adsabs/SciX_UAT_keywords huggingface dataset:
The Megamaser Cosmology Project. XI. A Geometric Distance to CGCG 074-064

As part of the survey component of the Megamaser Cosmology Project, we have discovered a disk megamaser system in the galaxy CGCG 074-064. Using the Green Bank Telescope and the Very Large Array, we have obtained spectral monitoring observations of this maser system at a monthly cadence over the course of two years. We find that the systemic maser features display line-of-sight accelerations of ∼4.4 km s-1 yr-1 that are nearly constant with velocity, while the high-velocity maser features show accelerations that are consistent with zero. We have also used the High-Sensitivity Array to make a high-sensitivity very long baseline interferometric map of the maser system in CGCG 074-064, which reveals that the masers reside in a thin, edge-on disk with a diameter of ∼1.5 mas (0.6 pc). Fitting a three-dimensional warped disk model to the data, we measure a black hole mass of ${2.42}_{-0.20}^{+0.22}\times {10}^{7}\,{M}_{\odot }$ and a geometric distance to the system of ${87.6}_{-7.2}^{+7.9}$ Mpc. Assuming a cosmic microwave background-frame recession velocity of 7308 ± 150 km s-1, we constrain the Hubble constant to ${H}_{0}={81.0}_{-6.9}^{+7.4}$ (stat.) ± 1.4 (sys.) km s-1 Mpc-1.

Keywords: active galactic nuclei; megamasers; water masers; supermassive black holes; very long baseline interferometry
The Role of Natal Kicks in Forming Asymmetric Compact Binary Mergers

In their most recent observing run, the LIGO-Virgo-KAGRA Collaboration observed gravitational waves from compact binary mergers with highly asymmetric mass ratios, including both binary black holes (BBHs) and neutron star-black holes (NSBHs). It appears that NSBHs with mass ratios q ≃ 0.2 are more common than equally asymmetric BBHs, but the reason for this remains unclear. We use the binary population synthesis code COSMIC to investigate the evolutionary pathways leading to the formation and merger of asymmetric compact binaries. We find that within the context of isolated binary stellar evolution, most asymmetric mergers start off as asymmetric stellar binaries. Because of the initial asymmetry, these systems tend to first undergo a dynamically unstable mass transfer phase. However, after the first star collapses into a compact object, the mass ratio is close to unity and the second phase of mass transfer is usually stable. According to our simulations, this stable mass transfer fails to shrink the orbit enough on its own for the system to merge. Instead, the natal kick received by the second-born compact object during its collapse is key in determining how many of these systems can merge. For the most asymmetric systems with mass ratios of q ≤ 0.1, the merging systems in our models receive an average kick magnitude of 255 km s-1 during the second collapse, while the average kick for non-merging systems is 59 km s-1. Because lower mass compact objects, like neutron stars, are expected to receive larger natal kicks than higher mass BHs, this may explain why asymmetric NSBH systems merge more frequently than asymmetric BBH systems.

Keywords: gravitational wave sources; massive stars; binary stars; astrophysical black holes; neutron stars; core-collapse supernovae
TOI-1518b: A Misaligned Ultra-hot Jupiter with Iron in Its Atmosphere

We present the discovery of TOI-1518b-an ultra-hot Jupiter orbiting a bright star (V = 8.95). The transiting planet is confirmed using high-resolution optical transmission spectra from EXPRES. It is inflated, with Rp = 1.875 ± 0.053 RJ, and exhibits several interesting properties, including a misaligned orbit ( ${240.34}_{-0.98}^{+0.93}$ degrees) and nearly grazing transit ( $b={0.9036}_{-0.0053}^{+0.0061}$ ). The planet orbits a fast-rotating F0 host star (Teff ≃ 7300 K) in 1.9 days and experiences intense irradiation. Notably, the TESS data show a clear secondary eclipse with a depth of 364 ± 28 ppm and a significant phase-curve signal, from which we obtain a relative day-night planetary flux difference of roughly 320 ppm and a 5.2σ detection of ellipsoidal distortion on the host star. Prompted by recent detections of atomic and ionized species in ultra-hot Jupiter atmospheres, we conduct an atmospheric cross-correlation analysis. We detect neutral iron (5.2σ), at ${K}_{p}={157}_{-44}^{+68}$ km s-1 and ${V}_{\mathrm{sys}}=-{16}_{-4}^{+2}$ , adding another object to the small sample of highly irradiated gas-giant planets with Fe detections in transmission. Detections so far favor particularly inflated gas giants with radii ≳1.78 RJ, which may be due to observational bias. With an equilibrium temperature of Teq = 2492 ± 38 K and a measured dayside brightness temperature of 3237 ± 59 K (assuming zero geometric albedo), TOI-1518b is a promising candidate for future emission spectroscopy to probe for a thermal inversion.

