adsabs/SciX_UAT_keywords huggingface dataset:
The Implication of the Helium-to-proton Flux Ratio in Galactic Cosmic Rays

The measurement of daily proton and helium fluxes by AMS-02 shows that the helium-to-proton flux ratio (He/H) is negatively correlated with the solar activity at rigidity 1.7-7 GV. What is the behavior of He/H at rigidity lower than 1.7 GV? How can this phenomenon be described quantitatively and linked to the underlying mechanisms? In this work, based on a theoretical derivation, we find that the slope (S) of $\mathrm{ln}(\mathrm{He}/{\rm{H}})$ versus ln(H) is a good indicator of the variation of He/H. S > 0 means the variation of He/H is anticorrelated with the solar activity, and vice versa. Furthermore, the value of S is quantitatively related to the difference in protons and helium nuclei in the local interstellar spectrum (LIS) and in solar modulation. A 3D time-dependent numerical model is used to reproduce the observed proton and helium data. The results of the simulation show that, with increasing rigidity, the parameter S increases from negative values to positive values at around 1 GV, reaches a maximum value at around 2 GV, and then decreases until it approaches 0. Interestingly, S is equal to 0 at around 1 GV. This means that He/H at this rigidity is almost unchanged with the variation in solar activity. Finally, the expression for S is validated by changing the LIS used in the numerical procedure. This shows that the overall profile of S as a function of rigidity is mainly determined by the mass-to-charge ratio, and the specific value of S is strongly affected by the difference in the LIS between protons and helium nuclei.

Keywords: galactic cosmic rays; heliosphere; solar activity
Effects of an Explicit Time-dependent Radiation Pressure Force on Trajectories of Primary Neutral Hydrogen in the Heliosphere

Radiation pressure exerted by solar photon output is salient to the motion of primary neutral hydrogen atoms streaming into the inner heliosphere directly from the local interstellar medium. The action of a time-dependent radiation pressure force, when coupled with the usual gravitational force, changes the characteristic velocities, and therefore energies, of the atoms when they reach regions in which explorer probes are present. A study is presented that uses a 2D code to backtrace neutral hydrogen trajectories from representative target points located 1 au from the Sun. It makes use of both a radiation pressure function and a function for the photoionization rate at 1 au that both oscillate with time based on measurements over a typical solar cycle, as well as a time-independent charge exchange ionization rate at 1 au. Assuming a Maxwellian distribution in the distant upwind direction, phase space data is calculated at the target points, at different moments in time. The dependence of the force on the radial particle velocity has been omitted in the analysis, such that the emphasis is on the effects of the global solar UV intensity variations through the solar cycle. This process allows for the analysis of direct and indirect Maxwellian components through time and space in the time-dependent force environment. Additionally, pseudo-bound orbits caused by energy losses associated with this force environment are observed, and their properties are evaluated with the aim of determining their effects on potential measurements by explorer probes.

Keywords: heliosphere; interstellar atomic gas; interstellar medium wind; solar cycle; solar ultraviolet emission; astronomical simulations; heliocentric orbit
The NANOGrav 12.5 yr Data Set: Search for Gravitational Wave Memory

We present the results of a Bayesian search for gravitational wave (GW) memory in the NANOGrav 12.5 yr data set. We find no convincing evidence for any gravitational wave memory signals in this data set. We find a Bayes factor of 2.8 in favor of a model that includes a memory signal and common spatially uncorrelated red noise (CURN) compared to a model including only a CURN. However, further investigation shows that a disproportionate amount of support for the memory signal comes from three dubious pulsars. Using a more flexible red-noise model in these pulsars reduces the Bayes factor to 1.3. Having found no compelling evidence, we go on to place upper limits on the strain amplitude of GW memory events as a function of sky location and event epoch. These upper limits are computed using a signal model that assumes the existence of a common, spatially uncorrelated red noise in addition to a GW memory signal. The median strain upper limit as a function of sky position is approximately 3.3 × 10‑14. We also find that there are some differences in the upper limits as a function of sky position centered around PSR J0613‑0200. This suggests that this pulsar has some excess noise that can be confounded with GW memory. Finally, the upper limits as a function of burst epoch continue to improve at later epochs. This improvement is attributable to the continued growth of the pulsar timing array.

