adsabs/SciX_UAT_keywords huggingface dataset:
Dwarf Galaxies with Central Cores in Modified Newtonian Dynamics Gravity

Some dwarf galaxies are within the Mondian regime at all radii, i.e., the gravitational acceleration provided by the observed baryons is always below the threshold of g † ≃ 1.2 × 10-10 m s-2. These dwarf galaxies often show cores, in the sense that, assuming Newton's gravity to explain their rotation curves, the total density profile ρ(r) presents a central plateau or core ( $d\mathrm{log}\rho /d\mathrm{log}r\to 0$ when r → 0). Here we show that under modified Newtonian dynamics (MOND) gravity, the existence of this core implies a baryon content whose density ρ bar must decrease toward the center of the gravitational potential (ρ bar → 0 when r → 0). Such a drop of baryons toward the central region is neither observed nor appears in numerical simulations of galaxy formation following MOND gravity. We analyze the problem posed for MOND as well as possible work-arounds.

Keywords: baryonic dark matter; dark matter; dwarf galaxies; galaxy dynamics; gravitation; galaxy structure; modified newtonian dynamics
Quick-look Pipeline Light Curves for 5.7 Million Stars Observed Over the Second Year of TESS' First Extended Mission

We present High-Level Science Products (HLSPs) containing light curves from MIT's Quick-Look Pipeline (QLP) from the second year of Transiting Exoplanet Survey Satellite (TESS') first Extended Mission (Sectors 40-55; 2021 July-2022 September). In total, 12.2 million per-sector light curves for 5.7 million unique stars were extracted from 10 minutes cadence Full-Frame Images (FFIs) and are made available to the community. As in previous deliveries, QLP HLSPs include both raw and detrended flux time series for all observed stars brighter than TESS magnitude T = 13.5 mag. Starting in Sector 41, QLP also produces light curves for select fainter M dwarfs. QLP has provided the community with one of the largest sources of FFI-extracted light curves to date since the start of the TESS mission.

Keywords: exoplanets; transit photometry; light curves
Shear-driven Transition to Isotropically Turbulent Solar Wind Outside the Alfvén Critical Zone

Motivated by prior remote observations of a transition from striated solar coronal structures to more isotropic "flocculated" fluctuations, we propose that the dynamics of the inner solar wind just outside the Alfvén critical zone, and in the vicinity of the first $\beta =1$ surface, is powered by the relative velocities of adjacent coronal magnetic flux tubes. We suggest that large-amplitude flow contrasts are magnetically constrained at lower altitude but shear-driven dynamics are triggered as such constraints are released above the Alfvén critical zone, as suggested by global magnetohydrodynamic (MHD) simulations that include self-consistent turbulence transport. We argue that this dynamical evolution accounts for features observed by Parker Solar Probe (PSP) near initial perihelia, including magnetic "switchbacks," and large transverse velocities that are partially corotational and saturate near the local Alfvén speed. Large-scale magnetic increments are more longitudinal than latitudinal, a state unlikely to originate in or below the lower corona. We attribute this to preferentially longitudinal velocity shear from varying degrees of corotation. Supporting evidence includes comparison with a high Mach number three-dimensional compressible MHD simulation of nonlinear shear-driven turbulence, reproducing several observed diagnostics, including characteristic distributions of fluctuations that are qualitatively similar to PSP observations near the first perihelion. The concurrence of evidence from remote sensing observations, in situ measurements, and both global and local simulations supports the idea that the dynamics just above the Alfvén critical zone boost low-frequency plasma turbulence to the level routinely observed throughout the explored solar system.

