Sazuna/UAT_keywords huggingface dataset:
Unresolved z   8 Point Sources and Their Impact on the Bright End of the Galaxy Luminosity Function. The distribution and properties of the first galaxies and quasars are critical pieces of the puzzle in understanding galaxy evolution and cosmic reionization. Previous studies have often excluded unresolved sources as potential low-redshift interlopers. We combine broadband color and photometric redshift analysis with morphological selections to identify a robust sample of candidates consistent with unresolved point sources at redshifts z ~ 8 using deep Hubble Space Telescope images. We also examine G141 grism spectroscopic data to identify and eliminate dwarf star contaminants. From these analyses, we identify three bright (M UV ≲ -22 AB mag) dropout point sources at 7.5 &lt; z &lt; 8.1. Spectral energy distribution analyses suggest that these sources are either quasars or compact star-forming galaxies. The flux captured by the IRAC 4.5 μm channel suggests that they have moderate Hβ + [O III] equivalent widths. We calculate the number density of point sources at z ~ 7-8, and find that a double-power-law model well describes the point-source distribution. We then extend our analysis to estimate the combined point-source + galaxy luminosity function and find that the point sources have a nonnegligible contribution to the bright-end excess. The fact that the point sources dominate only at M UV ≲ -22 suggests that their contribution to cosmic reionization is likely limited. While spectroscopic follow-up is needed to confirm the nature of these point sources, this work demonstrates that the inclusion of Lyman-dropout point sources is necessary for a complete census of early galaxies at the epoch of cosmic reionization.

Keywords: Luminosity function, Galaxy formation, Quasars, Hubble Space Telescope, Galaxy photometry, Reionization, High-redshift galaxies
Do All Low-Mass Stars Undergo Extra Mixing Processes?. Standard stellar evolution models that only consider convection as a physical process to mix material inside of stars predict the production of significant amounts of 3He in low-mass stars (M &lt; 2 M ⊙), with peak abundances of 3He/H ~ few × 10-3 by number. Over the lifetime of the Galaxy, this ought to produce 3He/H abundances that diminish with increasing Galactocentric radius. Observations of 3He+ in H II regions throughout the Galactic disk, however, reveal very little variation in the 3He abundance with values of 3He/H similar to the primordial abundance, ${\left({}^{3}{\rm{H}}{\rm{e}}/{\rm{H}}\right)}_{p}\sim {10}^{-5}$ . This discrepancy, known as the "3He problem," can be resolved by invoking in stellar evolution models an extra mixing mechanism due to the thermohaline instability. Here we observe 3He+ in the planetary nebula (PN) J320 (G190.3-17.7) with the Jansky Very Large Array to confirm a previous 3He+ detection made with the Very Large Array that supports standard stellar yields. This measurement alone indicates that not all stars undergo extra mixing. Our more sensitive observations do not detect 3He+ emission from J320 with an rms noise of 58.8 μJy beam-1 after smoothing the data to a velocity resolution of 11.4 km s-1. We estimate an abundance limit of 3He/H ≤ 2.75 × 10-3 by number using the numerical radiative transfer code NEBULA. This result nullifies the last significant detection of 3He+ in a PN and allows for the possibility that all stars undergo extra mixing processes.

Keywords: Radio spectroscopy, Planetary nebulae, Late stellar evolution
The Core Population and Kinematics of a Massive Clump at Early Stages: An Atacama Large Millimeter/submillimeter Array View. High-mass star formation theories make distinct predictions on the properties of the prestellar seeds of high-mass stars. Observations of the early stages of high-mass star formation can provide crucial constraints, but they are challenging and scarce. We investigate the properties of the prestellar core population embedded in the high-mass clump AGAL014.492-00.139, and we study the kinematics at the clump and clump-to-core scales. We have analyzed an extensive data set acquired with the Atacama Large Millimeter/submillimeter Array interferometer. Applying a dendrogram analysis to the Band 7 o−H2D+ data, we identified 22 cores. We fitted their average spectra in local thermodinamic equilibrium conditions, and we analyzed their continuum emission at 0.8 mm. The cores have transonic to mildly supersonic turbulence levels and appear to be mostly low-mass, with ${M}_{\mathrm{core}}\lt 30\,{\text{}}{M}_{\odot }$ . Furthermore, we have analyzed Band 3 observations of the N2H+ (1-0) transition, which traces the large-scale gas kinematics. Using a friend-of-friend algorithm, we identify four main velocity coherent structures, all of which are associated with prestellar and protostellar cores. One of them presents a filament-like structure, and our observations could be consistent with mass accretion toward one of the protostars. In this case, we estimate a mass accretion rate of ${\dot{M}}_{\mathrm{acc}}\approx 2\times {10}^{-4}\,{\text{}}{M}_{\odot }\,{\mathrm{yr}}^{-1}$ . Our results support a clump-fed accretion scenario in the target source. The cores in the prestellar stage are essentially low-mass, and they appear to be subvirial and gravitationally bound, unless further support is available, for instance, due to magnetic fields.

