Sazuna/UAT_keywords huggingface dataset:
Shape Asymmetries and the Relation between Lopsidedness and Radial Alignment in Simulated Galaxies. Galaxies are observed to be lopsided, meaning that they are more massive and more extended along one side than the opposite side. In this work, we provide a statistical analysis of the lopsided morphology of 1780 isolated satellite galaxies generated by the TNG50-1 simulation, incorporating the effect of tidal fields from halo centers. The isolated satellites are galaxies without nearby substructures whose mass is over 1% of the satellites within their virial radii. We study the radial alignment (RA) between the major axes of satellites and the radial direction of their halo centers in radial ranges of 0-2, 2-5, and 5-10 R  h , with R  h  being the stellar half-mass radius. According to our results, the RA is virtually undetectable in inner and intermediate regions, yet it is significantly evident in outer regions. We also calculate the far-to-near-side semiaxial ratios of the major axes, denoted by a -/a +, which measure the semiaxial ratios of the major axes in the hemispheres between those facing away from (far side) and facing toward (nearside) halo centers. In all the radial bins of the satellites, the numbers of satellites with longer semiaxes on the far side are found to be almost equal to those with longer semiaxes on the near side. Therefore, the tidal fields from halo centers play a minor role in the generation of lopsided satellites. The long semimajor-axes radial alignment (LRA), i.e., an alignment between the long semimajor axes of satellite galaxies and the radial directions to their halo centers, is further studied. No clear evidence of LRA is found in our sample within the framework of ΛCDM Newtonian dynamics. Finally, we briefly discuss the possible origins of the asymmetry of galaxies in TNG50-1.

Keywords: Galaxy dark matter halos, Galaxy mass distribution, Galaxy dynamics, Astronomical simulations
Diagnosis of Circumstellar Matter Structure in Interaction-powered Supernovae with Hydrogen Line Features. Some supernovae (SNe) are powered by the collision of the SN ejecta with dense circumstellar matter (CSM). Their emission spectra show characteristic line shapes of combined broad emission and narrow P Cygni lines, which should closely relate to the CSM structure and the mass-loss mechanism that creates the dense CSM. We quantitatively investigate the relationship between the line shape and the CSM structure by Monte Carlo radiative transfer simulations, considering two representative cases of dense CSM formed by steady and eruptive mass loss. Comparing the Hα emission between the two cases, we find that a narrow P Cygni line appears in the eruptive case but does not appear in the steady case due to the difference in the velocity gradient in the dense CSM. We also reproduce the blueshifted photon excess observed in some Type IIn SNe, which is formed by photon transport across the shock wave, and find the relationship between the velocity of the shocked matter and the amount of blueshift of the photon excess. We conclude that the presence or absence of narrow P Cygni lines can distinguish the mass-loss mechanism and suggest high-resolution spectroscopic observations with λ/Δλ ≳ 104 after the light-curve peak for applying this diagnostic method.

Keywords: Hydrodynamical simulations, Monte Carlo methods, Type II supernovae, H I line emission, Circumstellar matter, Stellar winds, Radiative transfer simulations
Observations of Nine Millisecond Pulsars at 8600 MHz Using the TMRT. We report detection results of nine millisecond pulsars (MSPs) at 8600 MHz using simultaneous 2250 and 8600 MHz observations conducted with the Shanghai Tian Ma Radio Telescope. Mainly benefiting from updated ephemerids with 2250 MHz observations, integrated profiles of all nine MSPs at 8600 MHz are successfully obtained by coherently adding multi-epoch (3-83 epochs) observation data spanning from 19-1210 days, which significantly increases the number of MSPs with published profiles (from 4 to 11) above 8000 MHz, as seven of our target MPSs had no related results previously. Combining our new flux density and pulse width measurements with previous low-frequency results, we study their integrated profile evolution and spectral behaviors in a wider frequency range. We find their component separations and pulse widths remain almost constant, which is consistent with previous findings. While dramatic evolution of integrated profiles exists at low frequencies, we observe a potential end of the related evolution around 5 GHz in eight MSPs. The spectra of four MSPs are found to deviate from a single power law, and we fit them with a broken power law. The change in the profile of PSR J1713+0747, which started around MJD 59320-59321, seems to be more prominent as the observation frequency increases. Compared with the effects of the interstellar medium, we prefer to explain this event as some changes in the magnetosphere. We also find its integrated profile possibly had not recovered to the pre-event state until MJD 59842-59857.

