adsabs/SciX_UAT_keywords huggingface dataset:
Three-dimensional Distribution Map of H I Gas and Galaxies around an Enormous Lyα Nebula and Three QSOs at z = 2.3 Revealed by the H I Tomographic Mapping Technique

We present an IGM H I tomographic map in a survey volume of $16\times 19\times 131\ {h}^{-3}\ \mathrm{comoving}\ {\mathrm{Mpc}}^{3}$ (cMpc3) centered at MAMMOTH-1 nebula and three neighboring quasars at z = 2.3. The MAMMOTH-1 nebula is an enormous Lyα nebula (ELAN), hosted by a type-II quasar dubbed MAMMOTH1-QSO, that extends over $1\ {h}^{-1}$ cMpc with no clear physical origin. Here we investigate the H I-gas distribution around MAMMOTH1-QSO with the ELAN and three neighboring type-I quasars, making the IGM H I tomographic map with a spatial resolution of 2.6 h-1 cMpc. Our H I tomographic map is reconstructed with H I Lyα forest absorption of bright background objects at z = 2.4-2.9: one eBOSS quasar and 16 Keck/LRIS galaxy spectra. We estimate the radial profile of H I overdensity for MAMMOTH1-QSO, and find that MAMMOTH1-QSO resides in a volume with fairly weak H I absorption. This suggests that MAMMOTH1-QSO may have a proximity zone where quasar illuminates and photoionizes the surrounding H I gas and suppresses H I absorption, and that the ELAN is probably a photoionized cloud embedded in the cosmic web. The H I radial profile of MAMMOTH1-QSO is very similar to those of three neighboring type-I quasars at z = 2.3, which is compatible with the AGN unification model. We compare the distributions of the H I absorption and star-forming galaxies in our survey volume, and identify a spatial offset between density peaks of star-forming galaxies and H I gas. This segregation may suggest anisotropic UV background radiation created by star-forming galaxy density fluctuations.

Keywords: galaxy formation; intergalactic medium; large-scale structure of the universe
Application of Synoptic Magnetograms to Global Solar Activity Forecast

Synoptic magnetograms provide us with knowledge about the evolution of magnetic fields on the solar surface and present important information for forecasting future solar activity. In this work, poloidal and toroidal magnetic field components derived from synoptic magnetograms are assimilated, using the Ensemble Kalman Filter method, into a mean-field dynamo model based on Parker's migratory dynamo theory complemented by magnetic helicity conservation. It was found that the predicted toroidal field is in good agreement with observations for almost the entire following solar cycle. However, poloidal field predictions agree with observations only for the first 2-3 yr of the predicted cycle. The results indicate that the upcoming Solar Maximum of Cycle 25 (SC25) is expected to be weaker than the current Cycle 24. The model results show that a deep extended solar activity minimum is expected during 2019-2021, and that the next solar maximum will occur in 2024-2025. The sunspot number at the maximum will be about 50 with an error estimate of 15%-30%. The maximum will likely have a double peak or show extended periods (for 2-2.5 yr) of high activity. According to the hemispheric prediction results, SC25 will start in 2020 in the southern hemisphere, and will have a maximum in 2024 with a sunspot number of about 28. In the northern hemisphere the cycle will be delayed for about 1 yr (with an error of ±0.5 yr), and reach a maximum in 2025 with a sunspot number of about 23.

Keywords: solar cycle; solar activity; solar magnetic fields; solar dynamo; sunspot cycle
Physical Properties of Type II Supernovae Inferred from ZTF and ATLAS Photometric Data

We report an analysis of a sample of 186 spectroscopically confirmed Type II supernova (SN) light curves (LCs) obtained from a combination of Zwicky Transient Facility (ZTF) and Asteroid Terrestrial-impact Last Alert System observations. We implement a method to infer physical parameters from these LCs using hydrodynamic models that take into account the progenitor mass, the explosion energy, and the presence of circumstellar matter (CSM). The CSM is modeled via the mass-loss rate, wind acceleration at the surface of the progenitor star with a β velocity law, and the CSM radius. We also infer the time of explosion, attenuation (A V ), and the redshift for each SN. Our results favor low-mass progenitor stars (M ZAMS < 14 M ⊙) with a dense CSM ( > 10‑3 M ⊙ yr‑1, CSM radius ∼ 1015 cm, and β > 2). Additionally, we find that the redshifts inferred from the SN LCs are significantly more accurate than those inferred using the host galaxy photometric redshift, suggesting that this method could be used to infer more accurate host galaxy redshifts from large samples of Type II SNe in the LSST era. Lastly, we compare our results with similar works from the literature.

