adsabs/SciX_UAT_keywords huggingface dataset:
Field-aligned and Magnetic Reconnection Flows in a Magnetohydrodynamic Simulation of Prominence-cavity System

Nested ring-shaped line-of-sight (LOS) oriented flows in coronal cavities have been observed in recent years but rarely explained. Using a magnetohydrodynamic simulation of a prominence-cavity system, we investigate the relationship between the simulated field-aligned flows, magnetic reconnection flows, and the LOS-oriented flows observed by the Coronal Multi-Channel Polarimeter. The field-aligned flows are along magnetic field lines toward the dips and driven by the hydrodynamic forces exerted by the prominence condensation. The reconnection flows are driven by the overlying reconnection and tether-cutting reconnection. The velocity of the reconnection flows increases from the quasi-static phase to the fast-rise phase, reaching several kilometers per second, which is similar to the speed of the field-aligned flows. We calculate the synthetic Doppler images by forward modeling and compare them with the observed LOS-oriented flows. The synthetic images show that the LOS-oriented flows of one ring with opposite internal flow driven by the field-aligned flows are identified in the simulation. And the synthetic images integrated along three different LOSs can resemble the observed direction reversal of the LOS-oriented flow in about 20 hr, when the included angle of two adjacent LOSs is about 10°. These results suggest that the observed LOS-oriented flows of one ring with an opposite internal flow may be explained by the LOS integration effect of field-aligned flows along different loops.

Keywords: magnetohydrodynamical simulations; solar magnetic reconnection; solar magnetic fields; solar prominences
FRECKLL: Full and Reduced Exoplanet Chemical Kinetics DistiLLed

We introduce a new Python 1D chemical kinetic code, Full and Reduced Exoplanet Chemical Kinetics distiLLed (FRECKLL), to evolve large chemical networks efficiently. FRECKLL employs "distillation" in computing the reaction rates, which minimizes the error bounds to the minimum allowed by double precision values (ϵ ≤ 10‑15). Compared to summation of rates with traditional algorithms like pairwise summation, distillation provides a tenfold reduction in solver time for both full and reduced networks. Both the full and reduced Venot2020 networks are packaged in FRECKLL as well as a TAUREX 3.1 plug-in for usage in forward modeling and retrievals of exoplanet atmospheres. We present TAUREX retrievals performed on a simulated HD 189733b JWST spectra using the full and reduced Venot2020 chemical networks and demonstrate the viability of total disequilibrium chemistry retrievals and the ability for JWST to detect disequilibrium processes.

Keywords: astrochemistry; exoplanet atmospheres; exoplanet atmospheric dynamics; chemical kinetics; chemical reaction network models; chemical abundances; exoplanet atmospheric structure
Strong Dark Matter Self-interactions Diversify Halo Populations within and surrounding the Milky Way

We perform a high-resolution cosmological zoom-in simulation of a Milky Way (MW)-like system, which includes a realistic Large Magellanic Cloud analog, using a large differential elastic dark matter self-interaction cross section that reaches ≈100 cm2 g-1 at relative velocities of ≈10 km s-1, motivated by the diverse and orbitally dependent central densities of dwarf galaxies within and surrounding the MW. We explore the effects of dark matter self-interactions on satellite, splashback, and isolated halos through their abundance, central densities, maximum circular velocities, orbital parameters, and correlations between these variables. We use an effective constant cross section model to analytically predict the stages of our simulated halos' gravothermal evolution, demonstrating that deviations from the collisionless ${R}_{\max }$ - ${V}_{\max }$ relation can be used to select deeply core-collapsed halos, where ${V}_{\max }$ is a halo's maximum circular velocity, and ${R}_{\max }$ is the radius at which it occurs. We predict that a sizable fraction (≈20%) of subhalos with masses down to ≈108 M ⊙ is deeply core collapsed in our SIDM model. Core-collapsed systems form ≈10% of the isolated halo population down to the same mass; these isolated, core-collapsed halos would host faint dwarf field galaxies with extremely steep central density profiles. Finally, most halos with masses above ≈109 M ⊙ are core-forming in our simulation. Our study thus demonstrates how self-interactions diversify halo populations in an environmentally dependent fashion within and surrounding MW-mass hosts, providing a compelling avenue to address the diverse dark matter distributions of observed dwarf galaxies.

