated within dense molecular clouds. Only at latitudes above 60° do we find evidence for the H I SPS slope being consistently more shallow. Those directions are largely within the Local Bubble, suggesting that the recent history of this cavity, shaped by multiple supernova explosions, has modified the turbulent state of H I and/or fractions of H I phases.

Keywords: Interstellar phases, Interstellar atomic gas, Neutral hydrogen clouds, Interstellar medium, Milky Way Galaxy
ALMA Observations of the Extraordinary Carina Pillars: A Complementary Sample. We present a study of six dusty and gaseous pillars (containing the Herbig-Haro (HH) objects HH 1004 and HH 1010) and globules (that contain the HH 666, HH 900, HH 1006, and HH 1066 objects) localized in the Carina Nebula using sensitive and high-angular-resolution (~0.″3) Atacama Large Millimeter/submillimeter Array observations. This is a more extensive study that the one presented in Cortes-Rangel et al. As in this former study, we also analyzed the 1.3 mm continuum emission and C18O(2-1), N2D+(3-2), and 12CO(2-1) spectral lines. These new observations revealed the molecular outflows emanating from the pillars, the dusty envelopes+disks that are exciting them, and the extended HH objects far from their respective pillars. We reveal that the masses of the disks+envelopes are in the range of 0.02-0.38 M ⊙, and those for the molecular outflows are of the order of 10-3 M ⊙, which suggest that their exciting sources might be low- or intermediate-mass protostars as already revealed in recent studies at infrared and submillimeter bands. In the regions associated with the objects HH 900 and HH 1004, we report multiple millimeter continuum sources, from where several molecular outflows emanate.

Keywords: Herbig-Haro objects, Protostars, Stellar jets, Interstellar medium
HST FUV Spectroscopy of Super Star Cluster A in the Green Pea Analog Mrk 71: Revealing the Presence of Very Massive Stars. Mrk 71 is a low-metallicity (Z = 0.16 Z ☉) starburst region in the local dwarf galaxy NGC 2366, hosting two super star clusters (SSCs A and B), and it is recognized as a Green Pea (GP) analog with SSC A responsible for the GP properties. We present STIS and FOS far-ultraviolet (FUV) spectra of the embedded SSC Mrk 71-A obtained with the Hubble Space Telescope. The STIS FUV spectrum shows the characteristic features of very massive stars (VMS; masses &gt;100 M ⊙) and we derive an age of 1 ± 1 Myr by comparison with the Charlot &amp; Bruzual suite of spectral population synthesis models with upper mass limits of 300 and 600 M ⊙. We compare the STIS spectrum with all known SSC spectra exhibiting VMS signatures: NGC 5253-5, R136a, NGC 3125-A1, and the z = 2.37 Sunburst cluster. We find that the cluster mass-loss rates and wind velocities, as characterized by the C IV P Cygni profiles and the He II emission line strengths, are very similar over Z = 0.16-0.4 Z☉. This agrees with predictions that the optically thick winds of VMS will be enhanced near the Eddington limit and show little metallicity dependence. We find very strong damped Lyα absorption with N(H I) =1022.2 cm-2 associated with Mrk 71-A. We discuss the natal environment of this young SSC in terms of radiatively driven winds, catastrophic cooling, and recent models where the cluster is surrounded by highly pressurized clouds with large neutral columns.

