adsabs/SciX_UAT_keywords huggingface dataset:
Inferring Maps of the Sun's Far-side Unsigned Magnetic Flux from Far-side Helioseismic Images Using Machine Learning Techniques

Accurate modeling of the Sun's coronal magnetic field and solar wind structures requires inputs of the solar global magnetic field, including both the near and far sides, but the Sun's far-side magnetic field cannot be directly observed. However, the Sun's far-side active regions are routinely monitored by helioseismic imaging methods, which only require continuous near-side observations. It is therefore both feasible and useful to estimate the far-side magnetic-flux maps using the far-side helioseismic images despite their relatively low spatial resolution and large uncertainties. In this work, we train two machine-learning models to achieve this goal. The first machine-learning training pairs simultaneous Solar Dynamics Observatory (SDO)/Helioseismic and Magnetic Imager-observed magnetic-flux maps and SDO/Atmospheric Imaging Assembly-observed extreme ultraviolet (EUV) 304 Å images, and the resulting model can convert 304 Å images into magnetic-flux maps. This model is then applied to the STEREO-observed far-side 304 Å images, available for about 4.3 yr, for the far-side magnetic-flux maps. These EUV-converted magnetic-flux maps are then paired with simultaneous far-side helioseismic images for a second machine-learning training, and the resulting model can convert far-side helioseismic images into magnetic-flux maps. These helioseismically derived far-side magnetic-flux maps, despite their limitations in spatial resolution and accuracy, can be routinely available on a daily basis, providing useful magnetic information on the Sun's far side using only the near-side observations.

Keywords: helioseismology; solar magnetic fields; solar active regions; space weather
Three Lyα Emitting Galaxies within a Quasar Proximity Zone at z ∼ 5.8

Quasar proximity zones at $z\gt 5.5$ correspond to overdense and overionized environments. Galaxies found inside proximity zones can therefore display features that would otherwise be masked by absorption in the intergalactic medium. We demonstrate the utility of this quasar-galaxy synergy by reporting the discovery of the first three "proximate Lyα emitters" (LAEs) within the proximity zone of quasar J0836+0054 at z = 5.795 (Aerith A, B, and C). Aerith A, located behind the quasar with an impact parameter ${D}_{\perp }=278\pm 8$ pkpc, provides the first detection of an Lyα transverse proximity effect. We model the transmission and show that it constrains the onset of J0836's quasar phase to $0.2\mathrm{Myr}\lt t\lt 28\mathrm{Myr}$ in the past. The second object, Aerith B at a distance $D\lt 912$ pkpc from the quasar, displays a bright and broad double-peaked Lyα emission line. The peak separation implies a low ionizing ${f}_{\mathrm{esc}}\lesssim 1 \% $ . We fit the Lyα line with an outflowing shell model, finding a typical central density $\mathrm{log}\ {N}_{{\rm{H}}{\rm{I}}}/{\mathrm{cm}}^{-2}={19.3}_{-0.2}^{+0.8}$ , outflow velocity ${V}_{\mathrm{out}}={16}_{-11}^{+4}$ km s-1, and gas temperature $\mathrm{log}T/K={3.8}_{-0.7}^{+0.8}$ compared to $2\lt z\lt 3$ analog LAEs. We detect object Aerith C via an Lyα emission line at z = 5.726. This corresponds with the edge of the quasar's proximity zone ( ${\rm{\Delta }}z\lt 0.02$ ), suggesting that the proximity zone is truncated by a density fluctuation. Via the analyses conducted here, we illustrate how proximate LAEs offer unique insight into the ionizing properties of both quasars and galaxies during hydrogen reionization.

