Sazuna/UAT_keywords huggingface dataset:
SOFIA Polarization Spectrum of Three Star-forming Clouds. The dust emission polarization spectrum—how the polarization percentage changes with wavelength—serves as a probe of dust grain properties in star-forming regions. In this paper, we present 89─214 μm polarization spectrum measurements obtained from SOFIA/HAWC+ for three star-forming clouds: OMC1, M17, and W3. We find that all three clouds have an overall decreasing polarization percentage with increasing wavelength (i.e., a "falling polarization spectrum"). We use SOFIA and Herschel data to create column density and temperature maps for each cloud. We fit for the slope of the polarization spectrum at each sky position in each cloud, and using the Pearson r coefficient, we probe each cloud for possible correlations of slope with column density and slope with temperature. We also create plots of slope versus column density and slope versus temperature for each cloud. For the case of OMC1, our results are consistent with those presented by J. Michail et al., who carried out a similar analysis for that cloud. Our plots of polarization spectrum slope versus column density reveal that for each cloud there exists a critical column density below which a falling polarization spectrum is not observed. For these more diffuse sight lines, the polarization spectrum is instead flat or slightly rising. This finding is consistent with a hypothesis presented 25 yr ago in a paper led by R. Hildebrand based on Kuiper Airborne Observatory data. This hypothesis is that regions shielded from near-IR radiation are required to produce a sharply falling polarization spectrum.

Keywords: Star forming regions, Far infrared astronomy, Interstellar magnetic fields, Young stellar objects, Star formation, Protostars, Polarimetry
Effect of Deviations from General Relativity on Searches for Gravitational-wave Microlensing and Type II Strong Lensing. As the gravitational-wave (GW) detector network is upgraded and the sensitivity of the detectors improves, novel scientific avenues open for exploration. For example, tests of general relativity (GR) will become more accurate as smaller deviations can be probed. Additionally, the detection of lensed GWs becomes more likely. However, these new avenues could also interact with each other, and a GW event presenting deviations from GR could be mistaken for a lensed one. Here, we explore how phenomenological deviations from GR or binaries of exotic compact objects could impact those lensing searches focusing on a single event. We consider strong lensing, millilensing, and microlensing, and find that certain phenomenological deviations from GR may be mistaken for all of these types of lensing. Therefore, our study shows that future candidate lensing events would need to be carefully examined to avoid a false claim of lensing where instead a deviation from GR has been seen.

Keywords: Gravitational microlensing, Gravitational lensing, Gravitational waves, General relativity
A Spectroscopic Analysis of the Ionizing Photon Production Efficiency in JADES and CEERS: Implications for the Ionizing Photon Budget. We have used a combined sample of JADES and CEERS objects in order to constrain ionizing photon production efficiency (ξion) from JWST/NIRSpec and JWST/NIRCam data. We examine 163 objects at 1.06 &lt; z &lt; 6.71 with significant (3σ) spectroscopic detections of Hα and Hβ in order to constrain intrinsic Hα luminosities corrected from nebular dust attenuation via Balmer decrements. We constrain dust-corrected UV luminosities from best-fit spectral energy distribution modeling. We find a sample median  , assuming fesc = 0 for the escape fraction of Lyman continuum (LyC) emission. We find significant (Spearman rs = 0.19, p = 0.01) correlation between ξion,0 and z, with objects at z &gt; 4.64 having median  , with those below having  . We also find significant, positive correlations between ξion,0 and LUV; Wλ([O III]); [O III]λ5007/[O II]λλ3726, 3729; and inverse correlations with metallicity. In contrast with some previous results, we find no trends between ξion,0 and stellar mass, stellar dust attenuation, or UV slope. Applying a multivariate fit to ξion,0, z, and MUV to an empirically motivated model of reionization, and folding in fesc estimates from direct observations of the LyC at z ∼ 3 from the Keck Lyman Continuum Spectroscopic Survey, we find that the number of ionizing photons entering the IGM causes reionization to end at z ∼ 5–7.

