adsabs/SciX_UAT_keywords huggingface dataset:
High-resolution Pan-STARRS and SMA Observations of IRAS 23077+6707: A Giant Edge-on Protoplanetary Disk

We present resolved images of IRAS 23077+6707 ("Dracula's Chivito") in 1.3 mm/225 GHz thermal dust and CO gas emission with the Submillimeter Array (SMA) and optical (0.5–0.8 μm) scattered light with the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS). The Pan-STARRS data show a bipolar distribution of optically scattering dust that is characteristic for disks observed at high inclinations. Its scattered light emission spans ∼14″, with two highly asymmetric filaments extending along the upper bounds of each nebula by ∼9″. The SMA data measure 1.3 mm continuum dust as well as 12CO, 13CO, and C18O J = 2 ‑ 1 line emission over 12″–14″ extents, with the gas presenting the typical morphology of a disk in Keplerian rotation, in both position–velocity space and in each CO line spectrum. IRAS 23077+6707 has no reported distance estimate, but if it is located in the Cepheus star-forming region (180–800 pc), it would have a radius spanning thousands of astronomical units. Taken together, we infer IRAS 23077+6707 to be a giant and gas-rich edge-on protoplanetary disk, which to our knowledge is the largest in extent so far discovered.

Keywords: protoplanetary disks; herbig ae/be stars; submillimeter astronomy; astrochemistry; young stellar objects; pre-main sequence stars
Rotation of Polarization Angle in Gamma-Ray Burst Prompt Phase

The rotations of the polarization angle (PA) with time (energy) can lead to the depolarization of the time-integrated (energy-integrated) polarization. However, we do not know how and when it will rotate. Here, we consider a magnetic reconnection model to investigate the polarizations, especially the PA rotations of gamma-ray burst (GRB) prompt emission. For a large-scale ordered aligned magnetic field configuration, we find that within T 50 PAs will rotate with time (energy) for slight off-axis observations. Our studies show that the rotations of the PAs are due to changes in the observed image of the emitting region before being averaged over the equal arrival time surface for the unresolved sources. We apply our model to the single-pulse bursts of GRB 170101A and GRB 170114A with time-resolved PA observations. We find it can interpret the violent PA variation of GRB 170101A, while the model could not predict the two 90° PA changes in GRB 170114A. A more detailed model should be considered.

Keywords: gamma-ray bursts; magnetic fields
The Quijote Simulations

The QUIJOTE simulations are a set of 44,100 full N-body simulations spanning more than 7000 cosmological models in the $\{{{\rm{\Omega }}}_{{\rm{m}}},{{\rm{\Omega }}}_{{\rm{b}}},h,{n}_{s},{\sigma }_{8},{M}_{\nu },w\}$ hyperplane. At a single redshift, the simulations contain more than 8.5 trillion particles over a combined volume of 44,100 ${\left({h}^{-1}\mathrm{Gpc}\right)}^{3};$ each simulation follows the evolution of 2563, 5123, or 10243 particles in a box of 1 h-1 Gpc length. Billions of dark matter halos and cosmic voids have been identified in the simulations, whose runs required more than 35 million core hours. The QUIJOTE simulations have been designed for two main purposes: (1) to quantify the information content on cosmological observables and (2) to provide enough data to train machine-learning algorithms. In this paper, we describe the simulations and show a few of their applications. We also release the petabyte of data generated, comprising hundreds of thousands of simulation snapshots at multiple redshifts; halo and void catalogs; and millions of summary statistics, such as power spectra, bispectra, correlation functions, marked power spectra, and estimated probability density functions.

Keywords: n-body simulations; cosmological parameters; astrostatistics; large-scale structure of the universe; cosmological neutrinos
FAUST. VII. Detection of a Hot Corino in the Prototypical Warm Carbon-chain Chemistry Source IRAS 15398-3359

