Sazuna/UAT_keywords huggingface dataset:
Ultrahigh-energy Cosmic-Ray Interactions as the Origin of Very High-energy γ-Rays from BL Lacertae Objects. We explain the observed multiwavelength photon spectrum of a number of BL Lacertae (BL Lac) objects detected at very high energy (VHE, E ≳ 30 GeV), using a lepto-hadronic emission model. The one-zone leptonic emission is employed to fit the synchrotron peak. Subsequently, the SSC spectrum is calculated, such that it extends up to the highest energy possible for the jet parameters considered. The data points beyond this energy, and also in the entire VHE range are well explained using a hadronic emission model. The ultrahigh-energy cosmic rays (UHECRs, E ≳ 0.1 EeV) escaping from the source interact with the extragalactic background light (EBL) during propagation over cosmological distances to initiate electromagnetic cascade down to ∼1 GeV energies. The resulting photon spectrum peaks at ∼1 TeV energies. We consider a random turbulent extragalactic magnetic field (EGMF) with a Kolmogorov power spectrum to find the survival rate of UHECRs within 0°1 of the direction of propagation in which the observer is situated. We restrict ourselves to an rms value of EGMF, Brms ∼ 10-5 nG, for a significant contribution to the photon spectral energy distribution from UHECR interactions. We found that UHECR interactions on the EBL and secondary cascade emission can fit gamma-ray data from the BL Lac objects we considered at the highest energies. The required luminosity in UHECRs and corresponding jet power are below the Eddington luminosities of the supermassive black holes in these BL Lac objects.

Keywords: High energy astrophysics, Blazars, Relativistic jets, Gamma-rays, Ultra-high-energy cosmic radiation, Extragalactic magnetic fields
Modeling Dust and Starlight in Galaxies Observed by Spitzer and Herschel: The KINGFISH Sample. Interstellar dust and starlight are modeled for the galaxies of the project "Key Insights on Nearby Galaxies: A Far-Infrared Survey with Herschel." The galaxies were observed by the Infrared Array Camera and the Multiband Imaging Photometer for Spitzer on Spitzer Space Telescope, and the Photodetector Array Camera and Spectrometer and the Spectral and Photometric Imaging Receiver on Herschel Space Observatory. With data from 3.6 to 500 μm, dust models are strongly constrained. Using a physical dust model, for each pixel in each galaxy we estimate (1) dust surface density, (2) dust mass fraction in polycyclic aromatic hydrocarbons (PAHs), (3) distribution of starlight intensities heating the dust, (4) total infrared (IR) luminosity emitted by the dust, and (5) IR luminosity originating in subregions with high starlight intensity. The dust models successfully reproduce the observed global and resolved spectral energy distributions. With the angular resolution of Herschel, we obtain well-resolved maps (available online) for the dust properties. As in previous studies, we find the PAH fraction ${q}_{\mathrm{PAH}}$ to be an increasing function of metallicity, with a threshold oxygen abundance Z/Z⊙ ≈ 0.1, but we find the data to be fitted best with ${q}_{\mathrm{PAH}}$ increasing linearly with $\mathrm{log}({\rm{O}}/{\rm{H}})$ above a threshold value of 0.15(O/H)⊙. We obtain total dust masses for each galaxy by summing the dust mass over the individual map pixels; these "resolved" dust masses are consistent with the masses inferred from a model fit to the global photometry. The global dust-to-gas ratios obtained from this study are found to correlate with galaxy metallicities. Systems with Z/Z⊙ ≳ 0.5 have most of their refractory elements locked up in dust, whereas in systems with Z/Z⊙ ≲ 0.3 most of these elements tend to remain in the gas phase. Within galaxies, we find that ${q}_{\mathrm{PAH}}$ is suppressed in regions with unusually warm dust with $\nu {L}_{\nu }(70\ \mu {\rm{m}})\gtrsim 0.4{L}_{\mathrm{dust}}$ . With knowledge of one long-wavelength flux density ratio (e.g., f160/f500), the minimum starlight intensity heating the dust ( ${U}_{\min }$ ) can be estimated to within ∼50%, despite a variation in ${U}_{\min }$ of more than two orders of magnitude. For the adopted dust model, dust masses can be estimated to within ∼0.2 dex accuracy using the f160/f500 flux ratio and the integrated dust luminosity, and to ∼0.07 dex accuracy using the 500 μm luminosity $\nu {L}_{\nu }(500\,\mu {\rm{m}})$ alone. There are additional systematic errors arising from the choice of dust model, but these are hard to estimate. These calibrated prescriptions for estimating starlight heating intensity and dust mass may be useful for studies of high-redshift galaxies.

