adsabs/SciX_UAT_keywords huggingface dataset:
Phase-curve Pollution of Exoplanet Transit Depths

The next generation of space telescopes will enable transformative science to understand the nature and origin of exoplanets. In particular, transit spectroscopy will reveal the chemical composition of the exoplanet atmospheres with unprecedented detail thanks to precise measurements of the visible-to-infrared transit depths down to 10 parts per million. Such a level of instrumental precision raises the challenge to obtain even more precise astrophysical models so as not to significantly influence the interpretation of the observed data. We must therefore critically revisit some of the commonly accepted assumptions that were adequate for analyzing past and current observations. A common approximation in the analysis of exoplanetary primary transits is that the planet does not contribute to the recorded flux, so-called dark planet hypothesis. In this paper, we investigate the impact of the dark planet hypothesis on the parameters obtained from the analysis of transits with particular attention to the transit depth. We develop mathematical formulae and release new software to estimate the magnitude of the potential bias. These tools will be useful in the preparation of observing proposals, as well as within the scientific consortia of the James Webb Space Telescope (JWST) and the Atmospheric Remote-sensing Infrared Exoplanet Large-survey (ARIEL) missions. We probe the accuracy of the mathematical formulae through the analysis of synthetic observations with the JWST Mid-InfraRed Instrument. We find that self-blending from nightside emission attenuates the transit depth by >3σ for some of the known exoplanet systems, in agreement with previous work. An additional unreported effect caused by the nightside rotating into view can also impart a significant effect, but in the opposite direction (increasing the transit depth); this effect can largely be removed with conventional detrending practices, at the expense of a slight increase in noise, and mixing astrophysical variations and instrumental drifts.

Keywords: exoplanet systems; transit photometry; exoplanet atmospheres; high time resolution astrophysics; observational astronomy; exoplanets; astronomical instrumentation; infrared photometry
The Mass of the Large Magellanic Cloud from the Three-dimensional Kinematics of Its Globular Clusters

We estimate the mass of the Large Magellanic Cloud (LMC) using the kinematics of 30 LMC globular clusters (GCs). We combine proper motions measured with the Hubble Space Telescope, Gaia, or a combination of the two, from a recent study by Bennet et al. with literature line-of-sight velocities (LOSVs) to give three components of motion. With these, we derive a 3D velocity dispersion anisotropy $\beta =-{0.72}_{-1.07}^{+0.62}$ , consistent with the GCs forming a flattened system with significant azimuthal motion. We then apply a tracer mass estimator and measure an enclosed mass $M(\lt 13.2\,\mathrm{kpc})={2.66}_{-0.36}^{+0.42}\times {10}^{10}$ M ⊙. This is broadly consistent with results from previous studies of the LOSVs of GCs and other luminous tracers. Assuming a cosmologically constrained Navarro–Frenk–White distribution for the dark matter, this implies a virial mass ${M}_{\mathrm{virial}}={1.80}_{-0.54}^{+1.05}\times {10}^{11}$ M ⊙. Despite being an extrapolation by almost an order of magnitude in radius, this result is consistent with published estimates from other methods that are directly sensitive to the LMC's total mass. Our results support the conclusion that the LMC is approximately ${17}_{-6}^{+10}$ % of the Milky Way's mass, making it a significant contributor to the Local Group potential.

Keywords: large magellanic cloud; galaxy masses; galaxy mass distribution; galaxy dynamics; galaxy kinematics
Redox Hysteresis of Super-Earth Exoplanets from Magma Ocean Circulation

Internal redox reactions may irreversibly alter the mantle composition and volatile inventory of terrestrial and super-Earth exoplanets and affect the prospects for atmospheric observations. The global efficacy of these mechanisms, however, hinges on the transfer of reduced iron from the molten silicate mantle to the metal core. Scaling analysis indicates that turbulent diffusion in the internal magma oceans of sub-Neptunes can kinetically entrain liquid iron droplets and quench core formation. This suggests that the chemical equilibration between core, mantle, and atmosphere may be energetically limited by convective overturn in the magma flow. Hence, molten super-Earths possibly retain a compositional memory of their accretion path. Redox control by magma ocean circulation is positively correlated with planetary heat flow, internal gravity, and planet size. The presence and speciation of remanent atmospheres, surface mineralogy, and core mass fraction of primary envelope-stripped exoplanets may thus constrain magma ocean dynamics.

