adsabs/SciX_UAT_keywords huggingface dataset:
Evaluating Climate Variability of the Canonical Hot-Jupiters HD 189733b and HD 209458b through Multi-epoch Eclipse Observations

Here we present the analysis of multi-epoch secondary eclipse observations of HD 189733b and HD 209458b as a probe of temporal variability in the planetary climate using both Spitzer channels 1 and 2 (3.6 and 4.5 μm). We expect hot-Jupiter atmospheres to be dynamic environments exhibiting time varying weather. However, it is uncertain to what extent temporal variability will be observable when considering disk integrated observations. We do not detect statistically significant variability and are able to place useful upper limits on the infrared variability amplitudes in these atmospheres. There are very few planets with multi-epoch observations at the required precision to probe variability in dayside emission. The observations considered in this study span several years, providing insight into temporal variability at multiple timescales. In the case of HD 189733b, the best-fit eclipse depths for the channel 2 observations exhibit a scatter of 102 ppm about a median depth of 1827 ppm and in channel 1 exhibit a scatter of 88 ppm about a median depth of 1481 ppm. For HD 209458b, the best-fit eclipse depths for the channel 2 observations exhibit a scatter of 22 ppm about a median depth of 1406 ppm, and in channel 1 exhibit a scatter of 131 ppm about a median depth of 1092 ppm. The precision and scatter in these observations allow us to constrain variability to less than (5.6% and 6.0%) and (12% and 1.6%) for channels (1, 2) of HD 189733b and HD 209458b, respectively.

Keywords: exoplanet atmospheres; exoplanet atmospheric variability; exoplanet astronomy; exoplanet structure
Flares, Jets, and Quasiperiodic Outbursts from Neutron Star Merger Remnants

Using numerical relativity simulations with a subgrid dynamo prescription to generate strong initial magnetic fields, we investigate the possibility of launching a jet-like outflow from the hypermassive neutron star (HMNS) during the early stages of the merger, prior to the remnant's collapse to a black hole. We demonstrate that buoyant instabilities in the strongly magnetized HMNS can lead to a periodic emission of powerful electromagnetic flares shortly after the merger. These are followed by a collimated mildly relativistic outflow. Both types of outflows feature quasiperiodic kilohertz substructure. These early-time outflows may power precursors to short-duration gamma-ray bursts (sGRBs) or in some cases the entire sGRB. While the overall temporal power spectrum we find broadly agrees with the one recently reported for quasiperiodic oscillations in the sGRB GRB910711, our simulations suggest that the periodic electromagnetic substructure is dominated by magnetohydrodynamic shearing processes rather than correlating with the corresponding postmerger gravitational-wave signal.

Keywords: gamma-ray bursts; neutron stars; gravitational waves; magnetohydrodynamical simulations; stellar flares; asteroseismology
A Spectroscopic Survey of Infrared 1-4 μm Spectra in Regions of Prominent Solar Coronal Emission Lines of Fe XIII, Si X, and Si IX

The infrared solar spectrum contains a wealth of physical data about the Sun and is being explored using modern detectors and technology with new ground-based solar telescopes. One such instrument will be the ground-based Cryogenic Near-IR Spectro-Polarimeter of the Daniel K. Inouye Solar Telescope (DKIST), which will be capable of sensitive imaging of the faint infrared solar coronal spectra with full Stokes I, Q, U, and V polarization states. Highly ionized magnetic dipole emission lines have been observed in galaxies and the solar corona. Quantifying the accuracy of spectral inversion procedures requires a precise spectroscopic calibration of observations. A careful interpretation of the spectra around prominent magnetic dipole lines is essential for deriving physical parameters and particularly for quantifying the off-limb solar coronal observations from DKIST. In this work, we aim to provide an analysis of the spectral regions around the infrared coronal emission lines of Fe XIII 1074.68 nm, Fe XIII 1079.79 nm, Si X 1430.10 nm, and Si IX 3934.34 nm, aligning with the goal of identifying solar photospheric and telluric lines that will help facilitate production of reliable inversions and data products from four sets of solar coronal observations. The outputs can be integrated in processing pipelines to produce level 2 science-ready data.