Keywords: exoplanet atmospheres; transit photometry; high resolution spectroscopy
Density Fluctuations in the Solar Wind Based on Type III Radio Bursts Observed by Parker Solar Probe

Radio waves are strongly scattered in the solar wind, so that their apparent sources seem to be considerably larger and shifted than the actual ones. Since the scattering depends on the spectrum of density turbulence, a better understanding of the radio wave propagation provides indirect information on the relative density fluctuations, $\epsilon =\langle \delta n\rangle /\langle n\rangle $ , at the effective turbulence scale length. Here, we analyzed 30 type III bursts detected by Parker Solar Probe (PSP). For the first time, we retrieved type III burst decay times, ${\tau }_{{\rm{d}}}$ , between 1 and 10 MHz thanks to an unparalleled temporal resolution of PSP. We observed a significant deviation in a power-law slope for frequencies above 1 MHz when compared to previous measurements below 1 MHz by the twin-spacecraft Solar TErrestrial RElations Observatory (STEREO) mission. We note that altitudes of radio bursts generated at 1 MHz roughly coincide with an expected location of the Alfvén point, where the solar wind becomes super-Alfvénic. By comparing PSP observations and Monte Carlo simulations, we predict relative density fluctuations, ɛ, at the effective turbulence scale length at radial distances between 2.5 and 14 ${R}_{\odot }$ to range from 0.22 to 0.09. Finally, we calculated relative density fluctuations, ɛ, measured in situ by PSP at a radial distance from the Sun of 35.7 ${R}_{\odot }$ during perihelion #1, and perihelion #2 to be 0.07 and 0.06, respectively. It is in a very good agreement with previous STEREO predictions ( $\epsilon =0.06\mbox{--}0.07$ ) obtained by remote measurements of radio sources generated at this radial distance.

Keywords: radio astronomy; radio bursts; solar flares
Reflected Spectroscopy of Small Exoplanets. III. Probing the UV Band to Measure Biosignature Gases

Direct-imaging observations of terrestrial exoplanets will enable their atmospheric characterization and habitability assessment. Considering Earth, the key atmospheric signatures for the biosphere are O2 and the photochemical product O3. However, this O2-O3 biosignature is not detectable in the visible wavelengths for most of the time after the emergence of oxygenic photosynthesis life (i.e., Proterozoic Earth). Here we demonstrate spectroscopic observations in the ultraviolet wavelengths for detecting and characterizing O2 and O3 in Proterozoic-Earth-like planets, using EXOREL ${}^{{\mathfrak{R}}}$ . For an O2 mixing ratio 2-3 orders of magnitude less than the present-day Earth and an O3 mixing ratio of 10-7 to 10-6, we find that O3 can be detected and its mixing ratio can be measured precisely (within 1 order of magnitude) in the ultraviolet (0.25-0.4 μm), in addition to visible-wavelength spectroscopy. With modest spectral resolution (R = 7) and signal-to-noise ratio (~10) in the ultraviolet, the O3 detection is robust against other potential gases absorbing in the ultraviolet (e.g., H2S and SO2), as well as the short-wavelength cutoff between 0.2 and 0.25 μm. While the O3 detection does not rely on the near-infrared spectra, extending the wavelength coverage to the near-infrared (1-1.8 μm) would provide essential information to interpret the O3 biosignature, including the mixing ratio of H2O, the cloud pressure, and the determination of the dominant gas of the atmosphere. The ultraviolet and near-infrared capabilities should thus be evaluated as critical components for future missions aiming at imaging and characterizing terrestrial exoplanets, such as the Habitable Worlds Observatory.

Keywords: exoplanet atmospheric composition; exoplanet atmospheres; bayesian statistics; bayes' theorem; posterior distribution; prior distribution; extrasolar rocky planets
Magnetic Fields and Afterglows of BdHNe: Inferences from GRB 130427A, GRB 160509A, GRB 160625B, GRB 180728A, and GRB 190114C

