adsabs/SciX_UAT_keywords huggingface dataset:
Triple Evolution: An Important Channel in the Formation of Type Ia Supernovae

Type Ia supernovae (SNe Ia) are thought to be the result of thermonuclear explosions in white dwarfs (WDs). Commonly considered formation pathways include two merging WDs (the double-degenerate channel) and a single WD accreting material from a H or He donor (the single-degenerate channel). Since the predicted SN Ia rates from WDs in binaries are thought to be insufficient to explain the observed SN Ia rate, it is important to study similar interactions in higher-order multiple-star systems such as triple systems. We use the evolutionary population synthesis code Multiple Stellar Evolution (MSE) to study the stellar evolution, binary interactions, and gravitational dynamics of the triple-star systems. Also, unlike previous studies, prescriptions are included to simultaneously take into account the single- and double-degenerate channels, and we consider triples across the entire parameter space (including those with tight inner binaries). We explore the impact of typically ignored or uncertain physics such as flybys and common envelope prescription parameters on our results. The majority of systems undergo circular mergers to explode as SNe Ia, while eccentric collisions contribute to 0.4%-4% of SN Ia events. The time-integrated SN Ia rate from the triple channel is found to be $(3.60\pm 0.04)\times {10}^{-4}\,{M}_{\odot }^{-1}$ , which is, surprisingly, similar to that of the isolated binary channel, where the SN Ia rate is $(3.2\pm 0.1)\times {10}^{-4}\,{M}_{\odot }^{-1}$ . This implies that triples, when considering their entire parameter space, yield an important contribution to the overall SN Ia rate.

Keywords: type ia supernovae; white dwarf stars; multiple stars
Magnetic Fields in Elliptical Galaxies: An Observational Probe of the Fluctuation Dynamo Action

Fluctuation dynamos are thought to play an essential role in the evolution of magnetized galaxies, saturating within ∼0.01 Gyr and thus potentially acting as seeds for large-scale mean-field dynamos. However, unambiguous observational confirmation of the fluctuation dynamo action in a galactic environment is still missing. This is because, in spiral galaxies, it is difficult to differentiate between small-scale magnetic fields generated by a fluctuation dynamo and those due to the tangling of the large-scale field. We propose that observations of magnetic fields in elliptical galaxies would directly probe the fluctuation dynamo action. This is motivated by the fact that in ellipticals, due to their lack of significant rotation, the conventional large-scale dynamo is absent and the fluctuation dynamo is responsible for controlling the strength and structure of the magnetic field. By considering turbulence injected by Type Ia supernova explosions and possible magnetic field amplification by cooling flows, we estimate expected magnetic field strengths of $0.2\mbox{--}1\,\mu {\rm{G}}$ in the centers of quiescent elliptical galaxies. We use a semianalytic model of galaxy formation to estimate the distribution and redshift evolution of field strengths, tentatively finding a decrease in magnetic field strength with decreasing redshift. We analyze a historical sample of radio sources that exhibit the Laing-Garrington effect (radio polarization asymmetry in jets) and infer magnetic field strengths between $0.14\,\mathrm{and}\,1.33\,\mu {\rm{G}}$ for a uniform thermal electron density and between $1.36\,\mathrm{and}\,6.21\,\mu {\rm{G}}$ for the thermal electron density following the King profile. We examine observational techniques for measuring the magnetic field saturation state in elliptical galaxies, focusing on Faraday rotation measure grids, the Laing-Garrington effect, synchrotron emission, and gravitational lensing, and finding appealing prospects for future empirical analysis.

Keywords: galaxy magnetic fields; elliptical galaxies; interstellar magnetic fields; polarimetry; magnetic fields
LB-1 Is Inconsistent with the X-Ray Source Population and Pulsar-Black Hole Binary Searches in the Milky Way

