adsabs/SciX_UAT_keywords huggingface dataset:
A Quake Quenching the Vela Pulsar

The remarkable null pulse coincident with the 2016 glitch in Vela rotation indicates a dynamical event involving the crust and the magnetosphere of the neutron star. We propose that a crustal quake associated with the glitch strongly disturbed the Vela magnetosphere and thus interrupted its radio emission. We present the first global numerical simulations of a neutron starquake. Our code resolves the elasto-dynamics of the entire crust and follows the evolution of Alfvén waves excited in the magnetosphere. We observe Rayleigh surface waves propagating away from the epicenter of the quake, around the circumference of the crust—an instance of the so-called whispering gallery modes. The Rayleigh waves set the initial spatial scale of the magnetospheric disturbance. Once launched, the Aflvén waves bounce in the closed magnetosphere, become de-phased, and generate strong electric currents, capable of igniting electric discharge. Most likely, the discharge floods the magnetosphere with electron-positron plasma, quenching the radio emission. We find that the observed ∼0.2 s disturbance is consistent with the damping time of the crustal waves if the crust is magnetically coupled to the superconducting core of the neutron star. The quake is expected to produce a weak X-ray burst of short duration.

Keywords: pulsars; magnetic fields; plasma astrophysics
The Autonomous Data Reduction Pipeline for the Cute Mission

The Colorado Ultraviolet Transit Experiment (CUTE) is a 6U NASA CubeSat carrying on-board a low-resolution, near-ultraviolet (2479-3306 Å) spectrograph. It has a Cassegrain telescope with a rectangular primary to maximize the collecting area, given the shape of the satellite bus, and an aberration correcting grating to improve the image quality, and thus spectral resolution. CUTE, launched on the of 2021 September 27th to a Low Earth Orbit, is designed to monitor transiting extra-solar planets orbiting bright, nearby stars to improve our understanding of planet atmospheric escape and star-planet interaction processes. We present here the CUTE autONomous daTa ReductiOn pipeLine, developed for reducing CUTE data. The pipeline has been structured with a modular approach, which also considers scalability and adaptability to other missions carrying on-board a long-slit spectrograph. The CUTE data simulator has been used to generate synthetic observations used for developing and testing the pipeline functionalities. The pipeline has been tested and updated employing flight data obtained during commissioning and initial science operations of the mission.

Keywords: astronomy software; ultraviolet astronomy; exoplanets; space telescopes
Narrowly Banded Spectra with Peak Frequency around 1 GHz of FRB 20201124A: Implications for Energy Function and Radiation Physics

The radiation physics of fast radio bursts (FRBs) remains an open question. Current observations have discovered that narrowly banded bursts of FRB 20201124A are active in 0.4–2 GHz, and their spectral peak frequency ( ${\nu }_{p}^{\mathrm{obs}}$ ) is mostly toward ∼1 GHz. Utilizing a sample of 1268 bursts of FRB 20201124A detected with the Five-hundred-meter Aperture Spherical radio Telescope (FAST), we show that the 1σ spectral regime of 71.4% of the events (in-band bursts) is within the FAST bandpass. The intrinsic burst energies ( ${E}_{\mathrm{BWe}}^{\mathrm{obs}}$ ) and spectral widths ( ${\sigma }_{s}^{\mathrm{obs}}$ ) are well measured by fitting the spectral profile with a Gaussian function. The derived ${E}_{\mathrm{BWe}}^{\mathrm{obs}}$ and ${\sigma }_{s}^{\mathrm{obs}}$ distributions are lognormal and centered at $\mathrm{log}{E}_{\mathrm{BWe}}^{\mathrm{obs}}/\mathrm{erg}=37.2\,(\sigma =0.76)$ and $\mathrm{log}{\sigma }_{s}^{\mathrm{obs}}/\mathrm{GHz}=-1.16\,(\sigma =0.17)$ . Our Monte Carlo simulation analysis infers its intrinsic ν p distribution as a normal function centered at ν p,c = 1.16 GHz (σ = 0.22) and its intrinsic energy function as ${\rm{\Phi }}(E)\propto {E}^{-0.60}{e}^{-E/{E}_{c}}$ with E c = 9.49 × 1037 erg. We compare these results with that of typical repeating FRBs 20121102A and 20190520B, which are active over a broad frequency range at several specific frequencies, and discuss possible observational biases on the estimation of the event rate and energy function. Based on these results, we argue that FRB 20201124A likely occurs in a fine-tuned plasma for maser radiation at a narrow frequency range, while FRB 20121102A and FRB 20190520B could involve clumpy plasma conditions that make maser emission around several specific frequencies in a broad range.