Keywords: Reionization, High-redshift galaxies, Galaxy evolution, Near infrared astronomy
RIOJA. Complex Dusty Starbursts in a Major Merger B14-65666 at z = 7.15. We present JWST NIRCam imaging of B14-65666 ("Big Three Dragons"), a bright Lyman-break galaxy system (MUV = ‑22.5 mag) at z = 7.15. The high angular resolution of NIRCam reveals the complex morphology of two galaxy components: galaxy E has a compact core (E-core), surrounded by diffuse, extended, rest-frame optical emission, which is likely to be tidal tails; and galaxy W has a clumpy and elongated morphology with a blue UV slope (βUV = ‑2.2 ± 0.1). The flux excess, F356W ‑ F444W, peaks at the E-core (  mag), tracing the presence of strong [O III] λλ4960,5008 emission. Atacama Large Millimeter/submillimeter Array archival data show that the bluer galaxy W is brighter in dust continua than the redder galaxy E, while the tails are bright in [O III] 88 μm. The UV/optical and submillimeter spectral energy distribution (SED) fitting confirms that B14-65666 is a major merger in a starburst phase as derived from the stellar mass ratio (3:1 to 2:1) and the star formation rate, ≃1 dex higher than the star formation main sequence at the same redshift. Galaxy E is a dusty (AV = 1.2 ± 0.1 mag) starburst with a possible high dust temperature (≥63–68 K). Galaxy W would have a low dust temperature (≤27–33 K) or patchy stellar-and-dust geometry, as suggested by the IR excess and βUV diagram. The high optical-to-far-IR [O III] line ratio of the E-core shows its lower gas-phase metallicity (≃0.2–0.4 Z⊙) than galaxy W. These results agree with a scenario where major mergers disturb morphology and induce nuclear dusty starbursts triggered by less-enriched inflows. B14-65666 shows a picture of complex stellar buildup processes during major mergers in the epoch of reionization.

Keywords: Galaxy mergers, High-redshift galaxies, Galaxy evolution, Near infrared astronomy
What Can We Learn from the Nitrogen Abundance of High-z Galaxies?. We present measurements of the gas-phase oxygen and nitrogen abundances obtained by applying the direct method to JWST NIRspec R ∼ 1000 spectroscopy for six galaxies at redshift greater than 3. Our measurements are based on rest-frame optical nitrogen [N II]λλ6548,6583 lines and are complemented by six additional objects from the literature at 3 ≤ z ≤ 6. We find that 9 out of 12 objects have values of log(N/O) that are compatible with those found for low-redshift, metal-poor, dwarf galaxies and for H II regions of more luminous local galaxies. However, 3 out of 12 objects have log(N/O) values that are overabundant compared to what is expected on the basis of their oxygen abundance. We explore a few standard scenarios to explain the observations and conclude that, within the limited statistics available to us, none of them can be definitely excluded even though we prefer dilution by pristine gas infall in between star formation bursts, as this is predicted by simulations to take place as a natural part of bursty star formation.

Keywords: High-redshift galaxies, Chemical abundances
Connecting Dust and Outflows in Active Galactic Nuclei: The Intriguing Case of NGC 6860. Cosmic dust plays a crucial role in the evolution of galaxies, significantly influencing star formation and the interstellar medium. However, in active galactic nuclei (AGNs), the role and origin of dust remain poorly understood. High-resolution X-ray spectroscopy is a powerful tool for probing the properties of dust in AGN. NGC 6860, an X-ray bright type-1 quasar, is an ideal target for investigating the connection between dust and winds in AGN. It exhibits reddening and X-ray absorption by both dust and winds. By modeling high-resolution X-ray spectra from XMM-Newton and Chandra observations, we determine the properties of dust and outflows in this AGN. Our analysis finds four photoionized components, outflowing with velocities of 50─300 km s−1. The first two are relatively highly ionized with   and  . The results of our photoionization modeling suggest that these two components are thermally unstable. The third component is ionized, with  , and is located farther away from the central black hole. The fourth component is less ionized and is possibly located in the host galaxy. The application of dust models enables us to probe the abundance and location of the dust in NGC 6860. Our findings suggest that dust absorption and reddening originates from the extended narrow-line region and its host galaxy.