GRB 190114C is the first binary-driven hypernova (BdHN) fully observed from initial supernova (SN) appearance to the final emergence of the optical SN signal. It offers an unprecedented testing ground for the BdHN theory, which is here determined and further extended to additional gamma-ray bursts (GRBs). BdHNe comprise two subclasses of long GRBs, with progenitors a binary system composed of a carbon-oxygen star (COcore) and a neutron star (NS) companion. The COcore explodes as an SN, leaving at its center a newborn NS (νNS). The SN ejecta hypercritically accretes on both the νNS and the NS companion. BdHNe I are very tight binaries, where the accretion leads the companion NS to gravitationally collapse into a black hole (BH). In BdHN II, the accretion rate onto the NS is lower, so there is no BH formation. We observe the same afterglow structure for GRB 190114C and other selected examples of BdHNe I (GRB 130427A, GRB 160509A, GRB 160625B) and for BdHN II (GRB 180728A). In all cases, the afterglows are explained via the synchrotron emission powered by the νNS, and their magnetic field structures and their spin are determined. For BdHNe I, we discuss the properties of the magnetic field embedding the newborn BH, which was inherited from the collapsed NS and amplified during the gravitational collapse process, and surrounded by the SN ejecta.

Keywords: high energy astrophysics; gamma-ray bursts; black hole physics
The QuaStar Survey: Detecting Hidden Low-velocity Gas in the Milky Way's Circumgalactic Medium

From our position embedded within the Milky Way's interstellar medium, we have limited ability to detect gas at low relative velocities in the extended Galactic halo because those spectral lines are blended with much stronger signals from dense foreground gas. As a result, the content of the Milky Way's circumgalactic medium (CGM) is poorly constrained at ∣vLSR∣ ≲150 km s-1. To overcome this complication, the QuaStar survey applies a spectral differencing technique using paired quasar-star sight lines to measure the obscured content of the Milky Way's CGM for the first time. We present measurements of the C IV doublet (λλ1548, 1550), a rest-frame UV metal line transition, detected in Hubble Space Telescope/Cosmic Origins Spectrograph spectra of 30 halo-star/quasar pairs evenly distributed across the sky at Galactic latitudes ∣b∣ > 30°. The 30 halo stars have well-constrained distances (d ≈ 5-14 kpc) and are paired with quasars separated by <2°8. We argue that the difference in absorption between the quasar and stellar sight lines originates primarily in the Milky Way's extended CGM beyond ∼10 kpc. For the Milky Way's extended, low-velocity CGM (∣v∣ <150 km s-1), we place an upper limit on the mean C IV column density of ${\rm{\Delta }}\mathrm{log}{N}_{\mathrm{LVCGM}}$ < 13.39 and find a covering fraction of ${f}_{{\rm{C}}{\rm\small{IV}},\mathrm{LVCGM}}(\mathrm{log}N\gt 13.65)\,=$ 20% [6/30], a value significantly lower than the covering fraction for star-forming galaxies at low redshift. Our results suggest either that the bulk of Milky Way's C IV -traced CGM lies at low Galactic latitudes or that the Milky Way's CGM is lacking in warm, ionized material compared to low-redshift (z < 0.1) star-forming galaxy halos.

Keywords: circumgalactic medium; warm ionized medium; milky way galaxy; magellanic clouds; galaxy kinematics; milky way evolution
Energy Supply by Low-frequency Break Sweeping for Heating the Fast Solar Wind from 0.3 to 4.8 au

Solar wind protons undergo significant heating during the expansion of the solar wind and turbulence plays an important role in this process. It is believed that the energy is injected from the energy-containing range into the inertial range and then transferred to dissipate into heat eventually. However, the energy injection process in the heliosphere remains unclear. Here we analyze this process. We utilize Helios 2 and Ulysses measurements of the fast solar wind at different radial distances from 0.29 to 4.8 au. We obtain the perpendicular heating rate based on the gradient of the magnetic moment. We estimate for the first time the energy supply rate due to the sweeping of low-frequency break based on the identification of low-frequency break and the corresponding power spectra density profile. We find that the energy supply rate is comparable to the perpendicular heating rate of protons, which support the idea that low-frequency range becomes part of the inertial range as the solar wind turbulence ages. These results help us understand the energy supply process from the energy-containing range and the heating process of solar wind protons.