Keywords: radio bursts; radio transient sources
Do Minihalos Affect Cosmic Reionization?

The role of unresolved structures ("minihalos") in determining the consumption of ionizing photons during cosmic reionization remains an unsolved problem in modeling cosmic reionization, despite recent extensive studies with small-box high-resolution simulations by Park et al. and Chan et al., because the small-box studies are not able to fully sample all environments. In this paper these simulations are combined with large-box simulations from the "Cosmic Reionization On Computers" (CROC) project, allowing one to account for the full range of environments and to produce an estimate for the number of recombinations per hydrogen atom that are missed in large-scale simulations like CROC or Thesan. I find that recombinations in unresolved minihalos are unimportant compared to recombinations produced in large-scale cosmic structures and inside more massive, fully resolved halos. Since both the Park et al. and Chan et al. studies have severe limitations, the conclusions of this paper may need to be verified with more representative sets of small-box high-resolution simulations.

Keywords: reionization; astronomical simulations
Cloudlet Capture Model for Asymmetric Molecular Emission Lines Observed in TMC-1A with ALMA

TMC-1A is a protostellar source harboring a young protostar, IRAS 04365+2353, and shows highly asymmetric features of a few 100 au scale in its molecular emission lines. Blueshifted emission is much stronger in the CS (J = 5-4) line than redshifted emission. This asymmetry can be explained if the gas accretion is episodic and takes the form of cloudlet capture, given that the cloudlet is approaching toward us. The gravity of the protostar transforms the cloudlet into a stream and changes its velocity along the flow. The emission from the cloudlet should be blueshifted before the periastron, while it should be redshifted after the periastron. If a major part of cloudlet has not reached the periastron, the former should be dominant. We perform hydrodynamical simulations to examine the validity of the scenario. Our numerical simulations can reproduce the observed asymmetry if the orbit of the cloudlet is inclined to the disk plane. The inclination can explain the slow infall velocity observed in the C18O (J = 2-1) line emission. Such episodic accretion may occur in various protostellar cores since actual clouds could have inhomogeneous density distributions. We also discuss the implication of the cloudlet capture on observations of related objects.

Keywords: protostars; interstellar medium; interstellar molecules; young stellar objects; star formation
ALMA Spectral Survey of an Eruptive Young Star, V883 Ori (ASSAY). I. What Triggered the Current Episode of Eruption?

An unbiased spectral survey of V883 Ori, an eruptive young star, was carried out with the Atacama Large Millimeter/submillimeter Array in Band 6. The detected line emission from various molecules reveals morphological/kinematical features in both the Keplerian disk and the infalling envelope. A direct infall signature, redshifted absorption against the continuum, has been detected in CO, HCO+, HCN, HNC, and H2CO. HCO+ and SO show large armlike structures that probably connect the infalling envelope to the disk. HCN and H2CO reveal a distinct boundary between the inner and outer disks and tentative spiral structures connecting the outer disk to the inner disk. HNC shows a large central emission hole (r ∼ 0.″3) due to its chemical conversion to HCN at high temperatures. HDO emission, a direct tracer of the water sublimation region, has been detected in the disk. Molecular emission from complex organic molecules is confined within the HDO emission boundary, and HCO+ has an emission hole in its distribution due to its destruction by water. Together, these features suggest that the current episode of eruption in V883 Ori may be triggered by the infall from the envelope to the outer disk, generating a spiral wave that propagates inward and greatly enhances the accretion onto the central star.