Keywords: type ii supernovae; core-collapse supernovae; surveys; supernovae; astronomy data analysis; markov chain monte carlo
Retrievals of Protoplanetary Disk Parameters Using Thermochemical Models. I. Disk Gas Mass from Hydrogen Deuteride Spectroscopy

We discuss statistical relationships between the mass of protoplanetary disks, the hydrogen deuteride (HD) line flux, and the dust spectral energy distribution (SED) determined using 3000 ProDiMo disk models. The models have 15 free parameters describing the disk physical properties, the central star, and the local radiation field. The sampling of physical parameters is done using a Monte Carlo approach to evaluate the probability density functions of observables as a function of physical parameters. We find that the mass-averaged HD fractional abundance is almost constant even though the ultraviolet flux varies by several orders of magnitude. Probing the statistical relation between the physical quantities and the HD flux, we find that low-mass (optically thin) disks display a tight correlation between the average disk gas temperature and HD line flux, while massive disks show no such correlation. We demonstrate that the central star luminosity, disk size, dust size distribution, and HD flux may be used to determine the disk gas mass within a factor of 3. We also find that the far-infrared and submillimeter/millimeter SEDs and the HD flux may serve as strong constraints for determining the disk gas mass to within a factor of 2. If the HD lines are fully spectrally resolved (R ≳ 1.5 × 106, Δv = 0.2 km s‑1), the 56 and 112 μm HD line profiles alone may constrain the disk gas mass to within a factor of 2.

Keywords: planet formation; chemical abundances; astrochemistry; far infrared astronomy
A Cacophony of Echoes from Daily Monitoring of the Crab Pulsar at Jodrell Bank

Using archival data from the 42-foot telescope at the Jodrell Bank Observatory, we produce daily stacks of aligned giant pulses for the Crab pulsar, to study changes to the daily profiles between 2012 April and 2016 December. From these, we identify echoes, where intervening material away from the line of sight causes pulsed emission to be redirected toward the observer, with delay corresponding to the increased distance of travel, resulting in additional profile components. These observations show that such echoes may be far more common than implied by the previous rate of detections. All the observed echoes are consistent with approaching zero delay at their closest approach to the normal giant pulse emission. This indicates that the structures responsible for producing these events must be highly anisotropic, with typical lengths greater than ∼4 au, typical widths on the sky of ∼0.1 au, and typical depths of ∼5 au, given the previously observed electron densities of the nebular filaments, on the order of 1000 cm‑3. This suggests that these inhomogeneities are likely to be offshoot substructure from the larger nebular filaments of the Crab nebula.

Keywords: pulsars; radio bursts; interstellar scattering; pulsar wind nebulae
Probing the Structure and Evolution of BASS Active Galactic Nuclei through Eddington Ratios

