adsabs/SciX_UAT_keywords huggingface dataset:
Bridging Model–Data Discrepancies in Mars' Dayside Ionosphere: Exploring Varying Reaction Rate Coefficients

Measurements of concentrations of neutral and ion species in the upper atmosphere of Mars by the Neutral Gas and Ion Mass Spectrometer (NGIMS) on board the Mars Atmosphere and Volatile EvolutioN mission have served as model input and/or for comparison with model output in numerous earlier studies of the Martian dayside ionosphere. While many models reproduce the altitudinal density profiles of key ion species within a factor of a few, it has proven challenging to achieve a level of agreement within tens of percent for multiple ion species over a wide range of altitudes. We explore means to overcome this issue while keeping with a reduced chemical model and utilizing the assumptions of photochemical equilibrium and that the NGIMS data are devoid of any measurement errors. We entertain, for instance, the idea that the rate coefficient for the charge-transfer reaction between and O may vary with altitude as a result of a pressure-controlled internal energy distribution of the population.

Keywords: mars; planetary ionospheres; space plasmas; reaction rates
Discovery of Transition from Marginally Stable Burning to Unstable Burning after a Superburst in Aql X-1

Superbursts are long duration, rare, and extremely energetic thermonuclear explosions of neutron star low-mass X-ray binaries (NS LMXBs), which are proposed to be due to unstable carbon ignition. We report the superburst properties and consequences from Aql X-1 observed by the Neutron Star Interior Composition Explorer (NICER), the Monitor of All-sky X-ray Image, Swift, and Insight Hard X-ray Modulation Telescope (Insight-HXMT) on the MJD 59130.7. We found two faint type I X-ray bursts 9.44 days after the superburst with a short recurrence time of 7.6 minutes, which is the most accurate measurement of the quenching time in all NS LMXBs with observed superbursts. We also discovered mHz quasi-periodic oscillations in the frequency range 2.7-11.3 mHz immediately after the superburst, before and after the resumption of the first type I X-ray burst from NICER, Swift, and Insight-HXMT observations. For the first time, we observed the transition from superburst, via marginally stable burning to unstable burning in NS LMXBs. We compared the quenching time and the recurrence time of type I X-ray bursts with simulations.

Keywords: x-ray bursts; low-mass x-ray binary stars; x-ray sources; neutron stars
Galaxies Going Bananas: Inferring the 3D Geometry of High-redshift Galaxies with JWST-CEERS

The 3D geometries of high-redshift galaxies remain poorly understood. We build a differentiable Bayesian model and use Hamiltonian Monte Carlo to efficiently and robustly infer the 3D shapes of star-forming galaxies in James Webb Space Telescope Cosmic Evolution Early Release Science observations with $\mathrm{log}{M}_{* }/{M}_{\odot }=9.0\mbox{--}10.5$ at z = 0.5–8.0. We reproduce previous results from the Hubble Space Telescope Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey in a fraction of the computing time and constrain the mean ellipticity, triaxiality, size, and covariances with samples as small as ∼50 galaxies. We find high 3D ellipticities for all mass–redshift bins, suggesting oblate (disky) or prolate (elongated) geometries. We break that degeneracy by constraining the mean triaxiality to be ∼1 for $\mathrm{log}{M}_{* }/{M}_{\odot }=9.0\mbox{--}9.5$ dwarfs at z > 1 (favoring the prolate scenario), with significantly lower triaxialities for higher masses and lower redshifts indicating the emergence of disks. The prolate population traces out a "banana" in the projected $b/a\mbox{--}\mathrm{log}a$ diagram with an excess of low-b/a, large- $\mathrm{log}a$ galaxies. The dwarf prolate fraction rises from ∼25% at z = 0.5–1.0 to ∼50%–80% at z = 3–8. Our results imply a second kind of disk settling from oval (triaxial) to more circular (axisymmetric) shapes with time. We simultaneously constrain the 3D size–mass relation and its dependence on 3D geometry. High-probability prolate and oblate candidates show remarkably similar Sérsic indices (n ∼ 1), nonparametric morphological properties, and specific star formation rates. Both tend to be visually classified as disks or irregular, but edge-on oblate candidates show more dust attenuation. We discuss selection effects, follow-up prospects, and theoretical implications.

