Sazuna/UAT_keywords huggingface dataset:
JWST/NIRSpec Observations of Lyman α Emission in Star-forming Galaxies at 6.5 ≲ z ≲ 13. We present an analysis of JWST Lyα spectroscopy of z ≳ 6.5 galaxies, using observations in the public archive covering galaxies in four independent fields: Great Observatories Origins Deep Survey (GOODS)-N, GOODS-S, A2744, and the Extended Groth Strip (EGS). We measure the Lyα emission line properties for a sample of 210 z ≃ 6.5–13 galaxies, with redshifts confirmed independently of Lyα in all cases. We present three new detections of Lyα emission in JWST spectra, including a large equivalent width (EW; =143 Å) Lyα emitter (LAE) with strong C IV emission (EW = 21 Å) at z = 7.1 in GOODS-N. We measure the redshift-dependent Lyα EW distribution across our sample. We find that strong Lyα emission (EW &gt; 25 Å) becomes increasingly rare at earlier epochs, suggesting that the transmission of Lyα photons decreases by 4× between z ≃ 5 and z ≃ 9. We describe potential implications for the intergalactic medium neutral fraction. There is significant field-to-field variance in the LAE fraction. In contrast to the three other fields, the EGS shows no evidence for reduced transmission of Lyα photons at z ≃ 7–8, suggesting a significantly ionized sight line may be present in the field. We use available NIRCam grism observations from the First Reionization Epoch Spectroscopically Complete Observations survey to characterize overdensities on large scales around known LAEs in the GOODS fields. The strongest overdensities appear linked with extremely strong Lyα detections (EW &gt; 50 Å) in most cases. Future Lyα spectroscopy with JWST has the potential to constrain the size of ionized regions around early galaxy overdensities, providing a new probe of the reionization process.

Keywords: Reionization, Observational cosmology, High-redshift galaxies
Convective Magnetic Flux Emergence Simulations from the Deep Solar Interior to the Photosphere: Comprehensive Study of Flux Tube Twist. The emergence of magnetic flux from the deep convection zone plays an important role in solar magnetism, such as the generation of active regions and triggering of various eruptive phenomena, including jets, flares, and coronal mass ejections. To investigate the effects of magnetic twist on flux emergence, we performed numerical simulations of flux tube emergence using the radiative magnetohydrodynamic code R2D2 and conducted a systematic survey on the initial twist. Specifically, we varied the twist of the initial tube both positively and negatively from zero to twice the critical value for kink instability. As a result, regardless of the initial twist, the flux tube was lifted by the convective upflow and reached the photosphere to create sunspots. However, when the twist was too weak, the photospheric flux was quickly diffused and not retained long as coherent sunspots. The degree of magnetic twist measured in the photosphere conserved the original twist relatively well and was comparable to actual solar observations. Even in the untwisted case, a finite amount of magnetic helicity was injected into the upper atmosphere because the background turbulence added helicity. However, when the initial twist exceeded the critical value for kink instability, the magnetic helicity normalized by the total magnetic flux was found to be unreasonably larger than the observations, indicating that the kink instability of the emerging flux tube may not be a likely scenario for the formation of flare-productive active regions.

Keywords: Magnetohydrodynamics, Solar flares, Solar interior, Emerging flux tubes, Sunspots, Solar magnetic fields, Solar coronal mass ejections
Measurements of Sunspot Group Tilt Angles Based on SOHO/MDI and SDO/HMI Magnetograms. The tilt angle of sunspot groups plays a crucial role in solar dynamo models for the generation of the poloidal field, yet the statistical properties of the tilt angle are not fully comprehended. This study employs magnetograms from the Solar and Heliospheric Observatory/Michelson Doppler Imager and Solar Dynamics Observatory/Helioseismic and Magnetic Imager to measure the tilt angles of 11,373 sunspot groups over the period from 2008 to 2023. This comprehensive analysis examines the relationship between the tilt angle and latitude of the sunspot groups, as well as the correlation between the tilt angle and solar cycle strength. The methodology involves calculating tilt angles within the ±45° central meridian distance, comparing mean-based and median-based measurements, and applying specific angular separation criteria. The findings reveal that during solar cycle 24, the tilt angles increase by approximately 4° for every 10° increase in latitude, in line with Joy's law. A significant anticorrelation is observed between the latitude-normalized tilt angle (γ/∣L∣) and solar cycle strength. The research also uncovers a substantial hemispheric asymmetry in tilt angle parameters, with the southern hemisphere (m Joy: 0.23 ± 0.092 ∼ 0.24 ± 0.074, γ = 8.°14 ± 0.°43 ∼ 9.°04 ± 0.°486) consistently showing larger tilt angles than the northern hemisphere (m Joy: 0.47 ± 0.096 ∼ 0.51 ± 0.062, γ = 6.°14 ± 0.°304 ∼ 6.°64 ± 0.°334).