Keywords: extrasolar rocky planets; super earths; planetary interior; exoplanet atmospheres; exoplanet surfaces
Unveiling the Solution to the Final-parsec Problem by Combining Millihertz Gravitational-wave Observation and Active Galactic Nucleus Survey

Massive black hole binaries (MBHBs) could be the loudest gravitational-wave (GW) sources in the millihertz (mHz) GW band, but their dynamical evolution may stall when the black holes reach the innermost parsec of a galaxy. Such a "final-parsec problem" could be solved if an MBHB forms in a gas-rich environment, such as an active galactic nucleus (AGN), but other solutions not involving AGNs also exist. Testing the correlation between these mHz GW sources and AGNs is difficult in real observation because AGNs are ubiquitous. To overcome this difficulty, we use a statistical method, first designed to constrain the host galaxies of stellar-mass binary black holes, to search for the MBHB-AGN correlation in different astrophysical scenarios. We find that by detecting only one MBHB at z ≲ 0.5, a mHz GW detector, such as the Laser Interferometer Space Antenna, can already distinguish different merger scenarios thanks to the precise localization of the source. Future detector networks and deeper AGNs surveys can further testify to the MBHB-AGN correlation up to a redshift of z ~ 2 even if only a small fraction of MBHBs merge inside AGNs. These constraints will help settle the long-standing debate on the possible solutions to the final-parsec problem.

Keywords: gravitational waves; supermassive black holes; active galactic nuclei; surveys; poisson distribution
India's First Robotic Eye for Time-domain Astrophysics: The GROWTH-India Telescope

We present the design and performance of the GROWTH-India telescope, a 0.7 m robotic telescope dedicated to time-domain astronomy. The telescope is equipped with a 4k back-illuminated camera that gives a 0.°82 field of view and a sensitivity of m g' ~ 20.5 in 5 minute exposures. Custom software handles observatory operations: attaining high on-sky observing efficiencies (≳80%) and allowing rapid response to targets of opportunity. The data processing pipelines are capable of performing point-spread function photometry as well as image subtraction for transient searches. We also present an overview of the GROWTH-India telescope's contributions to the studies of gamma-ray bursts, the electromagnetic counterparts to gravitational wave sources, supernovae, novae, and solar system objects.

Keywords: astronomical instrumentation; astronomical detectors; automated telescopes; ccd photometry; optical observatories; optical astronomy; time domain astronomy
Symmetries of CMB Temperature Correlation at Large Angular Separations

A new analysis is presented of the angular correlation function C(Θ) of cosmic microwave background temperature at large angular separation, based on published maps derived from Wilkinson Microwave Anisotropy Probe and Planck satellite data, using different models of astrophysical foregrounds. It is found that using a common analysis, the results from the two satellites are very similar. In particular, it is found that previously published differences between measured values of C(Θ) near Θ = 90° arise mainly from different choices of masks in regions of largest Galactic emissions, and that demonstrated measurement biases are reduced by eliminating masks altogether. Maps from both satellites are shown to agree with C(90°) = 0 to within estimated statistical and systematic errors, consistent with an exact symmetry predicted in a new holographic quantum model of inflation.

Keywords: cosmic microwave background radiation; cosmic inflation; quantum gravity; cosmic anisotropy
COOL-LAMPS. IV. A Sample of Bright Strongly Lensed Galaxies at 3 < z < 4

We report the discovery of five bright, strong gravitationally lensed galaxies at 3 < z < 4: COOL J0101+2055 (z = 3.459), COOL J0104-0757 (z = 3.480), COOL J0145+1018 (z = 3.310), COOL J0516-2208 (z = 3.549), and COOL J1356+0339 (z = 3.753). These galaxies have magnitudes of r AB, z AB < 21.81 mag and are lensed by galaxy clusters at 0.26 < z < 1. This sample nearly doubles the number of known bright lensed galaxies with extended arcs at 3 < z < 4. We characterize the lensed galaxies using ground-based grz/giy imaging and optical spectroscopy. We report model-based magnitudes and derive stellar masses, dust content, and star formation rates via stellar population synthesis modeling. Building lens models based on ground-based imaging, we estimate source magnifications ranging from ~29 to ~180. Combining these analyses, we derive demagnified stellar masses in the range ${\mathrm{log}}_{10}({M}_{* }/{M}_{\odot })\sim 9.69-10.75$ and star formation rates in the youngest age bin in the range ${\mathrm{log}}_{10}(\mathrm{SFR}/({M}_{\odot }\,{\mathrm{yr}}^{-1}))\sim 0.39-1.46$ , placing the sample galaxies on the massive end of the star-forming main sequence in this redshift interval. In addition, three of the five galaxies have strong Lyα emissions, offering unique opportunities to study Lyα emitters at high redshift in future work.