Keywords: star formation
Photochemistry and Spectral Characterization of Temperate and Gas-rich Exoplanets

Exoplanets that receive stellar irradiance approximately equal to Earth's or less have been discovered and many are suitable for spectral characterization. Here, we focus on the temperate planets that have massive H2-dominated atmospheres, and trace the chemical reactions and transport following the photodissociation of H2O, CH4, NH3, and H2S, with K2-18 b, PH2 b, and Kepler-167 e representing temperate/cold planets around M and G/K stars. We find that NH3 is likely depleted by photodissociation to the cloud deck on planets around G/K stars but remains intact in the middle atmosphere of planets around M stars. A common phenomenon on temperate planets is that the photodissociation of NH3 in the presence of CH4 results in HCN as the main photochemical product. The photodissociation of CH4 together with H2O leads to CO and CO2, and the synthesis of hydrocarbon is suppressed. Temperate planets with a supersolar atmospheric metallicity and appreciable internal heat may have additional CO and CO2 from the interior and less NH3, and thus less HCN. Our models of K2-18 b can explain the transmission spectrum measured by the Hubble Space Telescope, and indicate that future observations in 0.5-5.0 μm wavelength range would provide the sensitivity to detect the equilibrium gases CH4, H2O, and NH3, the photochemical gas HCN, as well as CO2 in some cases. Temperate and H2-rich exoplanets are thus laboratories of atmospheric chemistry that operate in regimes not found in the solar system, and spectral characterization of these planets in transit or reflected starlight promises to greatly expand the types of molecules detected in exoplanet atmospheres.

Keywords: exoplanet atmospheres; extrasolar gaseous planets; extrasolar ice giants; mini neptunes; habitable zone; transmission spectroscopy
The JCMT BISTRO Survey: Revealing the Diverse Magnetic Field Morphologies in Taurus Dense Cores with Sensitive Submillimeter Polarimetry

We have obtained sensitive dust continuum polarization observations at 850 μm in the B213 region of Taurus using POL-2 on SCUBA-2 at the James Clerk Maxwell Telescope as part of the B-fields in STar-forming Region Observations (BISTRO) survey. These observations allow us to probe magnetic field (B-field) at high spatial resolution (∼2000 au or ∼0.01 pc at 140 pc) in two protostellar cores (K04166 and K04169) and one prestellar core (Miz-8b) that lie within the B213 filament. Using the Davis-Chandrasekhar-Fermi method, we estimate the B-field strengths in K04166, K04169, and Miz-8b to be 38 ± 14, 44 ± 16, and 12 ± 5 μG, respectively. These cores show distinct mean B-field orientations. The B-field in K04166 is well ordered and aligned parallel to the orientations of the core minor axis, outflows, core rotation axis, and large-scale uniform B-field, in accordance with magnetically regulated star formation via ambipolar diffusion taking place in K04166. The B-field in K04169 is found to be ordered but oriented nearly perpendicular to the core minor axis and large-scale B-field and not well correlated with other axes. In contrast, Miz-8b exhibits a disordered B-field that shows no preferred alignment with the core minor axis or large-scale field. We found that only one core, K04166, retains a memory of the large-scale uniform B-field. The other two cores, K04169 and Miz-8b, are decoupled from the large-scale field. Such a complex B-field configuration could be caused by gas inflow onto the filament, even in the presence of a substantial magnetic flux.

Keywords: dust continuum emission; polarimetry; low mass stars; dense interstellar clouds; interstellar magnetic fields
Rankine-Hugoniot Relations Including Pickup Ions

The Rankine-Hugoniot relations are consequences of the global, magnetohydrodynamic conservation laws of mass, momentum, energy, and magnetic flux at shocks in plasma. They provide us with the boundary conditions, although these are insufficient to quantify the energy partition in substantially non-Maxwellian plasmas in the presence of nonthermal, pickup ions (PUIs). Ion dynamics inside the shock front is essentially nonadiabatic and gyrophase-dependent. The shock jump conditions are typically evaluated using the upstream and downstream distributions in the regions where they already become gyrotropic. The relation between the gyrophase-dependent motion inside the shock front and the gyrophase-averaged moments of the ion distributions is established using numerical ion tracing across a model shock profile, which includes the major basic features of a collisionless shock. The upstream distribution of PUIs is taken to be a filled shell. The obtained moments of the PUI distribution function are used to construct the Rankine-Hugoniot relations for a gyrotropic plasma regime. The quality of numerical ion tracing is checked by comparing it with full particle simulations. The moments of the distribution in the isotropic region are estimated.