Keywords: Astrophysical dust processes, Polycyclic aromatic hydrocarbons, Infrared galaxies, Interstellar medium
A Hybrid Deep Learning Approach to Cosmological Constraints from Galaxy Redshift Surveys. We present a deep machine learning (ML)-based technique for accurately determining σ8 and Ωm from mock 3D galaxy surveys. The mock surveys are built from the AbacusCosmos suite of N-body simulations, which comprises 40 cosmological volume simulations spanning a range of cosmological parameter values, and we account for uncertainties in galaxy formation scenarios through the use of generalized halo occupation distributions (HODs). We explore a trio of ML models: a 3D convolutional neural network (CNN), a power spectrum-based fully connected network, and a hybrid approach that merges the two to combine physically motivated summary statistics with flexible CNNs. We describe best practices for training a deep model on a suite of matched-phase simulations, and we test our model on a completely independent sample that uses previously unseen initial conditions, cosmological parameters, and HOD parameters. Despite the fact that the mock observations are quite small (∼0.07 h-3 Gpc3) and the training data span a large parameter space (six cosmological and six HOD parameters), the CNN and hybrid CNN can constrain estimates of σ8 and Ωm to ∼3% and ∼4%, respectively.

Keywords: Large-scale structure of the universe, Cosmology, Astrostatistics, Cosmological parameters from large-scale structure
What Would Happen if We Were About 1 pc Away from a Supermassive Black Hole?. We consider a hypothetical planet with the same mass m, radius R, angular momentum S, oblateness J2, semimajor axis a, eccentricity e, inclination I, and obliquity ɛ of the Earth orbiting a main-sequence star with the same mass ${M}_{\star }$ and radius ${R}_{\star }$ of the Sun at a distance ${r}_{\bullet }\simeq 1\,{\rm{pc}}$ from a supermassive black hole in the center of the hosting galaxy with the same mass ${M}_{\bullet }$ of, say, M87*. We preliminarily investigate some dynamical consequences of its presence in the neighborhood of such a stellar system on the planet's possibility of sustaining complex life over time. In particular, we obtain general analytic expressions for the long-term rates of change, doubly averaged over both the planetary and the galactocentric orbital periods ${P}_{{\rm{b}}}$ and ${P}_{\bullet }$ , of e, I, ɛ, which are the main quantities directly linked to stellar insolation. We find that, for certain orbital configurations, the planet's perihelion distance $q=a\left(1-e\right)$ may greatly shrink and even lead to, in some cases, an impact with the star. I may also notably change, with variations even of the order of tens of degrees. On the other hand, ɛ does not seem to be particularly affected, being shifted, at most, by $\simeq 0\buildrel{\circ}\over{.} 02$ over 1 Myr. Our results strongly depend on the eccentricity ${e}_{\bullet }$ of the galactocentric motion.

Keywords: Black holes, Exoplanets, Gravitation, Celestial mechanics, Astrobiology
Objectively Determining States of the Solar Wind Using Machine Learning. Conclusively determining the states of the solar wind will aid in tracing the origins of those states to the Sun, and in the process help to find the wind's origin and acceleration mechanism(s). Prior studies have characterized the various states of the wind, making lists that are only partially based on objective criteria; different approaches obtain substantially different results. To uncover the unbiased states of the solar wind, we use "k-means clustering"—an unsupervised machine learning method—including constructed multipoint variables. The method allows exploration of different descriptive state variables and numbers of fundamental states (clusters). We show that the clusters reveal structures similar to those found by more ad hoc means, including coronal hole wind, interplanetary coronal mass ejections, "slow wind" (better: noncoronal hole flow), "pseudostreamers," and stream interaction regions, but with differences that should be useful in refining our previous ideas. These results demonstrate the viability of the approach and warrant further study to understand the origin of remaining discrepancies. Complexity in k-means characterization of the wind may ultimately point to complexity at the source; studies closer to the Sun with Parker Solar Probe will help. We confirm the utility of a set of variables that can serve as a proxy for composition measurements. This proxy permits studies at high time resolution and where composition is not available. This and our recently developed unsupervised multivariate clustering technique are expected to be beneficial in the automated identification of structures and events in a variety of studies.