Keywords: Dwarf irregular galaxies, Starburst galaxies, Massive stars, Young massive clusters, Spectroscopy, H II regions
AGN STORM 2. IV. Swift X-Ray and Ultraviolet/Optical Monitoring of Mrk 817. The AGN STORM 2 campaign is a large, multiwavelength reverberation mapping project designed to trace out the structure of Mrk 817 from the inner accretion disk to the broad emission line region and out to the dusty torus. As part of this campaign, Swift performed daily monitoring of Mrk 817 for approximately 15 months, obtaining observations in X-rays and six UV/optical filters. The X-ray monitoring shows that Mrk 817 was in a significantly fainter state than in previous observations, with only a brief flare where it reached prior flux levels. The X-ray spectrum is heavily obscured. The UV/optical light curves show significant variability throughout the campaign and are well correlated with one another, but uncorrelated with the X-rays. Combining the Swift UV/optical light curves with Hubble Space Telescope UV continuum light curves, we measure interband continuum lags, τ(λ), that increase with increasing wavelength roughly following τ(λ) ∝ λ 4/3, the dependence expected for a geometrically thin, optically thick, centrally illuminated disk. Modeling of the light curves reveals a period at the beginning of the campaign where the response of the continuum is suppressed compared to later in the light curve-the light curves are not simple shifted and scaled versions of each other. The interval of suppressed response corresponds to a period of high UV line and X-ray absorption, and reduced emission line variability amplitudes. We suggest that this indicates a significant contribution to the continuum from the broad-line region gas that sees an absorbed ionizing continuum.

Keywords: Accretion, Supermassive black holes, Reverberation mapping, Seyfert galaxies, Active galactic nuclei
VVV-WIT-12 and Its Fashionable Nebula: A 4 yr Long-period Young Stellar Object with a Light Echo?. We report the serendipitous discovery of VVV-WIT-12, an unusual variable source that seems to induce variability in its surrounding nebula. The source belongs to the rare objects that we call WITs (short for What Is This?) discovered within the VISTA Variables in the Vía Láctea (VVV) survey. VVV-WIT-12 was discovered during a pilot search for light echoes from distant supernovae in the Milky Way using the near-IR images of the VVV survey. This source has an extremely red spectral energy distribution, consistent with a very reddened (A  V  ~ 100 mag) long-period variable star (P ~ 1525 days). Furthermore, it is enshrouded in a nebula that changes brightness and color with time, apparently in sync with the central source variations. The near-IR light curve and complementary follow-up spectroscopy observations are consistent with a variable young stellar object illuminating its surrounding nebula. In this case the source periodic variation along the cycles produces an unprecedented light echo in the different regions of the nebula.

Keywords: Stellar oscillations, Sky surveys, Galaxy stellar content, Variable stars
Hadronic Processes at Work in 5BZB J0630−2406. Recent observations are shedding light on the important role that active galactic nuclei play in the production of high-energy neutrinos. In this study, we focus on one object, 5BZB J0630−2406, which is among the blazars recently proposed as associated with neutrino emission during the first 7 yr of IceCube observations. Modeling the quasi-simultaneous, broadband spectral energy distribution, we explore various scenarios from purely leptonic to leptohadronic models, testing the inclusion of external photon fields. This theoretical study provides a complementary testing ground for the proposed neutrino─blazar association. Despite being historically classified as a BL Lac, our study shows that 5BZB J0630−2406 belongs to the relatively rare subclass of high-power flat-spectrum radio quasars. Our results indicate that interactions between protons and external radiation fields can produce a neutrino flux that is within the reach of the IceCube detector. Furthermore, the spectral shape of the X-ray emission suggests the imprint of hadronic processes related to very energetic protons.

Keywords: Neutrino astronomy, Non-thermal radiation sources, BL Lacertae objects, Gamma-rays
JWST Constraints on the UV Luminosity Density at Cosmic Dawn: Implications for 21 cm Cosmology. An unprecedented array of new observational capabilities are starting to yield key constraints on models of the epoch of first light in the Universe. In this Letter we discuss the implications of the UV radiation background at cosmic dawn inferred by recent JWST observations for radio experiments aimed at detecting the redshifted 21 cm hyperfine transition of diffuse neutral hydrogen. Under the basic assumption that the 21 cm signal is activated by the Lyα photon field produced by metal-poor stellar systems, we show that a detection at the low frequencies of the EDGES and SARAS3 experiments may be expected from a simple extrapolation of the declining UV luminosity density inferred at z ≲ 14 from JWST early galaxy data. Accounting for an early radiation excess above the cosmic microwave background suggests a shallower or flat evolution to simultaneously reproduce low- and high-z current UV luminosity density constraints, which cannot be entirely ruled out, given the large uncertainties from cosmic variance and the faint-end slope of the galaxy luminosity function at cosmic dawn. Our findings raise the intriguing possibility that a high star formation efficiency at early times may trigger the onset of intense Lyα emission at redshift z ≲ 20 and produce a cosmic 21 cm absorption signal 200 Myr after the Big Bang.