We have observed the low-mass protostellar source IRAS 15398-3359 at a resolution of 0.″2-0.″3, as part of the Atacama Large Millimeter/Submillimeter Array Large Program FAUST, to examine the presence of a hot corino in the vicinity of the protostar. We detect nine CH3OH lines including the high-excitation lines with upper-state energies up to 500 K. The CH3OH rotational temperature and the column density are derived to be ${119}_{-26}^{+20}$ K and ${3.2}_{-1.0}^{+2.5}\times {10}^{18}$ cm-2, respectively. The beam filling factor is derived to be ${0.018}_{-0.003}^{+0.005}$ , indicating that the emitting region of CH3OH is much smaller than the synthesized beam size and is not resolved. The emitting region of three high-excitation lines, 183,15-182,16, A (E u = 447 K), 193,16-192,17, A (E u = 491 K), and 203,17-202,18, A (E u = 537 K), is located within the 50 au area around the protostar and seems to have a slight extension toward the northwest. Toward the continuum peak, we also detect one emission line from CH2DOH and two features of multiple CH3OCHO lines. These results, in combination with previous reports, indicate that IRAS 15398-3359 is a source with hybrid properties showing both hot corino chemistry rich in complex organic molecules on small scales (~10 au) and warm carbon-chain chemistry rich in carbon-chain species on large scales (~100-1000 au). A possible implication of the small emitting region is further discussed in relation to the origin of the hot corino activity.

Keywords: interstellar molecules; protostars; astrochemistry; radio astrometry; star formation
The Redshift Evolution of Ultraluminous X-Ray Sources out to z 0.5: Comparison with X-Ray Binary Populations and Contribution to the Cosmic X-Ray Background

Ultraluminous X-ray sources (ULXs) are thought to be powerful X-ray binaries (XRBs) and may contribute significantly to the redshift-dependent X-ray emission from star-forming galaxies. We have assembled a uniform sample of 259 ULXs over the redshift range z = 0.002-0.51 to constrain their physical nature and their contribution to the cosmic X-ray background. The sample is constructed by crossmatching galaxies from the Sloan Digital Sky Survey with the Chandra Source Catalog and selecting off-nuclear X-ray sources after applying astrometric corrections. The fraction of contaminants is ~30% and shows no evolution with redshift. The host-galaxy star formation rates (SFRs) are systematically elevated relative to the parent sample when matched in host stellar mass. The specific SFRs suggest a slight preference for high-mass XRBs, and the X-ray luminosity scaling relations with host-galaxy stellar mass and SFR indicate that the highest-redshift sources represent relatively luminous XRB populations that dominate their host-galaxy X-ray emission. The fraction of galaxies hosting at least one ULX of a given luminosity increases with redshift over the full range of our sample, as expected if ULXs are preferentially found in galaxies with high SFRs and low metallicities. At z ~ 0.5, the ULX X-ray flux is consistent with the X-ray emission from star-forming galaxies. Moreover, ULXs may account for up to ~40% of the integrated flux from XRBs in the normal galaxy population out to z ~ 0.5, suggesting they may contribute significantly to the overall ionizing radiation from galaxies.

Keywords: x-ray binary stars; star formation; neutron stars; stellar mass black holes; metallicity; ultraluminous x-ray sources; x-ray sources
The Peculiar Ca-rich SN2019ehk: Evidence for a Type IIb Core-collapse Supernova from a Low-mass Stripped Progenitor

The nature of the peculiar "Ca-rich" SN 2019ehk in the nearby galaxy M100 remains unclear. Its origin has been debated as either a stripped core-collapse supernova or a thermonuclear helium detonation event. Here, we present very late-time photometry of the transient obtained with the Keck I telescope at ≈280 days from peak light. Using the photometry to perform accurate flux calibration of a contemporaneous nebular phase spectrum, we measure an [O I] luminosity of (0.19-1.08) × 1038 erg s-1 and [Ca II] luminosity of (2.7-15.6) × 1038 erg s-1 over the range of the uncertain extinction along the line of sight and distance to the host galaxy. We use these measurements to derive lower limits on the synthesized oxygen mass of ≈0.004-0.069 M⊙. The oxygen mass is a sensitive tracer of the progenitor mass for core-collapse supernovae, and our estimate is consistent with explosions of very low-mass CO cores of 1.45-1.5 M⊙, corresponding to He core masses of ≈1.8-2.0 M⊙. We present high-quality peak light optical spectra of the transient and highlight features of hydrogen in both the early ("flash") and photospheric phase spectra that suggest the presence of ≳0.02 M⊙ of hydrogen in the progenitor at the time of explosion. The presence of H, together with the large [Ca II]/[O I] ratio (≈10-15) in the nebular phase, is consistent with SN 2019ehk being a Type IIb core-collapse supernova from a stripped low-mass (≈9-9.5 M⊙) progenitor, similar to the Ca-rich SN IIb iPTF 15eqv. These results provide evidence for a likely class of "Ca-rich" core-collapse supernovae from stripped low-mass progenitors in star-forming environments, distinct from the thermonuclear Ca-rich gap transients in old environments.