Keywords: termination shock; shocks; space plasmas; pickup ions
A Massive, Clumpy Molecular Gas Distribution and Displaced AGN in Zw 3146

We present a recent Atacama Large Millimeter/submillimeter Array observation of the CO(1-0) line emission in the central galaxy of the Zw 3146 galaxy cluster (z = 0.2906). We also present updated X-ray cavity measurements from archival Chandra observations. The 5 × 1010 M⊙ supply of molecular gas, which is confined to the central 4 kpc, is marginally resolved into three extensions that are reminiscent of the filaments observed in similar systems. No velocity structure that would be indicative of ordered motion is observed. The three molecular extensions all trail X-ray cavities, and are potentially formed from the condensation of intracluster gas lifted in the wakes of the rising bubbles. Many cycles of feedback would be required to account for the entire molecular gas reservoir. The molecular gas and continuum source are mutually offset by 2.6 kpc, with no detected line emission coincident with the continuum source. It is the molecular gas, not the continuum source, that lies at the gravitational center of the brightest cluster galaxy. As the brightest cluster galaxy contains possible tidal features, the displaced continuum source may correspond to the nucleus of a merging galaxy. We also discuss the possibility that a gravitational wave recoil following a black hole merger may account for the displacement.

Keywords: active galaxies; brightest cluster galaxies; galaxy clusters; molecular gas; galaxy kinematics; intracluster medium
Exploring Viscosity Effects in Accretion Disk Simulations: A Code Comparison between FLASH and Athena

This project investigates the impact of viscosity on the evolution of black hole accretion disks through a comparative analysis between FLASH and Athena simulations. Our focus lies in understanding the role of viscosity in overall disk evolution. We present mass accretion rate plots that reveal near identical patterns in disk evolution when varying viscosity. We emphasize the need for additional code-comparison research, including exploration of a wider variety of codes and physics included to enhance our understanding and confidence in simulated models.

Keywords: hydrodynamical simulations; accretion; black holes
Heavy Double Neutron Stars: Birth, Midlife, and Death

Radio pulsar observations probe the lives of Galactic double neutron star (DNS) systems while gravitational waves enable us to study extragalactic DNS in their final moments. By combining measurements from radio and gravitational-wave astronomy, we seek to gain a more complete understanding of DNS from formation to merger. We analyze the recent gravitational-wave binary neutron star mergers GW170817 and GW190425 in the context of other DNS known from radio astronomy. By employing a model for the birth and evolution of DNS, we measure the mass distribution of DNS at birth, at midlife (in the radio), and at death (in gravitational waves). We consider the hypothesis that the high-mass gravitational-wave event GW190425 is part of a subpopulation formed through unstable case BB mass transfer, which quickly merge in ∼10-100 Myr. We find only mild evidence to support this hypothesis and that GW190425 is not a clear outlier from the radio population as previously claimed. If there are fast-merging binaries, we estimate that they constitute 8%-79% of DNS at birth (90% credibility). We estimate the typical delay time between the birth and death of fast-merging binaries to be ≈5-401 Myr (90% credibility). We discuss the implications for radio and gravitational-wave astronomy.

Keywords: neutron stars; gravitational waves; binary pulsars
Critical Balance and the Physics of Magnetohydrodynamic Turbulence

A discussion of the advantages and limitations of the concept of critical balance (CB), as employed in turbulence phenomenologies, is presented. The incompressible magnetohydrodynamic (MHD) case is a particular focus. The discussion emphasizes the status of the original Goldreich & Sridhar CB conjecture relative to related theoretical issues and models in an MHD description of plasma turbulence. Issues examined include variance and spectral anisotropy, influence of a mean magnetic field, local and nonlocal effects, and the potential for effects of external driving. Related models such as Reduced MHD provide a valuable context in the considerations. Some new results concerning spectral features and timescales are presented in the course of the discussion. Also mentioned briefly are some adaptations and variations of CB.