If confirmed, a wide binary system consisting of a 70 M⊙ black hole (BH) and an 8 M⊙ main-sequence star (LB-1) is observed to reside in the Milky Way (MW). While we remain agnostic about the nature of LB-1, we show that long-term evolution of an 8 M⊙ star around a BH with mass between 5 and 70 M⊙ makes them visible as ultraluminous X-ray (ULX) sources in the sky. Given the expected ULX phase lifetime (≈0.1 Myr) and their lack of detection in the MW, we conclude that the frequency of an 8-20 M⊙ star to be in binary around a stellar mass BH should be less (f < 4 × 10-3). This is in tension with Liu et al., who claimed the detection frequency of an LB-1-like system to be around 8-20 M⊙ stars (f ≈ 3 × 10-2). Moreover, the 8 M⊙ star is likely to end as a neutron star (NS) born with a very small kick from an electron-capture supernova (ECSN), leaving behind a wide NS-BH binary. So far, less than 1% of all the detectable pulsars in the MW have been mapped and there has been no detection of any pulsars in binary systems around BHs, which sets an upper bound of about 100 possible pulsar-BH systems in the MW. We show whether the NS is born from ECSN, a frequency upper limit of (f ≈ 10-3) for stars with masses ≈8-20 M⊙ in the MW to have a BH companion. The rate discrepancy will further increase as more pulsars are mapped in the MW, yet these searches would not be able to rule out the Liu et al. detection frequency if NSs are instead born in core collapse SNe with the commonly inferred high kick velocities.

Keywords: astrophysical black holes; pulsars; binary stars; common envelope binary stars; interstellar dust extinction
CLEAR: Survey Overview, Data Analysis, and Products

We present an overview of the CANDELS Lyα Emission At Reionization (CLEAR) survey. CLEAR is a 130 orbit program of the Hubble Space Telescope using the Wide Field Camera 3 (WFC3) IR G102 grism. CLEAR targets 12 pointings divided between the GOODS-N and GOODS-S fields of the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS). Combined with existing spectroscopic data from other programs, the full CLEAR data set includes spectroscopic imaging of these fields over 0.8-1.7 μm. In this paper, we describe the CLEAR survey, the survey strategy, the data acquisition, reduction, processing, and science products and catalogs released alongside this paper. The catalogs include emission line fluxes and redshifts derived from the combination of the photometry and grism spectroscopy for 6048 galaxies, primarily ranging from 0.2 ≲ z ≲ 3. We also provide an overview of CLEAR's science goals and results. In conjunction with this paper we provide links to electronic versions of the data products, including 1D+2D extracted spectra and emission line maps.

Keywords: emission line galaxies; early-type galaxies; galaxies; galaxy evolution; high-redshift galaxies; catalogs; redshift surveys
Early Results from GLASS-JWST. IV. Spatially Resolved Metallicity in a Low-mass z 3 Galaxy with NIRISS

We report the first gas-phase metallicity map of a distant galaxy measured with the James Webb Space Telescope (JWST). We use the NIRISS slitless spectroscopy acquired by the GLASS Early Release Science program to spatially resolve the rest-frame optical nebular emission lines in a gravitationally lensed galaxy at z = 3.06 behind the A2744 galaxy cluster. This galaxy (dubbed GLASS-Zgrad1) has stellar mass ~108.6 M ⊙, instantaneous star formation rate ~8.6 M ⊙ yr-1 (both corrected for lensing magnification), and global metallicity one-fourth solar. From its emission-line maps ([O III], Hβ, Hγ, [Ne III], and [O II]), we derive its spatial distribution of gas-phase metallicity using a well-established forward-modeling Bayesian inference method. The exquisite resolution and sensitivity of JWST/NIRISS, combined with lensing magnification, enable us to resolve this z ~ 3 dwarf galaxy in ≳50 resolution elements with sufficient signal, an analysis hitherto not possible. We find that the radial metallicity gradient of GLASS-Zgrad1 is strongly inverted (i.e., positive): ${\rm{\Delta }}\mathrm{log}({\rm{O}}/{\rm{H}})/{\rm{\Delta }}r$ = 0.165 ± 0.023 dex kpc-1. This measurement is robust at $\gtrsim 4-\,\sigma $ confidence level against known systematics. This positive gradient may be due to tidal torques induced by a massive nearby (~15 kpc projected) galaxy, which can cause inflows of metal-poor gas into the central regions of GLASS-Zgrad1. These first results showcase the power of JWST wide-field slitless spectroscopic modes to resolve the mass assembly and chemical enrichment of low-mass galaxies in and beyond the peak epoch of cosmic star formation (z ≳ 2). Reaching masses ≲ 109 M ⊙ at these redshifts is especially valuable to constrain the effects of galactic feedback and environment and is possible only with JWST's new capabilities. *Based on observations acquired by the JWST under the ERS program ID 1324 (PI T. Treu).

