adsabs/SciX_UAT_keywords huggingface dataset:
Accelerated Bayesian SED Modeling Using Amortized Neural Posterior Estimation

State-of-the-art spectral energy distribution (SED) analyses use a Bayesian framework to infer the physical properties of galaxies from observed photometry or spectra. They require sampling from a high-dimensional space of SED model parameters and take >10-100 CPU hr per galaxy, which renders them practically infeasible for analyzing the billions of galaxies that will be observed by upcoming galaxy surveys (e.g., the Dark Energy Spectroscopic Instrument, the Prime Focus Spectrograph, the Vera C. Rubin Observatory, the James Webb Space Telescope, and the Roman Space Telescope). In this work, we present an alternative scalable approach to rigorous Bayesian inference using Amortized Neural Posterior Estimation (ANPE). ANPE is a simulation-based inference method that employs neural networks to estimate posterior probability distributions over the full range of observations. Once trained, it requires no additional model evaluations to estimate the posterior. We present, and publicly release, SEDFLOW, an ANPE method for producing the posteriors of the recent Hahn et al. SED model from optical photometry and redshift. SEDFLOW takes ~1 s per galaxy to obtain the posterior distributions of 12 model parameters, all of which are in excellent agreement with traditional Markov Chain Monte Carlo sampling results. We also apply SEDFLOW to 33,884 galaxies in the NASA-Sloan Atlas and publicly release their posteriors.

Keywords: galaxies; galaxy photometry; algorithms; astrostatistics; astrostatistics techniques; astrostatistics tools; bayesian statistics; posterior distribution; astrostatistics strategies; redshift surveys; galaxy properties
The Gaia-Kepler Stellar Properties Catalog. I. Homogeneous Fundamental Properties for 186,301 Kepler Stars

An accurate and precise Kepler Stellar Properties Catalog is essential for the interpretation of the Kepler exoplanet survey results. Previous Kepler Stellar Properties Catalogs have focused on reporting the best-available parameters for each star, but this has required combining data from a variety of heterogeneous sources. We present the Gaia-Kepler Stellar Properties Catalog, a set of stellar properties of 186,301 Kepler stars, homogeneously derived from isochrones and broadband photometry, Gaia Data Release 2 parallaxes, and spectroscopic metallicities, where available. Our photometric effective temperatures, derived from $g\,\mathrm{to}\,{K}_{s}$ colors, are calibrated on stars with interferometric angular diameters. Median catalog uncertainties are 112 K for ${T}_{\mathrm{eff}}$ , 0.05 dex for $\mathrm{log}\,g$ , 4% for ${R}_{\star }$ , 7% for ${M}_{\star }$ , 13% for ${\rho }_{\star }$ , 10% for ${L}_{\star }$ , and 56% for stellar age. These precise constraints on stellar properties for this sample of stars will allow unprecedented investigations into trends in stellar and exoplanet properties as a function of stellar mass and age. In addition, our homogeneous parameter determinations will permit more accurate calculations of planet occurrence and trends with stellar properties.

Keywords: catalogs; fundamental parameters of stars; exoplanet systems
Final Compact Remnants in Core-collapse Supernovae from 20 to 40 M⊙: The Lower Mass Gap

A mass paucity of compact objects in the range of ∼2-5 M⊙ has been suggested by X-ray binary observations, namely, the "lower mass gap." Gravitational wave detections have unlocked another mass measurement method, and aLIGO/Virgo has observed some candidates in the gap. We revisit the numerical simulations on the core-collapse supernovae (CCSNe) for ∼20-40 M⊙ progenitor stars with different initial explosion energies. As a result, the lower explosion energy naturally causes more efficient fallback accretion for low-metallicity progenitors, and then the newborn black holes (BHs) in the center of the CCSNe can escape from the gap, but neutron stars cannot easily collapse into BHs in the gap; nevertheless, the final remnants of the solar-metallicity progenitors stick to the gap. If we consider that only drastic CCSNe can be observed and that those with lower explosion energies are universal, the lower mass gap can be reasonably built. The width and depth of the gap are mainly determined by the typical CCSN initial explosion energy and metallicity. One can expect that the future multimessenger observations of compact objects delineate the shape of the gap, which might constrain the properties of the CCSNe and their progenitors.