Keywords: strong gravitational lensing; high-redshift galaxies; spectral energy distribution; galaxy evolution
Robust RFI Excision for Pulsar Signals by a Novel Nonlinear M-type Estimator with an Application to Pulsar Timing

Radio frequency interference (RFI) mitigation for pulsar signals is a long perplexing issue in astrophysical measurements. Linear mitigation methods are often criticized for limited RFI excision range and weakness of RFI modeling. Meanwhile, thresholding methods (e.g., the SumThreshold) suffer from empirical factors. In our opinion, the main defect of the current status is the lack of a concise definition to distinguish signals from RFI with the aid of certain techniques, e.g., sparse representation. This point is the root cause of these problems and also forms our motivation. This paper aims to expand the excision range (e.g., the on-pulse and quasiperiodic RFI) and cut down some empirical factors. The main contribution is that we give a definition and derive a widely practicable nonlinear framework for RFI excision. This framework can overcome the susceptibility of the least-square criterion to RFI, and excise almost all types of RFI once and for all. A robust LnCosh criterion based nonlinear maximum likelihood-type (M-type) penalized smoothing estimator is introduced. The novelty is that this estimator is first embedded into the iterative shrinkage-thresholding algorithm (ISTA) and the fast ISTA. Nonlinearity highlights this method. Curvelet sparsity gives satisfying approximation for pulsar signals containing dispersion feature. Finally, useful signal details will be retrieved from the excision residual by a morphological component analysis. This method is applied to the time-frequency signals collected by the Nanshan 26 m Radio Telescope. The numerical experiments can persuasively prove that it has desired application prospects.

Keywords: radio pulsars; wavelet analysis; astronomy data modeling; astronomical techniques; algorithms; maximum likelihood estimation
High-energy Neutrino Constraints on Cosmic-Ray Reacceleration in Radio Halos of Massive Galaxy Clusters

A fraction of merging galaxy clusters host diffuse radio emission in their central region, termed a giant radio halo (GRH). The most promising mechanism of GRHs is the reacceleration of nonthermal electrons and positrons by merger-induced turbulence. However, the origin of these seed leptons has been under debate, and either protons or electrons can be primarily accelerated particles. In this work, we demonstrate that neutrinos can be used as a probe of physical processes in galaxy clusters and discuss possible constraints on the number of relativistic protons in the intracluster medium with the existing upper limits by IceCube. We calculate radio and neutrino emission from massive (>1014 M ⊙) galaxy clusters using the cluster population model of Nishiwaki & Asano. This model is compatible with the observed statistics of GRHs, and we find that the contribution of GRHs to the isotropic radio background observed with the ARCADE-2 experiment should be subdominant. Our fiducial model predicts the all-sky neutrino flux that is consistent with IceCube's upper limit from the stacking analysis. We also show that the neutrino upper limit gives meaningful constraints on the parameter space of the reacceleration model, such as the electron-to-proton ratio of the primary cosmic rays and the magnetic field; in particular, the secondary scenario, where the seed electrons mostly originate from inelastic pp collisions, can be constrained even in the presence of reacceleration.

Keywords: galaxy clusters
Operational Modeling of Heliospheric Space Weather for the Parker Solar Probe