Keywords: Radio pulsars, Millisecond pulsars
EMPRESS. XII. Statistics on the Dynamics and Gas Mass Fraction of Extremely Metal-poor Galaxies. We present the demography of the dynamics and gas mass fraction of 33 extremely metal-poor galaxies (EMPGs) with metallicities of 0.015-0.195 Z ⊙ and low stellar masses of 104-108 M ⊙ in the local universe. We conduct deep optical integral field spectroscopy (IFS) for the low-mass EMPGs with the medium-high resolution (R = 7500) grism of the 8 m Subaru FOCAS IFU instrument by the EMPRESS 3D survey, and investigate the Hα emission of the EMPGs. Exploiting the resolution high enough for the low-mass galaxies, we derive gas dynamics with the Hα lines by the fitting of three-dimensional disk models. We obtain an average maximum rotation velocity (v rot) of 15 ± 3 km s-1 and an average intrinsic velocity dispersion (σ 0) of 27 ± 10 km s-1 for 15 spatially resolved EMPGs out of 33 EMPGs, and find that all 15 EMPGs have v rot/σ 0 &lt; 1 suggesting dispersion-dominated systems. There is a clear decreasing trend of v rot/σ 0 with the decreasing stellar mass and metallicity. We derive the gas mass fraction (f gas) for all 33 EMPGs, and find no clear dependence on stellar mass and metallicity. These v rot/σ 0 and f gas trends should be compared with young high-z galaxies observed by the forthcoming JWST IFS programs to understand the physical origins of the EMPGs in the local universe.

Keywords: Galaxy dynamics, Galaxy kinematics, Galaxy evolution, Dwarf galaxies
The Star Formation Efficiency during Reionization as Inferred from the Hubble Frontier Fields. A recent ultraviolet luminosity function (UVLF) analysis in the Hubble Frontier Fields, behind foreground lensing clusters, has helped solidify estimates of the faint-end of the z ~ 5-9 UVLF at up to 5 mag fainter than in the field. These measurements provide valuable information regarding the role of low-luminosity galaxies in reionizing the universe and can help in calibrating expectations for JWST observations. We fit a semiempirical model to the lensed and previous UVLF data from Hubble. This fit constrains the average star formation efficiency (SFE) during reionization, with the lensed UVLF measurements probing halo mass scales as small as M ~ 2 × 109 M ☉. The implied trend of SFE with halo mass is broadly consistent with an extrapolation from previous inferences at M ≳ 1010 M ☉, although the joint data prefer a shallower SFE. This preference, however, is partly subject to systematic uncertainties in the lensed measurements. Near z ~ 6, we find that the SFE peaks at ~20% between ~1011 and 1012 M ☉. Our best-fit model is consistent with the Planck 2020 determinations of the electron scattering optical depth, and most current reionization history measurements, provided the escape fraction of ionizing photons is f esc ~ 10%-20%. The joint UVLF accounts for nearly 80% of the ionizing photon budget at z ~ 8. Finally, we show that recent JWST UVLF estimates at z ≳ 11 require strong departures from the redshift evolution suggested by the Hubble data.

Keywords: Luminosity function, Galaxy dark matter halos, Astronomical models, Stellar feedback, Model selection, Hubble Space Telescope, James Webb Space Telescope, Star formation, Gravitational lensing, Markov chain Monte Carlo, Reionization
On the Nature of Disks at High Redshift Seen by JWST/CEERS with Contrastive Learning and Cosmological Simulations. Visual inspections of the first optical rest-frame images from JWST have indicated a surprisingly high fraction of disk galaxies at high redshifts. Here, we alternatively apply self-supervised machine learning to explore the morphological diversity at z ≥ 3. Our proposed data-driven representation scheme of galaxy morphologies, calibrated on mock images from the TNG50 simulation, is shown to be robust to noise and to correlate well with the physical properties of the simulated galaxies, including their 3D structure. We apply the method simultaneously to F200W and F356W galaxy images of a mass-complete sample (M */M ⊙ &gt; 109) at 3 ≤ z ≤ 6 from the first JWST/NIRCam CEERS data release. We find that the simulated and observed galaxies do not exactly populate the same manifold in the representation space from contrastive learning. We also find that half the galaxies classified as disks—either convolutional neural network-based or visually—populate a similar region of the representation space as TNG50 galaxies with low stellar specific angular momentum and nonoblate structure. Although our data-driven study does not allow us to firmly conclude on the true nature of these galaxies, it suggests that the disk fraction at z ≥ 3 remains uncertain and possibly overestimated by traditional supervised classifications. Deeper imaging and spectroscopic follow-ups as well as comparisons with other simulations will help to unambiguously determine the true nature of these galaxies, and establish more robust constraints on the emergence of disks at very high redshift.