Keywords: fast solar wind; interplanetary turbulence; solar coronal heating
A Reanalysis of the Isolated Black Hole Candidate OGLE-2011-BLG-0462/MOA-2011-BLG-191

There are expected to be ~108 isolated black holes (BHs) in the Milky Way. OGLE-2011-BLG-0462/MOA-2011-BLG-191 (OB110462) is the only such BH with a mass measurement to date. However, its mass is disputed: Lam et al. measured a lower mass of 1.6-4.4 M ⊙, while Sahu et al. and Mróz et al. measured a higher mass of 5.8-8.7 M ⊙. We reanalyze OB110462, including new data from the Hubble Space Telescope (HST) and rereduced Optical Gravitational Lensing Experiment (OGLE) photometry. We also rereduce and reanalyze the HST data set with newly available software. We find significantly different (~1 mas) HST astrometry than Lam et al. in the unmagnified epochs due to the amount of positional bias induced by a bright star ~0.″4 from OB110462. After modeling the updated photometric and astrometric data sets, we find the lens of OB110462 is a ${6.0}_{-1.0}^{+1.2}{M}_{\odot }$ BH. Future observations with the Nancy Grace Roman Space Telescope, which will have an astrometric precision comparable or better to HST but a field of view 100× larger, will be able to measure hundreds of isolated BH masses via microlensing. This will enable the measurement of the BH mass distribution and improve understanding of massive stellar evolution and BH formation channels.

Keywords: gravitational microlensing; astrometric microlensing effect; stellar mass black holes; hubble space telescope
Probing X-Ray Continua with Accretion-Disk Wind in Black Hole X-Ray Binaries

High energy coronal radiation in Black Hole X-Ray Binary sources is often absorbed by accretion disk winds and the resulting absorption signatures heavily depend on its ionizing spectral energy distribution (SED). Considering multiple ion absorbers in the wind (e.g. Fe XXV/XXVI, S XVI, Si XIV, Ca XX and Mg XII), we find that the relative strength of absorption among these ions in general sensitively depends on the shape of the SED. We calculate a series of absorption line spectra from radiative transfer process for 9 distinct SED. Furthermore, we simulate 50 ks XRISM/Resolve spectra for each SED. We then fit the spectra by two-parameter wind model (SED and wind density normalization) to examine whether or not absorption features imprinted by the wind can be uniquely mapped to the ionizing SED.

Keywords: x-ray astronomy; high energy astrophysics; radiative transfer simulations; magnetohydrodynamical simulations; spectroscopy; quasar absorption line spectroscopy; black hole physics; accretion
Observations of GRB 221009A by the MAVEN-SEP Instrument at Mars

We report on the detection of the Brightest Of All Time (the BOAT) gamma-ray burst (GRB) 221009A by the MAVEN Solar Energetic Particle (SEP) silicon (Si) detectors. The SEP instrument on board the MAVEN spacecraft at Mars is designed to measure charged particle fluxes and energies. In this work, we show that the SEP Si detectors have detected populations of secondary charged particles and low-energy primary photons from the GRB. Our analysis relies on a series of simplified Geant4 Monte Carlo simulations. We show that electromagnetic and hadronic interactions between the GRB photons and the spacecraft's passive material and Si detectors produced the detected secondary particles.

Keywords: gamma-ray bursts
Rejuvenated Accretors Have Less Bound Envelopes: Impact of Roche Lobe Overflow on Subsequent Common Envelope Events

Common envelope (CE) evolution is an outstanding open problem in stellar evolution, critical to the formation of compact binaries including gravitational-wave sources. In the "classical" isolated binary evolution scenario for double compact objects, the CE is usually the second mass transfer phase. Thus, the donor star of the CE is the product of a previous binary interaction, often stable Roche lobe overflow (RLOF). Because of the accretion of mass during the first RLOF, the main-sequence core of the accretor star grows and is "rejuvenated." This modifies the core-envelope boundary region and decreases significantly the envelope binding energy for the remaining evolution. Comparing accretor stars from self-consistent binary models to stars evolved as single, we demonstrate that the rejuvenation can lower the energy required to eject a CE by ~42%-96% for both black hole and neutron star progenitors, depending on the evolutionary stage and final orbital separation. Therefore, binaries experiencing first stable mass transfer may more easily survive subsequent CE events and result in possibly wider final separations compared to current predictions. Despite their high mass, our accretors also experience extended "blue loops," which may have observational consequences for low-metallicity stellar populations and asteroseismology.

Keywords: binary stars; common envelope binary stars; roche lobe overflow
Analytic Understanding of the Resonant Nature of Kozai-Lidov Cycles with a Precessing Quadrupole Potential

The very long-term evolution of the hierarchical restricted three-body problem with a slightly aligned precessing quadrupole potential is studied analytically. This problem describes the evolution of a star and a planet that are perturbed either by a (circular and not too inclined) binary star system or by one other star and a second more distant star, as well as a perturbation by one distant star and the host galaxy or a compact-object binary system orbiting a massive black hole in nonspherical nuclear star clusters. Previous numerical experiments have shown that when the precession frequency is comparable to the Kozai-Lidov timescale, long-term evolution emerges that involves extremely high eccentricities with potential applications for a broad scope of astrophysical phenomena, including systems with merging black holes, neutron stars, or white dwarfs. By averaging the secular equations of motion over the Kozai-Lidov cycles (KLCs), we solve the problem analytically in the neighborhood of the KLC fixed point where the eccentricity vector is close to unity and aligned with the quadrupole axis and for a precession rate similar to the Kozai-Lidov timescale. In this regime the dynamics is dominated by a resonance between the perturbation frequency and the precession frequency of the eccentricity vector. While the quantitative evolution of the system is not reproduced by the solution far away from this fixed point, it sheds light on the qualitative behavior.