Keywords: accretion; neutron stars; core-collapse supernovae; stellar mass black holes
Effects of Magnetic Field Orientations in Dense Cores on Gas Kinematics in Protostellar Envelopes

Theoretically, misalignment between the magnetic field and rotational axis in a dense core is considered to be dynamically important in the star formation process; however, the extent of this influence remains observationally unclear. For a sample of 32 Class 0 and I protostars in the Perseus Molecular Cloud, we analyzed gas motions using C18O data from the SMA MASSES survey and the magnetic field structures using 850 μm polarimetric data from the JCMT BISTRO-1 survey and archive. We do not find any significant correlation between the velocity gradients in the C18O emission in the protostellar envelopes at a 1000 au scale and the misalignment between the outflows and magnetic field orientations in the dense cores at a 4000 au scale, and there is also no correlation between the velocity gradients and the angular dispersions of the magnetic fields. However, a significant dependence on the misalignment angles emerges after we normalize the rotational motion by the infalling motion, where the ratios increase from ≲1 to ≳1 with increasing misalignment angle. This suggests that the misalignment could prompt angular momentum transportation to the envelope scale but is not a dominant factor in determining the envelope rotation, and other parameters, such as mass accretion in protostellar sources, also play an important role. These results remain valid after taking into account projection effects. The comparison between our estimated angular momentum in the protostellar envelopes and the sizes of the known protostellar disks suggests that significant angular momentum is likely lost between radii of ~1000 and 100 au in protostellar envelopes.

Keywords: star formation; star forming regions; protostars; interstellar magnetic fields
A uvbyCaHβ CCD Analysis of the Open Cluster Standard, M67, and Its Relation to NGC 752

Precision CCD uvbyCaHβ photometry is presented of the old cluster, M67, covering one square degree with typical internal precision at the 0.005-0.020 mag level to V ~ 17. The photometry is calibrated using standards over a wide range in luminosity and temperature from NGC 752 and zeroed to the standard system via published photoelectric observations. Relative to NGC 752, differential offsets in reddening and metallicity are derived using astrometric members, supplemented by radial velocity information. From single-star members, offsets in the sense (M67-NGC 752) are δ E(b - y) = -0.005 ± 0.001 (sem) mag from 327 F/G dwarfs and δ[Fe/H] = 0.062 ± 0.006 (sem) dex from the combined m 1 and hk indices of 249 F dwarfs, leading to E(b - y) = 0.021 ± 0.004 (sem) and [Fe/H]M67 = +0.030 ± 0.016 (sem) assuming [Fe/H]Hyades = +0.12. With probable binaries eliminated using c 1, (b - y) indices, 83 members with (π/σ π ) > 50 generate (m - M)0 = 8.220 ± 0.005 (sem) for NGC 752 and an isochronal age of 1.45 ± 0.05 Gyr. Using the same parallax restriction for 312 stars, M67 has (m - M) = 9.77 ± 0.02 (sem), leading to an age tied solely to the luminosity of the subgiant branch of 3.70 ± 0.03 Gyr. The turnoff color spread implies ±0.1 Gyr, but the turnoff morphology defines a younger age/higher mass for the stars, consistent with recent binary analysis and broadband photometry indicating possible missing physics in the isochrones. Anomalous stars positioned blueward of the turnoff are discussed.

Keywords: open star clusters; strömgren photometry
Model-independent Constraints on Clustering and Growth of Cosmic Structures from BOSS DR12 Galaxies in Harmonic Space

We present a new, model-independent measurement of the clustering amplitude of galaxies and the growth of cosmic large-scale structures from the Baryon Oscillation Spectroscopic Survey (BOSS) 12th data release. This is achieved by generalizing harmonic-space power spectra for galaxy clustering to measure separately the magnitudes of the density and the redshift-space distortion terms, respectively related to the clustering amplitude of structures, b σ 8(z), and their growth, f σ 8(z). We adopt a tomographic approach with 15 redshift bins in z ∈ [0.15, 0.67]. We restrict our analysis to strictly linear scales, implementing a redshift-dependent maximum multipole for each bin. The measurements do not appear to suffer from systematic effects, and they show excellent agreement with the theoretical predictions from the Planck cosmic microwave background analysis assuming a ΛCDM cosmology. Our results also agree with previous analyses by the BOSS collaboration. Furthermore, our method provides the community with a new tool for data analyses of the cosmic large-scale structure, complementary to state-of-the-art approaches in configuration or Fourier space. Among its merits, we list: it being more agnostic with respect to the underlying cosmological model; its roots in a well-defined and gauge-invariant observable; the possibility to account naturally for wide-angle effects and even relativistic corrections on ultra-large scales; and the capability to perform an almost arbitrarily fine redshift binning with little computational effort. These aspects are all the more relevant for the oncoming generation of cosmological experiments such as Euclid, the Dark Energy Spectroscopic Instrument, the Legacy Survey of Space and Time, and the SKA Project.