Keywords: gravitational waves; gravitational wave astronomy
SWASTi-SW: Space Weather Adaptive Simulation Framework for Solar Wind and Its Relevance to the Aditya-L1 Mission

Solar wind streams, acting as a background, govern the propagation of space weather drivers in the heliosphere, which induce geomagnetic storm activities. Therefore, predictions of the solar wind parameters are the core of space weather forecasts. This work presents an indigenous three-dimensional (3D) solar wind model (SWASTi-SW). This numerical framework for forecasting the ambient solar wind is based on a well-established scheme that uses a semiempirical coronal model and a physics-based inner heliospheric model. This study demonstrates a more generalized version of the Wang-Sheeley-Arge relation, which provides a speed profile input to the heliospheric domain. Line-of-sight observations of GONG and Helioseismic and Magnetic Imager magnetograms are used as inputs for the coronal model, which in turn provides the solar wind plasma properties at 0.1 au. These results are then used as an initial boundary condition for the magnetohydrodynamics model of the inner heliosphere to compute the solar wind properties up to 2.1 au. Along with the validation run for multiple Carrington rotations, the effect of variation of specific heat ratio and study of the stream interaction region (SIR) are also presented. This work showcases the multidirectional features of SIRs and provides synthetic measurements for potential observations from the Solar Wind Ion Spectrometer subsystem of the Aditya Solar wind Particle Experiment payload on board ISRO's upcoming solar mission Aditya-L1.

Keywords: solar wind; magnetohydrodynamical simulations; interplanetary magnetic fields
Central BH Mass of Tidal Disruption Event Candidate SDSS J0159 through Long-term Optical Variabilities

In this manuscript, central BH mass is determined in the tidal disruption event (TDE) candidate SDSS J0159, through the 9 yr long variabilities, in order to check whether the virial BH mass is consistent with the mass estimated by other independent methods. First, the host galaxy spectroscopic features are described by 350 simple stellar templates, to confirm the total stellar mass of about 7 × 1010 M ⊙ in SDSS J0159, indicating the virial BH mass is about two magnitudes larger than the BH mass estimated by the total stellar mass. Second, based on an efficient method and fitting procedure, through the theoretical TDE model applied to describe the Sloan Digital Sky Survey ugriz-band light curves of SDSS J0159, the central BH mass can be determined as ${M}_{\mathrm{BH}}\sim {4.5}_{-1.1}^{+1.3}\times {10}^{6}\,{M}_{\odot }$ , well consistent with the Mσ relation expected BH mass and the total stellar mass expected BH mass. Third, the theoretical TDE model with the parameter of central BH mass limited to be higher than 108 M ⊙ cannot lead to reasonable descriptions of the light curves of SDSS J0159, indicating central BH mass higher than 108 M ⊙ is not preferred in SDSS J0159. Therefore, the TDE model determined central BH mass of SDSS J0159 is about two magnitudes lower than the virial BH mass, to support central broad-line regions, including accreting debris contributions from central TDE, and provide interesting clues to reconfirm that outliers in the space of virial BH mass versus stellar velocity dispersion should be better candidates of TDE.

Keywords: active galactic nuclei; emission line galaxies; supermassive black holes; tidal disruption; transient sources
A Close Look at Lyα Emitters with JWST/NIRCam at z ≈ 3.1

We study 10 spectroscopically confirmed Lyα emitters (LAEs) at z ≈ 3.1 in the Ultra Deep Survey field, covered by the James Webb Space Telescope/NIRCam in the Public Release Imaging for Extragalactic Research program. All LAEs are detected in all NIRCam bands from F090W to F444W, corresponding to rest frame wavelengths of 2200 Å to 1.2 μm. Based on morphological analysis of the F200W images, three out of the 10 targets are resolved into pair-like systems with separations of <0.″9, and another three show asymmetric structures. We then construct the spectral energy distributions (SEDs) of these LAEs, which show little to no extinction. All sources, including the pairs, show similar SED shapes, with a prominent flux excess in the F200W band, corresponding to extremely strong [O III]+Hβ emission lines (EWrest = 740–6500 Å). The median effective radii, stellar mass, and UV slope of our sample are 0.36 kpc, 3.8 × 107 M ⊙, and ‑2.48, respectively. The average burst age, estimated by stellar mass over star formation rate, is <40 Myr. These measurements reveal an intriguing starbursting dwarf galaxy population lying off the extrapolations of the z ∼ 3 scaling relations to the low-mass end: ∼0.7 dex above the star-forming main sequence, ∼0.35 dex below the mass–size relation, and bluer in the UV slope than typical high-z galaxies at similar UV luminosities. We speculate that these numbers may require a larger main-sequence scatter or tail in the dwarf galaxy regime toward the starburst outliers.