Keywords: Interstellar line emission, Massive stars, Star forming regions, Astrochemistry, Star formation, Interferometry
Constraining the Physical Properties of Stellar Coronal Mass Ejections with Coronal Dimming: Application to Far-ultraviolet Data of ϵ Eridani. Coronal mass ejections (CMEs) are a prominent contributor to solar system space weather and might have impacted the Sun's early angular momentum evolution. A signal diagnostic of CMEs on the Sun is coronal dimming: a drop in coronal emission, tied to the mass of the CME, that is the direct result of removing emitting plasma from the corona. We present the results of a coronal dimming analysis of Fe XII 1349 Å and Fe XXI 1354 Å emission from ϵ Eridani (ϵ Eri), a young K2 dwarf, with archival far-ultraviolet observations by the Hubble Space Telescope's Cosmic Origins Spectrograph. Following a flare in 2015 February, ϵ Eri's Fe XXI emission declined by 81 ± 5%. Although enticing, a scant 3.8 minutes of preflare observations allows for the possibility that the Fe XXI decline was the decay of an earlier, unseen flare. Dimming nondetections following each of three prominent flares constrain the possible mass of ejected Fe XII-emitting (1 MK) plasma to less than a few × 1015 g. This implies that CMEs ejecting this much or more 1 MK plasma occur less than a few times per day on ϵ Eri. On the Sun, 1015 g CMEs occur once every few days. For ϵ Eri, the mass-loss rate due to CME-ejected 1 MK plasma could be &lt; 0.6 ${\dot{M}}_{\odot }$ , well below the star's estimated 30 ${\dot{M}}_{\odot }$ mass-loss rate (wind + CMEs). The order-of-magnitude formalism we developed for these mass estimates can be broadly applied to coronal dimming observations of any star.

Keywords: Space weather, Stellar mass loss, Ultraviolet astronomy, Solar coronal mass ejections, Stellar coronal mass ejections
On the Kinematics of Cold, Metal-enriched Galactic Fountain Flows in Nearby Star-forming Galaxies. We use medium-resolution Keck/Echellette Spectrograph and Imager spectroscopy of bright quasars to study cool gas traced by Ca II λλ3934, 3969 and Na I λλ5891, 5897 absorption in the interstellar/circumgalactic media of 21 foreground star-forming galaxies at redshifts 0.03 &lt; z &lt; 0.20 with stellar masses 7.4 ≤ log M */M ⊙ ≤ 10.6. The quasar-galaxy pairs were drawn from a unique sample of Sloan Digital Sky Survey quasar spectra with intervening nebular emission, and thus have exceptionally close impact parameters (R ⊥ &lt; 13 kpc). The strength of this line emission implies that the galaxies' star formation rates (SFRs) span a broad range, with several lying well above the star-forming sequence. We use Voigt profile modeling to derive column densities and component velocities for each absorber, finding that column densities N(Ca II) &gt; 1012.5 cm-2 (N(Na I) &gt; 1012.0 cm-2) occur with an incidence f C(Ca II) = 0.63+0.10 -0.11 (f C(Na I) = 0.57+0.10 -0.11). We find no evidence for a dependence of f C or the rest-frame equivalent widths W  r (Ca II K) or W  r (Na I 5891) on R ⊥ or M *. Instead, W  r (Ca II K) is correlated with local SFR at &gt;3σ significance, suggesting that Ca II traces star formation-driven outflows. While most of the absorbers have velocities within ±50 km s-1 of the host redshift, their velocity widths (characterized by Δv 90) are universally 30-177 km s-1 larger than that implied by tilted-ring modeling of the velocities of interstellar material. These kinematics must trace galactic fountain flows and demonstrate that they persist at R ⊥ &gt; 5 kpc. Finally, we assess the relationship between dust reddening and W  r (Ca II K) (W  r (Na I 5891)), finding that 33% (24%) of the absorbers are inconsistent with the best-fit Milky Way E(B-V)-W  r  relations at &gt;3σ significance.

