adsabs/SciX_UAT_keywords huggingface dataset:
Laminar Flame Speeds in Degenerate Oxygen-Neon Mixtures

The collapse of degenerate oxygen-neon cores (I.e., electron-capture supernovae or accretion-induced collapse) proceeds through a phase in which a deflagration wave ("flame") forms at or near the center and propagates through the star. In models, the assumed speed of this flame influences whether this process leads to an explosion or to the formation of a neutron star. We calculate the laminar flame speeds in degenerate oxygen-neon mixtures with compositions motivated by detailed stellar evolution models. These mixtures include trace amounts of carbon and have a lower electron fraction than those considered in previous work. We find that trace carbon has little effect on the flame speeds, but that material with electron fraction Y_{e} ≈ 0.48-0.49 has laminar flame speeds that are ≈ 2 times faster than those at Y_{e}=0.5. We provide tabulated flame speeds and a corresponding fitting function so that the impact of this difference can be assessed via full star hydrodynamical simulations of the collapse process.

Keywords: white dwarf stars; degenerate matter; oxygen burning
Collisional Growth and Fragmentation of Dust Aggregates with Low Mass Ratios. I. Critical Collision Velocity for Water Ice

We investigated fundamental processes of collisional sticking and fragmentation of dust aggregates by carrying out N-body simulations of submicron-sized icy dust monomers. We examined the conditions for collisional growth of two colliding dust aggregates in a wide range of the mass ratio 1-64. We found that the mass transfer from a larger dust aggregate to a smaller one is a dominant process in collisions with a mass ratio of 2-30 and an impact velocity of ≈30-170 m s-1. As a result, the critical velocity, vfra, for fragmentation of the largest body is considerably reduced for such unequal-mass collisions; vfra of collisions with a mass ratio of 3 is about half of that obtained from equal-mass collisions. The impact velocity is generally higher for collisions between dust aggregates with higher mass ratios because of the difference between the radial drift velocities in the typical condition of protoplanetary disks (PPDs). Therefore, the reduced vfra for unequal-mass collisions would delay growth of dust grains in the inner region of PPDs.

Keywords: n-body simulations; protoplanetary disks; interstellar dust
Gnuastro: Measuring Radial Profiles from Images

Radial profiles play a crucial role in the analysis and interpretation of astronomical data, facilitating the extraction of spatial information. However, highly customizable (for different scenarios) measurements over each elliptical annulus can be challenging. In response, we present astscript-radial-profile, which is part of Gnuastro from version 0.15 and has an extensive documentation. A convenient feature of this program is its capability to make the measurements with different operators (mean, median, sigma-clipping, and many more) over ellipses, very quickly and directly on the command-line with minimal dependencies. This research note is reproducible with Maneage, on the Git commit f3ec942.

Keywords: astronomy software; astronomical techniques; astronomy data visualization; broad band photometry; open source software
Grand Design versus Multiarmed Spiral Galaxies: Dependence on Galaxy Structure

We developed an algorithm to use Galaxy Zoo 3D spiral arm masks produced by citizen scientist volunteers to semiautomatically classify spiral galaxies as either multiarmed or grand design spirals. Our final sample consists of 299 multiarmed and 245 grand design galaxies. On average, the grand design galaxies have smaller stellar masses than the multiarmed galaxies. For a given stellar mass, the grand design galaxies have larger concentrations, earlier Hubble types, smaller half-light radii, and larger central surface mass densities than the multiarmed galaxies. Lower-mass galaxies of both arm classes have later Hubble types and lower concentrations than higher-mass galaxies. In our sample, a higher fraction of grand design galaxies have classical bulges rather than pseudo-bulges, compared to multiarmed galaxies. These results are consistent with theoretical models and simulations, which suggest that dense classical bulges support the development and/or longevity of two-armed spiral patterns. Similar specific star formation rates (sSFRs) are found in multiarmed and grand design galaxies with similar stellar masses and concentrations. This implies that the sSFRs in spiral galaxies are a function of concentration and stellar mass, but independent of the number of spiral arms. Our classifications are consistent with arm counts from the Galaxy Zoo 2 project and published m = 3 Fourier amplitudes.