Keywords: core-collapse supernovae; oxygen burning; nucleosynthesis; massive stars
Influence of Large-scale Field Structures on the Scaling Anisotropy in 3D MHD Turbulence

Magnetohydrodynamic (MHD) turbulence is revealed to have scaling anisotropy based on structure function calculations. Recent studies on solar wind turbulence found that the scaling anisotropy disappears when removing large-scale field structures. This finding raises questions as to whether numerical MHD turbulences have large-scale field structures. How do these structures affect the scaling anisotropy therein? Here we investigate these questions with a driven compressible three-dimensional MHD turbulence. We introduce a new method to check how the random stationarity condition is satisfied. We find for the first time in the numerical MHD turbulence that the large-scale field structures destroy the random stationarity of the local fields and make samplings nonparallel to the instantaneous fields be calculated as apparent parallel samplings. This mixture makes statistical calculations show anisotropic scaling of the turbulence. When we select only the random stationary data intervals, the statistical results show an isotropic nature. We also find that among the large-scale field structures, one-third are tangential discontinuities (TDs), one-third are rotational discontinuities (RDs), and the rest are EDs (either TD or RD). These results show that the large-scale structures in the numerical MHD turbulence have important influence on the structure function analysis.

Keywords: solar wind; interplanetary turbulence; magnetohydrodynamical simulations
Implications of a Temperature-dependent Initial Mass Function. III. Mass Growth and Quiescence

The stellar initial mass function (IMF) is predicted to depend upon the temperature of gas in star-forming molecular clouds. The introduction of an additional parameter, T IMF, into photometric template fitting suggests most galaxies obey an IMF top heavier than the Galactic IMF. The implications of the revised fit on mass function, quiescence, and turnoff are discussed. At all redshifts, the highest-mass galaxies become quiescent first with the turnoff mass decreasing toward the present. The synchronous turnoff mass across galaxies suggests quiescence is driven by universal mechanisms rather than by stochastic or environmental processes.

Keywords: galaxy evolution; initial mass function; star formation; galaxy quenching; stellar mass functions
Morphological Evolution of the Hosts of Far-infrared/Submillimeter Galaxies

We present a host morphological study of 1266 far-infrared galaxies (FIRGs) and submillimeter galaxies (SMGs) in the Cosmic Evolution Survey field using the F160W and F814W images obtained by the Hubble Space Telescope. The FIRGs and SMGs are selected from the Herschel Multi-tiered Extragalactic Survey and the SCUBA-2 Cosmology Legacy Survey, respectively. Their precise locations are based on the interferometry data from the Atacama Large Millimeter/submillimeter Array and the Very Large Array. These objects are mostly at 0.1 ≲ z ≲ 3. The SMGs can be regarded as the population at the high-redshift tail of the FIRGs. Most of our FIRGs/SMGs have a total infrared luminosity (L IR) in the regimes of luminous and ultraluminous infrared galaxies (LIRGs, L IR = 1011-12 L ⊙; ULIRGs, L IR > 1012 L ⊙). The hosts of the SMG ULIRGs, FIRG ULIRGs, and FIRG LIRGs are of sufficient numbers to allow for detailed analysis, and they are only modestly different in their stellar masses. Their morphological types are predominantly disk galaxies (type D) and irregular/interacting systems (type Irr/Int). There is a morphological transition at z ≈ 1.25 for the FIRG ULIRG hosts, above which the Irr/Int galaxies dominate and below which the D and Irr/Int galaxies have nearly the same contributions. The SMG ULIRG hosts seem to experience a similar transition. This suggests a shift in the relative importance of galaxy mergers/interactions versus secular gas accretions in "normal" disk galaxies as the possible triggering mechanisms of ULIRGs. The FIRG LIRG hosts are predominantly D galaxies over z = 0.25-1.25, where they are of sufficient statistics.