Keywords: Interplanetary turbulence, Solar wind, Interplanetary magnetic fields, Solar coronal mass ejections, Interplanetary physics
LEGUS and H<SUB>α</SUB>-LEGUS Observations of Star Clusters in NGC 4449: Improved Ages and the Fraction of Light in Clusters as a Function of Age. We present a new catalog and results for the cluster system of the starburst galaxy NGC 4449, based on multiband imaging observations taken as part of the LEGUS and Hα-LEGUS surveys. We improve the spectral energy fitting method used to estimate cluster ages, and find that the results, particularly for older clusters, are in better agreement with those from spectroscopy. The inclusion of Hα measurements, the role of stochasticity for low-mass clusters, the assumptions about reddening, and the choices of SSP model and metallicity all have important impacts on the age dating of clusters. A comparison with ages derived from stellar color-magnitude diagrams for partially resolved clusters shows reasonable agreement, but large scatter in some cases. The fraction of light found in clusters relative to the total light (I.e., TL) in the U, B, and V filters in 25 different ≈ kiloparsec-size regions throughout NGC 4449 correlates with both the specific region luminosity, RL, and the dominant age of the underlying stellar population in each region. The observed cluster age distribution is found to decline over time as dN/dτ ∝ τγ, with γ = -0.85 ± 0.15, independent of cluster mass, and is consistent with strong, early cluster disruption. The mass functions of the clusters can be described by a power law with dN/dM ∝ Mβ and β = -1.86 ± 0.2, independent of cluster age. The mass and age distributions are quite resilient to differences in age-dating methods. There is tentative evidence for a factor of 2-3 enhancement in both the star and cluster formation rate ≈100-300 Myr ago, indicating that cluster formation tracks star formation generally. The enhancement is probably associated with an earlier interaction event.

Keywords: Globular star clusters, Dwarf irregular galaxies, Young massive clusters, Galaxy stellar content, Star clusters
Observations of the Orion Source I Disk and Outflow Interface. We imaged the continuum and molecular line emission from Orion Source I (SrcI) with up to 30 mas (12 au) resolution at 43, 99, 223, and 340 GHz in an attempt to probe the structure and chemistry of the circumstellar disk and bipolar outflow associated with this high-mass protostar. The continuum spectral index ranges from ∼2 along the midplane of the disk to ∼3 along the edges, consistent with dust that is optically thick in the midplane but becomes optically thin at the periphery. Salt (NaCl) emission is visible where the dust is optically thin; it provides a unique tracer of the velocity field within the disk. All other molecules that we have mapped—H2O, AlO, SiO, SiS, SO, and SO2—appear to originate primarily in the bipolar outflow. The base of the outflow is corotating with the disk. SiS shows a filamentary structure that is most prominent along the edges of the outflow. The molecular distributions suggest that Si and Al released from dust grains in the disk react with oxygen derived from H2O to form SiO and AlO, and with SO and SO2 to form SiS.

Keywords: Astrochemistry, Protostars, Molecular gas, Circumstellar disks
The Roles of Mass and Environment in the Quenching of Galaxies. II.. We take advantage of an analytic model of galaxy formation coupled to the merger tree of an N-body simulation to study the roles of environment and stellar mass in the quenching of galaxies. The model has been originally set in order to provide the observed evolution of the stellar mass function as well as reasonable predictions of the star formation rate-stellar mass relation, from high redshift to the present time. We analyze the stellar mass and environmental quenching efficiencies and their dependence on stellar mass, halo mass (taken as a proxy for the environment), and redshift. Our analysis shows that the two quenching efficiencies are dependent on redshift and stellar and halo mass, and that the halo mass is also a good proxy for the environment. The environmental quenching increases with decreasing redshift and is inefficient below log M* ∼ 9.5, reaches the maximum value at log M* ∼ 10.5, and decreases again, becoming poorly efficient at very high stellar mass (log M* ≳ 11.5). Central and satellites galaxies are mass quenched differently: for the former, the quenching efficiency depends very weakly on redshift but strongly on stellar mass; for the latter, it strongly depends on both stellar mass and redshift in the range $10\lesssim \mathrm{log}{M}_{* }\lesssim 11$ . According to the most recent observational results, we find that the two quenching efficiencies are not separable: intermediate-mass galaxies, as well as intermediate/massive galaxies in more massive halos, are environmentally quenched faster. At stellar masses lower than log M* ≲ 9.5, both quenching mechanisms become inefficient, independently of the redshift.

