adsabs/SciX_UAT_keywords huggingface dataset:
Illuminating the Dark Side of Cosmic Star Formation. III. Building the Largest Homogeneous Sample of Radio-selected Dusty Star-forming Galaxies in COSMOS with PhoEBO

In the last decades, an increasing scientific interest has been growing in the elusive population of dark (i.e., lacking an optical/near-IR, hereafter NIR, counterpart) dusty star-forming galaxies (DSFGs). Although extremely promising for their likely contribution to the cosmic star formation rate density (SFRD) and for their possible role in the evolution of the first massive and passive galaxies around z ∼ 3, the difficulty in selecting statistically significant samples of dark DSFGs is limiting their scientific potentialities. This work presents the first panchromatic study of a sample of 263 radio-selected NIR-dark (RS-NIRdark) galaxies discovered in the COSMOS field following the procedure by Talia et al. These sources are selected as radio-bright galaxies (S 3 GHz > 12.65 μJy) with no counterpart in the NIR-selected COSMOS2020 catalog (Ks ≳ 25.5 mag). For these sources, we build a new photometric catalog including accurate photometry from the optical to the radio obtained with a new deblending pipeline (Photometry Extractor for Blended Objects, or PHOEBO). We employ this catalog to estimate the photo-zs and the physical properties of the galaxies through an spectral energy distribution-fitting procedure performed with two different codes (MAGPHYS and CIGALE). Finally, we estimate the active galactic nucleus contamination in our sample by performing a series of complementary tests. The high values of the median extinction (A v ∼ 4) and star formation rate (SFR ∼ 500 M ⊙ yr‑1) confirm the likely DSFG nature of the RS-NIRdark galaxies. The median photo-z (z ∼ 3) and the presence of a significant tail of high-z candidates (z > 4.5) suggest that these sources are important contributors to the cosmic SFRD and the evolutionary path of galaxies at high redshifts.

Keywords: extragalactic radio sources; galaxy evolution; galaxy formation; high-redshift galaxies; star formation
Spectral Variability of the Blazar 3C 279 in the Optical to X-Ray Band during 2009-2018

We report on the spectral variability of the blazar 3C 279 in the optical to X-ray band between MJD 55100 and 58400 during which long-term radio variability was observed. We construct light curves and band spectra in each of the optical (2 × 1014-1.5 × 1015 Hz) and X-ray (0.3-10 keV) bands, measure the spectral parameters (flux F and spectral index α), and investigate the correlation between F and α within and across the bands. We find that the correlation of the optical properties dramatically change after ∼MJD 55500 and the light curves show more frequent activity after ∼MJD 57700. We therefore divide the time interval into three "states" based on the correlation properties and source activity in the light curves, and analyze each of the three states separately. We find various correlations between the spectral parameters in the states and an intriguing 65 day delay of the optical emission with respect to the X-ray one in state 2 (MJD 55500-57700). We attempt to explain these findings using a one-zone synchro-Compton emission scenario.

Keywords: active galactic nuclei; high energy astrophysics; blazars; spectral energy distribution
Estimating the Temperature and Density of a Spicule from 100 GHz Data Obtained with ALMA

We succeeded in observing two large spicules simultaneously with the Atacama Large Millimeter/submillimeter Array (ALMA), the Interface Region Imaging Spectrograph (IRIS), and the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory. One is a spicule seen in the IRIS Mg II slit-jaw images and AIA 304 Å images (Mg II/304 Å spicule). The other one is a spicule seen in the 100 GHz images obtained with ALMA (100 GHz spicule). Although the 100 GHz spicule overlapped with the Mg II/304 Å spicule in the early phase, it did not show any corresponding structures in the IRIS Mg II and AIA 304 Å images after the early phase. It suggests that the spicules are individual events and do not have a physical relationship. To obtain the physical parameters of the 100 GHz spicule, we estimate the optical depths as a function of temperature and density using two different methods. One is using the observed brightness temperature by assuming a filling factor, and the other is using an emission model for the optical depth. As a result of comparing them, the kinetic temperature of the plasma and the number density of ionized hydrogen in the 100 GHz spicule are ∼6800 K and 2.2 × 1010 cm-3. The estimated values can explain the absorbing structure in the 193 Å image, which appear as a counterpart of the 100 GHz spicule. These results suggest that the 100 GHz spicule presented in this Letter is classified to a macrospicule without a hot sheath in former terminology.