Keywords: dark matter; galaxy abundances; n-body simulations; galaxy dark matter halos; computational methods
The Discovery of 63 Giant Radio Galaxies in the FIRST Survey

Giant Radio Galaxies (GRGs) are Active Galactic Nuclei with radio emission that extends over projected sizes >0.7 Mpc. The large angular sizes associated with GRGs complicate their identification in radio survey images using traditional source finders. In this Note, we use DRAGNHUNTER, an algorithm designed to find double-lobed radio galaxies, to search for GRGs in the Faint Images of the Radio Sky at Twenty cm survey. Radio and optical images of identified candidates are visually inspected to confirm their authenticity, resulting in the discovery of 63 previously unreported GRGs.

Keywords: giant radio galaxies; radio galaxies; extragalactic radio sources; active galactic nuclei
The Kinematics and Excitation of Infrared Water Vapor Emission from Planet-forming Disks: Results from Spectrally Resolved Surveys and Guidelines for JWST Spectra

This work presents ground-based spectrally resolved water emission at R = 30,000-100,000 over infrared wavelengths covered by the JWST (2.9-12.8 μm). Two new surveys with iSHELL and the VISIR are combined with previous spectra from the CRIRES to cover parts of multiple rovibrational and rotational bands observable within telluric transmission bands, for a total of ≈160 spectra and 85 disks (30 of which are JWST targets in Cycle 1). The general expectation of a range of regions and excitation conditions traced by infrared water spectra is for the first time supported by the combined kinematics and excitation as spectrally resolved at multiple wavelengths. The main findings from this analysis are: (1) water lines are progressively narrower from the rovibrational bands at 2-9 μm to the rotational lines at 12 μm, and partly match broad and narrow emission components, respectively, as extracted from rovibrational CO spectra; (2) rotation diagrams of resolved water lines from upper-level energies of 4000-9500 K show vertical spread and curvatures indicative of optically thick emission (≈1018 cm-2) from a range of excitation temperatures (≈800-1100 K); and (3) the new 5 μm spectra demonstrate that slab model fits to the rotational lines at >10 μm strongly overpredict the rovibrational emission bands at <9 μm, implying vibrational excitation not in thermodynamic equilibrium. We discuss these findings in the context of emission from a disk surface and a molecular inner disk wind, and provide a list of guidelines to support the analysis of spectrally unresolved JWST spectra.

Keywords: circumstellar disks; protoplanetary disks; planet formation; exoplanet formation; star formation; classical t tauri stars; herbig ae/be stars; pre-main sequence stars; high resolution spectroscopy; molecular spectroscopy; infrared astronomy; vibrational spectroscopy
Visible-light Phase Curves from the Second Year of the TESS Primary Mission

We carried out a systematic study of full-orbit phase curves for known transiting systems in the northern ecliptic sky that were observed during Year 2 of the TESS primary mission. We applied the same methodology for target selection, data processing, and light-curve fitting as we did in our Year 1 study. Out of the 15 transiting systems selected for analysis, seven-HAT-P-7, KELT-1, KELT-9, KELT-16, KELT-20, Kepler-13A, and WASP-12-show statistically significant secondary eclipses and day-night atmospheric brightness modulations. Small eastward dayside hot-spot offsets were measured for KELT-9b and WASP-12b. KELT-1, Kepler-13A, and WASP-12 show additional phase-curve variability attributed to the tidal distortion of the host star; the amplitudes of these signals are consistent with theoretical predictions. We combined occultation measurements from TESS and Spitzer to compute dayside brightness temperatures, TESS-band geometric albedos, Bond albedos, and phase integrals for several systems. The new albedo values solidify the previously reported trend between dayside temperature and geometric albedo for planets with 1500 K < Tday < 3000 K. For Kepler-13Ab, we carried out an atmospheric retrieval of the full secondary eclipse spectrum, which revealed a noninverted temperature-pressure profile, significant H2O and K absorption in the near-infrared, evidence for strong optical atmospheric opacity due to sodium, and a confirmation of the high geometric albedo inferred from our simpler analysis. We explore the implications of the phase integrals (ratios of Bond to geometric albedos) for understanding exoplanet clouds. We also report updated transit ephemerides for all of the systems studied in this work.