Keywords: large-scale structure of the universe; cosmological parameters; observational cosmology
The First Dynamical Mass Measurement in the HR 8799 System

HR 8799 hosts four directly imaged giant planets, but none has a mass measured from first principles. We present the first dynamical mass measurement in this planetary system, finding that the innermost planet HR 8799 e has a mass of ${9.6}_{-1.8}^{+1.9}\,{M}_{\mathrm{Jup}}$ . This mass results from combining the well-characterized orbits of all four planets with a new astrometric acceleration detection (5σ) from the Gaia EDR3 version of the Hipparcos-Gaia Catalog of Accelerations. We find with 95% confidence that HR 8799 e is below 13 MJup, the deuterium-fusing mass limit. We derive a hot-start cooling age of ${42}_{-16}^{+24}$ Myr for HR 8799 e that agrees well with its hypothesized membership in the Columba association but is also consistent with an alternative suggested membership in the β Pictoris moving group. We exclude the presence of any additional ≳5 - MJup planets interior to HR 8799 e with semimajor axes between ≈3-16 au. We provide proper motion anomalies and a matrix equation to solve for the mass of any of the planets of HR 8799 using only mass ratios between the planets.

Keywords: exoplanets; extrasolar gaseous planets; astrometry; orbit determination
The Next Generation Virgo Cluster Survey (NGVS). III. A Catalog of Surface Brightness Fluctuation Distances and the Three-dimensional Distribution of Galaxies in the Virgo Cluster

The surface brightness fluctuation (SBF) method is a robust and efficient way of measuring distances to galaxies containing evolved stellar populations. Although many recent applications of the method have used space-based imaging, SBF remains a powerful technique for ground-based telescopes. Deep, wide-field imaging surveys with subarcsecond seeing enable SBF measurements for numerous nearby galaxies. Using a preliminary calibration, Cantiello et al. presented SBF distances for 89 bright, mainly early-type galaxies observed in the Next Generation Virgo Cluster Survey. Here we present a refined calibration and SBF distances for 278 galaxies extending several magnitudes fainter than in previous work. The derived distances have uncertainties of 5%–12% depending on the properties of the individual galaxies, and our sample is more than 3 times larger than any previous SBF study of this region. Virgo has a famously complex structure with numerous subclusters, clouds, and groups; we associate individual galaxies with the various substructures and map their three-dimensional spatial distribution. Curiously, subcluster A, centered around M87, appears to have two peaks in distance: the main peak at ∼16.5 Mpc, and a smaller one at ∼19.4 Mpc. Subclusters B and C have distances of ∼15.8 Mpc. The W and W ${}^{{\prime} }$ groups form a filament-like structure, extending more than 15 Mpc behind the cluster with a commensurate velocity increase of ∼1000 km s‑1 along its length. These measurements are a valuable resource for future studies of the relationship between galaxy properties and local environment within a dynamic and evolving region.

Keywords: distance indicators; galaxy distances; distance measure; virgo cluster; stellar populations; population ii stars
Constraints on Cosmic Rays in the Milky Way Circumgalactic Medium from O VIII Observations

We constrain the cosmic-ray (CR) population in the circumgalactic medium (CGM) of the Milky Way by comparing the observations of absorption lines of O VIII ions with predictions from analytical models of the CGM: the precipitation (PP) and isothermal (IT) models. For a CGM in hydrostatic equilibrium, the introduction of CR suppresses thermal pressure and affects the O VIII ion abundance. We explore the allowances given to the ratio of CR pressure to thermal pressure (P CR/P th = η), with varying boundary conditions, CGM mass content, photoionization by extragalactic ultraviolet background, and temperature fluctuations. We find that the allowed maximum values of η are η ≲ 10 in the PP model and η ≲ 6 in the IT model. We also explore the spatial variation of η: rising (η = Ax) or declining (η = A/x) with radius, where A is the normalization of the profiles. In particular, the models with a declining ratio of CR to thermal pressure fare better than those with a rising ratio with suitable temperature fluctuation (higher σ lnT for PP and lower for IT). The declining profiles allow A ≲ 8 and A ≲ 10 in the case of the IT and PP models, respectively, thereby accommodating a large value of η (≃200) in the central region but not in the outer regions. These limits, combined with the limits derived from the γ-ray and radio background, can be useful for building models of the Milky Way CGM including the CR population. However, the larger amount of CRs can be packed in the cold phase, which may be one way to circumvent these constraints.