Keywords: solar wind; interplanetary turbulence; space plasmas; interplanetary magnetic fields
Calibrating the Galactic Cepheid Period-Luminosity Relation from the Maximum-likelihood Technique

We present a realization of the maximum-likelihood technique, which is one of the latest modifications of the Baade-Becker-Wesselink method. Our approach is based on nonlinear calibrations of the effective temperature and bolometric correction, which take into account metallicity and surface gravity. It allows one to estimate the key Cepheid parameters, the distance modulus, and the interstellar reddening, combining photometric and spectroscopic data (including the effective temperature data). This method is applied to a sample of 44 Galactic Cepheids for which multiphase temperature measurements are available. The additional data correction is performed to subtract the impact of the component in binary/multiple systems. We also study the effect of shock waves, whose presence in the stellar atmosphere distorts the observational data and leads to systematic errors in the obtained parameters. We determine the optimal restriction on the input data to eliminate this effect. This restriction provides accurate period-radius and period-luminosity relations that are consistent with the results in previous studies. We found the following relations: log R = (0.68 ± 0.03) · log P + (1.14 ± 0.03), Mv = - (2.67 ± 0.16) · (log P - 1) - (4.14 ± 0.05).

Keywords: cepheid variable stars; cepheid distance
Reverberation Mapping of Two Luminous Quasars: The Broad-line Region Structure and Black Hole Mass

We report the results of a multiyear spectroscopic and photometric monitoring campaign of two luminous quasars, PG 0923+201 and PG 1001+291, both located at the high-luminosity end of the broad-line region (BLR) size-luminosity relation with optical luminosities above 1045 erg s-1. PG 0923+201 is monitored for the first time, while PG 1001+291 was previously monitored but our campaign has a much longer temporal baseline. We detect time lags of variations of the broad Hβ, Hγ, and Fe II lines with respect to those of the 5100 Å continuum. The velocity-resolved delay map of Hβ in PG 0923+201 indicates a complicated structure with a mix of Keplerian disk-like motion and outflow, and the map of Hβ in PG 1001+291 shows a signature of Keplerian disk-like motion. Assuming a virial factor of fBLR = 1 and FWHM line widths, we measure the black hole mass to be ${118}_{-16}^{+11}\times {10}^{7}{M}_{\odot }$ for PG 0923+201 and ${3.33}_{-0.54}^{+0.62}\times {10}^{7}{M}_{\odot }$ for PG 1001+291. Their respective accretion rates are estimated to be ${0.21}_{-0.07}^{+0.06}\times {L}_{\mathrm{Edd}}\,{c}^{-2}$ and ${679}_{-227}^{+259}\times {L}_{\mathrm{Edd}}\,{c}^{-2}$ , indicating that PG 0923+201 is a sub-Eddington accretor and PG 1001+291 is a super-Eddington accretor. While the Hβ time lag of PG 0923+201 agrees with the size-luminosity relation, the time lag of PG 1001+291 shows a significant deviation, confirming that in high-luminosity active galactic nuclei (AGNs), the BLR size depends on both luminosity and Eddington ratio. Black hole mass estimates from single-AGN spectra will be overestimated at high luminosities and redshifts if this effect is not taken into account.

Keywords: supermassive black holes; reverberation mapping; quasars
Optimized Photometric Redshifts for the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS)

We present the first comprehensive release of photometric redshifts (photo- z's) from the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS) team. We use statistics based upon the Quantile-Quantile (Q-Q) plot to identify biases and signatures of underestimated or overestimated errors in photo- z probability density functions (PDFs) produced by six groups in the collaboration; correcting for these effects makes the resulting PDFs better match the statistical definition of a PDF. After correcting each group's PDF, we explore three methods of combining the different groups' PDFs for a given object into a consensus curve. Two of these methods are based on identifying the minimum f-divergence curve, i.e., the PDF that is closest in aggregate to the other PDFs in a set (analogous to the median of an array of numbers). We demonstrate that these techniques yield improved results using sets of spectroscopic redshifts independent of those used to optimize PDF modifications. The best photo- z PDFs and point estimates are achieved with the minimum f-divergence using the best four PDFs for each object (mFDa4) and the hierarchical Bayesian (HB4) methods, respectively. The HB4 photo- z point estimates produced σ NMAD = 0.0227/0.0189 and ∣Δz/(1 + z)∣ > 0.15 outlier fraction = 0.067/0.019 for spectroscopic and 3D Hubble Space Telescope redshifts, respectively. Finally, we describe the structure and provide guidance for the use of the CANDELS photo- z catalogs, which are available at https://archive.stsci.edu/prepds/candels/.