Keywords: high-redshift galaxies; galaxy classification systems; dwarf galaxies; galaxy structure; james webb space telescope; galaxy disks; galaxy spheroids; galaxy radii; galaxy masses
A Possible Orbital Period of MAXI J0158-744

Optical Gravitational Lensing Experiment (OGLE) has observed Monitor of All-sky X-ray Image J0158-744 for at least 10 yr since the X-ray/optical burst in 2011, which is a Be+ White Dwarf Supersoft source. By analyzing the OGLE light curve, we noticed that the optical brightness was changing periodically, indicating a possible orbital period of ${439}_{-80}^{+114}$ days.

Keywords: white dwarf stars; periodic orbit
Structure of Brightest Cluster Galaxies and Intracluster Light

Observations of 170 local (z ≲ 0.08) galaxy clusters in the northern hemisphere have been obtained with the Wendelstein Telescope Wide Field Imager (WWFI). We correct for systematic effects such as point-spread function broadening, foreground star contamination, relative bias offsets, and charge persistence. Background inhomogeneities induced by scattered light are reduced down to ΔSB > 31 g' mag arcsec-2 by large dithering and subtraction of night-sky flats. Residual background inhomogeneities brighter than SBσ < 27.6 g' mag arcsec-2 caused by galactic cirrus are detected in front of 23% of the clusters. However, the large field of view allows discrimination between accretion signatures and galactic cirrus. We detect accretion signatures in the form of tidal streams in 22%, shells in 9.4%, and multiple nuclei in 47% of the brightest cluster galaxies (BCGs) and find two BCGs in 7% of the clusters. We measure semimajor-axis surface brightness profiles of the BCGs and their surrounding intracluster light (ICL) down to a limiting surface brightness of SB = 30 g' mag arcsec-2. The spatial resolution in the inner regions is increased by combining the WWFI light profiles with those that we measured from archival Hubble Space Telescope images or deconvolved WWFI images. We find that 71% of the BCG+ICL systems have surface brightness (SB) profiles that are well described by a single Sérsic function, whereas 29% require a double Sérsic function to obtain a good fit. We find that BCGs have scaling relations that differ markedly from those of normal ellipticals, likely due to their indistinguishable embedding in the ICL.

Keywords: cd galaxies; galaxy formation; galaxy stellar halos; surface photometry; scaling relations; brightest cluster galaxies
Multiwavelength View of the Type IIn Zoo: Optical to X-Ray Emission Model of Interaction-powered Supernovae

Transients powered by interaction with the circumstellar medium (CSM) are often observed in wavelengths other than the optical, and multiwavelength modeling can be important when inferring the properties of the explosion and CSM, or for distinguishing from other powering mechanisms. We develop a model calculating the time-dependent emission spectrum of interaction-powered transients. We solve the energy equations of electron-proton plasma in the shocked supernova ejecta and CSM and the radiation transfer equation out to the outer edge of the CSM, incorporating collisional relaxation and the Comptonization of bremsstrahlung radiation. We compare our model to observations of Type IIn supernovae covering a frequency range from the optical to X-rays. For SN 2010jl the observed optical and X-ray light curves can be consistently explained if a clumpy or asymmetric structure in the CSM is assumed, in agreement with previous studies. For SN 2014C our model successfully reproduces the X-ray bremsstrahlung component and the emergence of Hα emission at 400 days after explosion. Finally we find a parameter space where the supernova is extremely X-ray bright, reaching 1043-1044 erg s-1, for up to 100 days. Such X-ray transients are likely to be detectable with all-sky surveys by, e.g., eROSITA.

Keywords: type ii supernovae; stellar mass loss; x-ray sources
Securing the Legacy of TESS through the Care and Maintenance of TESS Planet Ephemerides