Keywords: the sun; solar chromosphere; solar radio emission; solar spicules; solar ultraviolet emission
Full Transport General Relativistic Radiation Magnetohydrodynamics for Nucleosynthesis in Collapsars

We model a compact black hole-accretion disk system in the collapsar scenario with full transport, frequency dependent, general relativistic radiation magnetohydrodynamics. We examine whether or not winds from a collapsar disk can undergo rapid neutron capture (r-process) nucleosynthesis and significantly contribute to solar r-process abundances. We find the inclusion of accurate transport has significant effects on outflows, raising the electron fraction above ${Y}_{{\rm{e}}}\sim 0.3$ and preventing third-peak r-process material from being synthesized. We analyze the time evolution of neutrino processes and electron fraction in the disk and present a simple one-dimensional model for the vertical structure that emerges. We compare our simulation to semi-analytic expectations and argue that accurate neutrino transport and realistic initial and boundary conditions are required to capture the dynamics and nucleosynthetic outcome of a collapsar.

Keywords: gamma-ray sources; astrophysical black holes; r-process; supernova neutrinos; relativistic disks; relativistic fluid dynamics; core-collapse supernovae
A General, Scale-independent Description of the Sound Speed in Neutron Stars

Using more than a million randomly generated equations of state that satisfy theoretical and observational constraints, we construct a novel, scale-independent description of the sound speed in neutron stars, where the latter is expressed in a unit cube spanning the normalized radius, r/R, and the mass normalized to the maximum one, M/M TOV. From this generic representation, a number of interesting and surprising results can be deduced. In particular, we find that light (heavy) stars have stiff (soft) cores and soft (stiff) outer layers, or that the maximum of the sound speed is located at the center of light stars but moves to the outer layers for stars with M/M TOV ≳ 0.7, reaching a constant value of ${c}_{s}^{2}\,=\,1/2$ as M → M TOV. We also show that the sound speed decreases below the conformal limit ${c}_{s}^{2}\,=\,1/3$ at the center of stars with M = M TOV. Finally, we construct an analytic expression that accurately describes the radial dependence of the sound speed as a function of the neutron-star mass, thus providing an estimate of the maximum sound speed expected in a neutron star.

Keywords: gravitation; fundamental parameters of stars; nuclear astrophysics; neutron stars; nuclear physics
Evolution of Planetary Obliquity: The Eccentric Kozai-Lidov Mechanism Coupled with Tide

Planetary obliquity plays a significant role in determining the physical properties of planetary surfaces and climate. As direct detection is constrained due to the present observation accuracy, kinetic theories are helpful for predicting the evolution of planetary obliquity. Here the coupling effect between the eccentric Kozai-Lidov effect and the equilibrium tide is extensively investigated; the planetary obliquity is observed to follow two kinds of secular evolution paths, based on the conservation of total angular momentum. The equilibrium timescale of the planetary obliquity t eq varies along with r t , which is defined as the initial timescale ratio of the tidal dissipation and secular perturbation. We numerically derive the linear relationship between t eq and r t with the maximum likelihood method. The spin-axis orientation of S-type terrestrials orbiting M-dwarfs reverses over 90° when r t > 100, then enters the quasi-equilibrium state between 40° and 60°, while the maximum obliquity can reach 130° when r t > 104. Numerical simulations show that the maximum obliquity increases with the semimajor axis ratio a 1/a 2, but is not so sensitive to the eccentricity e 2. The likelihood of an obliquity flip for S-type terrestrials in general systems with a 2 < 45 au is closely related to m 1. The observed potentially oblique S-type planets HD 42936 b, GJ 86 Ab, and τ Boo Ab are explored and found to have a great possibility of rotating head-down over the secular evolution of spin.