Keywords: galaxy abundances; galaxy evolution; galaxy formation; high-redshift galaxies; strong gravitational lensing
Tidal Disruption of Stellar Clusters and the Spatial Distribution of Their Remnants Near the Galactic Center

The accretion of massive star clusters via dynamical friction has previously been established to be a likely scenario for the buildup of nuclear stellar clusters (NSCs). A remaining issue is whether strong external tidal perturbation may lead to the severe disruption of loosely bound clusters well before they sink deeply into the center of their host galaxies. We carry out a series of N-body simulations and verify our early idealized analytic models. We show that if the density profile of the host galaxies can be described by a power-law distribution with an index of α < 1, the cluster would be compressed in the radial direction by the external galactic tidal field. In contrast, the galactic tidal perturbation is disruptive in regions with a steep, α > 1, density falloff or in the very center where gravity is dominated by the point-mass potential of supermassive black holes (SMBHs). This sufficient criterion supplements the conventional necessary Roche-lobe-filling condition in determining the preservation versus disintegration of satellite stellar systems. We simulate the disruption of stellar clusters that venture onto nearly circular, modestly, or highly eccentric orbits into the center of galaxies with a range of background density profiles and SMBHs. We obtain the spatial distribution of the stellar cluster remnants. We apply these results to the NSC within a few parsecs from SMBH Sgr A* at the Galactic Center. Recent observations indicate the coexistence of two populations of stars with distinctively separate ages and metallicities. We verify that the subsolar-metallicity population can be the debris of disrupted stellar clusters.

Keywords: globular star clusters; galactic center; galactic bulge; supermassive black holes; stellar dynamics; n-body simulations
Detecting Atmospheric Molecules of Nontransiting Temperate Terrestrial Exoplanets Using High-resolution Spectroscopy in the Mid-infrared Domain

Motivated by the development of high-dispersion spectrographs in the mid-infrared (MIR) range, we study their application to the atmospheric characterization of nearby nontransiting temperate terrestrial planets around M-type stars. We examine the detectability of CO2, H2O, N2O, and O3 features in high-resolution planetary thermal emission spectra at 12-18 μm assuming an Earth-like profile and a simplified thermal structure. The molecular line width of such planets can be comparable to or broader than the Doppler shift due to the planetary orbital motion. Given the likely difficulty in knowing the high-resolution MIR spectrum of the host star with sufficient accuracy, we propose observing the target system at two quadrature phases and extracting the differential spectra as the planetary signal. In this case, the signals can be substantially suppressed compared with the case where the host star spectrum is perfectly known, as some parts of the spectral features do not remain in the differential spectra. Despite this self-subtraction, the CO2 and H2O features of nearby (≲5 pc) systems with mid-/late-M host stars would be feasible with a 6.5 m class cryogenic space telescope, and orbital inclination could also be constrained for some of them. For CO2 and N2O in a 1 bar Earth-like atmosphere, this method would be sensitive when the mixing ratio is 1-103 ppm. The detectability of molecules except O3 is not significantly improved when the spectral resolution is higher than ${ \mathcal R }\gtrsim {\rm{10,000}}$ <!-- --> ,although the constraint on the orbital inclination is improved. This study provides some benchmark cases useful for assessing the value of MIR high-resolution spectroscopy in terms of characterization of potentially habitable planets.

Keywords: exoplanet astronomy; exoplanet atmospheres; exoplanet atmospheric composition; exoplanets; extrasolar rocky planets; habitable planets
Disk Dissipation, Giant Planet Formation, and Star Formation Rate Fluctuations in the 3 Myr History of Gould's Belt

Although episodic star formation (SF) has been suggested for nearby SF regions, a panoramic view of the recent episodic SF history in the solar neighborhood is still missing. By uniformly constraining the slope α of infrared spectral energy distributions (SEDs) of young stellar objects (YSOs) in the 13 largest Gould's Belt (GB) protoclusters surveyed by the Spitzer Space Telescope, we have constructed a cluster-averaged histogram of α representing the YSO evolution lifetime as a function of the α value. Complementary to the traditional SED classification scheme (0, I, F, II, and III) that is based on different α values, a staging scheme (A, B, C, D, and E) of SED evolution is proposed on the basis of the α statistical features that can be better matched to the physical stages of disk dissipation and giant planet formation. This has also allowed us to unravel the fluctuations of SF rate (SFR) in the 3 Myr history of these GB protoclusters. Diverse evolutionary patterns such as single peaks, double peaks, and ongoing acceleration of SFR are revealed. The SFR fluctuations are between 20% and 60% (~40% on average) and no dependence on the average SFR or the number of SFR episodes is found. However, spatially close protoclusters tend to have similar SFR fluctuation trends, indicating that the driving force of the fluctuations should be at size scales beyond the typical cluster sizes of several parsecs.