Keywords: Cosmology, Early universe, H I line emission, James Webb Space Telescope, Radio interferometers
JWST Detects Neon Line Variability in a Protoplanetary Disk. We report the first detection of variability in the mid-infrared neon line emission of a protoplanetary disk by comparing a JWST Mid-InfraRed Instrument Medium Resolution Spectrometer spectrum of SZ Cha taken in 2023 with a Spitzer Infrared Spectrograph Short-High spectrum of this object from 2008. We measure the [Ne III]-to-[Ne II] line flux ratio, which is a diagnostic of the high-energy radiation field, to distinguish between the dominance of EUV- or X-ray-driven disk photoevaporation. We find that the [Ne III]-to-[Ne II] line flux ratio changes significantly from ~1.4 in 2008 to ~0.2 in 2023. This points to a switch from EUV-dominated to X-ray-dominated photoevaporation of the disk. We present contemporaneous ground-based optical spectra of the Hα emission line that show the presence of a strong wind in 2023. We propose that this strong wind prevents EUV radiation from reaching the disk surface while the X-rays permeate the wind and irradiate the disk. We speculate that at the time of the Spitzer observations, the wind was suppressed and EUV radiation reached the disk. These observations confirm that the MIR neon emission lines are sensitive to changes in high-energy radiation reaching the disk surface. This highlights the [Ne III]-to-[Ne II] line flux ratio as a tool to gauge the efficiency of disk photoevaporation in order to provide constraints on the planet formation timescale. However, multiwavelength observations are crucial to interpret the observations and properly consider the star-disk connection.

Keywords: T Tauri stars, Protoplanetary disks
Halfway to the Peak: Spatially Resolved Star Formation and Kinematics in a z = 0.54 Dusty Galaxy with JWST/MIRI. We present JWST Mid-InfraRed Instrument/Medium-Resolution Spectrometer (MIRI/MRS) observations of an infrared luminous disk galaxy, FLS1, at z ∼ 0.54. With a lookback time of 5 Gyr, FLS1 is chronologically at the midpoint between the peak epoch of star formation and the present day. The MRS data provide maps of the atomic fine structure lines [Ar II]6.99, [Ar III]8.99, [Ne II]12.81, and [Ne III]15.55 μm, polycyclic aromatic hydrocarbon (PAH) features at 3.3, 6.2, and 11.3 μm, and the warm molecular gas indicators H2S(5) and H2S(3); all these emission features are spatially resolved. We find that the PAH emission is more extended along the northern side of the galaxy when compared to the well-studied star formation tracer [Ne II]. The H2 rotational lines, which are shock indicators, are strongest and most extended on the southern side of the galaxy. [Ar II] is the second brightest fine structure line detected in FLS1 and we show that it is a useful kinematic probe that can be detected with JWST out to z ∼ 3. Velocity maps of [Ar II] show a rotating disk with signs of turbulence. Our results provide an example of how spatially resolved mid-infrared spectroscopy can allow us to better understand the star formation and interstellar medium conditions in a galaxy halfway back to the peak epoch of galaxy evolution.

Keywords: AGN host galaxies, Luminous infrared galaxies
Elusive Iron: Detection of the FeC Radical (X <SUP>3</SUP>Δ<SUB> i </SUB>) in the Envelope of IRC+10216. A new interstellar molecule, FeC (X 3Δ i ), has been identified in the circumstellar envelope of the carbon-rich asymptotic giant branch star IRC+10216. FeC is the second iron-bearing species conclusively observed in the interstellar medium, in addition to FeCN, also found in IRC+10216. The J = 4 → 3, 5 → 4, and 6 → 5 rotational transitions of this free radical near 160, 201, and 241 GHz, respectively, were detected in the lowest spin-orbit ladder, Ω = 3, using the Submillimeter Telescope of the Arizona Radio Observatory (ARO) for the 1 mm lines and the ARO 12 m at 2 mm. Because the ground state of FeC is inverted, these transitions are the lowest energy lines. The detected features exhibit slight U shapes with LSR velocities near V LSR ≈ -26 km s-1 and linewidths of ΔV 1/2 ≈ 30 km s-1, line parameters characteristic of IRC+10216. Radiative transfer modeling of FeC suggests that the molecule has a shell distribution with peak radius near 300 R * (~6″) extending out to ~500 R * (~10″) and a fractional abundance, relative to H2, of f ~ 6 × 10-11. The previous FeCN spectra were also modeled, yielding an abundance of f ~ 8 × 10-11 in a larger shell situated near 800 R *. These distributions suggest that FeC may be the precursor species for FeCN. Unlike cyanides and carbon-chain molecules, diatomic carbides with a metallic element are rare in IRC+10216, with FeC being the first such detection.