Keywords: galaxies; infrared galaxies; submillimeter astronomy; star formation; far infrared astronomy; galaxy classification systems; interferometry
Modeling Radial Velocity Data of Resonant Planets to Infer Migration Histories

A number of giant-planet pairs with period ratios ≲2 discovered by the radial velocity (RV) method may reside in mean motion resonances. Convergent orbital migration and resonant capture at the time of formation would naturally explain the present-day resonant orbital configurations of these systems. Planets that experience smooth migration and eccentricity-damping forces due to a protoplanetary disk should not only be captured into mean motion resonances but also end up in a specific dynamical configuration within the resonance, sometimes referred to as apsidal corotation resonance (ACR). Here we develop a method for testing the hypothesis that a planet pair resides in an ACR by directly fitting RV data. The ACR hypothesis strongly restricts the number of free parameters describing the RV signal, and we compare fits using this highly restricted model to fits using a more conventional two-planet RV model by using nested sampling simulations. We apply our method to HD 45364 and HD 33844, two systems hosting giant-planet pairs in 3:2 and 5:3 resonances, respectively. The observations of both systems are consistent with ACR configurations, which are formally preferred based on the Bayes factors computed from nested sampling simulations. We use the results of our ACR model fits to constrain the possible migration histories of these systems.

Keywords: orbital resonances; radial velocity; exoplanet dynamics
IceCube Search for High-energy Neutrino Emission from TeV Pulsar Wind Nebulae

Pulsar wind nebulae (PWNe) are the main gamma-ray emitters in the Galactic plane. They are diffuse nebulae that emit nonthermal radiation. Pulsar winds, relativistic magnetized outflows from the central star, shocked in the ambient medium produce a multiwavelength emission from the radio through gamma-rays. Although the leptonic scenario is able to explain most PWNe emission, a hadronic contribution cannot be excluded. A possible hadronic contribution to the high-energy gamma-ray emission inevitably leads to the production of neutrinos. Using 9.5 yr of all-sky IceCube data, we report results from a stacking analysis to search for neutrino emission from 35 PWNe that are high-energy gamma-ray emitters. In the absence of any significant correlation, we set upper limits on the total neutrino emission from those PWNe and constraints on hadronic spectral components.

Keywords: neutrino astronomy; high energy astrophysics
Constraining the Milky Way Halo Kinematics via Its Linear Response to the Large Magellanic Cloud

We model the response of spherical, nonrotating Milky Way (MW) dark matter and stellar halos to the Large Magellanic Cloud using the matrix method of linear response theory. Our computations reproduce the main features of the dark halo response from simulations. We show that these features can be well separated by a harmonic decomposition: the large-scale over/underdensity in the halo (associated with its reflex motion) corresponds to the ℓ = 1 terms, and the local overdensity to the ℓ ≥ 2 multipoles. Moreover, the dark halo response is largely dominated by the first-order forcing term, with little influence from self-gravity. This makes it difficult to constrain the underlying velocity distribution of the dark halo using the observed response of the stellar halo, but it allows us to investigate the response of stellar halo models with various velocity anisotropies: a tangential (respectively radial) halo produces a shallower (respectively stronger) response. We also show that only the local wake is responsible for these variations, the reflex motion being solely dependent on the MW potential. Therefore, we identify the structure (orientation and winding) of the in-plane quadrupolar (m = 2) response as a potentially good probe of the stellar halo anisotropy. Finally, our method allows us to tentatively relate the wake strength and shape to resonant effects: the strong radial response could be associated with the inner Lindblad resonance, and the weak tangential one with corotation.

Keywords: milky way dark matter halo; milky way stellar halo; milky way dynamics; analytical mathematics; perturbation methods
An Analysis of the Shapes of Interstellar Extinction Curves. VIII. The Optical Extinction Structure

New Hubble Space Telescope/STIS optical spectra were obtained for a sample of early-type stars with existing International Ultraviolet Explorer UV spectra. These data were used to construct optical extinction curves whose general properties are discussed elsewhere. In this paper, we identify extinction features in the curves that are wider than diffuse interstellar bands (DIBs) but narrower than the well known broadband variability. This intermediate scale structure, or ISS, contains distinct features whose peaks can contribute a few percent to 20% of the total extinction. Most of the ISS variation can be captured by three principal components. We model the ISS with three Drude profiles and show that their strengths and widths vary from one sight line to another, but their central positions are stable, near 4370, 4870, and 6300 Å. The very broad structure (VBS) in optical curves appears to be a minimum between the 4870 and 6300 Å absorption peaks. We find relations among the fit parameters and provide a physical interpretation of them in terms of a simplistic grain model. Finally, we note that the strengths of the 4370 and 4870 Å features are correlated to the strength of the 2175 Å UV bump, but that the 6300 Å feature is not, and that none of the ISS features are related to R(V). However, we verify that the broadband curvature of the continuous optical extinction is strongly related to R(V).