Keywords: interplanetary turbulence; space plasmas; solar wind; spectral energy distribution; alfven waves; magnetohydrodynamics
Kepler-102: Masses and Compositions for a Super-Earth and Sub-Neptune Orbiting an Active Star

Radial velocity (RV) measurements of transiting multiplanet systems allow us to understand the densities and compositions of planets unlike those in the solar system. Kepler-102, which consists of five tightly packed transiting planets, is a particularly interesting system since it includes a super-Earth (Kepler-102d) and a sub-Neptune-sized planet (Kepler-102e) for which masses can be measured using RVs. Previous work found a high density for Kepler-102d, suggesting a composition similar to that of Mercury, while Kepler-102e was found to have a density typical of sub-Neptune size planets; however, Kepler-102 is an active star, which can interfere with RV mass measurements. To better measure the mass of these two planets, we obtained 111 new RVs using Keck/HIRES and Telescopio Nazionale Galileo/HARPS-N and modeled Kepler-102's activity using quasiperiodic Gaussian process regression. For Kepler-102d, we report a mass upper limit M d < 5.3 M ⊕ (95% confidence), a best-fit mass M d = 2.5 ± 1.4 M ⊕, and a density ρ d = 5.6 ± 3.2 g cm-3, which is consistent with a rocky composition similar in density to the Earth. For Kepler-102e we report a mass M e = 4.7 ± 1.7 M ⊕ and a density ρ e = 1.8 ± 0.7 g cm-3. These measurements suggest that Kepler-102e has a rocky core with a thick gaseous envelope comprising 2%-4% of the planet mass and 16%-50% of its radius. Our study is yet another demonstration that accounting for stellar activity in stars with clear rotation signals can yield more accurate planet masses, enabling a more realistic interpretation of planet interiors.

Keywords: exoplanets; super earths; mini neptunes; extrasolar rocky planets; gaussian processes regression; radial velocity
Application of Deep-learning Methods for Distinguishing Gamma-Ray Bursts from Fermi/GBM Time-tagged Event Data

To investigate gamma-ray bursts (GRBs) in depth, it is crucial to develop an effective method for identifying GRBs accurately. Current criteria, e.g., onboard blind search, ground blind search, and target search, are limited by manually set thresholds and perhaps miss GRBs, especially for subthreshold events. We proposed a novel approach that utilizes convolutional neural networks (CNNs) to distinguish GRBs and non-GRBs directly. We structured three CNN models, plain-CNN, ResNet, and ResNet-CBAM, and endeavored to exercise fusing strategy models. Count maps of NaI detectors on board Fermi/Gamma-ray Burst Monitor were employed, as the input samples of data sets and models were implemented to evaluate their performance on different timescale data. The ResNet-CBAM model trained on the 64 ms data set achieves high accuracy overall, which includes residual and attention mechanism modules. The visualization methods of Grad-CAM and t-SNE explicitly displayed that the optimal model focuses on the key features of GRBs precisely. The model was applied to analyze 1 yr data, accurately identifying approximately 98% of GRBs listed in the Fermi burst catalog, eight out of nine subthreshold GRBs, and five GRBs triggered by other satellites, which demonstrated that the deep-learning methods could effectively distinguish GRBs from observational data. Besides, thousands of unknown candidates were retrieved and compared with the bursts of SGR J1935+2154, for instance, which exemplified the potential scientific value of these candidates indeed. Detailed studies on integrating our model into real-time analysis pipelines thus may improve their accuracy of inspection and provide valuable guidance for rapid follow-up observations of multiband telescopes.

Keywords: gamma-ray bursts; convolutional neural networks; astronomy data analysis; high energy astrophysics; gamma-ray astronomy; dimensionality reduction
Measuring the Properties of Active Galactic Nuclei Disks with Gravitational Waves

Active galactic nuclei (AGNs) are promising environments for the assembly of merging binary black hole (BBH) systems. Interest in AGNs as nurseries for merging BBHs is rising, following the detection of gravitational waves from a BBH system from the purported pair-instability mass gap, most notably GW190521. AGNs have also been invoked to explain the formation of the high-mass-ratio system GW190814. We draw on simulations of BBH systems in AGNs to propose a phenomenological model for the distribution of black hole spins of merging binaries in AGN disks. The model incorporates distinct features that make the AGN channel potentially distinguishable from other channels, such as assembly in the field and in globular clusters. The model parameters can be mapped heuristically to the age and density of the AGN disks. We estimate the extent to which different populations of mergers in AGNs can be distinguished. If the majority of merging black holes are assembled in AGNs, future gravitational-wave observations may provide insights into the dynamics of AGN disks.

Keywords: gravitational waves; active galactic nuclei; bayesian statistics