Keywords: Dust composition, Active galactic nuclei
Early Accretion of Large Amounts of Solids for Directly Imaged Exoplanets. As the number of planetary-mass objects (PMOs; ⪅13 MJupiter) at wider separation (⪆10 au) grows, there is emerging evidence that they form differently from their higher-mass brown dwarf counterparts. Specifically, PMOs' atmospheres are often enriched by metals and show a large dispersion of metallicity, which is usually interpreted as a sign of solid accretion. As a first step toward a population-level study of the amount and timing of solid accretion, we analyze a sample of seven directly imaged exoplanets with measured stellar and planetary chemical abundances (51 Eri b, β Pic b, HIP 65426 b, HR 8799c and e, AF Lep b, and YSES 1 c). Our analysis uses existing data of stellar and planetary atmospheric metallicities and adopts a Bayesian framework that marginalizes the probabilities of disk conditions, formation locations, planetary interior structures, and accretion physics. We show that these PMOs accrete large amounts of solids regardless of whether they form via core accretion or disk instability. On average, ⪆50 M⊕ of solids are accreted to enrich planet atmospheres. An individual planet accretes between 23.3 and 223.2 M⊕ of solid mass, more than 75% of which is assumed to stay in the atmosphere and increase the observed metallicity. The result implies that the solid accretion process and therefore the planet formation process likely take place at an early stage (⪅2 Myr) when large amounts of solids are available in young massive protoplanetary disks.

Keywords: Exoplanet astronomy, Exoplanet atmospheric composition , Exoplanet formation
Simultaneous Existence of Oscillations, Counterstreaming Flows, and Mass Injections in Solar Quiescent Prominences. Solar prominences are very spectacular structures embedded in the tenuous and hot solar corona. Counterstreaming flows, a common feature in solar quiescent prominences, have been discovered for more than 20 yr. However, the mechanism driving the counterstreaming flows is still elusive. To unveil the nature of this phenomenon, we analyzed data of a quiescent prominence observed by the New Vacuum Solar Telescope, the Interface Region Imaging Spectrograph, and the Solar Dynamical Observatory. It is found that there is a distinct longitudinal oscillation of prominence plasma along the higher part of the prominence spine in Hα observations. The oscillation period is approximately 83 minutes and the amplitude is about 32 Mm. The counterstreaming flows are dominant in the middle part of the prominence spine. The velocities of the counterstreaming flows range from about 4 to 11 km s‑1. Moreover, intermittent mass flows with upward plumes from the top of the bubbles and tornado-like barbs are observed to be injected into the lower part of the prominence spine from the lower atmosphere. The velocities of these injected mass flows range from about 3 to 30 km s‑1. Some injected mass flows exhibit redshifted Doppler signals, while others exhibit blueshifted signals. Based on these high-resolution observations, it is found that different parts of the prominence spine exhibit different dynamic characteristics. These results further advance the understanding of the ubiquitous counterstreaming flows in solar quiescent prominences.

Keywords: Solar atmosphere, Solar prominences, The Sun, Solar physics, Solar activity
Radial Evolution of a Density Structure within a Solar Wind Magnetic Sector Boundary. This study focuses on a radial alignment between Parker Solar Probe (PSP) and Solar Orbiter (SolO) on 2021 April 29 (during a solar minimum), when the two spacecraft were, respectively, located at ∼0.075 and ∼0.9 au from the Sun. A previous study of this alignment allowed the identification of the same density enhancement (with a timescale of ∼1.5 hr) and substructures (timescales of ∼20–30 minutes), passing first by PSP and then by SolO after a ∼138 hr propagation time in the inner heliosphere. We show here that this structure belongs to the large-scale heliospheric magnetic sector boundary. In this region, the density is dominated by radial gradients, whereas the magnetic field reversal is consistent with longitudinal gradients in the Carrington reference frame. We estimate the density structure radial size to remain of the order LR ∼ 106 km, while its longitudinal and latitudinal sizes are estimated to expand from Lφ,θ ∼ 104–105 km in the high solar corona to Lφ,θ ∼ 105–106 km at PSP and Lφ,θ ∼ 106–107 km at SolO. This implies a strong evolution of the structure's aspect ratio during the propagation, due to the plasma's nearly spherical expansion. The structure's shape is therefore inferred to evolve from elongated in the radial direction at ∼2–3 solar radii (high corona) to sizes of nearly the same order in all directions at PSP and then becoming elongated in the directions transverse to the radial at SolO. Measurements are not concordant with local reconnection of open solar wind field lines, so we propose that the structure has been generated through interchange reconnection near the tip of a coronal streamer.