Keywords: solar corona; solar coronal lines; spectroscopy; galaxy spectroscopy; astronomy data analysis
After DART: Using the First Full-scale Test of a Kinetic Impactor to Inform a Future Planetary Defense Mission

NASA's Double Asteroid Redirection Test (DART) is the first full-scale test of an asteroid deflection technology. Results from the hypervelocity kinetic impact and Earth-based observations, coupled with LICIACube and the later Hera mission, will result in measurement of the momentum transfer efficiency accurate to ~10% and characterization of the Didymos binary system. But DART is a single experiment; how could these results be used in a future planetary defense necessity involving a different asteroid? We examine what aspects of Dimorphos's response to kinetic impact will be constrained by DART results; how these constraints will help refine knowledge of the physical properties of asteroidal materials and predictive power of impact simulations; what information about a potential Earth impactor could be acquired before a deflection effort; and how design of a deflection mission should be informed by this understanding. We generalize the momentum enhancement factor β, showing that a particular direction-specific β will be directly determined by the DART results, and that a related direction-specific β is a figure of merit for a kinetic impact mission. The DART β determination constrains the ejecta momentum vector, which, with hydrodynamic simulations, constrains the physical properties of Dimorphos's near-surface. In a hypothetical planetary defense exigency, extrapolating these constraints to a newly discovered asteroid will require Earth-based observations and benefit from in situ reconnaissance. We show representative predictions for momentum transfer based on different levels of reconnaissance and discuss strategic targeting to optimize the deflection and reduce the risk of a counterproductive deflection in the wrong direction.

Keywords: asteroids; near-earth objects; asteroid satellites; asteroid surfaces; impact phenomena
Statistical Recovery of 21 cm Visibilities and Their Power Spectra with Gaussian-constrained Realizations and Gibbs Sampling

Radio interferometers designed to probe the 21 cm signal from Cosmic Dawn and the Epoch of Reionization must contend with systematic effects that make it difficult to achieve sufficient dynamic range to separate the 21 cm signal from foreground emission and other effects. For instance, the instrument's chromatic response modulates the otherwise spectrally smooth foregrounds, making them difficult to model, while a significant fraction of the data must be excised due to the presence of radio-frequency interference, leaving gaps in the data. Errors in modeling the (modulated and gappy) foregrounds can easily generate spurious contamination of what should otherwise be 21 cm signal-dominated modes. Various approaches have been developed to mitigate these issues by, for example, using nonparametric reconstruction of the foregrounds, in-painting the gaps, and weighting the data to reduce the level of contamination. We present a Bayesian statistical method that combines these approaches, using the coupled techniques of Gaussian-constrained realizations and Gibbs sampling. This provides a way of drawing samples from the joint posterior distribution of the 21 cm signal modes and their power spectrum in the presence of gappy data and an uncertain foreground model in a computationally scalable manner. The data are weighted by an inverse covariance matrix that is estimated as part of the inference, along with a foreground model that can then be marginalized over. We demonstrate the application of this technique on a simulated Hydrogen Epoch of Reionization Array-like delay spectrum analysis, comparing three different approaches for accounting for the foreground components.

Keywords: bayesian statistics; reionization; interferometry
QLP Data Release Notes 003: GPU-based Transit Search

The Quick-Look Pipeline (QLP; Huang et al. 2020; Kunimoto et al. 2021, and references therein) searches for transit signals in the multi-sector light curves of several hundreds of thousand stars observed by TESS every 27.4 day sector. The computational expense of the planet search has grown considerably over time, especially as the TESS observing baseline continues to increase in the second Extended Mission. Starting in Sector 59, QLP has switched to a significantly faster GPU-based transit search capable of searching an entire sector in only ~1 day. We describe its implementation and performance.

