adsabs/SciX_UAT_keywords huggingface dataset:
Black Hole and Galaxy Coevolution in Moderately Luminous Active Galactic Nuclei at z ∼ 1.4 in SXDF

We investigate the relation of black hole mass versus host stellar mass and that of mass accretion rate versus star formation rate (SFR) in moderately luminous ( $\mathrm{log}{L}_{\mathrm{bol}}\sim 44.5\mbox{--}46.5\ \mathrm{erg}\,{{\rm{s}}}^{-1}$ <!-- --> ), X-ray selected broad-line active galactic nuclei (AGNs) at z = 1.18-1.68 in the Subaru/XMM-Newton Deep Field. The far-infrared to far-ultraviolet spectral energy distributions of 85 AGNs are reproduced with the latest version of Code Investigating GALaxy Emission (CIGALE), where the AGN clumpy torus model SKIRTOR is implemented. Most of their hosts are confirmed to be main-sequence star-forming galaxies. We find that the mean ratio of the black hole mass (MBH) to the total stellar mass (Mstellar) is $\mathrm{log}{M}_{\mathrm{BH}}/{M}_{\mathrm{stellar}}=-2.2$ <!-- --> ,which is similar to the local black hole-to-bulge mass ratio. This suggests that if the host galaxies of these moderately luminous AGNs at z ∼ 1.4 are dominated by bulges, they already established the local black hole mass-bulge mass relation; if they are disk dominant, their black holes are overmassive relative to the bulges. The AGN bolometric luminosities and SFR show a good correlation with ratios higher than that expected from the local black hole-to-bulge mass relation, suggesting that these AGNs are in a SMBH-growth dominant phase.

Keywords: active galaxies; active galactic nuclei; supermassive black holes
Revisiting WASP-47 with ESPRESSO and TESS

WASP-47 hosts a remarkable planetary system containing a hot Jupiter (WASP-47 b; P = 4.159 days) with an inner super-Earth (WASP-47 e; P = 0.7896 days), a close-orbiting outer Neptune (WASP-47 d; P = 9.031 days), and a long-period giant planet (WASP-47 c; P = 588.4 days). We use the new Transiting Exoplanet Survey Satellite (TESS) photometry to refine the orbital ephemerides of the transiting planets in the system, particularly the hot Jupiter WASP-47 b, for which we find an update equating to a 17.4 minute shift in the transit time. We report new radial-velocity measurements from the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO) spectrograph for WASP-47, which we use to refine the masses of WASP-47 d and WASP-47 e, with a high-cadence observing strategy aimed to focus on the super-Earth WASP-47 e. We detect a periodic modulation in the K2 photometry that corresponds to a 32.5 ± 3.9 day stellar rotation, and find further stellar activity signals in our ESPRESSO data consistent with this rotation period. For WASP-47 e we measure a mass of 6.77 ± 0.57 M ⊕ and a bulk density of 6.29 ± 0.60 g cm-3, giving WASP-47 e the second most precisely measured density to date of any super-Earth. The mass and radius of WASP-47 e, combined with the exotic configuration of the planetary system, suggest the WASP-47 system formed through a mechanism different to systems with multiple small planets or more typical isolated hot Jupiters.

Keywords: exoplanet astronomy; radial velocity; transit photometry; stellar activity
On the Generation and Evolution of Switchbacks and the Morphology of the Alfvénic Transition: Low Mach-number Boundary Layers

We investigate the generation and evolution of switchbacks (SBs), the nature of the sub-Alfvénic wind observed by the Parker Solar Probe (PSP), and the morphology of the Alfvénic transition, all of which are key issues in solar wind research. First we highlight a special structure in the pristine solar wind, termed a low Mach-number boundary layer (LMBL). An increased Alfvén radius and suppressed SBs are observed within an LMBL. A probable source on the Sun for an LMBL is the peripheral region inside a coronal hole with rapidly diverging open fields. The sub-Alfvénic wind detected by PSP is an LMBL flow by nature. The similar origin and similar properties of the sub-Alfvénic intervals favor a wrinkled surface for the morphology of the Alfvénic transition. We find that a larger deflection angle tends to be associated with a higher Alfvén Mach number. The magnetic deflections have an origin well below the Alfvén critical point, and deflection angles larger than 90° seem to occur only when M A ≳ 2. The velocity enhancement in units of the local Alfvén speed generally increases with the deflection angle, which is explained by a simple model. A nonlinearly evolved, saturated state is revealed for SBs, where the local Alfvén speed is roughly an upper bound for the velocity enhancement. In the context of these results, the most promising theory on the origin of SBs is the model of expanding waves and turbulence, and the patchy distribution of SBs is attributed to modulation by reductions in the Alfvén Mach number. Finally, a picture of the generation and evolution of SBs is created based on the results.