Keywords: exoplanet evolution; exoplanet dynamics
FRB 200428: An Impact between an Asteroid and a Magnetar

A fast radio burst (FRB) was recently detected to be associated with a hard X-ray burst from the Galactic magnetar SGR 1935+2154. Scenarios involving magnetars for FRBs are hence highly favored. In this work, we suggest that the impact between an asteroid and a magnetar could explain such a detection. According to our calculations, an asteroid of mass 1020 g will be disrupted at a distance of 7 × 109 cm when approaching the magnetar. The accreted material will flow along the magnetic field lines from the Alfvén radius ∼107 cm. After falling onto the magnetar's surface, an instant accretion column will be formed, producing a Comptonized X-ray burst and an FRB in the magnetosphere. We show that all the observational features of FRB 200428 could be interpreted self-consistently in this scenario. We predict quasi-periodic oscillations in this specific X-ray burst, which can serve as an independent observational test.

Keywords: minor planets; pulsars; radio pulsars; magnetars; soft gamma-ray repeaters; astronomical radiation sources; burst astrophysics; non-thermal radiation sources; neutron stars; radio bursts
A Solar Coronal Hole and Fast Solar Wind Turbulence Model and First-orbit Parker Solar Probe (PSP) Observations

We propose a turbulence-driven solar wind model for a fast solar wind flow in an open coronal hole where the solar wind flow and the magnetic field are highly aligned. We compare the numerical results of our model with Parker Solar Probe measurements of the fast solar wind flow and find good agreement between them. We find that (1) the majority quasi-2D turbulence is mainly responsible for coronal heating, raising the temperature to about $\sim {10}^{6}$ K within a few solar radii, which leads in turn to the acceleration of the solar wind; (2) the heating rate due to quasi-2D turbulence near the coronal base is larger than that due to nearly incompressible/slab turbulence; (3) the quasi-2D energy in forward-propagating modes decreases with increasing distance, while the nearly incompressible/slab energy in forward-propagating modes increases, reaching a peak value at ∼11.7 ${R}_{\odot }$ before decreasing with increasing heliocentric distance; (4) the correlation length increases with increasing distance from the coronal base; and (5) the variance of the density fluctuations decreases as a function of heliocentric distance.

Keywords: the sun; solar wind; interplanetary turbulence
Anticipated Geological Assessment of the (65803) Didymos-Dimorphos System, Target of the DART-LICIACube Mission

On 2022 September 26, the DART spacecraft will impact the surface of Dimorphos, the ~160 m size satellite of the binary near-Earth asteroid (NEA) (65803) Didymos. What will be observed on the surfaces of both asteroids and at the DART impact site is largely unknown, beyond the details of Didymos revealed by previous Arecibo and Goldstone radar observations. We present here the expected DART and LICIACube observations of the Didymos system and discuss the planned mapping strategies. By searching similar geological features and processes identified on other NEAs, we constrain the impact conditions that DART might encounter at Dimorphos, assessing both the asteroid's surface and interior structure.

Keywords: asteroids; asteroid surfaces; asteroid satellites
Insight-HXMT, NuSTAR, and INTEGRAL Data Show Disk Truncation in the Hard State of the Black Hole X-Ray Binary MAXI J1820+070

We study X-ray and soft gamma-ray spectra from the hard state of the accreting black hole binary MAXI J1820+070. We perform an analysis of joint spectra from HXMT, NuSTAR, and INTEGRAL. We find an overall agreement between the spectra from all three satellites. Satisfactory fits to the data require substantial spectral complexity, with our models including two Comptonization regions and their associated disk reflection, a disk blackbody, and a narrow Fe Kα line. Our fits confirm the presence of the truncation of the reflecting optically thick disk at least at >10 gravitational radii. However, we find that the HXMT data alone cannot significantly constrain the disk inner radii.