Much of the science from the exoplanets detected by the Transiting Exoplanet Survey Satellite (TESS) mission relies on precisely predicted transit times that are needed for many follow-up characterization studies. We investigate ephemeris deterioration for simulated TESS planets and find that the ephemerides of 81% of those will have expired (i.e., 1σ mid-transit time uncertainties greater than 30 minutes) 1 yr after their TESS observations. We verify these results using a sample of TESS planet candidates as well. In particular, of the simulated planets that would be recommended as James Webb Space Telescope (JWST) targets by Kempton et al., ∼80% will have mid-transit time uncertainties >30 minutes by the earliest time JWST would observe them. This rapid deterioration is driven primarily by the relatively short time baseline of TESS observations. We describe strategies for maintaining TESS ephemerides fresh through follow-up transit observations. We find that the longer the baseline between the TESS and the follow-up observations, the longer the ephemerides stay fresh, and that 51% of simulated primary mission TESS planets will require space-based observations. The recently approved extension to the TESS mission will rescue the ephemerides of most (though not all) primary mission planets, but the benefits of these new observations can only be reaped 2 yr after the primary mission observations. Moreover, the ephemerides of most primary mission TESS planets (as well as those newly discovered during the extended mission) will again have expired by the time future facilities such as the ELTs, Ariel, and the possible LUVOIR/Origins Space Telescope missions come online, unless maintenance follow-up observations are obtained.

Keywords: surveys; transits; ephemerides; exoplanets
Response of Pickup Ions in the Very Local Interstellar Medium to Solar Variations: Implications for the Evolution of the IBEX Ribbon and Interstellar Helium

The Interstellar Boundary Explorer (IBEX) observes the "ribbon" of enhanced energetic neutral atom (ENA) fluxes from the outer heliosphere. The ribbon flux is likely formed from the neutralization of energetic pickup ions (PUIs) gyrating in the interstellar magnetic field outside the heliopause. Voyager 1 crossed the heliopause in 2012 and has observed several shocks in the very local interstellar medium (VLISM) that likely originate from merged interaction regions in the inner heliosphere that propagated outside the heliopause. We simulate the response of PUIs and the IBEX ribbon flux to solar disturbances propagating into the VLISM. First, we show that PUIs outside the heliopause respond significantly to the dynamic neutralized solar wind (SW) via charge exchange and to interactions with shocks via adiabatic heating/cooling. However, the evolution of ribbon fluxes at 1 au is primarily driven by changes in the neutralized SW and not PUI interactions with shocks outside the heliopause. Comparisons with IBEX observations of the ribbon at 1.1 keV show that an abrupt decrease in ENA fluxes observed in 2012 was caused by a drop in SW (and thus neutralized SW) speed by ∼100 km s-1. Our simulation predicts a recovery of 1.1 keV ribbon fluxes starting in 2019 to levels observed early in the mission owing to an increase in SW speed. We also estimate that the presence of interstellar helium in the VLISM reduces the effectiveness of charge-exchange sources for PUIs and reduces the model ribbon flux at 1 au by ∼40%, matching well with IBEX ribbon fluxes.

Keywords: heliosphere; solar wind; pickup ions; interstellar medium; shocks; heliosheath; solar cycle; solar activity
Predicting the UV Escape Fraction of the First Galaxies in the Renaissance Simulations with Machine Learning

Cosmic reionization is likely driven by UV starlight emanating from the first generations of galaxies. A galaxy's UV escape fraction, or the fraction of photons escaping from the galaxy, is useful to quantify its contribution to reionization. However, the UV escape fraction is notoriously difficult to predict due to local environment dependency and variability over time. Using data from the Renaissance Simulations, we attempt to make predictions about the impact of the first stars and galaxies on their environments. We present a time-independent classification model using a general artificial neural network architecture to predict the UV escape fraction given other galaxy properties-namely halo mass, stellar mass, redshift, star formation rate, lookback time, and gas fraction. We find our validation accuracy to be approximately 50%-65%, depending on the data set size from each zoom-in region of the Renaissance Simulations.

Keywords: galaxy formation; reionization; high-redshift galaxies
The Origin of High-energy Emission in the Young Radio Source PKS 1718-649

We present a model for the broadband radio-to-γ-ray spectral energy distribution of the compact radio source PKS 1718-649. Because of its young age (≃100 yr) and proximity (z = 0.014), PKS 1718-649 offers a unique opportunity to study the nuclear conditions and the jet/host galaxy feedback process at the time of the initial radio jet expansion. PKS 1718-649 is one of a handful of young radio jets with γ-ray emission that has been confirmed by the Fermi/LAT detector. We show that in PKS1718-649 this γ-ray emission can be successfully explained by Inverse Compton scattering of the UV photons, presumably from an accretion flow, off nonthermal electrons in the expanding radio lobes. The origin of the X-ray emission in PKS 1718-649 is more elusive. While Inverse Compton scattering of the IR photons emitted by a cold gas in the vicinity of the expanding radio lobes contributes significantly to the X-ray luminosity, the data require an additional source of X-rays, e.g., a weak X-ray corona or a radiatively inefficient accretion flow, as expected from a LINER-type nucleus, such as that of PKS 1718-649. We find that the jet in PKS 1718-649 has low power, L j ≃ 2 × 1042 erg s-1, and expands in an environment with density n 0 ≃ 3-20 cm-3. The inferred mass accretion rate and gas mass reservoir within 50-100 pc of the galactic center are consistent with estimates from the literature obtained by tracing molecular gas in the innermost region of the host galaxy with SINFONI and the Atacama Large Millimeter/submillimeter Array.