Keywords: exoplanet astronomy
Neutral Stellar Winds toward the High-mass Star-forming Region G176.51+00.20

We observed the high-mass star-forming region G176.51+00.20 using the Five-hundred-meter Aperture Spherical radio Telescope with the 19 beam tracking observational mode. This is a pilot work of searching for neutral stellar winds traced by atomic hydrogen (i.e., H I winds) using the high-sensitivity H I line toward high-mass star-forming regions where bipolar molecular outflows have been detected with high sensitivity by Liu et al. H I wind was detected in this work only in Beam 1. We find here that, similar to low-mass star formation, no matter how large the inclination is, the H I wind is likely sufficiently strong to drive a molecular outflow. We also find that the abundance of H I in the H I wind is consistent with that of the H I narrow-line self-absorption (HINSA) in the same beam (i.e., Beam 1). This implies that there is probably an internal relationship between H I winds and HINSA. This result also reinforces the assertion that H I winds and detected molecular outflows are associated with each other.

Keywords: jets; interstellar atomic gas; star formation; interstellar abundances; interstellar dynamics; interstellar molecules
The Demagnetization of the Venusian Ionosphere under Nearly Flow-aligned Interplanetary Magnetic Fields

Previous studies suggested that the interplanetary magnetic field (IMF) has a significant influence on the Venusian-induced magnetosphere. We present observations by Venus Express under a nearly flow-aligned IMF condition to investigate the demagnetization of the Venusian ionosphere. Our results show that the magnetic barrier becomes weak and narrow, and the ionosphere can be demagnetized under the IMF with the dominating flow-aligned component while the solar wind dynamic pressure remains almost unchanged. The demagnetization of the Venusian ionosphere implies that the total pressure of the magnetic barrier above the ionopause decreases. The magnetic field lines upstream from Venus drape differently under the nearly flow-aligned IMF condition. And thus the upstream solar wind flow is affected by the outward magnetic tension, which leads to the decrease of the dynamic pressure that directly acts on the magnetic barrier.

Keywords: venus; interplanetary magnetic fields; solar wind; solar-planetary interactions
A Model for the Coupled Eruption of a Pseudostreamer and Helmet Streamer

A highly important aspect of solar activity is the coupling between eruptions and the surrounding coronal magnetic field topology, which determines the trajectory and morphology of the event and can even lead to sympathetic eruptions from multiple sources. In this paper, we report on a numerical simulation of a new type of coupled eruption, in which a coronal jet initiated by a large pseudostreamer filament eruption triggers a streamer-blowout coronal mass ejection (CME) from the neighboring helmet streamer. Our configuration has a large opposite-polarity region positioned between the polar coronal hole and a small equatorial coronal hole, forming a pseudostreamer flanked by the coronal holes and the helmet streamer. Further out, the pseudostreamer stalk takes the shape of an extended arc in the heliosphere. We energize the system by applying photospheric shear along a section of the polarity inversion line within the pseudostreamer. The resulting sheared-arcade filament channel develops a flux rope that eventually erupts as a classic coronal-hole-type jet. However, the enhanced breakout reconnection above the channel as the jet is launched progresses into the neighboring helmet streamer, partially launching the jet along closed helmet streamer field lines and blowing out the streamer top to produce a classic bubble-like CME. This CME is strongly deflected from the jet's initial trajectory and contains a mixture of open and closed magnetic field lines. We present the detailed dynamics of this new type of coupled eruption, its underlying mechanisms, and the implications of this work for the interpretation of in situ and remote-sensing observations.