Keywords: young stellar objects; protoclusters; pre-main sequence stars; star formation; infrared sources; star counts; protoplanetary disks; spectral energy distribution; extrasolar gaseous giant planets
Are These Planets or Brown Dwarfs? Broadly Solar Compositions from High-resolution Atmospheric Retrievals of ∼10–30 M Jup Companions

Using Keck Planet Imager and Characterizer high-resolution (R ∼ 35,000) spectroscopy from 2.29 to 2.49 μm, we present uniform atmospheric retrievals for eight young substellar companions with masses of ∼10–30 M Jup, orbital separations spanning ∼50–360 au, and T eff between ∼1500 and 2600 K. We find that all companions have solar C/O ratios and metallicities to within the 1σ–2σ level, with the measurements clustered around solar composition. Stars in the same stellar associations as our systems have near-solar abundances, so these results indicate that this population of companions is consistent with formation via direct gravitational collapse. Alternatively, core accretion outside the CO snowline would be compatible with our measurements, though the high mass ratios of most systems would require rapid core assembly and gas accretion in massive disks. On a population level, our findings can be contrasted with abundance measurements for directly imaged planets with m < 10 M Jup, which show tentative atmospheric metal enrichment compared to their host stars. In addition, the atmospheric compositions of our sample of companions are distinct from those of hot Jupiters, which most likely form via core accretion. For two companions with T eff ∼ 1700–2000 K (κ And b and GSC 6214–210 b), our best-fit models prefer a nongray cloud model with >3σ significance. The cloudy models yield 2σ‑3σ lower T eff for these companions, though the C/O and [C/H] still agree between cloudy and clear models at the 1σ level. Finally, we constrain 12CO/13CO for three companions with the highest signal-to-noise ratio data (GQ Lup b, HIP 79098b, and DH Tau b) and report and radial velocities for all companions.

Keywords: exoplanet atmospheres; brown dwarfs; high resolution spectroscopy; exoplanet atmospheric composition; atmospheric clouds; exoplanet formation; substellar companion stars
Relation between Latitude-dependent Sunspot Data and Near-Earth Solar Wind Speed

Solar wind is important for the space environment between the Sun and the Earth and varies with the sunspot cycle, which is influenced by solar internal dynamics. We study the impact of latitude-dependent sunspot data on solar wind speed using the Granger causality test method and a machine-learning prediction approach. The results show that the low-latitude sunspot number has a larger effect on the solar wind speed. The time delay between the annual average solar wind speed and sunspot number decreases as the latitude range decreases. A machine-learning model is developed for the prediction of solar wind speed considering latitude and time effects. It is found that the model performs differently with latitude-dependent sunspot data. It is revealed that the timescale of the solar wind speed is more strongly influenced by low-latitude sunspots and that sunspot data have a greater impact on the 30 day average solar wind speed than on a daily basis. With the addition of sunspot data below 7.°2 latitude, the prediction of the daily and 30 day averages is improved by 0.23% and 12%, respectively. The best correlation coefficient is 0.787 for the daily solar wind prediction model.

Keywords: space weather
Buckling Bars in Nearly Face-on Galaxies Observed with MaNGA

Over half of disk galaxies are barred, yet the mechanisms for bar formation and the lifetime of bar buckling remain poorly understood. In simulations, a thin bar undergoes a rapid (<1 Gyr) event called "buckling," during which the inner part of the bar is asymmetrically bent out of the galaxy plane and eventually thickens, developing a peanut/X-shaped profile when viewed side-on. Through analyzing stellar kinematics of N-body model snapshots of a galaxy before, during, and after the buckling phase, we confirm a distinct quadrupolar pattern of out-of-plane stellar velocities in nearly face-on galaxies. This kinematic signature of buckling allows us to identify five candidates of currently buckling bars among 434 barred galaxies in the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) Survey, an integral field unit spectroscopic survey that measures the composition and kinematic structure of nearby galaxies. The frequency of buckling events detected is consistent with the 0.5-1 Gyr timescale predicted by simulations. The five candidates we present more than double the total number of candidate buckling bars and are the only ones found using the kinematic signature.