Keywords: newtonian gravitation; keplerian orbit; eccentricity; three-body problem
Systematically Measuring Ultradiffuse Galaxies (SMUDGes). IV. Ultradiffuse Satellites of Milky Way Analogs

To better understand the formation of large, low-surface-brightness galaxies, we measure the correlation function between ultradiffuse galaxy (UDG) candidates and Milky Way analogs (MWAs). We find that: (1) the projected radial distribution of UDG satellites (projected surface density ∝r -0.84±0.06) is consistent with that of normal satellite galaxies; (2) the number of UDG satellites per MWA (S UDG) is ~0.5 ± 0.1 over projected radii from 20 to 250 kpc and -17 < M r < -13.5; (3) S UDG is consistent with a linear extrapolation of the relationship between the number of UDGs per halo versus halo mass obtained over galaxy group and cluster scales; (4) red UDG satellites dominate the population of UDG satellites (~80%); (5) over the range of satellite magnitudes studied, UDG satellites comprise ~10% of the satellite galaxy population of MWAs; and (6) a significant fraction of these (~13%) have estimated total masses >1010.9 M ⊙ or, equivalently, at least half the halo mass of the LMC, and populate a large fraction (~18%) of the expected subhalos down to these masses. All of these results suggest a close association between the overall low-mass galaxy population and UDGs, which we interpret as favoring models where UDG formation principally occurs within the general context of low-mass galaxy formation over models invoking more exotic physical processes specifically invoked to form UDGs.

Keywords: low surface brightness galaxies; galaxy properties
Search and Characterization of Remnant Radio Galaxies in the XMM-LSS Deep Field

The remnant phase of a radio galaxy is characterized by the cessation of active galactic nuclei activity, resulting in the jets ceasing to feed plasma to the radio lobes. In this paper, we present a search for and the characterization of remnant candidates in a 12.5 deg2 area of the XMM-Newton Large-Scale Structure field, using deep radio observations at 325 MHz from the Giant Meterwave Radio Telescope, at 150 MHz from the LOw Frequency ARray, at 1.4 GHz from the Jansky Very Large Array (VLA), and at 3 GHz from the VLA Sky Survey. By using both morphological criteria, i.e., undetected radio core as well as spectral criteria, i.e., high spectral curvature and ultra-steep spectrum, we identify 21 remnant candidates that are found to reside mostly in non-cluster environments, and exhibit diverse properties in terms of morphology, spectral index ( ${\alpha }_{150}^{1400}$ in the range of -1.71 to -0.75 with a median of -1.10), and linear radio size (ranging from 242 kpc-1.3 Mpc with a median of 469 kpc). Our study attempts to identify remnant candidates down to the flux density limit of 6.0 mJy at 325 MHz, and yields an upper limit on the remnant fraction (f rem) to be around 5%. The observed f rem seems consistent with the predictions of an evolutionary model assuming power-law distributions of the duration of the active phase and jet kinetic power with an index of -0.8 to -1.2.

Keywords: radio galaxies; active galactic nuclei; radio jets; radio active galactic nuclei
The Improved Orbit Solution and Component Masses of bet LMi

bet LMi is a double-lined visual binary with an orbital period of ∼39 yr. Via a simultaneous fitting to both astrometric and radial velocity measurements, we give a complete and improved orbit solution with high precision. Then, the component masses are precisely determined as 2.98 ± 0.10 M⊙ and 1.92 ± 0.04 M⊙ with a relative precision of ∼3%, respectively. The orbital parallax is determined to be 19.6 ± 0.2 mas, which is two times more precise than Hipparcos parallax. With the known apparent magnitudes and magnitude difference of the components, we derive the luminosity of the components as 50.7 ± 1.8 L⊙ and 9.1 ± 4.1 L⊙. The estimated radii of the components are 9.4 ± 0.3 R⊙ and 3.7 ± 1.5 R⊙.

Keywords: binary stars; fundamental parameters of stars; visual binary stars; spectroscopic binary stars