Keywords: interstellar dust; interstellar dust extinction
Infrared Spectroscopy of YZ Reticuli (Nova Reticuli 2020)

IR spectroscopy from three epochs is presented for the very bright, X-ray nova YZ Reticuli (Nova Reticuli 2020). The first spectrum, from 2.5 months after outburst, shows a nova well into the coronal phase, with strong lines of [Si VI] and [Si VII], and with little or no interstellar reddening, and no dust emission. The second spectrum, from one month later, shows a four-fold drop in brightness and a measurable increase in the coronal lines relative to the lower excitation features. The final spectrum, from 7 months post outburst, is a factor of six fainter and shows a decrease in the relative strength of the coronal lines from the previous epoch. Emission lines from O I and [N I] are present at all epochs, indicating the persistence of a region of largely neutral gas in this otherwise high excitation object.

Keywords: novae
Energy Deposition into the Ionosphere during a Solar Flare with Extreme-ultraviolet Late Phase

Solar extreme-ultraviolet (EUV) irradiance is the dominant energy source for ionizing and heating the Earth's upper atmosphere. It is common to assume that the spectra of different EUV lines have the same trend to fill the solar EUV irradiance gap for modeling purposes due to inadequate EUV irradiance measurements. However, the spectra across the EUV bands may not vary in the same trend. The flare radiation energy release in the EUV (10–120 nm) is about twice as much as X-rays (0.1–10 nm) during flare interval ∼03–06 UT on 2012 October 23. By assimilating the observed nonuniform varying, time-dependent, and high-resolution solar spectrum from the Solar Dynamics Observatory mission into the modeling framework, we provide the first direct evidence of nonuniform varying solar EUV fluxes during the solar flare EUV late phase (ELP) having appreciable effects on the dayside ionosphere. The total EUV radiation energy release (5.838 × 1028 erg) during the flare ELP is larger than that (5.698 × 1028 erg) during the flare main phase. The ELP of an X1.8-class solar flare on 2012 October 23 can increase the dayside ionospheric density at the subsolar point by ∼5 TECU and the ionospheric density enhancements extend from the bottom to the peak of the F2 region at low latitudes with relative changes ranging from ∼20% to ∼100%. Our results highlight the importance of incorporating a realistic, high spectral and temporal resolution solar irradiance spectrum into numerical models to capture the observed time-varying ionospheric response to solar flares.

Keywords: solar flares; solar flare spectra; earth ionosphere
Inferring the Rate of Technosignatures from 60 yr of Nondetection

For about the last 60 yr the search for extraterrestrial intelligence has been monitoring the sky for evidence of remotely detectable technological life beyond Earth, with no positive results to date. While the lack of detection can be attributed to the highly incomplete sampling of the search space, technological emissions may be actually rare enough that we are living in a time when none cross the Earth. Here we explore the latter possibility and derive the likelihood of the Earth not being crossed by signals for at least the last 60 yr to infer upper bounds on their rate of emission. Under the assumption that technological emitters are distributed uniformly in the Milky Way and that they generate technoemissions at a constant rate, we find less than about one to five emissions generated per century with 95% credible level. This implies optimistic waiting times until the next crossing event of no less than 60-1800 yr with a 50% probability. A significant fraction of highly directional signals increases the emission rates' upper bounds, but without systematically changing the waiting time. Although these probabilistic bounds are derived from a specific model and their validity depends on the model's assumptions, they are nevertheless quite robust against weak time dependences of the emission rate or nonuniform spatial distributions of the emitters. Our results provide therefore a benchmark for assessing the lack of detection and may serve as a basis to form optimal strategies for the search for extraterrestrial intelligence.

Keywords: search for extraterrestrial intelligence; astrobiology; technosignatures