Keywords: solar wind; solar magnetic fields; interplanetary turbulence; solar coronal waves; solar coronal holes
Restoration of the Tully–Fisher Relation by Statistical Rectification

I employ the Lucy rectification algorithm to recover the inclination-corrected distribution of local disk galaxies in the plane of absolute magnitude (M i ) and H I velocity width (W 20). By considering the inclination angle as a random variable with a known probability distribution, the novel approach eliminates one major source of uncertainty in studies of the Tully–Fisher relation: inclination angle estimation from axial ratio. Leveraging the statistical strength derived from the entire sample of 28,264 H I-selected disk galaxies at z < 0.06 from the Arecibo Legacy Fast ALFA survey, I show that the restored distribution follows a sharp correlation that is approximately a power law between ‑16 > M i > ‑22: ${M}_{i}={M}_{0}-2.5\beta \ [\mathrm{log}({W}_{20}/250\mathrm{km}/{\rm{s}})]$ , with M 0 = ‑19.77± 0.04 and β = 4.39 ± 0.06. At the brighter end (M i < ‑22), the slope of the correlation decreases to β ≈ 3.3, confirming previous results. Because the method accounts for measurement errors, the intrinsic dispersion of the correlation is directly measured: $\sigma (\mathrm{log}{W}_{20})\approx 0.06$ dex between ‑17 > M i > ‑23, while σ(M i ) decreases from ∼0.8 in slow rotators to ∼0.4 in fast rotators. The statistical rectification method holds significant potential, especially in the studies of intermediate-to-high-redshift samples, where limited spatial resolution hinders precise measurements of inclination angles.

Keywords: astrostatistics; scaling relations; disk galaxies; galaxy rotation; galaxy luminosities
Hydrodynamics of Collisions and Close Encounters between Stellar Black Holes and Main-sequence Stars

Recent analyses have shown that close encounters between stars and stellar black holes occur frequently in dense star clusters. Depending upon the distance at closest approach, these interactions can lead to dissipating encounters such as tidal captures and disruptions, or direct physical collisions, all of which may be accompanied by bright electromagnetic transients. In this study, we perform a wide range of hydrodynamic simulations of close encounters between black holes and main-sequence stars that collectively cover the parameter space of interest, and we identify and classify the various possible outcomes. In the case of nearly head-on collisions, the star is completely disrupted with roughly half of the stellar material becoming bound to the black hole. For more distant encounters near the classical tidal-disruption radius, the star is only partially disrupted on the first pericenter passage. Depending upon the interaction details, the partially disrupted stellar remnant may be tidally captured by the black hole or become unbound (in some cases, receiving a sufficiently large impulsive kick from asymmetric mass loss to be ejected from its host cluster). In the former case, the star will undergo additional pericenter passages before ultimately being disrupted fully. Based on the properties of the material bound to the black hole at the end of our simulations (in particular, the total bound mass and angular momentum), we comment upon the expected accretion process and associated electromagnetic signatures that are likely to result.

Keywords: astrophysical black holes; hydrodynamical simulations; tidal disruption; globular star clusters; transient sources
Effects of Supra-arcade Downflows Interacting with the Postflare Arcade

Supra-arcade downflows (SADs) are dark voids descending through plasma above the postflare arcade. Although they are generally viewed as byproducts of flare reconnections in the corona, the nature of SADs is under debate. Here we investigated six distinct episodes of SADs observed in the post-maximum phase of an M-class flare of 2013 April 11. Differential emission measure analysis revealed that SAD cases occurring close to the flare maximum contain an enhanced hot plasma component at 5-7 MK whereas those occurring later exhibit a depression in hot plasma at 7-12 MK compared to the ambient supra-arcade plasma. On-disk location of the flare enabled us to examine in detail the interaction of SADs with the postflare arcade, whose effects include (1) transverse oscillations of period ~160 s in the supra-arcade rays in the wake of voids, (2) footpoint brightening in 1700 Å whose peak is delayed by 22-46 s with respect to the SAD's arrival at the top of the arcade, and (3) EUV intensity perturbations expanding and propagating with a speed of ~400 km s-1. On the other hand, due to line-of-sight confusion in the optically thin corona, the ribbon enhancement following the interaction produces an illusion of plasma rebound at the top of the arcade, where the interaction fails to yield significant plasma heating. These effects indicate that the interaction mainly generates MHD waves propagating toward the surface, which may further produce quasi-periodic brightening at flare ribbons, therefore contributing to gradual phase emission from quasi-periodic EUV emission observed during the gradual phase of flares.