Keywords: Slow solar wind, Solar coronal transients, Solar magnetic reconnection, Heliosphere, Solar wind, Solar corona, Solar coronal streamers
Contaminating Electromagnetic Transients in LISA Gravitational-wave Localization Volumes. I. The Intrinsic Rates. The Laser Interferometer Space Antenna (LISA) will soon detect gravitational waves (GWs) emitted by massive black hole (MBH) mergers. Some theoretical models have predicted transient electromagnetic (EM) emission from these mergers, enabling the association of LISA GW sources with their EM counterparts via telescope follow-up. However, the number of unrelated EM transients that might contaminate telescope searches for the true transient counterparts of LISA MBH mergers is unknown. We investigate the expected numbers of unrelated EM transients that will coincide with simulated LISA localization volumes of MBH mergers as a function of the merger total mass and redshift. We find that the number of potential contaminants in LISA localization volumes drops to unity for mergers at z ≲ 0.8 and at 1 hr before coalescence. After coalescence, the parameter space corresponding to a maximum of one potential contaminant expands to z ≲ 1.5. In contrast, if the redshifts for all transients detected in LISA sky localization regions are not available, the number of potential contaminants increases by an average factor of ∼100 and never drops below unity. Overall, we expect the average number of contaminating transients in telescope follow-up of LISA MBH mergers to be nonnegligible, especially without redshift information for the detected transients. We recommend that endeavors designing follow-up strategies of LISA events should focus on (1) building large redshift catalogs for host galaxies, (2) developing robust real-time transient classification algorithms, and (3) coordinating telescope resources to obtain redshifts for candidate transient EM counterparts in a timely manner.

Keywords: Transient sources, Black holes, Gravitational wave sources
Amplifying Resonant Repulsion with Inflated Young Planets, Overlooked Inner Planets, and Nonzero Initial Δ. Most multiplanet systems around mature (∼5 Gyr old) host stars are nonresonant. Even the near-resonant planet pairs still display 1%–2% positive deviation from perfect period commensurabilities (Δ) near first-order mean motion resonances (MMRs). Resonant repulsion due to eccentricity tides was one of the first mechanisms proposed to explain the observed positive Δ. However, the inferred rates of tidal dissipation are often implausibly rapid (with a reduced tidal quality factor  ). In this work, we attempt to amplify eccentricity tides with three previously ignored effects. (1) Planets tend to be inflated when they were younger. (2) Kepler-like planets likely form as resonant chains parked at the disk inner edge; overlooked inner planets could have contributed to tidal dissipation of the whole system. (3) Disk migration captures planets into first-order MMR with nonzero initial deviation Δ, thereby lowering the amount of dissipation needed. We show that even after accounting for all three effects,   can only be amplified by about 1 order of magnitude, and still falls short of   values of solar system planets. Therefore, eccentricity tides alone cannot fully explain the observed Δ distribution. Other effects such as obliquity tides, planetesimal scattering, expanding disk inner edge, disk turbulence, divergent encounters, and dynamical instabilities must have contributed to dislodging planets from first-order MMR.

Keywords: Exoplanet astronomy, Exoplanet tides, Exoplanet dynamics
Discovery of an RRAT-like Pulsar via Its Single Pulses in a Murchison Widefield Array Imaging Survey. We report the discovery of PSR J0031–5726 in the Galactic and Extragalactic All-sky Murchison Widefield Array Extended imaging survey at a Galactic latitude of b ≈ ‑60∘. The pulsar exhibits both sporadic, extremely bright pulses reminiscent of rotating radio transients (RRATs) as well as persistent, dimmer pulses. The bright pulses tend to arrive at later rotation phases than their dimmer counterparts and have dramatically varying polarization angle curves, such that the integrated profile appears almost completely depolarized down to the system noise level. The rotation measure of individual pulses was found to sometimes vary by up to ∼0.8 rad m‑2, but was otherwise generally consistent with its average (ionosphere-corrected) value of 10.0 ± 0.1 rad m‑2. We surmise that J0031–5726 may represent a class of pulsars that is intermediate between normal pulsars and RRATs.