Keywords: Quasar absorption line spectroscopy, Quasar-galaxy pairs, Interstellar medium, Circumgalactic medium, Galaxies
A Rosetta Stone for Eccentric Gravitational Waveform Models. Orbital eccentricity is a key signature of dynamical binary black hole formation. The gravitational waves from a coalescing binary contain information about its orbital eccentricity, which may be measured if the binary retains sufficient eccentricity near merger. Dedicated waveforms are required to measure eccentricity. Several models have been put forward, and show good agreement with numerical relativity at the level of a few percent or better. However, there are multiple ways to define eccentricity for inspiralling systems, and different models internally use different definitions of eccentricity, making it difficult to compare eccentricity measurements directly. In this work, we systematically compare two eccentric waveform models, SEOBNRE and TEOBResumS, by developing a framework to translate between different definitions of eccentricity. This mapping is constructed by minimizing the relative mismatch between the two models over eccentricity and reference frequency, before evolving the eccentricity of one model to the same reference frequency as the other model. We show that for a given value of eccentricity passed to SEOBNRE, one must input a 20%-50% smaller value of eccentricity to TEOBResumS in order to obtain a waveform with the same empirical eccentricity. We verify this mapping by repeating our analysis for eccentric numerical relativity simulations, demonstrating that TEOBResumS reports a correspondingly smaller value of eccentricity than SEOBNRE.

Keywords: Stellar mass black holes, Compact binary stars, Gravitational waves, Eccentricity
Asteroid Measurements at Millimeter Wavelengths with the South Pole Telescope. We present the first measurements of asteroids in millimeter wavelength data from the South Pole Telescope (SPT), which is used primarily to study the cosmic microwave background (CMB). We analyze maps of two ~270 deg2 sky regions near the ecliptic plane, each observed with the SPTpol camera ~100 times over 1 month. We subtract the mean of all maps of a given field, removing static sky signal, and then average the mean-subtracted maps at known asteroid locations. We detect three asteroids-(324) Bamberga, (13) Egeria, and (22) Kalliope-with signal-to-noise ratios (S/N) of 11.2, 10.4, and 6.1, respectively, at 2.0 mm (150 GHz); we also detect (324) Bamberga with an S/N of 4.1 at 3.2 mm (95 GHz). We place constraints on these asteroids' effective emissivities, brightness temperatures, and light-curve modulation amplitude. Our flux density measurements of (324) Bamberga and (13) Egeria roughly agree with predictions, while our measurements of (22) Kalliope suggest lower flux, corresponding to effective emissivities of 0.64 ± 0.11 at 2.0 and &lt; 0.47 at 3.2 mm. We predict the asteroids detectable in other SPT data sets and find good agreement with detections of (772) Tanete and (1093) Freda in recent data from the SPT-3G camera, which has ~10× the mapping speed of SPTpol. This work is the first focused analysis of asteroids in data from CMB surveys, and it demonstrates we can repurpose historic and future data sets for asteroid studies. Future SPT measurements can help constrain the distribution of surface properties over a larger asteroid population.

Keywords: Millimeter astronomy, Cosmic microwave background radiation, Asteroids, Asteroid surfaces
Disentangling the Dominant Drivers of Gravity Wave Variability in the Martian Thermosphere. In this study, we extracted the amplitudes of the gravity waves (GWs) from the neutral densities measured in situ by the neutral gas and ion mass spectrometer aboard the Mars Atmosphere and Volatile Evolution mission. The spatial and temporal variabilities of the GWs show that solar activity (the F10.7 cm solar flux corrected for a heliocentric distance of 1.66 au), solar insolation, and the lower atmospheric dust are the dominant drivers of the GW variability in the thermosphere. We developed a methodology in which a linear regression analysis has been used to disentangle the complex variabilities of the GWs. The three dominant drivers could account for most of the variability in the GW amplitudes. Variability caused by the sources of GWs and the effects of winds and the global circulation in the mesosphere and lower thermosphere are the other factors that could not be addressed. The results of the present study show that for every 100 sfu increase in the solar activity, the GW amplitudes in the thermosphere decrease by ~9%. Solar insolation drives the diurnal, seasonal, and latitudinal variations of ~9%, ~4%, and ~6%, respectively. Using the historical data of the dust opacity and solar activity, we estimated the GW amplitudes of the Martian thermosphere from MY 24 to MY 35. The GW amplitudes were significantly reduced during the maximum of solar cycle 23 and were highest in the solar minimum. The global dust storms of MY 25, 28, and 34 lead to significant enhancements in the GW amplitudes.