Keywords: the sun; solar atmosphere; solar flares; solar magnetic reconnection; solar coronal loops
Stellar Loci. VI. An Updated Catalog of the Best and Brightest Metal-poor Stars

We employ Gaia, Two Micron All Sky Survey, and ALLWISE photometry, as well as astrometric data from Gaia, to search for relatively bright very metal-poor (VMP; [Fe/H] < -2.0) giant star candidates using three different criteria: (1) the derived Gaia photometric metallicities from Xu et al., (2) the lack of stellar molecular absorption near 4.6 μm, and (3) their high tangential velocities. With different combinations of these criteria, we have identified six samples of candidates with G < 15: the Gold sample (24,304 candidates), the Silver GW sample (40,157 candidates), the Silver GK sample (120,452 candidates), the Bronze G sample (291,690 candidates), the Bronze WK sample (68,526 candidates), and the Low-b sample (4645 candidates). The Low-b sample applies to sources with low Galactic latitude, ∣b∣ < 10°, while the others are for sources with ∣b∣ > 10°. By crossmatching with results derived from medium-resolution spectroscopy (R ~ 1800) from LAMOST DR8, we establish that the success rate for identifying VMP stars is 60.1% for the Gold sample, 39.2% for the Silver GW sample, 41.3% for the Silver GK sample, 15.4% for the Bronze G sample, 31.7% for the Bronze WK sample, and 16.6% for the Low-b sample, respectively. An additional strict cut on the quality parameter RUWE < 1.1 can further increase the success rate of the Silver GW, Silver GK, and Bronze G samples to 46.9%, 51.6%, and 29.3%, respectively. Our samples provide valuable targets for high-resolution follow-up spectroscopic observations and are made publicly available.

Keywords: population ii stars; milky way stellar halo; stellar abundances
Spectroscopic Confirmation of the Active Dwarf Nature of 2MASS J07363415+6538548

The star 2MASS J07363415+6538548 (hereafter 2M0736) was previously classified as a possible symbiotic binary, a cataclysmic variable, an H II region, a massive star cluster, a supernova remnant, or a high-mass X-ray binary. In the previous research, while analyzing disputable symbiotic candidates in our New Online Database of Symbiotic Variables, we employed multi-frequency photometric observations, and reclassified the object as an active K-type dwarf. Here, we analyze the low-resolution spectroscopy of 2M0736 to confirm its photometric classification and validate that our methods are able to provide comparable results with the optical spectroscopy. The obtained spectrum confirmed that 2M0736 is a K6 dwarf. The presence and strength of the Hα emission line have verified that the object is very active.

Keywords: k dwarf stars; late-type dwarf stars; spectroscopy; astronomical techniques
Say Hello to Algol's New Companion Candidates

Constant orbital period ephemerides of eclipsing binaries give the computed eclipse epochs (C). These ephemerides based on the old data cannot accurately predict the observed future eclipse epochs (O). Predictability can be improved by removing linear or quadratic trends from the O - C data. Additional companions in an eclipsing binary system cause light-time travel effects that are observed as strictly periodic O - C changes. Recently, Hajdu et al. estimated that the probability of detecting the periods of two new companions from the O - C data is only 0.00005. We apply the new discrete chi-square method to 236 yr of O - C data of the eclipsing binary Algol (β Persei). We detect the tentative signals of at least five companion candidates having periods between 1.863 and 219.0 yr. The weakest one of these five signals does not reveal a "new" companion candidate, because its 680.4 ± 0.4 day signal period differs only 1.4σ from the well-known 679.85 ± 0.04 day orbital period of Algol C. We detect these same signals also from the first 226.2 yr of data, and they give an excellent prediction for the last 9.2 yr of our data. The orbital planes of Algol C and the new companion candidates are probably coplanar because no changes have been observed in Algol's eclipses. The 2.867 day orbital period has been constant since it was determined by Goodricke.