We constrain the intrinsic Eddington ratio (λ Edd) distribution function for local active galactic nuclei (AGN) in bins of low and high obscuration $[\mathrm{log}({N}_{{\rm{H}}}/{\mathrm{cm}}^{-2})\leqslant 22$ and $22\lt \mathrm{log}({N}_{{\rm{H}}}/{\mathrm{cm}}^{-2})\lt 25$ ], using the Swift Burst Alert Telescope 70 month/BASS DR2 survey. We interpret the fraction of obscured AGN in terms of circumnuclear geometry and temporal evolution. Specifically, at low Eddington ratios ( $\mathrm{log}\,{\lambda }_{\mathrm{Edd}}\,\lt \,$ -2), obscured AGN outnumber unobscured ones by a factor of ~4, reflecting the covering factor of the circumnuclear material (0.8, or a torus opening angle of ~34°). At high Eddington ratios ( $\mathrm{log}\,{\lambda }_{\mathrm{Edd}}\,\gt \,$ -1), the trend is reversed, with <30% of AGN having $\mathrm{log}({N}_{{\rm{H}}}/{\mathrm{cm}}^{-2})\gt 22$ , which we suggest is mainly due to the small fraction of time spent in a highly obscured state. Considering the Eddington ratio distribution function of narrow-line and broad-line AGN from our prior work, we see a qualitatively similar picture. To disentangle temporal and geometric effects at high λ Edd, we explore plausible clearing scenarios such that the time-weighted covering factors agree with the observed population ratio. We find that the low fraction of obscured AGN at high λ Edd is primarily due to the fact that the covering factor drops very rapidly, with more than half the time spent with <10% covering factor. We also find that nearly all obscured AGN at high-λ Edd exhibit some broad lines. We suggest that this is because the height of the depleted torus falls below the height of the broad-line region, making the latter visible from all lines of sight.

Keywords: active galactic nuclei; supermassive black holes; x-ray surveys; astronomy data modeling; astronomical models; x-ray active galactic nuclei; luminosity function; accretion
EXPRES. II. Searching for Planets around Active Stars: A Case Study of HD 101501

By controlling instrumental errors to below 10 cm s-1, the EXtreme PREcision Spectrograph (EXPRES) allows for a more insightful study of photospheric velocities that can mask weak Keplerian signals. Gaussian processes (GP) have become a standard tool for modeling correlated noise in radial velocity data sets. While GPs are constrained and motivated by physical properties of the star, in some cases they are still flexible enough to absorb unresolved Keplerian signals. We apply GP regression to EXPRES radial velocity measurements of the 3.5 Gyr old chromospherically active Sun-like star, HD 101501. We obtain tight constraints on the stellar rotation period and the evolution of spot distributions using 28 seasons of ground-based photometry, as well as recent Transiting Exoplanet Survey Satellite data. Light-curve inversion was carried out on both photometry data sets to reveal the spot distribution and spot evolution timescales on the star. We find that the >5 m s-1 rms radial velocity variations in HD 101501 are well modeled with a GP stellar activity model without planets, yielding a residual rms scatter of 45 cm s-1. We carry out simulations, injecting and recovering signals with the GP framework, to demonstrate that high-cadence observations are required to use GPs most efficiently to detect low-mass planets around active stars like HD 101501. Sparse sampling prevents GPs from learning the correlated noise structure and can allow it to absorb prospective Keplerian signals. We quantify the moderate to high-cadence monitoring that provides the necessary information to disentangle photospheric features using GPs and to detect planets around active stars.

Keywords: exoplanet detection methods; radial velocity; gaussian processes regression
Anomalous Hα Emission Line Profile Detected at the Center of DDO 53

We present the detection of a very broad (FWHM = 670 ± 17 km s-1), low-intensity Hα emission line component near the center of DDO 53, a star-forming dwarf irregular galaxy located in the M81 group. The broad component is found at the base of a bright and narrow (FWHM = 38 ± 2 km s-1) component. Using WIYN/Sparsepak optical spectroscopy of the region in addition to multiwavelength archival data, we evaluate the plausibility of several candidate sources, and find that stellar winds from embedded young stars are the most likely origin. However, this result is surprising for such a faint H II region.

Keywords: interstellar medium; stellar wind bubbles; dwarf irregular galaxies; wolf-rayet stars; stellar feedback
The Pantheon+ Analysis: SuperCal-fragilistic Cross Calibration, Retrained SALT2 Light-curve Model, and Calibration Systematic Uncertainty