Keywords: Interstellar molecules, Circumstellar envelopes, Evolved stars, Astrochemistry, Asymptotic giant branch stars, Radio astronomy
Constraining the AGN Luminosity Function from JWST with the X-Ray Background. We predict the X-ray background (XRB) expected from the population of quasars detected by the James Webb Space Telescope spectroscopic surveys over the redshift range z ~ 4-7. We find that the measured UV emissivities imply a ~10 times higher unresolved XRB than constrained by current experiments. We illustrate the difficulty of simultaneously matching the faint end of the quasar luminosity function and the XRB constraints. We discuss possible origins and consequences of this discrepancy.

Keywords: Cosmology, Diffuse x-ray background, Quasars
The First X-Ray Polarization Observation of the Black Hole X-Ray Binary 4U 1630-47 in the Steep Power-law State. The Imaging X-ray Polarimetry Explorer (IXPE) observed the black hole X-ray binary 4U 1630-47 in the steep power-law (or very high) state. The observations reveal a linear polarization degree of the 2-8 keV X-rays of 6.8% ± 0.2% at a position angle of 21.°3 ± 0.°9 east of north (all errors at 1σ confidence level). Whereas the polarization degree increases with energy, the polarization angle stays constant within the accuracy of our measurements. We compare the polarization of the source in the steep power-law state with the previous IXPE measurement of the source in the high soft state. We find that, even though the source flux and spectral shape are significantly different between the high soft state and the steep power-law state, their polarization signatures are similar. Assuming that the polarization of both the thermal and power-law emission components are constant over time, we estimate the power-law component polarization to be 6.8%-7.0% and note that the polarization angle of the thermal and power-law components must be approximately aligned. We discuss the implications for the origin of the power-law component and the properties of the emitting plasma.

Keywords: X-ray astronomy, Polarimetry, Stellar mass black holes, High energy astrophysics
Radio Emission and Electric Gaps in Pulsar Magnetospheres. The origin of pulsar radio emission is one of the old puzzles in theoretical astrophysics. In this Letter, we present a global kinetic plasma simulation that shows from first principles how and where radio emission can be produced in pulsar magnetospheres. We observe the self-consistent formation of electric gaps that periodically ignite electron-positron discharge. The gaps form above the polar cap and in the bulk return current. Discharge of the gaps excites electromagnetic modes, which share several features with the radio emission of real pulsars. We also observe the excitation of plasma waves and charge bunches by beam instabilities in the outer magnetosphere. Our numerical experiment demonstrates that global kinetic models can provide deep insight into the emission physics of pulsars and may help interpret their multiwavelength observations.