Keywords: lyman-break galaxies; lyman alpha forest; spectroscopy; quasar-galaxy pairs; quasars; galaxies; galaxy formation; reionization; early universe
A Gaia Data Release 3 View on the Tip of the Red Giant Branch Luminosity

The tip of the red giant branch (TRGB) is a standard candle that can be used to help refine the determination of the Hubble constant. Gaia Data Release 3 (DR3) provides synthetic photometry constructed from low-resolution BP/RP spectra for Milky Way field stars that can be used to directly calibrate the luminosity of the TRGB in the Johnson-Cousins I band, where the TRGB is least sensitive to metallicity. We calibrate the TRGB luminosity using a two-dimensional maximum likelihood algorithm with field stars and Gaia synthetic photometry and parallaxes. For a high-contrast and low-contrast break (characterized by the values of the contrast parameter R or the magnitude of the break β), we find M TRGB I = -4.02 and -3.92 mag respectively, or a midpoint of -3.970 ${}_{-0.024}^{+0.042}$ (sys) ± 0.062 (stat) mag. This measurement improves upon the TRGB measurement from Li et al., as the higher precision photometry based on Gaia DR3 allows us to constrain two additional free parameters of the luminosity function. We also investigate the possibility of using Gaia DR3 synthetic photometry to calibrate the TRGB luminosity with ω Centauri, but find evidence of blending within the inner region for cluster member photometry that precludes accurate calibration with Gaia DR3 photometry. We instead provide an updated TRGB measurement of m TRGB I = 9.82 ± 0.04 mag in ω Centauri using ground-based photometry from the most recent version of the database described in Stetson et al., which gives M TRGB I = -3.97 ± 0.04 (stat) ± 0.10 (sys) mag when tied to the Gaia EDR3 parallax distance from the consensus of Vasiliev & Baumgardt, Soltis et al., and Maíz Apellániz.

Keywords: milky way galaxy; calibration; red giant tip; distance indicators; hubble constant; parallax; maximum likelihood estimation; absolute magnitude; field stars
ALMA Reveals Hidden Morphologies in the Molecular Envelope of VY Canis Majoris

The J = 2 → 1 transition of CO near 230 GHz and the J = 3 → 2 line of HCN at 265 GHz have been imaged in the envelope of the red hypergiant star, VY Canis Majoris (VY CMa), using the Atacama Large Millimeter Array (ALMA) with angular resolutions 0.″2-1.″5; single-dish data were added to provide sensitivity up to 30″. These images reveal a far more complex envelope, with previously unseen outflows extending 4″-9″ from the star. These new structures include an arc-like outflow with an angular separation of ~9″ northeast from the stellar position ("NE Arc"), twin fingerlike features approximately 4″ to the north/northeast ("NE Extension"), and a roughly spherical region observed ~7″ E of the star ("E Bubble"). The NE Arc appears to be decelerating from base (V LSR ~ 7 km s-1) to tip (V LSR ~ 18 km s-1), while the NE Extension is blueshifted with V LSR ~ -7 km s-1. Among the new features, HCN is only detected in the NE Arc. In addition, known structures Arc 1, Arc 2, and NW Arc, as well as other features closer to the star, are closely replicated in CO, suggesting that the gas and dust are well mixed. The CO spectra are consistent with the kinematic picture of VY CMa derived from HST data. Arc 2, however, has added complexity. Preliminary results from CO suggest 12C/13C ~ 22-38 across the envelope. The additional presence of at least three major episodic mass ejection events significantly broadens the current perspective of the envelope structure and mass-loss history of VY CMa.

Keywords: hypergiant stars; millimeter astronomy; circumstellar envelopes; stellar evolution; stellar mass loss; stellar winds
First Release of PLATO Consortium Stellar Limb-darkening Coefficients

We release the first grid of stellar limb-darkening coefficients (LDCs) and intensity profiles (IPs) computed by the consortium of the PLAnetary Transits and Oscillations of stars (PLATO), the next medium-class (M3) mission under development by the European Space Agency to be launched in 2026. We have performed spectral synthesis with TurboSpectrum on a grid of MARCS model atmospheres. Finally, we adopted ExoTETHyS to convolve the high-resolution spectra (R = 2 × 105) with the state-of-the-art response functions for all the PLATO cameras, and computed the LDCs that best approximate the convolved IPs. In addition to the PLATO products, we provide new LDCs and IPs for the Kepler mission, based on the same grid of stellar atmospheric models and calculation procedures. The data can be downloaded from the following link: https://doi.org/10.5281/zenodo.7339706.