Keywords: Galaxy formation, High-redshift galaxies, Galaxy evolution, Neural networks
Accuracy Analysis for Shack–Hartmann Wave Front Sensing with Extended Sources. Correlating the Shack–Hartmann wave front sensor (SH-WFS) with extended targets is widely used in solar adaptive optics systems. This paper aims to introduce a theoretical analysis that evaluates the accuracy of the SH-WFS on extended sources, with a specific focus on the implementation of the Normalized Cross-correlation (NCC) algorithm. To obtain an accurate error description, we utilized the calculation formula of the NCC algorithm to directly express the coordinates of the maximum value in the correlation function matrix. Furthermore, we determined the variance of the centroid position through the error transfer function, which quantifies the measurement error. In comparison with the previous findings of Michau et al., our result exhibits a coefficient disparity, specifically obtaining results 1.5 times higher than their work. The extensive solar granulation simulation and experimental results validate the theoretical error formulas. These error formulas can effectively estimate the accuracy of the SH-WFS, providing a theoretical foundation for the design of optical systems.

Keywords: Solar instruments
Stochastic Modeling of Star Formation Histories. III. Constraints from Physically Motivated Gaussian Processes. Galaxy formation and evolution involve a variety of effectively stochastic processes that operate over different timescales. The extended regulator model provides an analytic framework for the resulting variability (or "burstiness") in galaxy-wide star formation due to these processes. It does this by relating the variability in Fourier space to the effective timescales of stochastic gas inflow, equilibrium, and dynamical processes influencing giant molecular clouds' creation and destruction using the power spectral density (PSD) formalism. We use the connection between the PSD and autocovariance function for general stochastic processes to reformulate this model as an autocovariance function, which we use to model variability in galaxy star formation histories (SFHs) using physically motivated Gaussian processes in log star formation rate (SFR) space. Using stellar population synthesis models, we then explore how changes in model stochasticity can affect spectral signatures across galaxy populations with properties similar to the Milky Way and present-day dwarfs, as well as at higher redshifts. We find that, even at fixed scatter, perturbations to the stochasticity model (changing timescales vs. overall variability) leave unique spectral signatures across both idealized and more realistic galaxy populations. Distributions of spectral features including Hα and UV-based SFR indicators, Hδ and Ca H and K absorption-line strengths, D  n (4000), and broadband colors provide testable predictions for galaxy populations from present and upcoming surveys with the Hubble Space Telescope, James Webb Space Telescope, and Nancy Grace Roman Space Telescope. The Gaussian process SFH framework provides a fast, flexible implementation of physical covariance models for the next generation of spectral energy distribution modeling tools. Code to reproduce our results can be found at https://github.com/kartheikiyer/GP-SFH.

Keywords: Astrostatistics techniques, Computational methods, Spectral energy distribution, Galaxy evolution, Galaxy processes
Ultradeep ATCA Imaging of 47 Tucanae Reveals a Central Compact Radio Source. We present the results of an ultradeep radio continuum survey, containing ~480 hr of observations, of the Galactic globular cluster 47 Tucanae with the Australia Telescope Compact Array. This comprehensive coverage of the cluster allows us to reach rms noise levels of 1.19 μJy beam-1 at 5.5 GHz, 940 nJy beam-1 at 9 GHz, and 790 nJy beam-1 in a stacked 7.25 GHz image. This is the deepest radio image of a globular cluster and the deepest image ever made with the Australia Telescope Compact Array. We identify ATCA J002405.702-720452.361, a faint (6.3 ± 1.2 μJy at 5.5 GHz, 5.4 ± 0.9 μJy at 9 GHz), flat-spectrum (α = -0.31 ± 0.54) radio source that is positionally coincident with the cluster center and potentially associated with a faint X-ray source. No convincing optical counterpart was identified. We use radio, X-ray, optical, and UV data to show that explanations involving a background active galactic nucleus, a chromospherically active binary, or a binary involving a white dwarf are unlikely. The most plausible explanations are that the source is an undiscovered millisecond pulsar or a weakly accreting black hole. If the X-ray source is associated with the radio source, the fundamental plane of black-hole activity suggests a black hole mass of ~54-6000 M ☉, indicating an intermediate-mass black hole or a heavy stellar-mass black hole.