Keywords: disk galaxies; galaxy evolution; spiral galaxies
Variations of Heavy Ions in Interplanetary Shock Driven by Interplanetary Coronal Mass Ejections and Stream Interaction Regions

In the solar wind, the fluctuation of heavy ion abundance serves as a crucial physical metric. This not only mirrors the attributes of the solar wind's originating solar region but also signifies its influence on Earth's magnetosphere. Utilizing data from the Advanced Composition Explorer satellite, this investigation scrutinizes heavy ion variations in stream interaction region (SIR)- and interplanetary coronal mass ejection (ICME)-driven shocks. We further delineate the disparities in heavy ion fluctuations between these two types of interplanetary shocks across diverse solar activity cycles. Our findings reveal that ICME-driven shocks typically manifest elevated shock velocities and magnetic field strengths relative to their SIR-driven counterparts. Additionally, heavy ion abundance ratios, such as C6+/O4+, O7+/O6+, He/O, Si/O, and Fe/O, are consistently higher in ICME-driven shocks than in SIR-driven shocks. During varying solar activity cycles, these ratios surge postarrival of ICME-driven shocks. At solar maximum, these elevated ratios persist, whereas they revert to baseline levels swiftly during solar minimum. For SIR-driven shocks, the alteration in heavy ion abundance ratios is comparatively subdued, yet a noteworthy correlation with the solar activity cycle is evident.

Keywords: solar coronal mass ejection shocks; solar wind; abundance ratios; corotating streams
Subaru Infrared Adaptive Optics-assisted High-spatial-resolution Imaging Search for Luminous Dual Active Galactic Nuclei in Nearby Ultraluminous Infrared Galaxies

We present infrared K'-band (2.1 μm) and L'-band (3.8 μm) high-spatial-resolution (<0"3) imaging observations of 17 nearby (z < 0.17) ultraluminous infrared galaxies (ULIRGs) assisted with the adaptive optics of the Subaru Telescope. We search for compact red K' - L' color emission as the indicator of luminous active galactic nuclei (AGNs) due to AGN-heated hot dust emission. Two luminous dual AGN candidates are revealed. Combining these results with those of our previous study, we can state that the detected fraction of luminous dual AGNs in nearby ULIRGs is much less than unity (<20%), even when infrared wavelengths >2 μm are used that should be sensitive to buried AGNs due to small dust extinction effects. For ULIRGs with resolved multiple nuclear K'-band emission, we estimate the activation of supermassive black holes (SMBHs) in individual galaxy nuclei in the form of AGN luminosity normalized by SMBH mass inferred from the stellar luminosity of the host galaxy. We confirm a trend that more massive SMBHs in K'-band brighter primary galaxy nuclei are generally more active, with higher SMBH-mass-normalized AGN luminosity, than less massive SMBHs in K'-band fainter secondary galaxy nuclei, as predicted by numerical simulations of gas-rich major galaxy mergers. In two sources, the presence of even infrared-elusive extremely deeply buried AGNs is indicated by comparisons with available (sub)millimeter data. Non-synchronous SMBH activation (I.e., less activation of less massive SMBHs) and the possible presence of such infrared-elusive AGNs may be responsible for the small fraction of infrared-detected luminous dual AGNs in nearby merging ULIRGs.

Keywords: supermassive black holes; galaxy mergers; active galactic nuclei; ultraluminous infrared galaxies; near infrared astronomy
A Mechanistic Study on the Formation of Acetic Acid (CH3COOH) in Polar Interstellar Analog Ices Exploiting Photoionization Reflectron Time-of-flight Mass Spectrometry

Acetic acid (CH3COOH) is considered a key molecule in the formation of the simplest amino acid, glycine, and consequently peptides. It is ubiquitous in the interstellar medium and has been detected toward hot cores, in the coma of comets, and on the surface of the comet 67P/Churyumov-Gerasimenko by the Rosetta mission. Here we present the isomer-selective formation of acetic acid in polar ice mixtures of water/acetaldehyde upon exposure to ionizing radiation in the form of energetic electrons as a proxy for secondary electrons generated once Galactic cosmic rays pass through interstellar ices. Acetic acid is formed even at low irradiation doses of only 0.13 eV molecule-1 (deuterium oxide) and 0.29 eV molecule-1 (acetaldehyde), representing molecular cloud lifetimes of 1 × 106 yr. Isotopic substitutions reveal that the dominant formation pathway is the barrierless radical-radical recombination of acetyl (CH3CO) with hydroxyl-d1 radicals (OD), whereas oxygen insertion does not yield any detectable amounts of acetic acid. This hitherto unknown reaction pathway will influence the relative abundances of distinct C2H4O2 isomers in chemical models aiming to constrain the reaction conditions by comparing these abundances. In contrast to its formation in nonpolar model ices, the formation in this polar binary ice is isomer-selective and produces acetic acid only.