Keywords: astronomy data analysis; eclipsing binary stars; algol variable stars; time series analysis
M31N 2013-10c: A Newly Identified Recurrent Nova in M31

The nova M31N 2023-11f (2023yoa) has been recently identified as the second eruption of a previously recognized nova, M31N 2013-10c, establishing the latter object as the 21st recurrent nova system thus far identified in M31. Here we present well sampled R-band lightcurves of both the 2013 and 2023 eruptions of this system. The photometric evolution of each eruption was quite similar as expected for the same progenitor system. The 2013 and 2023 eruptions each reached peak magnitudes just brighter than R ~ 16, with fits to the declining branches of the eruptions yielding times to decline by two magnitudes of t 2(R) = 5.5 ± 1.7 and t 2(R) = 3.4 ± 1.5 days, respectively. M31N 2013-10c has an absolute magnitude at peak, M R = - 8.8 ± 0.2, making it the most luminous known recurrent nova in M31.

Keywords: novae; recurrent novae; andromeda galaxy
Ultracool Dwarfs Observed with the Spitzer Infrared Spectrograph. I. An Accurate Look at the L-to-T Transition at 300 Myr from Optical Through Mid-infrared Spectrophotometry

We present Spitzer IRS 5-14 μm spectra and 16 μm and 22 μm photometry of the T2.5 companion to the ~300 Myr old G0V star HN Peg. We incorporate previous 0.8-5 μm observations to obtain the most comprehensive spectral energy distribution (SED) of an intermediate-gravity L/T-transition dwarf that, together with an accurate Gaia EDR3 parallax of the primary, enables us to derive precise fundamental parameters. We find that young (≈0.1-0.3 Gyr) early-T dwarfs on average have ≈140 K lower effective temperatures, ≈20% larger radii, and similar bolometric luminosities compared to ≳1 Gyr old field dwarfs with similar spectral types. Our accurate infrared spectrophotometry offers new detail at wavelengths where the dominant carbon-bearing molecules have their strongest transitions: at 3.4 μm for methane and at 4.6 μm for carbon monoxide. We assess the performance of various widely available photospheric models and find that models with condensates and/or clouds better reproduce the full SED of this moderately young early-T dwarf. However, cloud-free models incorporating a more general convective instability treatment reproduce at least the low-resolution near-infrared spectrum similarly well. Our analysis of R ≈ 2300 J-band spectra shows that the near-infrared potassium absorption lines in HN Peg B have similar strengths to those seen in both younger and older T2-T3 dwarfs. We conclude that while alkali lines are well established as surface gravity indicators for L-type or warmer stars, they are insensitive to surface gravity in early-T dwarfs.

Keywords: brown dwarfs
Exploring Thousands of Nearby Hierarchical Systems with Gaia and Speckle Interferometry

There should be about 10,000 stellar hierarchical systems within 100 pc with primary stars more massive than 0.5 M ⊙, and a similar amount of less-massive hierarchies. A list of 8000 candidate multiples is derived from wide binaries found in the Gaia Catalog of Nearby Stars where one or both components have excessive astrometric noise or other indicators of inner subsystems. A subset of 1243 southern candidates were observed with high angular resolution at the 4.1 m Southern Astrophysical Research Telescope, and 503 new pairs with separations from 0.″03 to 1″ were resolved. These data allow estimation of the inner mass ratios and periods, and help to quantify the ability of Gaia to detect close pairs. Another 621 hierarchies with known inner periods come from the Gaia catalog of astrometric and spectroscopic orbits. These two nonoverlapping groups, combined with existing ground-based data, bring the total number of known nearby hierarchies to 2754, reaching a completeness of ~22% for stars above 0.5 M ⊙. Distributions of their periods and mass ratios are briefly discussed, and the prospects of further observations are outlined.