Keywords: galaxy accretion; non-thermal radiation sources; x-ray binary stars; low-mass x-ray binary stars
On the Origin of the Multi-GeV Photons from the Closest Burst with Intermediate Luminosity: GRB 190829A

Very high energy (VHE) emission is usually interpreted in the synchrotron self-Compton scenario and expected from the low-redshift and high-luminosity gamma-ray bursts (GRBs), such as GRB 180720B and GRB 190114C. Recently, the H.E.S.S. telescopes reported VHE emission from one of the closest bursts, GRB 190829A, which was associated with the supernova 2019oyw. In this paper, we present a temporal and spectral analysis from optical bands to the Fermi-LAT energy range over multiple observational periods beginning after the trigger time and extending for almost 3 months. We show that the X-ray and optical observations are consistent with synchrotron forward-shock emission evolving between the characteristic and cooling spectral breaks during the early and late afterglow in a uniform-density medium. Modeling the light curves together with the spectral energy distribution, we show that the outflow expanded with an initial bulk Lorentz factor of Γ ~ 30, which is high for low-luminosity GRBs and low for high-luminosity GRBs. The values of the initial bulk Lorentz factor and the isotropic-equivalent energy suggest that GRB 190829A is an intermediate-luminosity burst; consequently, it becomes the first burst of this class to be detected in the VHE gamma-ray band by an imaging atmospheric Cherenkov telescope and, in turn, the first event to not be simultaneously observed by the Fermi-LAT instrument. Analyzing the intermediate-luminosity bursts with z ≲ 0.2, such as GRB 130702A, we show that bursts with intermediate luminosities are potential candidates to be detected in VHEs.

Keywords: high energy astrophysics
Intrinsic Shapes of Brightest Cluster Galaxies

We discuss the statistical distribution of galaxy shapes and viewing angles under the assumption of triaxiality by deprojecting observed surface brightness profiles of 56 brightest cluster galaxies (BCGs) coming from a recently published large deep-photometry sample. For the first time, we address this issue by directly measuring axis ratio profiles without limiting ourselves to a statistical analysis of average ellipticities. We show that these objects are strongly triaxial, with triaxiality parameters 0.39 ≤ T ≤ 0.72, they have average axis ratios <p(r)> = 0.84 and <q(r)> = 0.68, and they are more spherical in the central regions but flatten out at large radii. Measured shapes in the outskirts agree well with the shapes found for simulated massive galaxies and their dark matter halos from both the IllustrisTNG and the Magneticum simulations, possibly probing the nature of dark matter. In contrast, both simulations fail to reproduce the observed inner regions of BCGs, producing objects that are too flattened.

Keywords: galaxy evolution; galaxy dynamics; magnetohydrodynamical simulations
The Orbit of Planet Nine

The existence of a giant planet beyond Neptune-referred to as Planet Nine (P9)-has been inferred from the clustering of longitude of perihelion and pole position of distant eccentric Kuiper belt objects (KBOs). After updating calculations of observational biases, we find that the clustering remains significant at the 99.6% confidence level. We thus use these observations to determine orbital elements of P9. A suite of numerical simulations shows that the orbital distribution of the distant KBOs is strongly influenced by the mass and orbital elements of P9 and thus can be used to infer these parameters. Combining the biases with these numerical simulations, we calculate likelihood values for discrete set of P9 parameters, which we then use as input into a Gaussian-process emulator that allows a likelihood computation for arbitrary values of all parameters. We use this emulator in a Markov chain Monte Carlo analysis to estimate parameters of P9. We find a P9 mass of ${6.2}_{-1.3}^{+2.2}$ Earth masses, semimajor axis of ${380}_{-80}^{+140}$ au, inclination of 16 ± 5° and perihelion of ${300}_{-60}^{+85}$ au. Using samples of the orbital elements and estimates of the radius and albedo of such a planet, we calculate the probability-distribution function of the on-sky position of Planet Nine and of its brightness. For many reasonable assumptions, Planet Nine is closer and brighter than initially expected, though the probability distribution includes a long tail to larger distances, and uncertainties in the radius and albedo of Planet Nine could yield fainter objects.