Keywords: Globular star clusters, Intermediate-mass black holes, Black holes, Millisecond pulsars, Radio astronomy
Pulsation in TESS Objects of Interest. We report the discovery of three Transiting Exoplanet Survey Satellite Objects of Interest (TOI) with signatures of pulsation, observed in more than one sector. Our main goal is to explore how large is the variety of classical pulsators such as δ Sct, γ Dor, RR Lyrae and Cepheid among TOI pulsators. The analysis reveals two stars with signatures of δ Sct and one of γ Dor, out of a sample of 3901 TOIs with available light curves (LCs). To date, there is a very scarce number of known pulsating stars hosting planets. The present finding also emerges as an exciting laboratory for studying different astrophysical phenomena, including the effects of star-planet interaction on pulsation and timing detection of planetary companions. We have also identified 16 TOI stars with periodicities and LCs morphology compatible with different classical pulsating classes, but for most of them, the dominant frequency signals originate from contaminating sources.

Keywords: Star-planet interactions, Transit photometry, Substellar companion stars, Stellar pulsations
Simulating the Detection of the Global 21 cm Signal with MIST for Different Models of the Soil and Beam Directivity. The Mapper of the IGM Spin Temperature (MIST) is a new ground-based, single-antenna, radio experiment attempting to detect the global 21 cm signal from the Dark Ages and Cosmic Dawn. A significant challenge in this measurement is the frequency dependence, or chromaticity, of the antenna beam directivity. MIST observes with the antenna above the soil and without a metal ground plane, and the beam directivity is sensitive to the electrical characteristics of the soil. In this paper, we use simulated observations with MIST to study how the detection of the global 21 cm signal from Cosmic Dawn is affected by the soil and the MIST beam directivity. We simulate observations using electromagnetic models of the directivity computed for single- and two-layer models of the soil. We test the recovery of the Cosmic Dawn signal with and without beam chromaticity correction applied to the simulated data. We find that our single-layer soil models enable a straightforward recovery of the signal even without chromaticity correction. Two-layer models increase the beam chromaticity and make the recovery more challenging. However, for the model in which the bottom soil layer has a lower electrical conductivity than the top layer, the signal can be recovered even without chromaticity correction. For the other two-layer models, chromaticity correction is necessary for the recovery of the signal, and the accuracy requirements for the soil parameters vary between models. These results will be used as a guideline to select observation sites that are favorable for the detection of the Cosmic Dawn signal.

Keywords: Population III stars, Bayesian statistics, H I line emission, Bayesian information criterion, Radio receivers, Intergalactic medium, Reionization
Jovian Electrons in the Inner Heliosphere: Opportunities for Multi-spacecraft Observations and Modeling. In this paper we explore the idea of using multi-spacecraft observations of Jovian electrons to measure the 3D distribution of these particles in the inner heliosphere. We present simulations of Jovian electron intensities along selected spacecraft trajectories for 2021 and compare these, admittedly qualitatively, to these measurements. Using the data-model comparison we emphasize how such a study can be used to constrain the transport parameters in the inner heliosphere, and how this can lead to additional insight into energetic particle transport. Model results are also shown along the expected trajectories of selected spacecraft, including the off-ecliptic phase of the Solar Orbiter mission from 2025 onward. Lastly, we revisit the use of historical data and discuss upcoming missions that may contribute to Jovian electron measurements.