Keywords: exoplanets; exoplanet detection methods; transit photometry; time series analysis
Understanding the Phase Reversals of Galactic Cosmic-Ray Anisotropies

Energy spectra and anisotropies are very important probes of the origin of cosmic rays. Recent measurements show that complicated but very interesting structures exist at similar energies in both the spectra and energy-dependent anisotropies, indicating a common origin of these structures. A particularly interesting phenomenon is that there is a reversal of the phase of the dipole anisotropies, which challenges theoretical modeling. In this work, for the first time, we identify that there might be an additional phase reversal at ~100 GeV energies of the dipole anisotropies as indicated by a few underground muon detectors and the first direct measurement by the Fermi satellite, coincident with the hundreds of GV hardening of the spectra. We propose that these two phase reversals, together with the energy evolution of the amplitudes and spectra, can be naturally explained with a nearby source overlapping onto the diffuse background. As a consequence, the spectra and anisotropies can be understood as the scalar and vector components of this model, and the two reversals of the phases characterize just the competition of the cosmic-ray streamings between the nearby source and the background. The alignment of the cosmic-ray streamings along the local large-scale magnetic field may play an important but subdominant role in regulating the cosmic-ray propagation. More precise measurements of the anisotropy evolution at both low energies by space detectors and high energies by air shower experiments for individual species will be essential to further test this scenario.

Keywords: cosmic rays; cosmic anisotropy; supernova remnants
Measurements of the Crab Pulsar's Giant Radio Pulse Amplitude Power-law Index Using Low-frequency Arecibo and Green Bank Telescope Observations

We report two low-frequency measurements of the power-law index for the amplitudes of giant radio pulses from the Crab pulsar. The two observations were taken with the Arecibo and Green Bank radio telescopes at center frequencies of 327 MHz and 350 MHz, respectively. We find best-fit values for the differential power-law index β (where ${dN}/{dS}\propto {S}^{\beta }$ and S is the pulse amplitude) of -2.63 ± 0.05 and -3.6 ± 0.5 from the Arecibo and Green Bank data sets, respectively. Both values are broadly consistent with other values previously measured for the Crab pulsar at low radio frequencies. These reported values may be useful in future giant pulse studies of the Crab pulsar.

Keywords: pulsars; radio transient sources
Constraints on Coasting Cosmological Models from Gravitational-wave Standard Sirens

We present the first test of coasting cosmological models with gravitational-wave (GW) standard sirens observed in the first three observing runs of the LIGO-Virgo-KAGRA detector network. We apply the statistical galaxy catalog method adapted to coasting cosmologies and infer constraints on the H 0 Hubble constant for the three fixed values of the curvature parameter $k=\left\{-1,0,+1\right\}$ in ${H}_{0}^{2}{c}^{-2}$ units. The maximum posteriors and 68.3% highest density intervals we obtained from a combined analysis of 46 dark siren detections and a single bright siren detection are ${H}_{0}=\left\{{68.1}_{-5.6}^{+8.5},{67.5}_{-5.2}^{+8.3},{67.1}_{-5.8}^{+6.6}\right\}\,\mathrm{km}\ {{\rm{s}}}^{-1}\ {\mathrm{Mpc}}^{-1}$ , respectively. All our constraints on H 0 are consistent within 1σ with the H 0 measured with the differential age method, which provides a constraint on H 0 in coasting cosmologies independently from k. Our results constrain all cosmological models with a(t) ∝ t linear expansion in the luminosity distance and redshift range of the 47 LIGO-Virgo detections, i.e., d L ≲ 5Gpc and z ≲ 0.8, which practically include all (both strictly linear and quasi-linear) models in the coasting model family. As we have found, the coasting models and the Lambda cold dark matter (or ΛCDM) model fit equally well to the applied set of GW detections.

Keywords: gravitational wave astronomy; cosmology; observational cosmology; hubble constant
Stellar and Accretion Disk Parameters of the Close Binary HD 50526