Keywords: Galaxy formation, Galaxy evolution
Ages of Dwarfs in the Solar Neighborhood: Considering C and O Enhancements. Precise stellar ages of stars are necessary to study the evolution of the Milky Way. The age determination is significantly affected by C and O abundances of stars due to their contribution to the overall metallicity and opacity. On the basis of C and O abundances derived from high-resolution observations, we determine the ages of 148 FGK-type dwarfs in the solar neighborhood by considering C and O enhancements individually. Our results show that using C and O enhancements individually could affect the age determination of the high-α population, especially for stars with [O/α] &gt; 0.2 dex, making them about 1 Gyr younger compared to the results using traditional α-enhanced models. This results in a steeper slope in the age-[α/Fe] relation for the high-α population (changes from 0.0339 ± 0.0075 to 0.0436 ± 0.0086), indicating a higher formation rate. We find no tight relation between age and [α/Fe] or [O/Fe] in the high-α populations. The distribution of space velocity for young α-rich stars shows that they are more likely characterized to the low-α populations.

Keywords: Galaxy formation, Stellar ages, Fundamental parameters of stars, Chemical abundances, Stellar flares
The Effects of Plasma Lensing on the Inferred Dispersion Measures of Fast Radiobursts. Radio signals are delayed when propagating through plasma. This type of delay is frequency dependent and is usually used for estimating the projected number density of electrons along the line of sight, called the dispersion measure (DM). The dense and clumpy distribution of plasma can cause refractive deflections of radio signals, analogous to lensing effects. Similar to gravitational lensing, there are two contributions to the time delay effect in plasma lensing: a geometric delay, due to increased path length of the signal, and a dispersive delay due to the change of speed of light in a plasma medium. We show the delay time for two models of the plasma distribution, and point out that the estimated DM can be biased. Since the contribution of the geometric effect can be comparable to that of the dispersive delay, the bias in the measured DM can be dramatically large if plasma lensing effects are not taken into account when signals propagate through a high-density gradient clump of plasma.

Keywords: Strong gravitational lensing, Interstellar medium, Radio transient sources
X-Ray Ionization of Planet-opened Gaps in Protostellar Disks. Young planets with masses approaching Jupiter's have tides strong enough to clear gaps around their orbits in the protostellar disk. Gas flow through the gaps regulates the planets' further growth and governs the disk's evolution. Magnetic forces may drive that flow if the gas is sufficiently ionized to couple to the fields. We compute the ionizing effects of the X-rays from the central young star, using Monte Carlo radiative transfer calculations to find the spectrum of Compton-scattered photons reaching the planet's vicinity. The scattered X-rays ionize the gas at rates similar to or greater than the interstellar cosmic-ray rate near planets with the masses of Saturn and of Jupiter, located at 5 au and at 10 au, in disks with the interstellar mass fraction of sub-micron dust and with the dust depleted by a factor 100. Solving a gas-grain recombination reaction network yields charged particle populations whose ability to carry currents is sufficient to partly couple the magnetic fields to the gas around the planet. Most cases can undergo Hall-shear instability, and some can launch magnetocentrifugal winds. However, the material on the planet's orbit has diffusivities so large in all the cases we examine that magnetorotational turbulence is prevented and the non-ideal terms govern the magnetic field's evolution. Thus the flow of gas in the gaps opened by young giant planets depends crucially on the finite conductivity.

Keywords: Magnetic fields, Protoplanetary disks, Radiative transfer, X-ray stars
Two New Outbursts and Transient Hard X-Rays from 1E 1048.1-5937. Since its discovery, 1E 1048.1-5937 has been one of the most active magnetars, both in terms of radiative outbursts, and changes to its spin properties. Here we report on a continuing monitoring campaign with the Neil Gehrels Swift Observatory X-ray Telescope in which we observe two new outbursts from this source. The first outburst occurred in 2016 July, and the second in 2017 December, reaching peak 0.5-10 keV absorbed fluxes of ${3.2}_{-0.3}^{+0.2}\times {10}^{-11}$ erg s-1 cm-2 and ${2.2}_{-0.2}^{+0.2}\times {10}^{-11}$ erg s-1 cm-2, respectively, factors of ∼5 and ∼4 above the quiescent flux. Both new outbursts were accompanied by spin-up glitches with amplitudes of ${\rm{\Delta }}\nu =4.47(6)\times {10}^{-7}$ Hz and ${\rm{\Delta }}\nu =4.32(5)\times {10}^{-7}$ Hz, respectively. Following the 2016 July outburst, we observe, as for past outbursts, a period of delayed torque fluctuations, which reach a peak spin-down of 1.73 ± 0.01 times the quiescent rate, and which dominates the spin evolution compared to the spin-up glitches. We also report an observation near the peak of the first of these outbursts with NuSTAR in which hard X-ray emission is detected from the source. This emission is well characterized by an absorbed blackbody plus a broken power law, with a power-law index above 13.4 ± 0.6 keV of ${0.5}_{-0.2}^{+0.3}$ , similar to those observed in both persistent and transient magnetars. The hard X-ray results are broadly consistent with models of electron/positron cooling in twisted magnetic field bundles in the outer magnetosphere. However, the repeated outbursts and associated torque fluctuations in this source remain puzzling.