Keywords: Interplanetary turbulence, Heliosphere, Cosmic rays
Mapping Observations of Peptide-like Molecules around Sagittarius B2. Peptide-like molecules, which have a close connection with the origin of life, have been detected in the Universe. Mapping observations of HCONH2 and CH3CONH2, two of the simplest peptide-like molecules, are performed toward the Sagittarius B2 (Sgr B2) complex with the IRAM 30 m telescope. Seven transitions of HCONH2 and five transitions of CH3CONH2 are used in the analysis. The spatial distributions of the excitation temperature and column density of HCONH2 in the molecular envelope of Sgr B2 are obtained by rotation diagrams. Assuming the same excitation temperature of HCONH2, the column densities of CH3CONH2 are also calculated. The results show that the excitation temperature ranges from 6 to 46 K in the molecular envelope of Sgr B2. The abundance ratios between HCONH2 and CH3CONH2 are calculated to explore the relationship between them, as are those between HCONH2 and HNCO. The abundance ratio of CH3CONH2/HCONH2 varies from 10% to 20%, while that of HCONH2/HNCO ranges from 1.5% to 10%. CH3CONH2 is enhanced with respect to HCONH2 in the northwest region of Sgr B2. One transition of H13CONH2 is detected toward 12 positions of Sgr B2, from which a 12C/13C ratio of 28.7 is obtained. A time-dependent chemical model with a short-duration X-ray burst is used to explain the observed abundances of HCONH2 and CH3CONH2, with the best-fitting result at T dust = 53-56 K. More chemical reactions are required to be included in the model since the modeled abundance is lower than the observed one at the observed T dust.

Keywords: Interstellar molecules, Isotopic abundances, Molecular clouds, Abundance ratios
Buzzard to Cardinal: Improved Mock Catalogs for Large Galaxy Surveys. We present the Cardinal mock galaxy catalogs, a new version of the Buzzard simulation that has been updated to support ongoing and future cosmological surveys, including the Dark Energy Survey (DES), DESI, and LSST. These catalogs are based on a one-quarter sky simulation populated with galaxies out to a redshift of z = 2.35 to a depth of m r = 27. Compared to the Buzzard mocks, the Cardinal mocks include an updated subhalo abundance matching model that considers orphan galaxies and includes mass-dependent scatter between galaxy luminosity and halo properties. This model can simultaneously fit galaxy clustering and group-galaxy cross-correlations measured in three different luminosity threshold samples. The Cardinal mocks also feature a new color assignment model that can simultaneously fit color-dependent galaxy clustering in three different luminosity bins. We have developed an algorithm that uses photometric data to further improve the color assignment model and have also developed a novel method to improve small-scale lensing below the ray-tracing resolution. These improvements enable the Cardinal mocks to accurately reproduce the abundance of galaxy clusters and the properties of lens galaxies in the DES data. As such, these simulations will be a valuable tool for future cosmological analyses based on large sky surveys.

Keywords: Cosmology, Galaxy dark matter halos, Large-scale structure of the universe, Galaxy evolution, N-body simulations, Dark matter
AWSoM Magnetohydrodynamic Simulation of a Solar Active Region. II. Statistical Analysis of Alfvén Wave Dissipation and Reflection, Scaling Laws, and Energy Budget on Coronal Loops. The coronal heating problem has been a major challenge in solar physics, and a tremendous amount of effort has been made over the past several decades to solve it. In this paper, we aim at answering how the physical processes behind the Alfvén wave turbulent heating adopted in the Alfvén Wave Solar atmosphere Model (AWSoM) unfold in individual plasma loops in an active region (AR). We perform comprehensive investigations in a statistical manner on the wave dissipation and reflection, temperature distribution, heating scaling laws, and energy balance along the loops, providing in-depth insights into the energy allocation in the lower solar atmosphere. We demonstrate that our 3D global model with a physics-based phenomenological formulation for the Alfvén wave turbulent heating yields a heating rate exponentially decreasing from loop footpoints to top, which had been empirically assumed in the past literature. A detailed differential emission measure (DEM) analysis of the AR is also performed, and the simulation compares favorably with DEM curves obtained from Hinode/Extreme-ultraviolet Imaging Spectrometer observations. This is the first work to examine the detailed AR energetics of our AWSoM model with high numerical resolution and further demonstrates the capabilities of low-frequency Alfvén wave turbulent heating in producing realistic plasma properties and energetics in an AR.

Keywords: Solar spectral irradiance, Solar coronal heating, Extreme ultraviolet astronomy, Solar active regions, Alfven waves, Solar magnetic fields, Magnetohydrodynamical simulations