Keywords: active solar corona; solar coronal mass ejections; solar coronal streamers; solar filament eruptions; solar magnetic reconnection; solar flares
Physical Properties of Hyperluminous, Dust-obscured Quasars at z ∼ 3: Multiwavelength Spectral Energy Distribution Analysis and Cold Gas Content Revealed by ALMA

We present a UV to millimeter spectral energy distribution (SED) analysis of 16 hyperluminous, dust-obscured quasars at z ∼ 3, selected by the Wide-field Infrared Survey Explorer. We aim to investigate the physical properties of these quasars, with a focus on their molecular gas content. We decompose the SEDs into three components: stellar, cold dust, and active galactic nucleus (AGN). By doing so, we are able to derive and analyze the relevant properties of each component. We determine the molecular gas mass from CO line emission based on Atacama Large Millimeter/submillimeter Array (ALMA) observations. By including ALMA observations in the multiwavelength SED analysis, we derive the molecular gas fractions, gas depletion timescales, and star formation efficiencies (SFEs). Their sample median and 16th–84th quartile ranges are ${f}_{\mathrm{gas}}\,\sim \,{0.33}_{-0.17}^{+0.33}$ , t depl ∼ ${39}_{-28}^{+85}$ Myr, and SFE ∼ ${297}_{-195}^{+659}$ K km s‑1 pc‑2, respectively. Compared to main-sequence galaxies, they have lower molecular gas content and higher SFEs, similar to quasars in the literature. This suggests that the gas in these quasars is rapidly depleted, likely as the result of intense starburst activity and AGN feedback. The observed correlations between these properties and the AGN luminosities further support this scenario. Additionally, we infer the black hole to stellar mass ratio and black hole mass growth rate, which indicate significant central black hole mass assembly over short timescales. Our results are consistent with the scenario that our sample represents a short transition phase toward unobscured quasars.

Keywords: active galaxies; high-redshift galaxies; starburst galaxies; quasars
Search for Large-scale Anisotropy on Arrival Directions of Ultra-high-energy Cosmic Rays Observed with the Telescope Array Experiment

Motivated by the detection of a significant dipole structure in the arrival directions of ultra-high-energy cosmic rays above 8 EeV reported by the Pierre Auger Observatory (Auger), we search for a large-scale anisotropy using data collected with the surface detector array of the Telescope Array Experiment (TA). With 11 yr of TA data, a dipole structure in a projection of the R.A. is fitted with an amplitude of 3.3% ± 1.9% and a phase of 131° ± 33°. The corresponding 99% confidence-level upper limit on the amplitude is 7.3%. At the current level of statistics, the fitted result is compatible with both an isotropic distribution and the dipole structure reported by Auger.

Keywords: cosmic rays; ultra-high-energy cosmic radiation; cosmic ray sources; cosmic ray showers; cosmic ray detectors; cosmic ray astronomy; extragalactic astronomy; extragalactic magnetic fields
Barycentric Corrections for Precise Radial Velocity Measurements of Sunlight

We provide formulae for the calculation of precise Doppler velocities of sunlight, in both the case of direct observations of the Sun and in reflection from the surfaces of solar system objects such as the Moon or asteroids. We discuss the meaning of a "barycentric correction" of measurements of these Doppler velocities, which is a different procedure from the analogous correction for starlight, and provide a formula for reducing such measurements to the component of the Sun's motion in the direction of Earth or other solar system object. We have implemented this procedure in the public barycorrpy Python package and use it to explore the properties of the barycentric-corrected Doppler velocity of sunlight over 30 yr. When measured directly, we show that it is dominated by nonperiodic motion due to Jupiter and that the signals of the other planets, including Venus, are not discernible in Fourier space. We show that "detecting" Venus in Doppler velocities of sunlight will require either observing sunlight in reflection from an asteroid or modeling their individual contributions to the motion of the Sun in counterfactual kinematic or dynamical simulations of the solar system with and without them.