We present a recalibration of the photometric systems in the Pantheon+ sample of Type Ia supernovae (SNe Ia) including those in the SH0ES distance-ladder measurement of H 0. We utilize the large and uniform sky coverage of the public Pan-STARRS stellar photometry catalog to cross calibrate against tertiary standards released by individual SN Ia surveys. The most significant updates over the "SuperCal" cross calibration used for the previous Pantheon and SH0ES analyses are: (1) expansion of the number of photometric systems (now 25) and filters (now 105), (2) solving for all filter offsets in all systems simultaneously to produce a calibration uncertainty covariance matrix for cosmological-model constraints, and (3) accounting for the change in the fundamental flux calibration of the Hubble Space Telescope CALSPEC standards from previous versions on the order of 1.5% over a Δλ of 4000 Å. We retrain the SALT2 model and find that our new model coupled with the new calibration of the light curves themselves causes a net distance modulus change (d μ/dz) of 0.04 mag over the redshift range 0 < z < 1. We introduce a new formalism to determine the systematic impact on cosmological inference by propagating the covariance in the fitted calibration offsets through retraining simultaneously with light-curve fitting and find a total calibration uncertainty impact of σ w = 0.013; roughly half the size of the sample statistical uncertainty. Similarly, we find the systematic SN calibration contribution to the SH0ES H 0 uncertainty is less than 0.2 km s-1 Mpc-1, suggesting that SN Ia calibration cannot resolve the current level of the "Hubble Tension."

Keywords: catalogs; type ia supernovae; flux calibration; dark energy; dark matter; cosmology
The Formation of a U-shaped Filament Due to the Successive Magnetic Reconnection between a Filament and Its Nearby Chromospheric Fibrils

Although magnetic reconnection plays a key role in the formation of a solar filament, the detailed formation process is still ambiguous. Combining the observational data from the New Vacuum Solar Telescope and the Solar Dynamics Observatory, we analyzed the formation of a U-shaped filament via successive magnetic reconnection in the AR NOAA 11598 on 2012 October 25. The successive reconnection occurred between a filament (F) and its nearby chromospheric fibrils (CF). The associated brightening and magnetic cancellation were observed. The changes in appearance of the CF at the reconnection site were accompanied by the formation and accumulation of some new magnetic loops, as well as plasmas propagated along the formed magnetic loops from the reconnection site, indicating the changes in the topology of the F and CF. These can provide comprehensive observational evidence for successive reconnection. After the reconnection, a longer U-shaped filament was formed. During the formation of the U-shaped filament, two major magnetic energy releases took place. While in the two energy release processes, the injected plasma from the reconnection site can provide part of the material for the formation of the U-shaped filament. Therefore, we conclude that the successive reconnection results in both the dynamical evolution and the subsequent formation associated with the U-shaped filament. And the results of nonlinear force-free field extrapolation demonstrated that the magnetic topology of the F was changed significantly; this is consistent with the observational results and further confirms the formation of the U-shaped filament.

Keywords: solar active regions; solar filaments; solar magnetic reconnection
False Alarms Revealed in a Planet Search of TESS Light Curves

In this paper, we investigate the impact of false alarms on planet searches of TESS data by performing a search of a large number of stars. We examine the period distribution of transit-like signatures uncovered in a Box-Least Squares transit search of TESS light curves, and show significant pileups at periods related to instrumental and astrophysical noise sources. Signatures uncovered in a search of inverted light curves feature similar structures in the period distribution. Automated vetting methods will need to remove these excess detections, and light curve inversion appears to be a suitable method for simulating false alarms and designing new vetting metrics. Automated vetting will be a significant step toward making TESS data useful for demographic studies.

Keywords: exoplanets; transit photometry
Delivery of Dust Particles from Protoplanetary Disks onto Circumplanetary Disks of Giant Planets

The principal regular satellites of gas giants are thought to be formed by the accumulation of solid materials in circumplanetary disks (CPDs). While there has been significant progress in the study of satellite formation in CPDs, details of the supply of satellite building blocks to CPDs remain unclear. We perform the orbital integration of solid particles in the protoplanetary disk (PPD) approaching a planet, considering the gas drag force by using the results of three-dimensional hydrodynamical simulations of a local region around the planet. We investigate the planetary mass dependence of the capture positions and the capture rates of dust particles accreting onto the CPD. We also examine the degree of dust retention in the accreting gas onto the CPD, which is important for determining the ratio of the dust-to-gas inflow rates, a key parameter in satellite formation. We find that the degree of dust retention increases with increasing planetary mass for a given dust scale height in the PPD. In the case of a small planet (M p = 0.2M Jup), most particles with insufficient initial altitudes in the PPD are isolated from the gas in the accreting region. On the other hand, in the case of a massive planet (M p = 1M Jup), dust particles can be coupled to the vertically accreting gas, even when the dust scale height is about 10%–30% of the gas scale height. The results of this study can be used for models of dust delivery and satellite formation in the CPDs of gas giants of various masses, including exoplanets.