Keywords: Neutron stars, X-ray astronomy, Transient sources, Pulsars, X-ray transient sources, Compact objects, Magnetars
The Lyman Continuum Escape Survey. II. Ionizing Radiation as a Function of the [O III]/[O II] Line Ratio. We discuss the rest-frame optical emission line spectra of a large (∼50) sample of z ∼ 3.1 Lyα emitting galaxies (LAEs) whose physical properties suggest such sources are promising analogs of galaxies in the reionization era. Reliable Lyman continuum (LyC) escape fractions have now been determined for a large sample of such LAEs from the LymAn Continuum Escape Survey (LACES) undertaken via deep Hubble Space Telescope imaging in the SSA22 survey area reported in Fletcher et al. Using new measures of [O II] emission secured from Keck MOSFIRE spectra we re-examine, for a larger sample, earlier claims that LyC leakages may correlate with the nebular emission line ratio [O III]/[O II] as expected for density-bound H II regions. We find that a large [O III]/[O II] line ratio is indeed a necessary condition for LyC leakage, strengthening earlier claims made using smaller samples at various redshifts. However, not all LAEs with large [O III]/[O II] line ratios are leakers and leaking radiation appears not to be associated with differences in other spectral diagnostics. This suggests the detection of leaking radiation is modulated by an additional property, possibly the viewing angle for porous H II regions. We discuss our new results in the context of the striking bimodality of LAE leakers and non-leakers found in the LACES program and the implications for the sources of cosmic reionization.

Keywords: Reionization, High-redshift galaxies, Galaxy evolution
Probing the Full CO Spectral Line Energy Distribution (SLED) in the Nuclear Region of a Quasar-starburst System at z = 6.003. We report Atacama Large Millimeter/submillimeter Array observations of CO(8-7), (9-8), ${{\rm{H}}}_{2}{\rm{O}}({2}_{\mathrm{0,2}}\mbox{--}{1}_{\mathrm{1,1}})$ , and ${\mathrm{OH}}^{+}({1}_{1}\mbox{--}{0}_{1})$ and NOrthern Extended Millimeter Array observations of CO(5-4), (6-5), (12-11), and (13-12) toward the z = 6.003 quasar SDSS J231038.88+185519.7, aiming to probe the physical conditions of the molecular gas content of this source. We present the best sampled CO spectral line energy distribution (SLED) at z = 6.003, and analyzed it with the radiative transfer code MOLPOP-CEP. Fitting the CO SLED to a one-component model indicates a kinetic temperature Tkin = 228 K, molecular gas density $\mathrm{log}(n({{\rm{H}}}_{2})/{\mathrm{cm}}^{-3}$ ) = 4.75, and CO column density $\mathrm{log}(N(\mathrm{CO})/{\mathrm{cm}}^{-2})=17.5$ ; although, a two-component model better fits the data. In either case, the CO SLED is dominated by a "warm" and "dense" component. Compared to samples of local (Ultra) Luminous Infrared Galaxies, starburst galaxies, and high-redshift submillimeter galaxies, J2310+1855 exhibits higher CO excitation at (J ≥ 8), like other high-redshift quasars. The high CO excitation, together with the enhanced ${L}_{{{\rm{H}}}_{2}{\rm{O}}}/{L}_{\mathrm{IR}}$ , ${L}_{{{\rm{H}}}_{2}{\rm{O}}}/{L}_{\mathrm{CO}}$ , and ${L}_{{\mathrm{OH}}^{+}}/{L}_{{{\rm{H}}}_{2}{\rm{O}}}$ ratios, suggests that besides the UV radiation from young massive stars, other mechanisms such as shocks, cosmic-rays, and X-rays might also be responsible for the heating and ionization of the molecular gas. In the nuclear region probed by the molecular emissions lines, any of these mechanisms might be present due to the powerful quasar and the starburst activity.

Keywords: AGN host galaxies, Starburst galaxies, Molecular gas, Interstellar phases, Early universe, Quasars, Infrared galaxies, Interstellar medium, Submillimeter astronomy, High-redshift galaxies