Keywords: redshift surveys; hierarchical models; galaxy distances
Three-stage Acceleration of Solar Energetic Particles Detected by Parker Solar Probe

Coronal mass ejections (CMEs) drive powerful shocks and thereby accelerate solar energetic particles (SEPs) as they propagate from the corona into interplanetary space. Here we present the processes of three-stage particle acceleration by a CME-driven shock detected by the in situ spacecraft—Parker Solar Probe (PSP) on 2022 August 27. The onset of SEPs is produced by a fast CME with a speed of 1284 km s‑1 when it propagates to ∼2.85 R ⊙. The second stage of particle acceleration occurs when the fast CME catches up and interacts with a preceding slow one in interplanetary space at ∼40 R ⊙ (∼0.19 au). The CME interaction is accompanied by an intense interplanetary type II radio enhancement. Such direct measurement of particle acceleration during interplanetary CME interaction/radio enhancement is rarely recorded in previous studies. The third stage of energetic storm particles is associated with the CME-driven shock passage of the PSP at ∼0.38 au. Obviously, harder particle spectra are found in the latter two stages than the first one, which can arise from a stronger shock produced by the CME interaction and the enriched seed particles inside the preceding CME.

Keywords: solar energetic particles; solar coronal mass ejections; interplanetary shocks
Semidetached Mass-transfer Massive Binaries in the Nearby Galaxy M31

Semidetached binaries provide a valuable test of the evolutionary models of interacting binaries where the mass is transferring from one component to the other, and the evolutions of both components will be changed. Many results of semidetached binaries have been obtained in the Milky Way, while there are few studies in the Andromeda galaxy (M31). By analyzing the light curves of 12 eclipsing binaries observed by Vilardell et al., we determined the fundamental parameters of these systems using the Wilson and Devinney method. It is discovered that they are semidetached binaries where the less massive components have filled their Roche lobes, while the more massive ones are detached from the lobes. We calculated their times of light minimum for the first time. The primary stars in those semidetached binaries have different mass ratios and fill-out factors and they are good sources to investigate the binary evolution in M31. It is found that the mass ratio is correlated with the fill-out factor of the primary. Systems with higher mass ratios tend to have lower fill-out factors. These results can be explained that the mass transfer from the less massive component to the more massive one. Moreover, the photometric solutions reveal that the secondary components are more evolved than the primary ones indicating that they are formed from originally detached binary systems via a case A mass transfer. These binaries have experienced the mass-reverse evolution and are at the late stage of a case A evolution in the nearby galaxy M31.

Keywords: eclipsing binary stars; close binary stars; andromeda galaxy; early stellar evolution
A Compact Full-disk Solar Magnetograph Based on Miniaturization of the GONG Instrument

The design of compact instruments is crucial for the scientific exploration by smaller spacecraft such as CubeSats and deep space missions, as these missions require minimal instrument mass. In this proof-of-concept study, we demonstrate the miniaturization of the Global Oscillation Network Group (GONG) instrument. GONG instruments routinely produce full-disk maps of the Sun's photosphere using the Ni I 676 nm absorption line, measuring Doppler shifts and magnetic fields. To miniaturize the GONG optical design, we propose replacing the bulky Lyot filter with a narrow-band interference filter. We validate this concept through numerical modeling and proof-of-concept observations. Finally, we propose a simple optical design for building a compact version of GONG. *Submitted January XX, 2023.

Keywords: solar magnetic fields; solar instruments; space weather; interferometers; michelson interferometry; optical phase shifting interferometry; polarimetry; radial velocity; space observatories; helioseismology
ALMA Millimeter/Submillimeter Sources among Spitzer SMUVS Galaxies at z > 2 in the COSMOS Field