Keywords: Solar activity, Sunspots, Solar magnetic fields
Radiative Pressure on Fractal Dust Grains in Oxygen-rich AGB Stars. There is still considerable debate on the exact composition of grains formed in the outflows of O-rich, asymptotic giant branch stars. Estimates of the expected condensation distances based on radiative transfer calculations show that iron-free silicates can condense close to the star but typically lack the opacity to drive an outflow unless they are large enough that radiation pressure due to scattering on the grains becomes significant. Iron-containing silicates have a much higher absorption opacity, but due to this stronger absorption, their expected condensation location is well beyond the expected dust formation zone. Recent measurements of the efficiency of SiO condensational growth have shown that this rate is low. The result of this low growth efficiency is that nucleation may persist for longer, giving a larger number of smaller primary particles, leading to an increased likelihood of particle aggregation in these outflows. In this work, we examine how the radiation pressure changes with the possible aggregation of these primary particles into fractal aggregates. Opacity calculations are made using optical properties of both forsterite and astronomical silicate for aggregates containing up to 256 primary particles and for fractal dimensions of 1.8 and 2.8. For primary particles of radius less than ∼0.1 μm, aggregation leads to an enhancement of the radiation pressure over an equivalent cloud of isolated primary particles.

Keywords: Circumstellar dust
Efficient Stochastic Template Bank Using Inner Product Inequalities. Gravitational wave searches are crucial for studying compact sources such as neutron stars and black holes. Many sensitive modeled searches use matched filtering to compare gravitational strain data to a set of waveform models known as template banks. We introduce a new stochastic placement method for constructing template banks, offering efficiency and flexibility to handle arbitrary parameter spaces, including orbital eccentricity, tidal deformability, and other extrinsic parameters. This method can be computationally limited by the ability to compare proposal templates with the accepted templates in the bank. To alleviate this computational load, we introduce the use of inner product inequalities to reduce the number of required comparisons. We also introduce a novel application of Gaussian Kernel Density Estimation to enhance waveform coverage in sparser regions. Our approach has been employed to search for eccentric binary neutron stars, low-mass neutron stars, primordial black holes, and supermassive black hole binaries. We demonstrate that our method produces self-consistent banks that recover the required minimum fraction of signals. For common parameter spaces, our method shows comparable computational performance and similar template bank sizes to geometric placement methods and stochastic methods, while easily extending to higher-dimensional problems. The time to run a search exceeds the time to generate the bank by a factor of  O(105)  for dedicated template banks, such as geometric, mass-only stochastic, and aligned spin cases,  O(104)  for eccentric and  O(103)  for the tidal deformable bank. With the advent of efficient template bank generation, the primary area for improvement is developing more efficient search methodologies.