Keywords: planet formation; galilean satellites; jovian satellites
Revised Architecture and Two New Super-Earths in the HD 134606 Planetary System

Multiplanet systems exhibit a diversity of architectures that diverge from the solar system and contribute to the topic of exoplanet demographics. Radial velocity (RV) surveys form a crucial component of exoplanet surveys, as their long observational baselines allow for searches for more distant planetary orbits. This work provides a significantly revised architecture for the multiplanet system HD 134606 using both HARPS and UCLES RVs. We confirm the presence of previously reported planets b, c, and d with periods of ${12.0897}_{-0.0018}^{+0.0019}$ , ${58.947}_{-0.054}^{+0.056}$ , and ${958.7}_{-5.9}^{+6.3}$ days and masses of ${9.14}_{-0.63}^{+0.65}$ , 11.0 ± 1, and 44.5 ± 2.9 Earth masses, respectively, with the planet d orbit significantly revised to over double that originally reported. We report two newly detected super-Earths, e and f, with periods of ${4.31943}_{-0.00068}^{+0.00075}$ and ${26.9}_{-0.017}^{+0.019}$ days and masses of ${2.31}_{-0.35}^{+0.36}$ and ${5.52}_{-0.73}^{+0.74}$ Earth masses, respectively. In addition, we identify a linear trend in the RV time series, and the cause of this acceleration is deemed to be a newly detected massive companion with a very long orbital period. HD 134606 now displays four low-mass planets in a compact region near the star, one gas giant further out in the habitable zone, an additional companion in the outer regime, and a low-mass M dwarf stellar companion at large separation, making it an intriguing target for system formation/evolution studies. The location of planet d in the habitable zone proves to be an exciting candidate for future space-based direct imaging missions, whereas continued RV observations of this system are recommended for understanding the nature of the massive, long-period companion.

Keywords: exoplanets; exoplanet detection methods; exoplanet dynamics; exoplanet systems; radial velocity; photometry; high contrast techniques; astrometry; orbits; stellar activity
Identifying Exo-Earth Candidates in Direct Imaging Data through Bayesian Classification

Future space telescopes may be able to directly image between approximately 10 and 100 planets with sizes and orbits consistent with habitable surface conditions (“exo-Earth candidates” or EECs), but observers will face difficulty in distinguishing these from the potentially hundreds of nonhabitable “false positives” which will also be detected. To maximize the efficiency of follow-up observations, a prioritization scheme must be developed to determine which planets are most likely to be EECs. In this paper, we present a Bayesian method for estimating the likelihood that any directly imaged extrasolar planet is a true EEC by interpreting the planet’s apparent magnitude and separation in the context of existing exoplanet statistics. As a specific application of this general framework, we use published estimates of the discovery yield of future space-based direct-imaging mission concepts to conduct “mock surveys” in which we compute the likelihood that each detected planet is an EEC. We find that it will be difficult to determine which planets are EECs with >50% confidence using single-band photometry immediately upon their detection. The best way to reduce this ambiguity would be to constrain the orbit of a given planet by revisiting the system multiple times or through a radial velocity precursor survey. Astrometric or radial velocity constraints on the mass of the planet would offer a lesser benefit. Finally, we show that a Bayesian approach to prioritizing targets would improve the follow-up efficiency of a direct imaging survey versus a blind approach using the same data. For example, the prioritized approach could reduce the amount of integration time required for the spectral detection (or rejection) of water absorption in most EECs by a factor of two.

Keywords: direct imaging; habitable planets; astronomical techniques; bayesian statistics; space telescopes; astrobiology