Keywords: transit photometry; space telescopes; exoplanets; limb darkening; stellar atmospheres
JWST/NIRCam Imaging of Young Stellar Objects. I. Constraints on Planets Exterior to the Spiral Disk Around MWC 758

MWC 758 is a young star hosting a spiral protoplanetary disk. The spirals are likely companion-driven, and two previously identified candidate companions have been identified—one at the end the Southern spiral arm at ∼0.″6, and one interior to the gap at ∼0.″1. With JWST/NIRCam, we provide new images of the disk and constraints on planets exterior to ∼1″. We detect the two-armed spiral disk, a known background star, and a spatially resolved background galaxy, but no clear companions. The candidates that have been reported are at separations that are not probed by our data with sensitivity sufficient to detect them‑nevertheless, these observations place new limits on companions down to ∼2 M Jup at ∼150 au and ∼0.5 M Jup at ≳600 au. Owing to the unprecedented sensitivity of JWST and youth of the target, these are among the deepest mass-detection limits yet obtained through direct imaging observations, and provide new insights into the system's dynamical nature.

Keywords: exoplanets; protoplanetary disks; high contrast techniques; james webb space telescope; planet formation; exoplanet formation; extrasolar gaseous giant planets
Investigating the Observational Properties of Type Ib Supernova SN 2017iro

We report results of optical imaging and low-resolution spectroscopic monitoring of supernova (SN) 2017iro that occurred in the nearby (~31 Mpc) galaxy NGC 5480. The He I λ5876 feature present in the earliest spectrum (-7 days) classified it as a Type Ib SN. The follow-up observations span from -7 to +266 days with respect to the B-band maximum. With a peak absolute magnitude in V band M V = -17.76 ± 0.15 mag and bolometric luminosity log10 L = 42.39 ± 0.09 erg s-1, SN 2017iro is a moderately luminous Type Ib SN. The overall light-curve evolution of SN 2017iro is similar to that of SN 2012au and SN 2009jf during the early (up to ~100 days) and late phases (>150 days), respectively. The line velocities of both Fe II λ5169 and He I λ5876 are ~9000 km s-1 near the peak. The analysis of the nebular phase spectrum (~+209 days) indicates an oxygen mass of ~0.35 M ⊙. The smaller [O I]/[Ca II] flux ratio of ~1 favors a progenitor with a zero-age main-sequence mass in the range ~13-15 M ⊙, most likely in a binary system, similar to the case of iPTF13bvn. The explosion parameters are estimated by applying different analytical models to the quasi-bolometric light curve of SN 2017iro. 56Ni mass synthesized in the explosion has a range of ~0.05-0.10 M ⊙, ejecta mass ~1.4-4.3 M ⊙, and kinetic energy ~(0.8-1.9) × 1051 erg.

Keywords: type ib supernovae; supernovae; core-collapse supernovae
Tidal Disruption Event Demographics with the Zwicky Transient Facility: Volumetric Rates, Luminosity Function, and Implications for the Local Black Hole Mass Function