Keywords: galaxy formation; galaxy evolution; high-redshift galaxies; galaxy stellar content; galaxy structure
Monitoring AGNs with Hβ Asymmetry. IV. First Reverberation Mapping Results of 14 Active Galactic Nuclei

We report first-time reverberation-mapping results for 14 active galactic nuclei (AGNs) from the ongoing Monitoring AGNs with Hβ Asymmetry campaign (MAHA). These results utilize optical spectra obtained with the Long Slit Spectrograph on the Wyoming Infrared 2.3 m Telescope between 2017 November and 2023 May. MAHA combines long-duration monitoring with high cadence. We report results from multiple observing seasons for nine of the 14 objects. These results include Hβ time lags, supermassive black hole masses, and velocity-resolved time lags. The velocity-resolved lags allow us to investigate the kinematics of the broad-line region.

Keywords: reverberation mapping; active galactic nuclei; active galaxies; supermassive black holes; quasars
A New Flaring Black Widow Candidate and Demographics of Black Widow Millisecond Pulsars in the Galactic Field

We present the discovery of a new optical/X-ray source likely associated with the Fermi γ-ray source 4FGL J1408.6-2917. Its high-amplitude periodic optical variability, large spectroscopic radial-velocity semiamplitude, evidence for optical emission lines and flaring, and X-ray properties together imply the source is probably a new black widow millisecond pulsar binary. We compile the properties of the 41 confirmed and suspected field black widows, finding a median secondary mass of 0.027 ± 0.003 M ⊙. Considered jointly with the more massive redback millisecond pulsar binaries, we find that the "spider" companion mass distribution remains strongly bimodal, with essentially zero systems having companion masses of between ~0.07 and 0.1 M ⊙. X-ray emission from black widows is typically softer and less luminous than in redbacks, consistent with less efficient particle acceleration in the intrabinary shock in black widows, excepting a few systems that appear to have more efficient "redback-like" shocks. Together black widows and redbacks dominate the census of the fastest spinning field millisecond pulsars in binaries with known companion types, making up ≳80% of systems with P spin < 2 ms. Similar to redbacks, the neutron star masses in black widows appear on average significantly larger than the canonical 1.4 M ⊙, and many of the highest-mass neutron stars claimed to date are black widows with M NS ≳ 2.1 M ⊙. Both of these observations are consistent with an evolutionary picture where spider millisecond pulsars emerge from short orbital period progenitors that had a lengthy period of mass transfer initiated while the companion was on the main sequence, leading to fast spins and high masses.

Keywords: millisecond pulsars
Extended Calculations of Energy Levels and Transition Rates for Singly Ionized Lanthanide Elements. II. Tb-Yb

In this work, we continue large-scale ab initio computations for single ionized lanthanides. Extended atomic calculations for the set of ions from Pr II (Z = 59) to Gd II (Z = 64) have been performed in our previous work. In this study, ions from Tb II (Z = 65) to Yb II (Z = 70) are analyzed. By employing the same multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction methods that are implemented in the general-purpose relativistic atomic structure package GRASP2018, the energy levels and transition data of electric dipole (E1) transitions are computed. These computations are based on the strategies (with small variations) of Paper I. Accuracy of data is evaluated by comparing the computed energy levels with the data provided by the National Institute of Standards and Technology (NIST) database and with data from various methods. We obtain the average accuracy in the energy level compared with the NIST database: 6%, 5%, 4%, 5%, 3%, and 3% for Tb II, Dy II, Ho II, Er II, Tm II, and Yb II, respectively. We also provide extensive comparison of transition probabilities and wavelengths. Our results reach the average accuracy of transition wavelengths: 9%, 9%, 9%, 3%, 4%, and 11% for Tb II, Dy II, Ho II, Er II, Tm II, and Yb II, respectively.