Keywords: Thermosphere, Mars, Planetary atmospheres, Upper atmosphere
Dropouts of Fully Stripped Ions in the Solar Wind: A Diagnostic for Wave Heating versus Reconnection. The SWICS instrument on board the ACE satellite has detected frequent intervals in the slow solar wind and interplanetary coronal mass ejections in which C6+ and other fully stripped ions are strongly depleted, though the ionization states of elements such as Si and Fe indicate that those ions should be present. It has been suggested that these "outlier" or "dropout" events can be explained by the resonant cyclotron heating process, because these ions all have the same cyclotron frequency as He2+. We investigate the region in the corona where these outlier events form. It must be above the ionization freeze-in height and the transition to collisionless plasma conditions, but low enough that the wind still feels the effects of solar gravity. We suggest that the dropout events correspond to relatively dense blobs of gas in which the heating is reduced because local variations in the Alfvén speed change the reflection of Alfvén waves and the turbulent cascade. As a result, the wave power at the cyclotron frequency of the fully stripped ions is absorbed by He2+ and may not be able to heat the other fully stripped ions enough to overcome solar gravity. If this picture is borne out, it may help to discriminate between resonant cyclotron heating and stochastic heating models of the solar wind.

Keywords: Slow solar wind, Solar magnetic reconnection, Alfven waves, Solar coronal mass ejections, Ionization
DRAFT: A Method for Wave Analyses in Space Plasmas. In this study, we apply a method for wave analyses in space plasmas, to better understand the nature of plasma waves and turbulence. Such a method is based on four-spacecraft measurements of magnetic fields or electric fields; it calculates the phase velocity of each single-frequency wave by using the timing analysis, then divides the wave frequency by the phase velocity to obtain the wavevector, and finally solves the dispersion relation (ω-k relation) by considering all frequency channels, and thus is termed Dispersion RelAtion From Timing (DRAFT). Quantitatively, we define three parameters, match of amplitude (MOA), ratio of half-wavelength to spacecraft separation (λ/2R sc), and correlation coefficient (CC), to judge the reliability of this method. We illustrate the usage of this method and validate the efficiency of the three parameters by analyzing the Magnetospheric Multiscale data. We find that the DRAFT results are generally accurate under conditions MOA &gt; 0.5, λ/2R sc &gt; 1, CC &gt; 0.8. As a support, we compare our method with the previous methods such as Means and singular value decomposition (SVD). We find that if the three criteria (MOA, λ/2R sc, CC) are satisfied, the DRAFT, Means, and SVD are consistent in resolving the wave normal angle. Such a comparison robustly validates the reliability and rationality of the DRAFT method. Using DRAFT, we successfully solve the dispersion relation of an Alfvén wave in Earth's magnetosheath and obtain its three-dimensional K -spectrum. Our method should be useful to study the low-frequency waves and weak turbulence in space plasmas.

Keywords: Space plasmas, Astronomical techniques, Alfven waves, Astronomy data analysis
Modeling the Hα and He 10830 Transmission Spectrum of WASP-52b. Escaping atmosphere has been detected by the excess absorption of Lyα, Hα and He triplet (λ10830) lines. Simultaneously modeling the absorption of the Hα and He λ10830 lines can provide useful constraints about the exoplanetary atmosphere. In this paper, we use a hydrodynamic model combined with a non-local thermodynamic model and a new Monte Carlo simulation model to obtain the H(2) and He(23 S) populations. The Monte Carlo simulations of Lyα radiative transfer are performed with assumptions of a spherical stellar Lyα radiation and a spherical planetary atmosphere, for the first time, to calculate the Lyα mean intensity distribution inside the planetary atmosphere, necessary in estimating the H(2) population. We model the transmission spectra of the Hα and He λ10830 lines simultaneously in hot Jupiter WASP-52b. We find that models with many different H/He ratios can reproduce the Hα observations well if the host star has (1) a high X-ray and extreme-ultraviolet (XUV) flux (F XUV) and a relatively low X-ray fraction in XUV radiation (β  m ) or (2) a low F XUV and a high β  m . The simulations of the He λ10830 triplet suggest that a high H/He ratio (~98/2) is required to fit the observation. The models that fit both lines well confine F XUV to be about 0.5 times the fiducial value and β  m  to have a value around 0.3. The models also suggest that hydrogen and helium originate from the escaping atmosphere, and the mass-loss rate is about 2.8 × 1011 g s-1.