We conduct a systematic tidal disruption event (TDE) demographics analysis using the largest sample of optically selected TDEs. A flux-limited, spectroscopically complete sample of 33 TDEs is constructed using the Zwicky Transient Facility over 3 yr (from 2018 October to 2021 September). We infer the black hole (BH) mass (M BH) with host galaxy scaling relations, showing that the sample M BH ranges from 105.1 M ⊙ to 108.2 M ⊙. We developed a survey efficiency corrected maximum volume method to infer the rates. The rest-frame g-band luminosity function can be well described by a broken power law of $\phi ({L}_{g})\propto {\left[{\left({L}_{g}/{L}_{\mathrm{bk}}\right)}^{0.3}+{\left({L}_{g}/{L}_{\mathrm{bk}}\right)}^{2.6}\right]}^{-1}$ , with L bk = 1043.1 erg s-1. In the BH mass regime of 105.3 ≲ (M BH/M ⊙) ≲ 107.3, the TDE mass function follows $\phi ({M}_{\mathrm{BH}})\propto {M}_{\mathrm{BH}}^{-0.25}$ , which favors a flat local BH mass function ( ${{dn}}_{\mathrm{BH}}/d\mathrm{log}{M}_{\mathrm{BH}}\approx \mathrm{constant}$ ). We confirm the significant rate suppression at the high-mass end (M BH ≳ 107.5 M ⊙), which is consistent with theoretical predictions considering direct capture of hydrogen-burning stars by the event horizon. At a host galaxy mass of M gal ~ 1010 M ⊙, the average optical TDE rate is ≈3.2 × 10-5 galaxy-1 yr-1. We constrain the optical TDE rate to be [3.7, 7.4, and 1.6] × 10-5 galaxy-1 yr-1 in galaxies with red, green, and blue colors.

Keywords: tidal disruption; time domain astronomy; black holes; galaxy nuclei; supermassive black holes; luminosity function
First-principles Demonstration of Diffusive-advective Particle Acceleration in Kinetic Simulations of Relativistic Plasma Turbulence

Nonthermal relativistic plasmas are ubiquitous in astrophysical systems like pulsar wind nebulae and active galactic nuclei, as inferred from their emission spectra. The underlying nonthermal particle acceleration (NTPA) processes have traditionally been modeled with a Fokker-Planck (FP) diffusion-advection equation in momentum space. In this Letter, we directly test the FP framework in ab initio kinetic simulations of driven magnetized turbulence in relativistic pair plasma. By statistically analyzing the motion of tracked particles, we demonstrate the diffusive nature of NTPA and measure the FP energy diffusion (D) and advection (A) coefficients as functions of particle energy $\gamma {m}_{e}{c}^{2}$ . We find that $D(\gamma )$ scales as ${\gamma }^{2}$ in the high-energy nonthermal tail, in line with second-order Fermi acceleration theory, but has a much weaker scaling at lower energies. We also find that A is not negligible and reduces NTPA by tending to pull particles toward the peak of the particle energy distribution. This study provides strong support for the FP picture of turbulent NTPA, thereby enhancing our understanding of space and astrophysical plasmas.

Keywords: high energy astrophysics; non-thermal radiation sources; plasma astrophysics
The JCMT BISTRO Survey: An 850/450 μm Polarization Study of NGC 2071IR in Orion B

We present the results of simultaneous 450 μm and 850 μm polarization observations toward the massive star-forming region NGC 2071IR, a target of the BISTRO (B-fields in STar-forming Region Observations) Survey, using the POL-2 polarimeter and SCUBA-2 camera mounted on the James Clerk Maxwell Telescope. We find a pinched magnetic field morphology in the central dense core region, which could be due to a rotating toroidal disklike structure and a bipolar outflow originating from the central young stellar object IRS 3. Using the modified Davis-Chandrasekhar-Fermi method, we obtain a plane-of-sky magnetic field strength of 563 ± 421 μG in the central ~0.12 pc region from 850 μm polarization data. The corresponding magnetic energy density of 2.04 × 10-8 erg cm-3 is comparable to the turbulent and gravitational energy densities in the region. We find that the magnetic field direction is very well aligned with the whole of the IRS 3 bipolar outflow structure. We find that the median value of polarization fractions is 3.0% at 450 μm in the central 3' region, which is larger than the median value of 1.2% at 850 μm. The trend could be due to the better alignment of warmer dust in the strong radiation environment. We also find that polarization fractions decrease with intensity at both wavelengths, with slopes, determined by fitting a Rician noise model of 0.59 ± 0.03 at 450 μm and 0.36 ± 0.04 at 850 μm, respectively. We think that the shallow slope at 850 μm is due to grain alignment at the center being assisted by strong radiation from the central young stellar objects.