Keywords: active galaxies; extragalactic radio sources; radio jets; non-thermal radiation sources; accretion; x-ray active galactic nuclei; gamma-rays; radio lobes; galaxy evolution
The Hubble Constant from Infrared Surface Brightness Fluctuation Distances

We present a measurement of the Hubble constant H0 from surface brightness fluctuation (SBF) distances for 63 bright, mainly early-type galaxies out to 100 Mpc observed with the WFC3/IR on the Hubble Space Telescope (HST). The sample is drawn from several independent HST imaging programs using the F110W bandpass, with the majority of the galaxies being selected from the MASSIVE survey. The distances reach the Hubble flow with a median statistical uncertainty per measurement of 4%. We construct the Hubble diagram with these IR SBF distances and constrain H0 using four different treatments of the galaxy velocities. For the SBF zero-point calibration, we use both the existing tie to Cepheid variables, updated for consistency with the latest determination of the distance to the Large Magellanic Cloud from detached eclipsing binaries, and a new tie to the tip of the red giant branch (TRGB) calibrated from the maser distance to NGC 4258. These two SBF calibrations are consistent with each other and with theoretical predictions from stellar population models. From a weighted average of the Cepheid and TRGB calibrations, we derive H0 = 73.3 ± 0.7 ± 2.4 km s-1 Mpc-1, where the error bars reflect the statistical and systematic uncertainties. This result accords well with recent measurements of H0 from Type Ia supernovae, time delays in multiply lensed quasars, and water masers. The systematic uncertainty could be reduced to below 2% by calibrating the SBF method with precision TRGB distances for a statistical sample of massive early-type galaxies out to the Virgo cluster measured with the James Webb Space Telescope. * Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555. These observations come from GO Programs #11711, #11712, #12450, #14219, #14654, #14771, #14804, #15265, #15329.

Keywords: galaxy distances; distance indicators; cosmological parameters; early-type galaxies; observational cosmology
Time-resolved Rotational Velocities in the Upper Atmosphere of WASP-33 b

While steady empirical progress has been made in understanding the structure and composition of hot-planet atmospheres, direct measurements of velocity signatures, including winds, rotation, and jets, have lagged behind. Quantifying atmospheric dynamics of hot planets is critical for a complete understanding of their atmospheres, and such measurements may even illuminate other planetary properties, such as magnetic field strengths. In this manuscript we present the first detection of the Balmer lines Hα and Hβ in the atmosphere of the ultra-hot Jupiter WASP-33 b. Using atmospheric models that include the effects of atmospheric dynamics, we show that the shape of the average Balmer line transmission spectrum is consistent with rotational velocities in the planet's thermosphere of ${v}_{\mathrm{rot}}={10.1}_{-1.0}^{+0.8}$ km s-1. We also measure a low-significance day- to nightside velocity shift of $-{4.6}_{-3.4}^{+3.4}$ km s-1 in the transmission spectrum, which is naturally explained by a global wind across the planet's terminator. In a separate analysis the time-resolved velocity centroids of individual transmission spectra show unambiguous evidence of rotation, with a best-fit velocity of ${10.0}_{-2.0}^{+2.4}$ km s-1, consistent with the value of vrot derived from the shape of the average Balmer line transmission spectrum. Our observations and analysis confirm the power of time-resolved transmission spectra with a high signal-to-noise ratio to measure the velocity structures in exoplanet atmospheres. The high rotational and wind velocities we measure highlight the need for more detailed 3D global climate simulations of the rarefied upper atmospheres of ultra-hot gas giants. * Based on data acquired with PEPSI using the Large Binocular Telescope (LBT). The LBT is an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are the University of Arizona on behalf of the Arizona university system; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Leibniz-Institute for Astrophysics Potsdam (AIP), and Heidelberg University; the Ohio State University; and the Research Corporation, on behalf of the University of Notre Dame, University of Minnesota and University of Virginia.