Keywords: cosmic rays; circumgalactic medium
Optical Spectroscopic Observations of Gamma-Ray Blazar Candidates. XII. Follow-up Observations from SOAR, Blanco, NTT, and OAN-SPM

Roughly one third of the sources in the Fermi-LAT catalogs are listed as unidentified/unassociated γ-ray sources (UGS), i.e., they lack a low-energy counterpart. In addition, there is a growing population of blazars of uncertain type (BCUs). Spectroscopic observations are crucial to confirm the blazar nature of the UGSs candidate counterparts and BCUs. Hence, in 2013 we started an optical spectroscopic campaign to carry out the identifications and classifications. In this paper, as a continuation of the campaign we report the spectra of 39 sources: the sample comprises 37 sources classified as BCUs, one source classified as a BL Lac in the Fourth Source Catalog of the Fermi-LAT (4FGL), and one source classified as UGS. We classify 19 of the sources in the sample as BL Lacs, 13 as blazars with nonnegligible host-galaxy emission, six as Flat Spectrum Radio Quasars, and one as a normal elliptical galaxy. The source listed as BL Lac in the 4FGL seems to be a blazar with nonnegligible host-galaxy emission in our observations, most likely due to an ongoing quiescent state. We classified the UGS source as a BL Lac. Six out of the 39 sources were previously reported in the campaign; in general, both the classifications and redshifts are in agreement, except for one of them with no redshift reported before. Altogether, we provided reliable redshift estimates to 21 out of the 39 sources. Finally, we describe the statistics of the data collected in our campaign so far.

Keywords: optical identification; blazars; bl lacertae objects; flat-spectrum radio quasars
Semiempirical Modeling of the Atmospheres of the M Dwarf Exoplanet Hosts GJ 832 and GJ 581

Stellar ultraviolet (UV) radiation drives photochemistry, and extreme-ultraviolet (EUV) radiation drives mass loss in exoplanet atmospheres. However, the UV flux is partly unobservable due to interstellar absorption, particularly in the EUV range (100-912 Å). It is therefore necessary to reconstruct the unobservable spectra in order to characterize the radiation environment of exoplanets. In the present work, we use a radiative transfer code SSRPM to build one-dimensional semiempirical models of two M dwarf exoplanet hosts, GJ 832 and GJ 581, and synthesize their spectra. SSRPM is equipped with an extensive atomic and molecular database and full-NLTE capabilities. We use observations in the visible, ultraviolet, and X-ray ranges to constrain atmospheric structures of the modeled stars. The synthesized integrated EUV fluxes are found to be in good agreement with other reconstruction techniques, but the spectral energy distributions disagree significantly across the EUV range. More than two-thirds of the EUV flux is formed above 105 K. We find that the far-ultraviolet (FUV) continuum contributes 42%-54% of the entire FUV flux between 1450 and 1700 Å. The comparison of stellar structures of GJ 832 and GJ 581 suggests that GJ 832 is a more magnetically active star, which is corroborated by other activity indicators.

Keywords: m dwarf stars; stellar chromospheres; ultraviolet astronomy; stellar coronae; stellar activity; radiative transfer
Mid-infrared Properties of Narrow-line Seyfert 1 Galaxies Detected by LoTSS DR2

Narrow-line Seyfert 1 galaxies (NLS1s), a subclass of active galactic nuclei (AGNs) in an early stage of the accretion process, are also found to host relativistic jets. However, currently known jetted NLS1s are rare. The majority of NLS1s are undetected at the radio band. The radio detection rate of NLS1s increases with the LOFAR Two-metre Sky Survey (LoTSS), which provides a good opportunity for finding more jetted NLS1s. The better sensitivity raises the question whether the radio emission of NLS1s with a low radio luminosity originates from the jet activity. In order to clarify the origin of the radio emission for NLS1s and search for more jetted NLS1s, we explore the mid-infrared properties of LoTSS-detected NLS1s by comparing them with known jetted AGNs and star-forming galaxies (SFGs), which are located above and on the well-studied radio/far-infrared correlation, respectively. The majority of NLS1s show mid-infrared (MIR) excess compared with SFGs. Their radio emission shows a significant correlation with the MIR emission. In the MIR color–color diagram, NLS1s overlap flat spectrum radio quasars, but they are well separated from SFGs and optically selected radio galaxies. The flux ratio of the radio and MIR emission of these NLS1s is also similar to that of a radio-quiet quasar with a weak jet. These results imply substantial contributions from the AGN activities for both the radio and MIR emission of NLS1s. A small fraction of NLS1s with relatively higher radio luminosities are located in a similar region as blazars in the radio-MIR diagram, which suggests that the radio emission of these NLS1s is dominated by the jet. We obtain a sample of jetted NLS1 candidates through their radio excess in the radio-MIR diagram.