Keywords: interstellar magnetic fields; interstellar medium; polarimetry
LAMOST J2043+3413-a Fast Disk Precession SW Sextans Candidate in Period Gap

We present follow-up photometric observations and time-series analysis of a nova-like, SW Sextans-type, cataclysmic variable (CV) candidate, LAMOST J204305.95+341340.6 (hereafter J2043+3413), with a Gaia G-band magnitude of 15.30 and a distance of 990 pc, which was identified from the LAMOST spectrum. The photometric data were collected with the Tsinghua-NAOC 0.8 m telescope (TNT), Transiting Exoplanet Survey Satellite (TESS), Zwicky Transient Facility (ZTF), and ASAS-SN. The TESS light curve reveals the presence of two prominent periods of 2.587(8) hr and 1.09(5) days, corresponding to the orbital and superorbital (precession) period, respectively. The TNT data obtained in 2020 shows a possible quasiperiodic oscillation of 1426 s. The precession period is about three times shorter than that of CVs with similar orbital periods, indicating an unusually fast precessing accretion disk. The ZTF data is found to show a sudden decline of ~0.4 mag on MJD 58979. From the intermittent behavior of the eclipse, we deduce that J2043+3413 is an intermediate inclination system of CV, similar to V795 Her, which is also situated in the period gap.

Keywords: cataclysmic variable stars; nova-like variable stars; stellar accretion disks; eclipsing binary stars
The Magnetic Fields of Starburst Galaxies. I. Identification and Characterization of the Thermal Polarization in the Galactic Disk and Outflow

Far-infrared polarized emission by means of magnetically aligned dust grains is an excellent tracer of the magnetic fields (B-fields) in the cold phase of the galactic outflows of starburst galaxies. We present a comprehensive study of the B-fields in three nearby (3.5-17.2 Mpc) starbursts (M82, NGC 253, and NGC 2146) at 5 pc-1.5 kpc resolutions using publicly available 53-890 μm imaging polarimetric observations with Stratospheric Observatory for Infrared Astronomy/HAWC+, James Clerk Maxwell Telescope/POL-2, and ALMA. We find that the polarized spectral energy distributions (SEDs) of the full galaxies are dominated by the polarized SEDs of the outflows with dust temperatures of ${T}_{{\rm{d}},\mathrm{outflow}}^{\mathrm{PI}}\sim 45$ K and an emissive index of ${\beta }_{\mathrm{outflow}}^{\mathrm{PI}}\sim 2.3$ . The disks are characterized by low ${T}_{{\rm{d}},\mathrm{disk}}^{\mathrm{PI}}=[24,31]$ K and ${\beta }_{\mathrm{disk}}^{\mathrm{PI}}\sim 1$ . We show that disk- and outflow-dominated galaxies can be better distinguished by using polarized SEDs instead of total SEDs. We compute the 53-850 μm polarization spectrum of the disk and outflow, and find that dust models of the diffuse ISM can reproduce the fairly constant polarization spectrum of the disk, < P disk> = 1.2% ± 0.5%. The dust models of heterogenous clouds and two-temperature components are required to explain the polarization spectrum of the outflow (2%-4% at 53 μm, ~1% at 850 μm, and a minimum within 89-154 μm). We conclude that the polarized dust grains in the outflow arise from a dust population with higher dust temperature and emissivities than those from the total flux. The B-fields of the outflows have maximum extensions within 89-214 μm reaching heights of ~4 kpc, and have flatter polarized fluxes than total fluxes. The extension of the B-field permeating the circumgalactic medium increases as the star formation rate increases.