The interpretation of multi-spacecraft heliospheric observations and three-dimensional reconstruction of the structured and evolving solar wind with propagating and interacting coronal mass ejections (CMEs) is a challenging task. Numerical simulations can provide global context and suggest what may and may not be observed. The Community Coordinated Modeling Center (CCMC) provides both mission science and space weather support to all heliospheric missions. Currently, this is realized by real-time simulations of the corotating and transient disturbances by the WSA-ENLIL-Cone model. We have simulated the heliospheric space weather relevant to the Parker Solar Probe (PSP) mission since 2018 September and provided numerical results to our colleagues analyzing in situ measurements published in the ApJS Special Issue. In this paper, we do not analyze PSP data, but we present recent updates in simulating the background solar wind and compare them with an existing operational model around the first PSP Perihelion, from 2018 October to 2018 December. We introduce new tools that assist in the interpretation of remote observations and in situ measurements useful for PSP and other missions, and for predicting heliospheric space weather. We also use this opportunity to evaluate recent improvements in the WSA and ADAPT-WSA coronal models that are being transitioned and considered to be transitioned, respectively, to operations. Finally, we simulate CME-like hydrodynamic ejecta with various parameters and calculated synthetic white-light images that can be used for “mid-course” correction of operational predictions.

Keywords: magnetohydrodynamical simulations; solar coronal mass ejections; solar wind; space weather
Is There an Earth-like Planet in the Distant Kuiper Belt?

The orbits of trans-Neptunian objects (TNOs) can indicate the existence of an undiscovered planet in the outer solar system. Here we used N-body computer simulations to investigate the effects of a hypothetical Kuiper Belt planet (KBP) on the orbital structure of TNOs in the distant Kuiper Belt beyond ~50 au. We used observations to constrain model results, including the well-characterized Outer Solar System Origins Survey (OSSOS). We determined that an Earth-like planet (m ~ 1.5-3 M ⊕) located on a distant (semimajor axis a ~ 250-500 au, perihelion q ~ 200 au) and inclined (i ~ 30°) orbit can explain three fundamental properties of the distant Kuiper Belt: a prominent population of TNOs with orbits beyond Neptune's gravitational influence (i.e., detached objects with q > 40 au), a significant population of high-i objects (i > 45°), and the existence of some extreme objects with peculiar orbits (e.g., Sedna). Furthermore, the proposed KBP is compatible with the existence of identified gigayear-stable TNOs in the 2:1, 5:2, 3:1, 4:1, 5:1, and 6:1 Neptunian mean motion resonances. These stable populations are often neglected in other studies. We predict the existence of an Earth-like planet and several TNOs on peculiar orbits in the outer solar system, which can serve as observationally testable signatures of the putative planet's perturbations.

Keywords: kuiper belt; solar system; trans-neptunian objects; solar system planets; resonant kuiper belt objects; scattered disk objects; detached objects; neptune
Collapsar Gamma-Ray Bursts Grind Their Black Hole Spins to a Halt

The spin of a newly formed black hole (BH) at the center of a massive star evolves from its natal value due to two competing processes: accretion of gas angular momentum that increases the spin and extraction of BH angular momentum by outflows that decreases the spin. Ultimately, the final, equilibrium spin is set by a balance between both processes. In order for the BH to launch relativistic jets and power a γ-ray burst (GRB), the BH magnetic field needs to be dynamically important. Thus, we consider the case of a magnetically arrested disk (MAD) driving the spin evolution of the BH. By applying the semianalytic MAD BH spin evolution model of Lowell et al. to collapsars, we show that if the BH accretes ∼20% of its initial mass, its dimensionless spin inevitably reaches small values, a ≲ 0.2. For such spins, and for mass accretion rates inferred from collapsar simulations, we show that our semianalytic model reproduces the energetics of typical GRB jets, L jet ∼ 1050 erg s‑1. We show that our semianalytic model reproduces the nearly constant power of typical GRB jets. If the MAD onset is delayed, this allows powerful jets at the high end of the GRB luminosity distribution, L jet ∼ 1052 erg s‑1, but the final spin remains low, a ≲ 0.3. These results are consistent with the low spins inferred from gravitational wave detections of binary BH mergers. In a companion paper by Gottlieb et al., we use GRB observations to constrain the natal BH spin to be a ≃ 0.2.