Submillimeter observations reveal the star formation activity obscured by dust in the young Universe. It still remains unclear how galaxies detected at submillimeter wavelengths are related to ultraviolet/optical-selected galaxies in terms of their observed quantities, physical properties, and evolutionary stages. Deep near- and mid-infrared observational data are crucial to characterize the stellar properties of galaxies detected with submillimeter emission. In this study, we make use of a galaxy catalog from the Spitzer Matching survey of the UltraVISTA ultra-deep Stripes. By crossmatching with a submillimeter source catalog constructed with archival data of the Atacama Large Millimeter/submillimeter Array (ALMA), we search for galaxies at z > 2 with a submillimeter detection in our galaxy catalog. We find that the ALMA-detected galaxies at z > 2 are systematically massive and have redder K s -[4.5] colors than the nondetected galaxies. The redder colors are consistent with the larger dust reddening values of the ALMA-detected galaxies obtained from spectral energy distribution (SED) fitting. We also find that the ALMA-detected galaxies tend to have brighter 4.5 μm magnitudes. This may suggest that they tend to have smaller mass-to-light ratios and thus to be younger than star-forming galaxies fainter at submillimeter wavelengths with similar stellar masses. We identify starburst galaxies with high specific star formation rates among both ALMA-detected and nondetected SMUVS sources. Irrespective of their brightness at submillimeter wavelengths, these populations have similar dust reddening values, which may suggest a variety of dust SED shapes among the starburst galaxies at z > 2.

Keywords: high-redshift galaxies; submillimeter astronomy; galaxy evolution
Improving Photometric Redshift Estimation for Cosmology with LSST Using Bayesian Neural Networks

We present results exploring the role that probabilistic deep learning models can play in cosmology from large-scale astronomical surveys through photometric redshift (photo-z) estimation. Photo-z uncertainty estimates are critical for the science goals of upcoming large-scale surveys such as the Legacy Survey of Space and Time (LSST); however, common machine learning methods typically provide only point estimates and lack uncertainties on predictions. We turn to Bayesian neural networks (BNNs) as a promising way to provide accurate predictions of redshift values with uncertainty estimates. We have compiled a galaxy data set from the Hyper Suprime-Cam Survey with grizy photometry, which is designed to be a smaller-scale version of large surveys like LSST. We use this data set to investigate the performance of a neural network and a probabilistic BNN for photo-z estimation and evaluate their performance with respect to LSST photo-z science requirements. We also examine the utility of photo-z uncertainties as a means to reduce catastrophic outlier estimates. The BNN outputs the estimate in the form of a Gaussian probability distribution. We use the mean and standard deviation as the redshift estimate and uncertainty. We find that the BNN can produce accurate uncertainties. Using a coverage test, we find excellent agreement with expectation—67.2% of galaxies between 0 < 2.5 have 1σ uncertainties that cover the spectroscopic value. We also include a comparison to alternative machine learning models using the same data. We find the BNN meets two out of three of the LSST photo-z science requirements in the range 0 < z < 2.5.

Keywords: cosmology; neural networks; bayesian statistics; galaxy distances; redshift surveys; galaxy photometry
A Blueprint for the Milky Way's Stellar Populations. IV. A String of Pearls-the Galactic Starburst Sequence

We continue our series of papers on phase-space distributions of stars in the Milky Way based on photometrically derived metallicities and Gaia astrometry, with a focus on the halo-disk interface in the local volume. To exploit various photometric databases, we develop a method of empirically calibrating synthetic stellar spectra based on a comparison with observations of stellar sequences and individual stars in the Sloan Digital Sky Survey, the SkyMapper Sky Survey, and the Pan-STARRS1 surveys, overcoming band-specific corrections employed in our previous work. In addition, photometric zero-point corrections are derived to provide an internally consistent photometric system with a spatially uniform metallicity zero-point. Using our phase-space diagrams, we find a remarkably narrow sequence in the rotational velocity (v ϕ ) versus metallicity ([Fe/H]) space for a sample of high proper-motion stars (>25 mas yr-1), which runs along Gaia Sausage/Enceladus (GSE) and the Splash substructures and is linked to the disk, spanning nearly 2 dex in [Fe/H]. Notably, a rapid increase of v ϕ from a nearly zero net rotation to ~180 km s-1 in a narrow metallicity interval (-0.6 ≲ [Fe/H] ≲ -0.4) suggests that some of these stars emerged quickly on a short gas-depletion timescale. Through measurements of a scale height and length, we argue that these stars are distinct from those heated dynamically by mergers. This chain of high proper-motion stars provides additional support for recent discoveries suggesting that a starburst took place when the young Milky Way encountered the gas-rich GSE progenitor, which eventually led to the settling of metal-enriched gas onto the disk.