Keywords: starburst galaxies; extragalactic magnetic fields; interstellar magnetic fields; polarimetry; far infrared astronomy; galaxy winds; interstellar dust
Impact of the New Measurement of the 12C + 12C Fusion Cross Section on the Final Compactness of Massive Stars

We discuss how the new measurement of the 12C + 12C fusion cross section carried out with the Trojan Horse Method affects the compactness of a star, i.e., basically the binding energy of the inner mantle, at the onset of the core collapse. In particular, we find that this new cross section significantly changes the dependence of the compactness on the initial mass with respect to previous findings obtained in Chieffi & Limongi by adopting the classical cross section provided by Caughlan & Fowler. A non-monotonic but well-defined behavior is also confirmed in this case and no scatter of the compactness around the main trend is found. Such an occurrence could impact the possible explodability of the stars.

Keywords: stellar evolution; stellar physics; late stellar evolution; stellar evolutionary models
Polytropic Behavior of Solar Wind Protons Observed by Parker Solar Probe

A polytropic process describes the transition of a fluid from one state to another through a specific relationship between the fluid density and temperature. The value of the polytropic index that governs this relationship determines the heat transfer and the effective degrees of freedom during a specific process. In this study, we analyze solar wind proton plasma measurements, obtained by the Faraday cup instrument on board the Parker Solar Probe. We examine the large-scale variations of the proton plasma density and temperature within the inner heliosphere explored by the spacecraft. We then address the polytropic behavior in the density and temperature fluctuations in short time intervals, which we analyze in order to derive the effective polytropic index of small-scale processes. The large-scale variations of the solar wind proton density and temperature, which are associated with the plasma expansion into the heliosphere, follow a polytropic model with a polytropic index ∼5/3. On the other hand, the short-scale fluctuations, which are potentially associated with turbulence, follow a model with a larger polytropic index. We investigate possible correlations between the polytropic index of short-scale fluctuations and the plasma speed, plasma β, and the magnetic field direction. We discuss candidate mechanisms leading to this behavior including energy transfer and possible mechanisms restricting the effective particle degrees of freedom at smaller scales.

Keywords: solar wind; space plasmas; solar physics
Gemini Multi-Object Spectrograph Integral Field Unit Spectroscopy of the Double-peaked Broad Emission Line of a Red Active Galactic Nucleus

Galaxy mergers are expected to produce multiple supermassive black holes (SMBHs) in close-separation, but the detection of such SMBHs has been difficult. 2MASS J165939.7 + 183436 is a red active galactic nucleus (AGN) that is a prospective merging SMBH candidate owing to its merging features in Hubble Space Telescope imaging and double-peaked broad emission lines (BELs). Herein, we report a Gemini Multi-Object Spectrograph Integral Field Unit observation of a double-peaked broad Hα line of 2MASS J165939.7+183436. Furthermore, we confirm the existence of two BEL peaks that are kinematically separated by 3000 km s-1, with the SMBH of each BEL component weighing at ${10}^{8.92\pm 0.06}\,{M}_{\odot }$ and ${10}^{7.13\pm 0.06}\,{M}_{\odot }$ , if they arise from independent BELs near the two SMBHs. The BEL components were not separated at >0"1; however, under several plausible assumptions regarding the fitting of each spaxel, the two components are found to be spatially separated at 0"085 (∼250 pc). Different assumptions for the fitting can lead to a null (<0"05) or a larger spatial separation (∼0"15). Given the uncertainty regarding the spatial separation, various models, such as the disk emitter and multiple SMBH models, are viable solutions to explain the double BEL components. These results will promote future research for finding more multiple SMBH systems in red AGNs, and higher-resolution imaging validates these different models.

Keywords: active galactic nuclei; galaxy evolution; galaxy mergers; galaxies; quasars; galaxy nuclei; gravitational wave sources; astrophysical black holes