Keywords: Gravitational wave astronomy, Gravitational waves
Impact of Systematic Modeling Uncertainties on Kilonova Property Estimation. The precise atomic structure and therefore the wavelength-dependent opacities of lanthanides are highly uncertain. This uncertainty introduces systematic errors in modeling transients like kilonovae and estimating key properties such as mass, characteristic velocity, and heavy metal content. Here, we quantify how atomic data from across the literature as well as choices of thermalization efficiency of r-process radioactive decay heating impact the light curve and spectra of kilonovae. Specifically, we analyze the spectra of a grid of models produced by the radiative transfer code Sedona that span the expected range of kilonova properties to identify regions with the highest systematic uncertainty. Our findings indicate that differences in atomic data have a substantial impact on estimates of lanthanide mass fraction, spanning approximately 1 order of magnitude for lanthanide-rich ejecta, and demonstrate the difficulty in precisely measuring the lanthanide fraction in lanthanide-poor ejecta. Mass estimates vary typically by 25%–40% for differing atomic data. Similarly, the choice of thermalization efficiency can affect mass estimates by 20%–50%. Observational properties such as color and decay rate are highly model dependent. Velocity estimation, when fitting solely based on the light curve, can have a typical error of ∼100%. Atomic data of light r-process elements can strongly affect blue emission. Even for well-observed events like GW170817, the total lanthanide production estimated using different atomic data sets can vary by a factor of ∼6.

Keywords: Gravitational wave sources, Time domain astronomy, Transient sources, High energy astrophysics
No Redshift Evolution in the Fe II/Mg II Flux Ratios of Quasars across Cosmic Time. The Fe II/Mg II emission line flux ratio in quasar spectra serves as a proxy for the relative Fe to α-element abundances in the broad-line regions of quasars. Due to the expected different enrichment timescales of the two elements, they can be used as a cosmic clock in the early Universe. We present a study of the Fe II/Mg II ratios in a sample of luminous quasars exploiting high-quality near-IR spectra taken primarily by the XQR-30 program with VLT XSHOOTER. These quasars have a median bolometric luminosity of log(L bol[erg s−1]) ∼ 47.3 and cover a redshift range of z = 6.0─6.6. The median value of the measured Fe II/Mg II ratios is ∼7.9 with a normalized median absolute deviation of ∼2.2. In order to trace the cosmic evolution of Fe II/Mg II in an unbiased manner, we select two comparison samples of quasars with similar luminosities and high-quality spectra from the literature, one at intermediate redshifts (z = 3.5─4.8) and the other at low redshifts (z = 1.0─2.0). We perform the same spectral analysis for all these quasars, including the usage of the same iron template, the same spectral fitting method, and the same wavelength fitting windows. We find no significant redshift evolution in the Fe II/Mg II ratio over the wide redshift range from z = 1 to 6.6. The result is consistent with previous studies and supports the scenario of a rapid iron enrichment in the vicinity of accreting supermassive black holes at high redshift.

Keywords: High-redshift galaxies, High-luminosity active galactic nuclei, Quasars
Joint Observations of Late Universe Probes: Cosmological Parameter Constraints from Gravitational Wave and Type Ia Supernova Data. The growing tensions between the early Universe and the late Universe increasingly highlight the importance of developing precise probes for late cosmology. As significant late-Universe probes, Type Ia supernovae (SNe Ia) and gravitational waves (GWs) can provide measurements of relative and absolute distances, respectively. Their complementary nature is likely to break the degeneracies among cosmological parameters, thereby yielding more precise constraints. In this study, we use 43 gravitational-wave sources from the Third LIGO–Virgo–KAGRA Gravitational-Wave Transient Catalog (GWTC-3) and 1590 light curves from Pantheon+ compilation to constrain the dark energy models, as an attempt to achieve precise late-Universe cosmological constraints. For the dark siren GW event, we estimate the corresponding redshift using the binary black hole redshift distribution model. The combination of GW and SNe Ia data could provide the precision on the Hubble constant H 0 and the present matter density Ω m  of approximately 16% and 8% for the ΛCDM model. If we consider the equation of state of dark energy w, the combination sample constrains the precision of w to approximately 24%. Although the combination of GWs and SNe Ia observations effectively breaks degeneracies among various cosmological parameters, yielding more stringent constraints, the precision of these constraints still does not meet the stringent standards required by precision cosmology. However, it is reasonable to anticipate that, in the near future, the joint observations of GWs and SNe Ia will become a powerful tool, particularly in the late Universe, for the precise measurement of cosmological parameters.