Keywords: gamma-ray bursts; astrophysical black holes; relativistic jets; accretion
StellarGAN: Classifying Stellar Spectra with Generative Adversarial Networks in SDSS and APOGEE Sky Surveys

Extracting precise stellar labels is crucial for large spectroscopic surveys like the Sloan Digital Sky Survey (SDSS) and APOGEE. In this paper, we report the newest implementation of StellarGAN, a data-driven method based on generative adversarial networks (GANs). Using 1D operators like convolution, the 2D GAN is modified into StellarGAN. This allows it to learn the relevant features of 1D stellar spectra without needing labels for specific stellar types. We test the performance of StellarGAN on different stellar spectra trained on SDSS and APOGEE data sets. Our result reveals that StellarGAN attains the highest overall F1-score on SDSS data sets (F1-score = 0.82, 0.77, 0.74, 0.53, 0.51, 0.61, and 0.55, for O-type, B-type, A-type, F-type, G-type, K-type, and M-type stars) when the signal-to-noise ratio (S/N) is low (90% of the spectra have an S/N < 50), with 1% of labeled spectra used for training. Using 50% of the labeled spectral data for training, StellarGAN consistently demonstrates performance that surpasses or is comparable to that of other data-driven models, as evidenced by the F1-scores of 0.92, 0.77, 0.77, 0.84, 0.84, 0.80, and 0.67. In the case of APOGEE (90% of the spectra have an S/N < 500), our method is also superior regarding its comprehensive performance (F1-score = 0.53, 0.60, 0.56, 0.56, and 0.78 for A-type, F-type, G-type, K-type, and M-type stars) with 1% of labeled spectra for training, manifesting its learning ability out of a limited number of labeled spectra. Our proposed method is also applicable to other types of data that need to be classified (such as gravitational-wave signals, light curves, etc.).

Keywords: stellar classification; stellar spectral types
The PDFI_SS Electric Field Inversion Software

We describe the PDFI_SS software library, which is designed to find the electric field at the Sun's photosphere from a sequence of vector magnetogram and Doppler velocity measurements and estimates of horizontal velocities obtained from local correlation tracking using the recently upgraded Fourier Local Correlation Tracking code. The library, a collection of FORTRAN subroutines, uses the "PDFI" technique described by Kazachenko et al., but modified for use in spherical, Plate Carrée geometry on a staggered grid. The domain over which solutions are found is a subset of the global spherical surface, defined by user-specified limits of colatitude and longitude. Our staggered grid approach, based on that of Yee, is more conservative and self-consistent compared to the centered, Cartesian grid used by Kazachenko et al. The library can be used to compute an end-to-end solution for electric fields from data taken by the HMI instrument aboard NASA's SDO mission. This capability has been incorporated into the HMI pipeline processing system operating at SDO's Joint Science Operations Center. The library is written in a general and modular way so that the calculations can be customized to modify or delete electric field contributions, or used with other data sets. Other applications include "nudging" numerical models of the solar atmosphere to facilitate assimilative simulations. The library includes an ability to compute "global" (whole-Sun) electric field solutions. The library also includes an ability to compute potential magnetic field solutions in spherical coordinates. This distribution includes a number of test programs that allow the user to test the software.

Keywords: solar magnetic fields; solar active region magnetic fields; active solar corona; solar photosphere; space weather; solar activity; theoretical techniques; magnetohydrodynamical simulations
GENGA. II. GPU Planetary N-body Simulations with Non-Newtonian Forces and High Number of Particles

We present recent updates and improvements of the graphical processing unit (GPU) N-body code GENGA. Modern state-of-the-art simulations of planet formation require the use of a very high number of particles to accurately resolve planetary growth and to quantify the effect of dynamical friction. At present the practical upper limit is in the range of 30,000-60,000 fully interactive particles; possibly a little more on the latest GPU devices. While the original hybrid symplectic integration method has difficulties to scale up to these numbers, we have improved the integration method by (i) introducing higher level changeover functions and (ii) code improvements to better use the most recent GPU hardware efficiently for such large simulations. We added treatments of non-Newtonian forces such as general relativity, tidal interaction, rotational deformation, the Yarkovsky effect, and Poynting-Robertson drag, as well as a new model to treat virtual collisions of small bodies in the solar system. We added new tools to GENGA, such as semi-active test particles that feel more massive bodies but not each other, a more accurate collision handling and a real-time openGL visualization. We present example simulations, including a 1.5 billion year terrestrial planet formation simulation that initially started with 65,536 particles, a 3.5 billion year simulation without gas giants starting with 32,768 particles, the evolution of asteroid fragments in the solar system, and the planetesimal accretion of a growing Jupiter simulation. GENGA runs on modern NVIDIA and AMD GPUs.

Keywords: celestial mechanics; n-body simulations; planet formation; solar system formation; gpu computing; computational methods; asteroid dynamics; n-body problem