Keywords: exoplanet atmospheres; exoplanets; hot jupiters
Modeling the Galactic Neutron Star Population for Use in Continuous Gravitational-wave Searches

Searches for continuous gravitational waves (GW) from unknown Galactic neutron stars provide limits on the shapes of neutron stars. A rotating neutron star will produce GW if asymmetric deformations exist in its structure that are characterized by the star's ellipticity. In this study, we use a simple model of the spatial and spin distribution of Galactic neutron stars to estimate the total number of neutron stars probed, using GW, to a given upper limit on the ellipticity. This may help optimize future searches with improved sensitivity. The improved sensitivity of third-generation GW detectors may increase the number of neutron stars probed, to a given ellipticity, by factors of 100 to 1000.

Keywords: neutron stars; gravitational waves
The Intrinsic Properties of Multiwavelength Energy Spectra for Fermi Teraelectronvolt Blazars

In this paper, we have selected a sample of 64 teraelectronvolt blazars, with redshift, from those classified in the fourth Fermi Large Area Telescope source catalog.3 We have obtained the values of the relevant physical parameters by performing a log-parabolic fitting of the average-state multiwavelength spectral energy distributions. We estimate the range of the radiation zone parameters, such as the Doppler factor (D), the magnetic field strength (B), the radiative zone radius (R), and the peak Lorentz factor (γp) of nonthermal electrons. Here, we show that (1) there is a strong linear positive correlation between the intrinsic synchrotron peak frequency and the intrinsic inverse Compton scattering (ICs) peak frequency among different types of blazars; (2) if radio bands are excluded, the spectral index of each band is negatively correlated with the intrinsic peak frequency; (3) there is a strong linear negative correlation between the curvature at the peak and the intrinsic peak frequency of the synchrotron bump, and a weak positive correlation between the curvature at the peak and the intrinsic peak frequency of the ICs bump; (4) there is a strong linear positive correlation between the intrinsic ICs peak luminosity and intrinsic γ-ray luminosity and between the intrinsic ICs peak frequency and peak Lorentz factor; (5) there is a strong negative linear correlation between $\mathrm{log}\,B$ and $\mathrm{log}\,{\gamma }_{{\rm{p}}}$ ; and (6) there is no correlation between $\mathrm{log}\,R$ and $\mathrm{log}\,{\gamma }_{{\rm{p}}}$ .

Keywords: blazars; bl lacertae objects
BASS. XXXV. The M BH-σ* Relation of 105 Month Swift-BAT Type 1 AGNs

We present two independent measurements of stellar velocity dispersions (σ ⋆) from the Ca II H+K λ3969, 3934 and Mg I b λ 5183, 5172, 5167 region (3880-5550 Å) and the calcium triplet region (8350-8750 Å) for 173 hard X-ray-selected Type 1 active galactic nuclei (AGNs; z ≤ 0.08) from the 105 month Swift-BAT catalog. We construct one of the largest samples of local Type 1 AGNs that have both single-epoch virial black hole mass (M BH) estimates and σ ⋆ measurements obtained from high spectral resolution data, allowing us to test the usage of such methods for supermassive black hole studies. We find that the two independent σ ⋆ measurements are highly consistent with each other, with an average offset of only 0.002 ± 0.001 dex. Comparing M BH estimates based on broad emission lines and stellar velocity dispersion measurements, we find that the former is systematically lower by ≈0.12 dex. Consequently, Eddington ratios estimated through broad-line M BH determinations are similarly biased (but in the opposite way). We argue that the discrepancy is driven by extinction in the broad-line region. We also find an anticorrelation between the offset from the M BH-σ ⋆ relation and the Eddington ratio. Our sample of Type 1 AGNs shows a shallower M BH-σ ⋆ relation (with a power-law exponent of ≈3.5) compared with that of inactive galaxies (with a power-law exponent of ≈4.5), confirming earlier results obtained from smaller samples.

Keywords: supermassive black holes; x-ray surveys; agn host galaxies; x-ray active galactic nuclei; active galaxies; galaxies; galaxy bulges