Keywords: Observational cosmology, Dark energy, Gravitational waves, Cosmological constant
Analysis of the Full Spitzer Microlensing Sample. I. Dark Remnant Candidates and Gaia Predictions. In the pursuit of understanding the population of stellar remnants within the Milky Way, we analyze the sample of ∼950 microlensing events observed by the Spitzer Space Telescope between 2014 and 2019. In this study we focus on a subsample of nine microlensing events, selected based on their long timescales, small microlensing parallaxes, and joint observations by the Gaia mission, to increase the probability that the chosen lenses are massive and the mass is measurable. Among the selected events we identify lensing black holes and neutron star candidates, with potential confirmation through forthcoming release of the Gaia time-series astrometry in 2026. Utilizing Bayesian analysis and Galactic models, along with the Gaia Data Release 3 proper-motion data, four good candidates for dark remnants were identified: OGLE-2016-BLG-0293, OGLE-2018-BLG-0483, OGLE-2018-BLG-0662, and OGLE-2015-BLG-0149, with lens masses of  3.0‑1.3+1.8M⊙ ,  4.7‑2.1+3.2M⊙ ,  3.15‑0.64+0.66M⊙  and  1.40‑0.55+0.75M⊙ , respectively. Notably, the first two candidates are expected to exhibit astrometric microlensing signals detectable by Gaia, offering the prospect of validating the lens masses. The methodologies developed in this work will be applied to the full Spitzer microlensing sample, populating and analyzing the timescale (t E) versus parallax (π E) diagram to derive constraints on the population of lenses in general and massive remnants in particular.

Keywords: Microlensing parallax, Neutron stars, Black holes, Astrometric microlensing effect, Satellite microlensing parallax, Stellar masses, Gravitational microlensing, Stellar remnants, Gaia
Determining the Magnetic Field in the Galactic Plane from New Arecibo Pulsar Faraday Rotation Measurements. We develop a new method for studying the Galactic magnetic field along the spiral arms using pulsar Faraday rotation measures (RMs). Our new technique accounts for the dot-product nature of Faraday rotation and also splits the associated path integral into segments corresponding to particular zones along the line of sight. We apply this geometrically corrected, arm-by-arm technique to the low-latitude portion of a recently published set of Arecibo Faraday RMs for 313 pulsars, along with previously obtained RMs in the same regions. We find disparities &gt;1σ between the magnitude of the field above and below the plane in the Local Arm, Sagittarius Arm, Sagittarius-to-Scutum Interarm, Scutum Arm, and Perseus Arm. We find evidence for a single field reversal near the Local Arm–Sagittarius Arm boundary. Interestingly, our results suggest that this field reversal is dependent on latitude, occurring inside the Sagittarius Arm at negative Galactic latitudes and at the Local Arm–Sagittarius Arm boundary at positive Galactic latitudes. We discuss all of our results in the context of different models and other observational Galactic magnetic field analyses.

Keywords: Milky Way magnetic fields, Radio astronomy, Interstellar medium, Radio pulsars
Quiescent Solar Wind Regions in the Near-Sun Environment: Properties and Radial Evolution. Regions of magnetic fields with near-radial, Parker-spiral-like geometry known as quiescent regions have been observed in Parker Solar Probe data. These regions have very low δ B/&lt;∣B∣&gt; compared to nonquiescent solar wind at the same heliocentric distances. Quiescent regions are observed to have lower solar wind bulk speeds, lower proton temperatures, and lower proton density. Inside of 15 solar radii ( R ⊙ ), identified quiescent regions show distinct thermal properties, having higher proton temperature anisotropies and lower parallel plasma betas compared to switchback patches observed at the same heliocentric distances. When placed on  R -versus-β ∥p  plots (where  R  is the proton temperature anisotropy), quiescent region solar wind is shown to be more stable to proton cyclotron and firehose instabilities than nonquiescent solar wind at the same heliocentric distances. It is shown that quiescent regions evolve similarly to the surrounding nonquiescent solar wind, but quiescent solar wind begins at a different location in the  R -versus-β ∥p  parameter space, suggesting that these regions have separate origins from the more turbulent nonquiescent solar wind. Namely, enhanced temperature anisotropies and enhanced magnetic field strength may be consistent with magnetic field lines that have undergone less magnetic field expansion compared to nonquiescent wind at the same heliocentric distances.