We present a photometric and spectroscopic study of HD 50526, an ellipsoidal binary member of the group Double Periodic Variable stars. Performing data mining in photometric surveys and conducting new spectroscopic observations with several spectrographs during 2008-2015, we obtained orbital and stellar parameters of the system. The radial velocities were analyzed with the genetic PIKAIA algorithm, whereas Doppler tomography maps for the Hα and Hβ lines were constructed with the Total Variation Minimization code. An optimized simplex algorithm was used to solve the inverse problem adjusting the light curve with the best stellar parameters for the system. We find an orbital period of 6.701d ± 0.001d and a long photometric cycle of 191 ± 2 days. We detected the spectral features of the coldest star and modeled it with a $\mathrm{log}g=2.79\pm 0.02\,\mathrm{dex}$ giant of mass 1.13 ± 0.02 M⊙ and effective temperature 10500 ± 125 K. In addition, we determine a mass ratio q = 0.206 ± 0.033 and that the hot star is a B-type dwarf of mass 5.48 ± 0.02 M⊙. The V-band orbital light curve can be modeled including the presence of an accretion disk around the hotter star. This fills the Roche lobe of the hotter star and has a radius 14.74 ± 0.02 R⊙ and the temperature at the outer edge is 9400 K. Two bright spots located in the disk account for the global morphology of the light curve. The Doppler tomography maps of Hα and Hβ reveal complex structures of mass fluxes in the system.

Keywords: close binary stars; semi-detached binary stars; spectroscopic binary stars; early-type stars; stellar mass loss
Galaxy Look-back Evolution Models: A Comparison with Magneticum Cosmological Simulations and Observations

We construct empirical models of star-forming galaxy evolution assuming that individual galaxies evolve along well-known scaling relations between stellar mass, gas mass, and star formation rate following a simple description of chemical evolution. We test these models by a comparison with observations and detailed Magneticum high-resolution hydrodynamic cosmological simulations. Galaxy star formation rates, stellar masses, gas masses, ages, interstellar medium, and stellar metallicities are compared. It is found that these simple look-back models capture many of the crucial aspects of galaxy evolution reasonably well. Their key assumption of a redshift-dependent power-law relationship between galaxy interstellar medium gas mass and stellar mass is in agreement with the outcome of the complex Magneticum simulations. Star formation rates decline toward lower redshift not because galaxies are running out of gas, but because the fraction of the cold interstellar medium gas, which is capable of producing stars, becomes significantly smaller. Gas accretion rates in both model approaches are of the same order of magnitude. Metallicity in the Magneticum simulations increases with the ratio of stellar mass to gas mass as predicted by the look-back models. The mass-metallicity relationships agree, and the star formation rate dependence of these relationships is also reproduced. We conclude that these simple models provide a powerful tool for constraining and interpreting more complex models based on cosmological simulations and for population synthesis studies analyzing the integrated spectra of stellar populations.

Keywords: d galaxies; galaxy evolution; metallicity; star formation; galaxy accretion
An Analytical Fourier Transformation Model for the Production of Hard and Soft X-Ray Time Lags in Active Galactic Nuclei: Application to 1H 0707-495

The variability of the X-ray emission from active galactic nuclei is often characterized using time lags observed between soft and hard energy bands in the detector. The time lags are usually computed using the complex cross-spectrum, which is based on the Fourier transforms of the hard and soft time series data. It has been noted that some active galactic nuclei display soft X-ray time lags, in addition to the more ubiquitous hard lags. Hard time lags are thought to be produced via propagating fluctuations, spatial reverberation, or via the thermal Comptonization of soft seed photons injected into a hot electron cloud. The physical origin of the soft lags has been a subject of debate over the last decade. Currently, the reverberation interpretation is recognized as a leading theory. In this paper, we explore the alternative possibility that the soft X-ray time lags result partially from the thermal and bulk Comptonization of monochromatic seed photons which, in the case of the narrow-line Seyfert 1 galaxy 1H 0707-495, may correlate with fluorescence of iron L-line emission. In our model, the seed photons are injected into a hot, quasi-spherical corona in the inner region of the accretion flow. We develop an exact, time-dependent analytical model for the thermal and bulk Comptonization of the seed photons based on a Fourier-transformed radiation transport equation, and we demonstrate that the model successfully reproduces both the hard and soft time lags observed from 1H 0707-495.