Keywords: Plasma astrophysics, Gamma-rays, Magnetic fields, Radio pulsars
Nebular C IV λ1550 Imaging of the Metal-poor Starburst Mrk 71: Direct Evidence of Catastrophic Cooling. We use the Hubble Space Telescope Advanced Camera for Surveys to obtain the first spatially resolved, nebular imaging in the light of C IV λ λ1548, 1551 by using the F150LP and F165LP filters. These observations of the local starburst Mrk 71 in NGC 2366 show emission apparently originating within the interior cavity around the dominant super star cluster (SSC), Knot A. Together with imaging in He II λ4686 and supporting Space Telescope Imaging Spectrograph far-ultraviolet spectroscopy, the morphology and intensity of the C IV nebular surface brightness and the C IV/He II ratio map provide direct evidence that the mechanical feedback is likely dominated by catastrophic radiative cooling, which strongly disrupts adiabatic superbubble evolution. The implied extreme mass loading and low kinetic efficiency of the cluster wind are reasonably consistent with the wind energy budget, which is probably enhanced by radiation pressure. In contrast, the Knot B SSC lies within a well-defined superbubble with associated soft X-rays and He II λ1640 emission, which are signatures of adiabatic, energy-driven feedback from a supernova-driven outflow. This system lacks clear evidence of C IV from the limb-brightened shell, as expected for this model, but the observations may not be deep enough to confirm its presence. We also detect a small C IV-emitting object that is likely an embedded compact H II region. Its C IV emission may indicate the presence of very massive stars (&gt;100 M ⊙) or strongly pressure-confined stellar feedback.

Keywords: Starburst galaxies, Stellar feedback, Young massive clusters, Emission line galaxies, Galaxy winds, Galaxy evolution, Ultraviolet photometry, Direct imaging, H II regions, Superbubbles
CECILIA: The Faint Emission Line Spectrum of z   2-3 Star-forming Galaxies. We present the first results from Chemical Evolution Constrained Using Ionized Lines in Interstellar Aurorae (CECILIA), a Cycle 1 JWST NIRSpec/MSA program that uses ultra-deep ~30 hr G235M/F170LP observations to target multiple electron temperature-sensitive auroral lines in the spectra of 33 galaxies at z ~ 1-3. Using a subset of 23 galaxies, we construct two ~600 object-hour composite spectra, both with and without the stellar continuum, and use these to investigate the characteristic rest-optical (λ rest ≈ 5700-8500 Å) spectrum of star-forming galaxies at the peak epoch of cosmic star formation. Emission lines of eight different elements (H, He, N, O, Si, S, Ar, and Ni) are detected, with most of these features observed to be ≲3% the strength of Hα. We report the characteristic strength of three auroral features ([N II]λ5756, [S III]λ6313, and [O II]λ λ7322, 7332), as well as other semi-strong and faint emission lines, including forbidden [Ni II]λ λ7380, 7414 and permitted O I λ8449, some of which have never before been observed outside of the local Universe. Using these measurements, we find T  e [N II] = 13,630 ± 2540 K, representing the first measurement of electron temperature using [N II] in the high-redshift Universe. We also see evidence for broad line emission with a FWHM of ${536}_{-167}^{+45}$ km s-1; the broad component of Hα is 6.01%-28.31% the strength of the narrow component and likely arises from star-formation-driven outflows. Finally, we briefly comment on the feasibility of obtaining large samples of faint emission lines using JWST in the future.

Keywords: Galaxy spectroscopy, High-redshift galaxies, Chemical abundances, Emission line galaxies
High-energy Neutrino Emission Associated with GWs from Binary Black Hole Mergers in AGN Accretion Disks. The search for multimessenger signals of binary black hole (BBH) mergers is crucial to understanding the merger process of BBH and the relative astrophysical environment. Considering BBH mergers occurring in the active galactic nuclei (AGN) accretion disks, we focus on the accompanying high-energy neutrino production from the interaction between the jet launched by the postmerger remnant BH and disk materials. Particles can be accelerated by the shocks generated from the jet-disk interaction and subsequently interact with the disk gas and radiations to produce high-energy neutrinos through hadronic processes. We demonstrate that the identification of the high-energy neutrino signal from BBH merger in AGN disks is feasible. In addition, the joint BBH gravitational wave (GW) and neutrino detection rate is derived, which can be used to constrain the BBH merger rate and the accretion rate of the remnant BH based on the future associated detections of GWs and neutrinos. To date, an upper limit of BBH merger rate density in AGN disks of R 0 ≲ 3 Gpc-3 yr-1 is derived for the fiducial parameter values based on the current null association of GWs and neutrinos.

Keywords: Black holes, High energy astrophysics, Neutrino astronomy, Active galactic nuclei, Gravitational waves