Keywords: Space plasmas, Heliosphere, Interplanetary turbulence, Solar wind, Solar magnetic fields
Studying the Effect of Radiation Pressure on Evolution of a Population III Stellar Cluster. Recent numerical simulations have shown that the unstable disk within the central regime of the primordial gas cloud fragments to form multiple protostars on several scales. Their evolution depends on the mass accretion phenomenon, interaction with the surrounding medium and radiative feedback respectively. In this work, we use a fast semianalytical framework in order to model multiple protostars within a rotating cloud, where the mass accretion is estimated via a Bondi–Hoyle flow and the feedback process is approximated through radiation pressure. We observe that while some of the evolving protostars possibly grow massive (≈1–75 M ⊙) via accretion and mergers, a fraction of them (≈20%) are likely to be ejected from the parent cloud with a mass corresponding to M * ≲ 0.8 M ⊙. These low-mass protostars may be considered as the potential candidates to enter the zero-age-main-sequence phase and possibly survive until the present epoch.

Keywords: Population III stars, Stellar feedback, Bondi accretion, Survival analysis, N-body simulations
Testing the Accuracy of Spectral Energy Distribution Modeling Techniques Using the NIHAO-SKIRT-Catalog. We use simulated galaxy observations from the NIHAO-SKIRT-Catalog to test the accuracy of spectral energy distribution (SED) modeling techniques. SED modeling is an essential tool for inferring star formation histories from nearby galaxy observations but is fraught with difficulty due to our incomplete understanding of stellar populations, chemical enrichment processes, and the nonlinear, geometry-dependent effects of dust. The NIHAO-SKIRT-Catalog uses hydrodynamic simulations and radiative transfer to produce SEDs from the ultraviolet (UV) through the infrared (IR), accounting for dust. We use the commonly used Prospector software to perform inference on these SEDs and compare the inferred stellar masses and star formation rates (SFRs) to the known values in the simulation. We match the stellar population models to isolate the effects of differences in the star formation history, the chemical evolution history, and the dust. For the high-mass NIHAO galaxies (&gt;109.5 M ⊙), we find that model mismatches lead to inferred SFRs that are on average underestimated by a factor of 2 when fit to UV through IR photometry, and a factor of 3 when fit to UV through optical photometry. These biases lead to significant inaccuracies in the resulting specific SFR–mass relations, with UV through optical fits showing particularly strong deviations from the true relation of the simulated galaxies. In the context of massive existing and upcoming photometric surveys, these results highlight that star formation history inference from photometry may remain imprecise and inaccurate and that there is a pressing need for more realistic testing of existing techniques.

Keywords: Interstellar dust, Astronomy data modeling, Stellar populations, Galaxy evolution, Radiative transfer simulations, Astronomical simulations
The Role of Magnetic Skeleton in Solar Flare Filaments Activity. We report an M9.3 flare and filaments activities from NOAA Active Region 11261 that are strongly modulated by the 3D magnetic skeleton. Magnetic field extrapolation from the vector magnetic field suggests complex magnetic connectivity and the existence of a high coronal null point southeast of the active region. A small filament over the inversed V-shaped polarity inversion line erupted and resulted in the M9.3 flare associated with a weak ejection in the EUV hot channel and the formation of a relatively large filament. Both the weak ejection and the eruption of the large filament were toward the southeast. Comparative analyses have disclosed the following new facts. First, the trajectory of looptop hard X-ray emission provides solid evidence that the magnetic reconnection site propagated up toward the coronal null point as the flare and filaments erupted. Second, the EVU observations show coronal mass ejection-like eruption features in the ejection region of the magnetic skeleton. Third, the closed fan confined the west end of the large filament and the corresponding flare ribbons. We demonstrate a spatiotemporal relationship between the magnetic skeleton and the flare filament activity. We conclude that the magnetic skeleton can modulate and determine almost all the characteristics of the studied activity in the corresponding scale.

Keywords: Solar active region magnetic fields, Solar flares, Solar magnetic reconnection, Solar coronal mass ejections, Solar filament eruptions