Keywords: Hydrodynamical simulations, Radiative transfer simulations, Exoplanet atmospheres
Lyα Emitting Galaxies (LAEs) at Cosmic Dawn: Implications and Predictions. The detection of Lyα emitting galaxies (LAEs) puts severe constraints on the reionization history. In this paper, we derive the properties of very high-z LAEs predicted in the only two reionization scenarios shown in a previous paper to be consistent with the current data on 15 independent evolving global (or averaged) cosmic properties regarding luminous objects and the intergalactic medium and the optical depth to electron scattering of ionized hydrogen to cosmic microwave background photons: one with a monotonic behavior, which is completed by z = 6, as commonly considered, and another one with a nonmonotonic behavior with two full ionization events at z = 6 and z = 10. We find that the Lyα luminosity functions of very high-z LAEs are very distinct in those two scenarios. Thus, comparing these predictions to the observations that will soon be available thanks to new instruments such as the James Webb Space Telescope, it should be possible to unveil the right reionization scenario. In the meantime, we can compare the predicted redshift distribution and UV (or Lyα) luminosities of very high-z LAEs to those of the few objects already observed at z &gt; 7.5. By doing that, we find that such data are in tension with the single reionization scenario, while they are fully compatible with the double reionization scenario.

Keywords: Galaxy abundances, Galaxy evolution, Intergalactic medium, Lyman-alpha galaxies, Reionization
Spinning Nanoparticles Impacted by C-shock: Implications for Radio-millimeter Emission from Star-forming Regions. We investigate the impact of anomalous microwave emission (AME) on the radio-millimeter spectral energy distribution for three typical interstellar medium (ISM) conditions surrounding star-forming regions-cold neutral medium, warm neutral medium, and photodissociation regions-by comparing the emissivities of three major contributors: free-free, thermal dust emission, and AME. In particular, for spinning nanoparticles (i.e., potential carriers of AME), we consider a known grain destruction mechanism due to a centrifugal force from spin-up processes caused by collisions between dust grains and supersonic neutral streams in a magnetized shock (C-shock). We demonstrate that, if the ISM in a magnetic field is impacted by a C-shock developed by a supernova explosion in the early phase of massive star formation (≲10 Myr), AME can be significantly or almost entirely suppressed relative to free-free and thermal dust continuum emission if the grain tensile strength is small enough. This study may shed light on explaining the rare observations of AME from extragalactic star-forming regions preferentially observed from massive star clusters and suggest a scenario of "the rise and fall of AME" in accordance with the temporal evolution of star-forming regions.

Keywords: Interstellar dust, Millimeter astronomy, Interstellar dust processes, Star forming regions, Astrophysical dust processes, Interstellar medium, Radiative processes, Radio astronomy
On the Rotation Curve of Disk Galaxies in General Relativity. Recently, it has been suggested that the phenomenology of flat rotation curves observed at large radii in the equatorial plane of disk galaxies can be explained as a manifestation of general relativity (GR) instead of the effect of dark matter (DM) halos. In this paper, by using the well-known weak-field, low-velocity gravitomagnetic formulation of GR, the expected rotation curves in GR are rigorously obtained for purely baryonic disk models with realistic density profiles and compared with the predictions of Newtonian gravity for the same disks in absence of DM. As expected, the resulting rotation curves are indistinguishable, with GR corrections at all radii of the order v 2/c 2 ≈ 10-6. Next, the gravitomagnetic Jeans equations for two-integral stellar systems are derived, and then solved for the Miyamoto-Nagai disk model, showing that finite-thickness effects do not change the previous conclusions. Therefore, the observed phenomenology of galactic rotation curves at large radii requires DM in GR exactly as in Newtonian gravity, unless the cases here explored are reconsidered in the full GR framework with substantially different results (with the surprising consequence that the weak-field approximation of GR cannot be applied to the study of rotating systems in the weak-field regime). In this article, the mathematical framework is described in detail, so that the present study can be extended to other disk models, or to elliptical galaxies (where DM is also required in Newtonian gravity, but their rotational support can be much less than in disk galaxies).

Keywords: Galaxy dark matter halos, Galaxy rotation curves, General relativity