Keywords: planetary dynamics; solar system planets; orbit determination
USmorph: An Updated Framework of Automatic Classification of Galaxy Morphologies and Its Application to Galaxies in the COSMOS Field

Morphological classification conveys abundant information on the formation, evolution, and environment of galaxies. In this work, we refine a two-step galaxy morphological classification framework (USmorph), which employs a combination of unsupervised machine-learning and supervised machine-learning techniques, along with a self-consistent and robust data-preprocessing step. The updated method is applied to galaxies with I mag < 25 at 0.2 < z < 1.2 in the COSMOS field. Based on their Hubble Space Telescope/Advanced Camera for Survey I-band images, we classify them into five distinct morphological types: spherical (SPH, 15,200), early-type disk (17,369), late-type disk (21,143), irregular disk (IRR, 28,965), and unclassified (UNC, 17,129). In addition, we have conducted both parametric and nonparametric morphological measurements. For galaxies with stellar masses exceeding 109 M ☉, a gradual increase in effective radius from SPHs to IRRs is observed, accompanied by a decrease in the Sérsic index. Nonparametric morphologies reveal distinct distributions of galaxies across the Gini‑M 20 and C‑A parameter spaces for different categories. Moreover, different categories exhibit significant dissimilarity in their G 2 and Ψ distributions. We find morphology to be strongly correlated with redshift and stellar mass. The consistency of these classification results with expected correlations among multiple parameters underscores the validity and reliability of our classification method, rendering it a valuable tool for future studies.

Keywords: galaxy structure; astrostatistics techniques; astronomy data analysis
A Green Pea Starburst Arising from a Galaxy-Galaxy Merger

Green Pea galaxies are low-redshift starburst dwarf galaxies, with properties similar to those of the high-redshift galaxies that reionized the universe. We report the first mapping of the spatial distribution of atomic hydrogen (HI) in and around a Green Pea, GP J0213+0056 at z = 0.0399, using the Giant Metrewave Radio Telescope (GMRT). Like many Green Peas, GP J0213+0056 shows strong HI 21 cm emission in single-dish spectroscopy, strong Lyα emission, and a high [OIII]λ5007 Å/[OII]λ3727 Å luminosity ratio, O32 ≈ 8.8, consistent with a high leakage of Lyman-continuum radiation. Our GMRT HI 21 cm images show that the HI 21 cm emission in the field of GP J0213+0056 arises from an extended broken-ring structure around the Green Pea, with the strongest emission coming from a region between GP J0213+0056 and a companion galaxy lying ≈4.7 kpc away, and little HI 21 cm emission coming from the Green Pea itself. We find that the merger between GP J0213+0056 and its companion is likely to have triggered the starburst, and led to a disturbed HI spatial and velocity distribution, which in turn allowed Lyα (and, possibly, Lyman-continuum) emission to escape the Green Pea. Our results suggest that such mergers, and the resulting holes in the HI distribution, are a natural way to explain the tension between the requirements of cold gas to fuel the starburst and the observed leakage of Lyα and Lyman-continuum emission in Green Pea galaxies and their high-redshift counterparts.

Keywords: galaxies; h i line emission; radio interferometry; starburst galaxies
SN 2013ai: A Link between Hydrogen-rich and Hydrogen-poor Core-collapse Supernovae

We present a study of the optical and near-infrared (NIR) spectra of SN 2013ai along with its light curves. These data range from discovery until 380 days after explosion. SN 2013ai is a fast declining Type II supernova (SN II) with an unusually long rise time, 18.9 ± 2.7 days in the V-band, and a bright V-band peak absolute magnitude of -18.7 ± 0.06 mag. The spectra are dominated by hydrogen features in the optical and NIR. The spectral features of SN 2013ai are unique in their expansion velocities, which, when compared to large samples of SNe II, are more than 1,000 km s-1 faster at 50 days past explosion. In addition, the long rise time of the light curve more closely resembles SNe IIb rather than SNe II. If SN 2013ai is coeval with a nearby compact cluster, we infer a progenitor zero-age main-sequence mass of ∼17 M⊙. After performing light-curve modeling, we find that SN 2013ai could be the result of the explosion of a star with little hydrogen mass, a large amount of synthesized 56Ni, 0.3-0.4 M⊙, and an explosion energy of 2.5-3.0 × 1051 erg. The density structure and expansion velocities of SN 2013ai are similar to those of the prototypical SN IIb, SN 1993J. However, SN 2013ai shows no strong helium features in the optical, likely due to the presence of a dense core that prevents the majority of γ-rays from escaping to excite helium. Our analysis suggests that SN 2013ai could be a link between SNe II and stripped-envelope SNe.

Keywords: core-collapse supernovae; type ii supernovae; late stellar evolution