Keywords: active galactic nuclei; radio active galactic nuclei; low-luminosity active galactic nuclei
Electron Heating in 2D Particle-in-cell Simulations of Quasi-perpendicular Low-beta Shocks

We measure the thermal electron energization in 1D and 2D particle-in-cell simulations of quasi-perpendicular, low-beta (β p = 0.25) collisionless ion–electron shocks with mass ratio m i/m e = 200, fast Mach number ${{ \mathcal M }}_{\mathrm{ms}}=1$ –4, and upstream magnetic field angle θ Bn = 55°–85° from the shock normal $\hat{{\boldsymbol{n}}}$ . It is known that shock electron heating is described by an ambipolar, B -parallel electric potential jump, Δϕ ∥, that scales roughly linearly with the electron temperature jump. Our simulations have ${\rm{\Delta }}{\phi }_{\parallel }/(0.5{m}_{{\rm{i}}}{{u}_{\mathrm{sh}}}^{2})\sim 0.1$ –0.2 in units of the pre-shock ions' bulk kinetic energy, in agreement with prior measurements and simulations. Different ways to measure ϕ ∥, including the use of de Hoffmann–Teller frame fields, agree to tens-of-percent accuracy. Neglecting off-diagonal electron pressure tensor terms can lead to a systematic underestimate of ϕ ∥ in our low-β p shocks. We further focus on two θ Bn = 65° shocks: a ${{ \mathcal M }}_{{\rm{s}}}\,=\,4$ ( ${{ \mathcal M }}_{{\rm{A}}}\,=\,1.8$ ) case with a long, 30d i precursor of whistler waves along $\hat{{\boldsymbol{n}}}$ , and a ${{ \mathcal M }}_{{\rm{s}}}\,=\,7$ ( ${{ \mathcal M }}_{{\rm{A}}}\,=\,3.2$ ) case with a shorter, 5d i precursor of whistlers oblique to both $\hat{{\boldsymbol{n}}}$ and B ; d i is the ion skin depth. Within the precursors, ϕ ∥ has a secular rise toward the shock along multiple whistler wavelengths and also has localized spikes within magnetic troughs. In a 1D simulation of the ${{ \mathcal M }}_{{\rm{s}}}\,=\,4$ , θ Bn = 65° case, ϕ ∥ shows a weak dependence on the electron plasma-to-cyclotron frequency ratio ω pe/Ωce, and ϕ ∥ decreases by a factor of 2 as m i/m e is raised to the true proton–electron value of 1836.

Keywords: shocks; interplanetary shocks; planetary bow shocks
Novel Cosmological Joint Constraints in Multidimensional Observable Space with Redshift-free Inferences

Cosmology constraints serve as a crucial criterion in discriminating cosmological models. The traditional combined method to constrain the cosmological parameters designates the corresponding theoretical value and observational data as functions of redshift; however, sometimes the redshift cannot be measured directly, or the measurement error is large, or the definition of redshift is controversial. In this paper, we propose a novel joint method to constrain parameters that eliminates the redshift z and makes full use of the multiple observables $\left\{{{ \mathcal F }}_{1,\mathrm{obs}},{{ \mathcal F }}_{2,\mathrm{obs}},\cdots ,{{ \mathcal F }}_{M,\mathrm{obs}}\right\}$ spanning in M-dimensional joint observable space. Considering the generality of the mathematical form of the cosmological models and the guidance from low to high dimensions, we first validate our method in a 3D joint observable space spanned by H(z), f σ 8(z), and D A (z), where the three coordinates can be considered redshift-free measurements of the same celestial body (or shared-redshift data-reconstructed model independently). Our results are consistent with the traditional combined method but with lower errors, yielding H 0 = 68.7 ± 0.1 km s-1 Mpc-1, Ω m0 = 0.289 ± 0.003, and σ 8 = 0.82 ± 0.01 and showing alleviated parametric degeneracies to some extent. In principle, our joint constraint method allows an extended form keeping the redshift information as an independent coordinate and can also be readily degraded to the form of a traditional combined method to constrain parameters.

Keywords: observational cosmology; computational methods; astronomy data analysis; cosmological parameters; astrostatistics strategies