Keywords: atomic physics; atomic spectroscopy
Profiles of Cosmic Filaments Since z = 4.0 in Cosmological Hydrodynamical Simulation

A large portion of the baryons at low redshifts are still missing from detection. Most of the missing baryons are believed to reside in large-scale cosmic filaments. Understanding the distribution of baryons in filaments is crucial to the search for missing baryons. We investigate the properties of cosmic filaments since z = 4.0 in a cosmological hydrodynamic simulation, focusing on the density and temperature profiles perpendicular to the filament spines. Our quantitative evaluation confirms the rapid growth of thick and prominent filaments after z = 2. We find that the local linear density of filaments shows a correlation with the local diameter since z = 4.0. The averaged density profiles of both dark matter and baryonic gas in filaments of different widths show self-similarity, and can be described by an isothermal single-beta model. The typical gas temperature increases as the filament width increases, and is hotter than 106 K for filaments with width Dfil ≳ 4.0 Mpc, which would be the optimal targets for the search of missing baryons via the thermal Sunyaev-Zel'dovich effect. The temperature rises significantly from the boundary to the inner core regime in filaments with Dfil ≳ 4.0 Mpc, probably due to heating by accretion shock, while the temperature rises modestly in filaments with Dfil < 4.0 Mpc.

Keywords: large-scale structure of the universe; cosmic web; hydrodynamical simulations; intergalactic medium
Interpreting the Atmospheric Composition of Exoplanets: Sensitivity to Planet Formation Assumptions

Constraining planet formation based on the atmospheric composition of exoplanets is a fundamental goal of the exoplanet community. Existing studies commonly try to constrain atmospheric abundances, or to analyze what abundance patterns a given description of planet formation predicts. However, there is also a pressing need to develop methodologies that investigate how to transform atmospheric compositions into planetary formation inferences. In this study we summarize the complexities and uncertainties of state-of-the-art planet formation models and how they influence planetary atmospheric compositions. We introduce a methodology that explores the effect of different formation model assumptions when interpreting atmospheric compositions. We apply this framework to the directly imaged planet HR 8799e. Based on its atmospheric composition, this planet may have migrated significantly during its formation. We show that including the chemical evolution of the protoplanetary disk leads to a reduced need for migration. Moreover, we find that pebble accretion can reproduce the planet's composition, but some of our tested setups lead to too low atmospheric metallicities, even when considering that evaporating pebbles may enrich the disk gas. We conclude that the definitive inversion from atmospheric abundances to planet formation for a given planet may be challenging, but a qualitative understanding of the effects of different formation models is possible, opening up pathways for new investigations.

Keywords: exoplanet atmospheric composition; exoplanet formation
Negative-energy Waves in the Vertical Threads of a Solar Prominence

Solar prominences, intricate structures on the Sun's limb, have been a subject of fascination owing to their threadlike features and dynamic behaviors. Utilizing data from the New Vacuum Solar Telescope, Chinese Hα Solar Explorer, and Solar Dynamics Observatory, this study investigates the transverse swaying motions observed in the vertical threads of a solar prominence during its eruption onset on 2023 May 11. The transverse swaying motions were observed to propagate upward, accompanied by upflowing materials at an inclination of 31° relative to the plane of the sky. These motions displayed small-amplitude oscillations with corrected velocities of around 3–4 km s‑1 and periods of 13–17 minutes. Over time, the oscillations of swaying motion exhibited an increasing pattern in displacement amplitudes, oscillatory periods, and projected velocity amplitudes. Their phase velocities are estimated to be about 26–34 km s‑1. An important finding is that these oscillations' phase velocities are comparable to the upward flow velocities, measured to be around 30–34 km s‑1. We propose that this phenomenon is associated with negative-energy wave instabilities, which require comparable velocities of the waves and flows, as indicated by our findings. This phenomenon may contribute to the instability and observed disruption of the prominence. By using prominence seismology, the Alfvén speed and magnetic field strength of the vertical threads have been estimated to be approximately 21.5 km s‑1 and 1–3G, respectively. This study reveals the dynamics and magnetic properties of solar prominences, contributing to our understanding of their behavior in the solar atmosphere.