Keywords: binary stars; multiple stars; solar neighborhood; speckle interferometry
GALFIT-ing AGN Host Galaxies in COSMOS: HST versus Subaru

The COSMOS field has been extensively observed by most major telescopes, including Chandra, HST, and Subaru. HST imaging boasts very high spatial resolution and is used extensively in morphological studies of distant galaxies. Subaru provides lower spatial resolution imaging than HST but a substantially wider field of view with greater sensitivity. Both telescopes provide near-infrared imaging of COSMOS. Successful morphological fitting of Subaru data would allow us to measure morphologies of over 104 known active galactic nucleus (AGN) hosts, accessible through Subaru wide-field surveys, currently not covered by HST. The morphological parameters indicate the types of galaxies that host AGNs. For 4016 AGNs between 0.03 < z < 6.5, we study the morphology of their galaxy hosts using GALFIT, fitting components representing the AGN and host galaxy simultaneously using the i-band imaging from both HST and Subaru. Comparing the fits for the differing telescope spatial resolutions and image signal-to-noise ratios, we identify parameter regimes for which there is strong disagreement between distributions of fitted parameters for HST and Subaru. In particular, the Sérsic index values strongly disagree between the two sets of data, including sources at lower redshifts. In contrast, the measured magnitude and radius parameters show reasonable agreement. Additionally, large variations in the Sérsic index have little effect on the ${\chi }_{\nu }^{2}$ of each fit, whereas variations in other parameters have a more significant effect. These results indicate that the Sérsic index distributions of high-redshift galaxies that host AGNs imaged at ground-based spatial resolution are not reliable indicators of galaxy type and should be interpreted with caution.

Keywords: agn host galaxies; active galactic nuclei; galaxy classification systems; surveys
Spacecraft Charging Simulations of Probe B1 of Comet Interceptor during the Cometary Flyby

Comet Interceptor will be the first mission to make a flyby of a long-period or interstellar comet. After launch, the spacecraft will wait at the Sun-Earth Lagrange point L2 for a yet-to-be-discovered comet to appear. The mission comprises three spacecraft: One main spacecraft, A, developed by ESA, and two subprobes, B1 and B2, developed by JAXA and ESA, respectively. All spacecraft will carry plasma instruments for a three-dimensional sampling of the cometary plasma environment. The plasma measurements will likely be affected by the spacecraft potential and by particles emitted from the spacecraft surface. In this work, we use the Spacecraft Plasma Interaction Software and the ElectroMagnetic Spacecraft Environment Simulator to make particle-in-cell simulations of the spacecraft-plasma interactions of probe B1 in different environments during the cometary flyby. This is done for two production rates of the target comet and two relative flyby velocities of the probe. At low flyby velocities, the spacecraft potential varies from 9 V in the solar wind to -5 V in the inner coma for a comet similar to comet 67P/Churyumov-Gerasimenko. For a comet similar to 1P/Halley, the potential is slightly less negative in the inner coma due to the more effective collisional cooling of the electrons in the environment. At high flyby velocities, secondary electron emissions from neutral gas impacts dominate the currents, charging the probe to positive potentials in most of the studied environments.

Keywords: comets; space plasmas
Call and Response: A Time-resolved Study of Chromospheric Evaporation in a Large Solar Flare

We studied an X1.6 solar flare produced by NOAA Active Region 12602 on 2014 October 22. The entirety of this event was covered by RHESSI, IRIS, and Hinode/EIS, allowing analysis of the chromospheric response to a nonthermal electron driver. We derived the energy contained in nonthermal electrons via RHESSI spectral fitting and linked the time-dependent parameters of this call to the response in Doppler velocity, density, and nonthermal width across a broad temperature range. The total energy injected was 4.8 × 1030 erg and lasted 352 s. This energy drove explosive chromospheric evaporation, with a delineation in both Doppler and nonthermal velocities at the flow reversal temperature, between 1.35 and 1.82 MK. The time of peak electron injection (14:06 UT) corresponded to the time of highest velocities. At this time, we found 200 km s-1 blueshifts in the core of Fe XXIV, which is typically assumed to be at rest. Shortly before this time, the nonthermal electron population had the shallowest spectral index (≈6), corresponding to the peak nonthermal velocity in Si IV and Fe XXI. Nonthermal velocities in Fe XIV, formed near the flow reversal temperature, were low and not correlated with density or Doppler velocity. Nonthermal velocities in ions with similar temperatures were observed to increase and correlate with Doppler velocities, implying unresolved flows surrounding the flow reversal point. This study provides a comprehensive, time-resolved set of chromospheric diagnostics for a large X-class flare, along with a time-resolved energy injection profile, ideal for further modeling studies.

Keywords: solar flares; solar flare spectra; solar x-ray flares; solar extreme ultraviolet emission; solar ultraviolet emission; active solar chromosphere; solar active region velocity fields; solar activity; solar chromosphere; solar transition region