Keywords: milky way galaxy; milky way stellar halo; milky way dynamics; milky way formation; milky way evolution; stellar abundances; stellar populations
Two Planets Straddling the Habitable Zone of the Nearby K Dwarf Gl 414A

We present the discovery of two planets orbiting the nearby (D = 11.9 pc) K7 dwarf Gl 414A. Gl 414A b is a sub-Neptune mass planet with ${M}_{b}\sin {i}_{b}={7.60}_{-2.19}^{+2.44}$ M⊕ and a semimajor axis of 0.23 ± 0.01 au. Gl 414A c is a sub-Saturn mass planet with ${M}_{c}\sin {i}_{c}={53.83}_{-8.58}^{+9.18}$ M⊕ and a semimajor axis of 1.43 ± 0.06 au. We jointly analyzed radial velocity data from Keck/HIRES and the Automated Planet Finder at Lick Observatory, as well as photometric data from KELT, to detect the two planets and two additional signals related to the rotationally modulated activity and the long-term magnetic activity cycle of the star. The outer planet in this system may be a potential candidate for future direct-imaging missions.

Keywords: exoplanets; radial velocity; gaussian processes regression; k dwarf stars; exoplanet systems
Tidal Response and Shape of Hot Jupiters

We study the response of hot Jupiters to a static tidal perturbation using the concentric MacLaurin spheroid method. For strongly irradiated planets, we first performed radiative transfer calculations to relate the planet's equilibrium temperature, Teq, to its interior entropy. We then determined the gravity harmonics, shape, moment of inertia, and static Love numbers for a range of two-layer interior models that assume a rocky core plus a homogeneous and isentropic envelope composed of hydrogen, helium, and heavier elements. We identify general trends and then study HAT-P-13b, the WASP planets 4b, 12b, 18b, 103b, and 121b, and Kepler-75b and CoRot-3b. We compute the Love numbers, knm, and transit radius correction, ΔR, which we compare with predictions in the literature. We find that the Love number, k22, of tidally locked giant planets cannot exceed a value of 0.6, and that the high Teq consistent with strongly irradiated hot Jupiters tends to further lower k22. While most tidally locked planets are well described by a linear regime response of k22 = 3J2/q0 (where q0 is the rotation parameter of the gravitational potential), for extreme cases such as WASP-12b, WASP-103b, and WASP-121b, nonlinear effects can account for over 10% of the predicted k22. The k22 values larger than 0.6, as they have been reported for planets WASP-4b and HAT-P13B, cannot result from a static tidal response without extremely rapid rotation and thus are inconsistent with their expected tidally locked state.

Keywords: exoplanets; hot jupiters; exoplanet tides; tides; tidal interaction; planetary interior; oblateness; tidal radius; gravitational fields; tidal distortion
Electron Heating by Magnetic Pumping and Whistler-mode Waves

The investigation of mechanisms responsible for the heating of cold solar wind electrons around the Earth's bow shock is an important problem in heliospheric plasma physics because such heating is vitally required to run the shock drift acceleration at the bow shock. The prospective mechanism for electron heating is magnetic pumping, which considers electron adiabatic (compressional) heating by ultralow-frequency waves and simultaneous scattering by high-frequency fluctuations. Existing models of magnetic pumping have operated with external sources of such fluctuations. In this study, we generalize these models by introducing the self-consistent electron scattering by whistler-mode waves generated due to the anisotropic electron heating process. We consider an electron population captured within a magnetic trap created by ultralow-frequency waves. Periodical adiabatic heating and cooling of this population drives the generation of whistler-mode waves scattering electrons in the pitch-angle space. The combination of adiabatic heating and whistler-driven scattering provides electron acceleration and the formation of a suprathermal electron population that can further participate in the shock drift acceleration.

Keywords: space plasmas; plasma astrophysics; plasma physics; planetary bow shocks; solar wind