Keywords: solar oscillations; solar prominences; solar coronal waves
BASS XXXII: Studying the Nuclear Millimeter-wave Continuum Emission of AGNs with ALMA at Scales ≲100-200 pc

To understand the origin of nuclear (≲100 pc) millimeter-wave (mm-wave) continuum emission in active galactic nuclei (AGNs), we systematically analyzed subarcsecond resolution Band-6 (211-275 GHz) Atacama Large Millimeter/submillimeter Array data of 98 nearby AGNs (z < 0.05) from the 70 month Swift/BAT catalog. The sample, almost unbiased for obscured systems, provides the largest number of AGNs to date with high mm-wave spatial resolution sampling (~1-200 pc), and spans broad ranges of 14-150 keV luminosity { $40\lt \mathrm{log}[{L}_{14-150}/(\mathrm{erg}\,{{\rm{s}}}^{-1})]\lt 45$ }, black hole mass $[5\lt \mathrm{log}({M}_{\mathrm{BH}}/{M}_{\odot })\lt 10$ ], and Eddington ratio ( $-4\lt \mathrm{log}{\lambda }_{\mathrm{Edd}}\lt 2$ ). We find a significant correlation between 1.3 mm (230 GHz) and 14-150 keV luminosities. Its scatter is ≈0.36 dex, and the mm-wave emission may serve as a good proxy of the AGN luminosity, free of dust extinction up to N H ~ 1026 cm-2. While the mm-wave emission could be self-absorbed synchrotron radiation around the X-ray corona according to past works, we also discuss different possible origins of the mm-wave emission: AGN-related dust emission, outflow-driven shocks, and a small-scale (<200 pc) jet. The dust emission is unlikely to be dominant, as the mm-wave slope is generally flatter than expected. Also, due to no increase in the mm-wave luminosity with the Eddington ratio, a radiation-driven outflow model is possibly not the common mechanism. Furthermore, we find independence of the mm-wave luminosity on indicators of the inclination angle from the polar axis of the nuclear structure, which is inconsistent with a jet model whose luminosity depends only on the angle.

Keywords: x-ray active galactic nuclei; active galactic nuclei; millimeter astronomy; astrophysical black holes; active galaxies
Drifting Pulsation Structure at the Very Beginning of the 2017 September 10 Limb Flare

Drifting pulsation structures (DPSs) are important radio fine structures usually observed at the beginning of eruptive solar flares. It has been suggested that DPSs carry important information on the energy release processes in solar flares. We study DPS observed in an X8.2-class flare on 2017 September 10 in the context of spatial and spectral diagnostics provided by microwave, EUV, and X-ray observations. We describe DPS and its substructures that were observed for the first time. We use a new wavelet technique to reveal characteristic periods in DPS and their frequency bands. Comparing the periods of pulsations found in this DPS with those in previous DPSs, we found new very short periods in the 0.09-0.15 s range. We present Expanded Owens Valley Solar Array images and spectra of microwave sources observed during the DPS. This DPS at its very beginning has pulsations in two frequency bands (1000-1300 MHz and 1600-1800 MHz), which are interconnected by fast drifting bursts. We show that these double-band pulsations started just at the moment when the ejected filament splits apart in a tearing motion at the location where a signature of the flare current sheet later appeared. Using the standard flare model and previous observations of DPSs, we interpret these double-band pulsations as a radio signature of superthermal electrons trapped in the rising magnetic rope and flare arcade at the moment when the flare magnetic reconnection starts. The results are discussed in a scenario with the plasmoid in the rising magnetic rope.

Keywords: solar flares; solar radio emission
Dual-band Observations of the Asymmetric Ring around CIDA 9A: Dead or Alive?

While the most exciting explanation of the observed dust asymmetries in protoplanetary disks is the presence of protoplanets, other mechanisms can also form the dust features. This paper presents dual-wavelength Atacama Large Millimeter/submillimeter Array observations of a large asymmetric dusty ring around the M-type star CIDA 9A. We detect a dust asymmetry in both 1.3 and 3.1 mm data. To characterize the asymmetric structure, a parametric model is used to fit the observed visibilities. We report a tentative azimuthal shift of the dust emission peaks between the observations at the two wavelengths. This shift is consistent with a dust trap caused by a vortex, which may be formed by an embedded protoplanet or other hydrodynamical instabilities, such as a dead zone. Deep high-spatial-resolution observations of dust and molecular gas are needed to constrain the mechanisms that formed the observed millimeter cavity and dust asymmetry in the protoplanetary disk around CIDA 9A.

Keywords: circumstellar disks; planet formation; protoplanetary disks