Keywords: barred spiral galaxies; galaxy structure; galaxy kinematics
Sporadic Spin-orbit Variations in Compact Multiplanet Systems and Their Influence on Exoplanet Climate

Climate modeling has shown that tidally influenced terrestrial exoplanets, particularly those orbiting M-dwarfs, have unique atmospheric dynamics and surface conditions that may enhance their likelihood to host viable habitats. However, sporadic libration and rotation induced by planetary interactions, such as those due to mean motion resonances (MMR) in compact planetary systems, may destabilize attendant exoplanets away from synchronized states (1:1 spin-orbit ratios). Here, we use a three-dimensional N-rigid-body integrator and an intermediately complex general circulation model to simulate the evolving climates of TRAPPIST-1 e and f with different orbital- and spin-evolution pathways. Planet f scenarios perturbed by MMR effects with chaotic spin variations are colder and dryer compared to their synchronized counterparts due to the zonal drift of the substellar point away from open ocean basins of their initial eyeball states. On the other hand, the differences between perturbed and synchronized planet e are minor due to higher instellation, warmer surfaces, and reduced climate hysteresis. This is the first study to incorporate the time-dependent outcomes of direct gravitational N-rigid-body simulations into 3D climate modeling of extrasolar planets, and our results show that planets at the outer edge of the habitable zones in compact multiplanet systems are vulnerable to rapid global glaciations. In the absence of external mechanisms such as orbital forcing or tidal heating, these planets could be trapped in permanent snowball states.

Keywords: exoplanet atmospheres; planetary climates; extrasolar rocky planets; n-body simulations; habitable planets; planetary dynamics
The Donor of the Black Hole X-Ray Binary MAXI J1820+070

We estimate the parameters of the donor of the accreting black hole binary MAXI J1820+070. The measured values of the binary period, rotational and radial velocities, and constraints on the orbital inclination imply the donor is a subgiant with the mass of ${M}_{2}\approx {0.49}_{-0.10}^{+0.10}{M}_{\odot }$ and the radius of ${R}_{2}\approx {1.19}_{-0.08}^{+0.08}{R}_{\odot }$ . We reanalyze the previously obtained optical spectrum from the Gran Telescopio Canarias and found it yields a strict lower limit on the effective temperature of T > 4200 K. We compile optical and infrared fluxes observed during the quiescence of this system. From the minima r- and i-band fluxes found in Pan-STARSS1 Data Release 2 prediscovery imaging and for a distance of D ≈ 3 kpc, reddening of E(B - V) = 0.23, and R 2 ≈ 1.11R ⊙, we find T ≲ 4230 K, very close to the above lower limit. For a larger distance, the temperature can be higher, up to about 4500 K (corresponding to a K5 spectral type, preferred by previous studies) at D = 3.5 kpc, allowed by the Gaia parallax. We perform evolutionary calculations for the binary system and compare them to the observational constraints. Our model fitting the above temperature and radius constraints at D ≈ 3 kpc has a mass of 0.4M ⊙, T ≈ 4200 K, and solar metallicity. Two alternative models require D ≳ 3.3-3.4 kpc at 0.4M ⊙, T ≈ 4500 K and half-solar metallicity, and 0.5M ⊙, T ≈ 4300 K, and solar metallicity. These models yield mass-transfer rates of ~10-10 M ⊙ yr-1, compatible with those based on the estimated accreted mass of ≈2 × 1025 g and the time between the 2018 discovery and the 1934 historical outburst.

Keywords: stellar mass black holes; low-mass x-ray binary stars; x-ray binary stars; astrophysical black holes
The Large Flux Variations of 17 Com A as Recorded by FUSE

Inspection of archival FUSE spectra of the Ap star 17 Com A (HD 108662) reveals large flux variations from 905 to 1187 Å over the 5.0808 days rotational period. These variations are of larger amplitude than those observed in the ultraviolet range with IUE from 1200 to 2000 Å. At 1161 Å, where the flux reaches a maximum, the variation of flux with rotational phase shows a double-wave structure similar to that of the Transiting Exoplanet Survey Satellite lightcurve. These large flux variations are most likely caused by the passage of spots or belts of overabundant elements in the line of sight as the star rotates The FUSE spectrum of 17 Com A contains mostly blends of low-excitation lines of Mn II, Cr II and Fe II and interesting lines of C I, C III, P II, S II and Cl I.

Keywords: chemically peculiar stars