Keywords: Sky surveys, Radio pulsars
X-Ray Spectra from General Relativistic Radiation Magnetohydrodynamic Simulations of Thin Disks. We compare X-ray emission from several general relativistic, multifrequency, radiation magnetohydrodynamic simulations of thin black hole accretion disks with different accretion rates and spins. The simulations were performed using the M1 closure scheme, resolved with 12 frequency (energy) bins logarithmically spaced from 5 × 10‑3 to 5 × 103 keV. We apply a general relativistic Monte Carlo transport code to postprocess the simulation data with greater fidelity in frequency resolution and Compton scattering treatment. Despite the relatively few energy bins and Kompaneets approximation to Compton scattering utilized in the M1 method, we find generally good agreement between the methods. Both produce prominent thermal profiles with peaks around 2–2.5 keV, where agreement is particularly strong and representative of the soft state. Both also find weaker (lower-luminosity) thermally sourced emission extending out to 100 keV due to the hotter innermost regions of the disks. Inverse Compton scattering becomes increasingly effective at hardening spectral outputs with increasing black hole spin, and becomes the dominant mechanism for photons that escape with energies between 10 to several hundred keV. At very high rates of spin, the radiation flux in this upscattered component becomes comparable to the thermal flux, a phenomenon typically associated with intermediate states. Beyond 104 keV, we observe faint, free–free emission from hot, optically thin coronal regions developing near the horizon, common to both spinning and nonspinning black holes.

Keywords: Accretion, Radiative magnetohydrodynamics, Monte Carlo methods, Rotating black holes, Radiative transfer, X-ray sources, Low-mass x-ray binary stars, Astrophysical fluid dynamics, Relativistic disks
Revision of Two-temperature Magnetically Arrested Flows onto a Black Hole. We revisit the radiative properties of 3D general relativistic magnetohydrodynamics (GRMHD) two-temperature magnetically arrested disk (MAD) models in which electrons are heated by a magnetic turbulent cascade. We focus on studying the model emission, whose characteristics include variability in both total intensity and linear/circular polarizations as well as rotation measures at energies around the synchrotron emission peak in millimeter waves. We find that the radiative properties of MAD models with turbulent electron heating are well converged with respect to the numerical grid resolution, which has not been demonstrated before. We compare radiation from two-temperature simulations with turbulent heating to single-temperature models with electron temperatures calculated based on the commonly used R(β) prescription. We find that the self-consistent two-temperature models with turbulent heating do not significantly outperform the R(β) models and, in practice, may be indistinguishable from the R(β) models. Accounting for physical effects such as radiative cooling and the nonthermal electron distribution function makes a weak impact on properties of millimeter emission. Models are scaled to Sgr A*, an accreting black hole in the center of our galaxy, and compared to the most complete observational data sets. We point out the consistencies and inconsistencies between the MAD models and observations of this source and discuss future prospects for GRMHD simulations.

Keywords: Supermassive black holes, Low-luminosity active galactic nuclei, Plasma physics, Magnetohydrodynamical simulations
The Stationary Point: A New Method for Solar Wind Speed Measurements from a Moving Vantage Point. The WISPR imager on Parker Solar Probe (PSP) provides a unique view of the young solar wind as it flies through solar wind structures at high speed. It is of interest to use WISPR image sequences to measure the velocity of both large features (such as coronal mass ejections) and the background, ambient wind. However, WISPR's close-up, rapidly moving perspective makes the usual methods for measuring velocities from images difficult or impossible to apply, as most apparent motion through the image is due to the motion or rotation of the imager. In this work, we propose a new method of looking for features at the "stationary point"—a direction from which some plasma parcels appear to approach the spacecraft, remaining at a constant direction in the image sequence. This direction is a function of the plasma's radial velocity, the encounter geometry, and the spacecraft velocity, allowing the former two to be inferred. We demonstrate the technique with forward-modeled images, and we apply it to WISPR observations, inferring the speed and trajectory of a particular density feature. This method promises to enable speed measurements of the young solar wind in an important acceleration region, from a close-up perspective and at latitudes well outside the PSP orbital plane. And while we present this method in a solar wind context, it is broadly applicable to any situation of a moving viewpoint traveling through an expanding cloud of features.

Keywords: Solar coronal transients, Solar wind, Solar corona