Keywords: high energy astrophysics; active galactic nuclei; accretion
Independent Validation of the Temperate Super-Earth HD 79211 b using HARPS-N

We present high-precision radial velocities (RVs) from the HARPS-N spectrograph for HD 79210 and HD 79211, two M0V members of a gravitationally bound binary system. We detect a planet candidate with a period of ${24.421}_{-0.017}^{+0.016}$ days around HD 79211 in these HARPS-N RVs, validating the planet candidate originally identified in CARMENES RV data alone. Using HARPS-N, CARMENES, and RVs spanning a total of 25 yr, we further refine the planet candidate parameters to P = 24.422 ± 0.014 days, K = 3.19 ± 0.27 m s-1, M sin i = 10.6 ± 1.2M ⊕, and a = 0.142 ± 0.005 au. We do not find any additional planet candidate signals in the data of HD 79211, nor do we find any planet candidate signals in HD 79210. This system adds to the number of exoplanets detected in binaries with M-dwarf members and serves as a case study for planet formation in stellar binaries.

Keywords: exoplanet detection methods; radial velocity; m dwarf stars; binary stars
SN 2017cfd: A Normal Type Ia Supernova Discovered Very Young

The Type Ia supernova (SN Ia) 2017cfd in IC 0511 (redshift z=0.01209 ± 0.00016) was discovered by the Lick Observatory Supernova Search 1.6 ± 0.7 day after the fitted first-light time (15.2 days before B-band maximum brightness). Photometric and spectroscopic follow-up observations show that SN 2017cfd is a typical, normal SN Ia with a peak luminosity MB ≈ -19.2± 0.2 mag, Δm15(B) = 1.16 mag, and reached a B-band maximum ∼16.8 days after the first light. We estimate there to be moderately strong host-galaxy extinction (AV = 0.39 ± 0.03 mag) based on MLCS2k2 fitting. The spectrum reveals a Si II λ6355 velocity of ∼11,200 km s-1 at peak brightness. SN 2017cfd was discovered very young, with multiband data taken starting 2 days after the first light, making it a valuable complement to the currently small sample (fewer than a dozen) of SNe Ia with color data at such early times. We find that its intrinsic early-time (B-V)0 color evolution belongs to the "blue" population rather than to the distinct "red" population. Using the photometry, we constrain the companion-star radius to be ≲2.5 R⊙ with the Kasen model, thus ruling out a red-giant companion.

Keywords: type ia supernovae
A Census of Archival X-Ray Spectra for Modeling Tidal Disruption Events

Tidal disruption events (TDEs) are highly energetic phenomena that occur when a star is tidally disrupted by the central massive black hole in a galaxy. Fitting the observed X-ray spectra of TDEs with a first-principles, general-relativistic slim-disk model for the emission from the inner accretion disk can constrain the black hole mass M • and dimensionless spin a •. Multiepoch spectra can break degeneracies in parameter estimation, particularly when they include a period of super-Eddington mass accretion. Even one observed super-Eddington epoch can be useful. Constraints on {M •, a •} improve as a power law with the number of spectral counts; the power-law index is higher for a higher mass accretion rate. These results are supported by the successful modeling of real spectra in the nearby (0.0206 ≤ z ≤ 0.145) TDEs ASASSN-14li, 3XMM J150052.0+015452, and 3XMM J215022.4-055108, which were observed over multiple epochs with >1 ks exposure times. Guided by these results, we create an updated and expanded TDE catalog from the Open TDE compilation. We then explore the XMM-Newton and Chandra archives to identify 37 TDE candidates with promising spectra for constraining {M •, a •} with slim-disk model fits. At least seven TDEs are likely associated with intermediate-mass black holes. Three of the 24 TDEs with multiepoch UV/optical photometry from Swift have late-time observations that allow their light curves to be compared directly to model predictions from the X-ray spectral fits. Existing X-ray spectra for other TDEs can be augmented with future optical/UV data. Ultimately, our new TDE catalog will reveal the {M •, a •} distributions traced by TDEs, thereby discriminating among black hole growth scenarios and providing insights on general relativity and dark matter particle candidates. The new TDE catalog is here: https://github.com/aarongoldtooth/Census-of-TDE-and-Archival-X-Ray-UV-Data/blob/main/Full%20New%20TDE%20Catalog%20(Published).tsv, and the codes used to construct it are here: https://github.com/aarongoldtooth/Census-of-TDE-and-Archival-X-Ray-UV-Data.

Keywords: astronomy databases; x-ray transient sources; ultraviolet transient sources; tidal disruption; intermediate-mass black holes; supermassive black holes