Keywords: ephemerides; radial velocity
Stellar Obliquity from Spot Transit Mapping of Kepler-210

Stellar obliquity, the angle between the stellar spin and the perpendicular to the planetary orbit, also known as the spin-orbit angle, holds clues to the formation and evolution of planetary systems. When a planet transits a star periodically, it may cross in front of a stellar spot, producing a noticeable signal on the transit light curve. Spot transit mapping can be used to measure stellar obliquity. Here we present the analysis of Kepler-210, a K-dwarf star with two mini-Neptune-size planets in orbit. Interestingly, the spot mapping from the outer planet, Kepler-210 c, resulted in a spot distribution with no spots detected at longitudes >38°, whereas the spots occulted by Kepler-210 b displayed all range of longitudes. The best explanation for this was that Kepler-210 c exhibited an inclined orbit, while the orbit of Kepler-210 b was parallel to the stellar equator. Thus, transits of Kepler-210 c occulted different latitude bands of the star. The observed maximum spot topocentric longitude of 38° implied an orbital obliquity of 18°-45° for Kepler-210 c. Further considering a symmetric spot distribution in latitude with respect to the stellar equator, the obliquity was restricted to 34.°8, implying a maximum spot latitude of 40°. The differential rotation profile calculated from the oblique orbit for Kepler-210 c agreed with that obtained from the spots occulted by Kepler-210 b. Combining results from both planets yields a rotational shear of ΔΩ = 0.0353 ± 0.0002 rad day-1 and a relative rotational shear of 6.9%. The causes of the Kepler-210 c misalignment remain to be explained.

Keywords: stellar activity; starspots; stellar rotation; transit photometry; oblique rotators
Overmassive Black Holes in Dwarf Galaxies Out to z 0.9 in the VIPERS Survey

Supermassive black holes (SMBHs) are thought to originate from early universe seed black holes of mass M BH ~ 102-105 M ⊙ and grown through cosmic time. Such seeds could be powering the active galactic nuclei (AGN) found in today's dwarf galaxies. However, probing a connection between the early seeds and local SMBHs has not yet been observationally possible. Massive black holes hosted in dwarf galaxies at intermediate redshifts, on the other hand, may represent the evolved counterparts of the seeds formed at very early times. We present a sample of seven broad-line AGN in dwarf galaxies with a spectroscopic redshift ranging from z = 0.35 to z = 0.93. The sources are drawn from the VIPERS survey as having an Large Magellanic Cloud (LMC) like stellar mass (M ∗) derived from spectral energy distribution fitting, and they are all star-forming galaxies. Six of these sources are also X-ray AGN. The AGN are powered by SMBHs of >107 M ⊙, more massive than expected from the M BH-M ∗ scaling relation of AGN. Based on semianalytical simulations, we find that these objects are likely overmassive with respect to their hosts since early times (z > 4), independently of whether they formed as heavy (~105 M ⊙) or light (~102 M ⊙) seed black holes. In our simulations, these objects tend to grow faster than their host galaxies, contradicting models of synchronized growth. The host galaxies are found to possibly evolve into massive systems by z ~ 0, indicating that local SMBHs in massive galaxies could originate in dwarf galaxies hosting seed black holes at higher z.

Keywords: dwarf galaxies
Comparison of Solar Wind Interaction with Mars and Earth: Energy Transfer

Using a global magnetohydrodynamics numerical simulation, this work compares the interaction of the solar wind with Mars and Earth from the perspective of energy transfer under north–south interplanetary magnetic fields (IMFs). Mars lacks a global dipole magnetic field like Earth's and instead has a small-scale crustal magnetic field near highlands in the southern hemisphere. Unlike Earth's magnetopause reconnection (at the subsolar point or tail under a southward IMF, or behind the cusp under a northward IMF), the reconnection of the Martian magnetic pileup boundary (MPB) occurs near solar zenith angle (SZA) ≈ 45° (SZA ≈ 30° and 60°) for a southward (northward) IMF, resulting in asymmetric energy transfer between the northern and southern hemispheres. The Martian outflow of mechanical energy appears near SZA ≈ 45° (SZA ≈ 30° and 60°) under a southward (northward) IMF, accompanied by an inflow due to the process of "solar wind pickup." For energy transfer across the MPB, whether the IMF is northward or southward, the input of electromagnetic energy is twice as large as the input of mechanical energy, which is similar to Earth's magnetopause for a southward IMF, but opposite to it for a northward IMF. The energy transfer rate of the MPB is slightly higher in a northward IMF than in a southward one, whereas the energy transfer rate of Earth's magnetopause is far higher in a southward IMF than in a northward one.

Keywords: interplanetary magnetic fields; planetary magnetospheres; mars; solar wind