Keywords: laboratory astrophysics; interdisciplinary astronomy; chemical abundances; astrochemistry; interstellar molecules
The Pantheon+ Analysis: Evaluating Peculiar Velocity Corrections in Cosmological Analyses with Nearby Type Ia Supernovae

Separating the components of redshift due to expansion and peculiar motion in the nearby universe (z < 0.1) is critical for using Type Ia Supernovae (SNe Ia) to measure the Hubble constant (H 0) and the equation-of-state parameter of dark energy (w). Here, we study the two dominant "motions" contributing to nearby peculiar velocities: large-scale, coherent-flow (CF) motions and small-scale motions due to gravitationally associated galaxies deemed to be in a galaxy group. We use a set of 584 low-z SNe from the Pantheon+ sample, and evaluate the efficacy of corrections to these motions by measuring the improvement of SN distance residuals. We study multiple methods for modeling the large and small-scale motions and show that, while group assignments and CF corrections individually contribute to small improvements in Hubble residual scatter, the greatest improvement comes from the combination of the two (relative standard deviation of the Hubble residuals, Rel. SD, improves from 0.167 to 0.157 mag). We find the optimal flow corrections derived from various local density maps significantly reduce Hubble residuals while raising H 0 by ~0.4 km s-1 Mpc-1 as compared to using CMB redshifts, disfavoring the hypothesis that unrecognized local structure could resolve the Hubble tension. We estimate that the systematic uncertainties in cosmological parameters after optimally correcting redshifts are 0.06-0.11 km s-1 Mpc-1 in H 0 and 0.02-0.03 in w which are smaller than the statistical uncertainties for these measurements: 1.5 km s-1 Mpc-1 for H 0 and 0.04 for w.

Keywords: cosmology; cosmological parameters; hubble constant; galaxy groups; type ia supernovae
Evolved Eclipsing Binaries and the Age of the Open Cluster NGC 752

We present analyses of improved photometric and spectroscopic observations for two detached eclipsing binaries at the turnoff of the open cluster NGC 752: the 1.01 days binary DS And and the 15.53 days BD +37 410. For DS And, we find M 1 = 1.692 ± 0.004 ± 0.010M ⊙, R 1 = 2.185 ± 0.004 ± 0.008R ⊙, M 2 = 1.184 ± 0.001 ± 0.003M ⊙, and R 2 = 1.200 ± 0.003 ± 0.005R ⊙. We either confirm or newly identify unusual characteristics of both stars in the binary: the primary star is found to be slightly hotter than the main-sequence turnoff and there is a more substantial discrepancy in its luminosity compared to models (model luminosities are too large by about 40%), while the secondary star is oversized and cooler compared to other main-sequence stars in the same cluster. The evidence points to nonstandard evolution for both stars, but most plausible paths cannot explain the low luminosity of the primary star. BD +37 410 only has one eclipse per cycle, but extensive spectroscopic observations and the Transiting Exoplanet Survey Satellite light curve constrain the stellar masses well: M 1 = 1.717 ± 0.011M ⊙ and M 2 = 1.175 ± 0.005M ⊙. The radius of the main-sequence primary star near 2.9R ⊙ definitively requires large convective core overshooting (>0.2 pressure scale heights) in models for its mass, and multiple lines of evidence point toward an age of 1.61 ± 0.03 ± 0.05 Gyr (statistical and systematic uncertainties). Because NGC 752 is currently undergoing the transition from nondegenerate to degenerate He ignition of its red clump stars, BD +37 410 A directly constrains the star mass where this transition occurs. * Based on observations made with with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen.

Keywords: eclipsing binary stars; spectroscopic binary stars; open star clusters; low mass stars; stellar ages; stellar physics
Connecting Infrared Surface Brightness Fluctuation Distances to Type Ia Supernova Hosts: Testing the Top Rung of the Distance Ladder

We compare infrared surface brightness fluctuation (IR SBF) distances measured in galaxies that have hosted type Ia supernovae (SNe Ia) to distances estimated from SNe Ia light-curve fits. We show that the properties of the SNe Ia found in IR SBF hosts are very different from those exploding in Cepheid calibrators, therefore this is a direct test of systematic uncertainties on the estimation of the Hubble constant (H 0) using SNe. The IR SBF results from Jensen et al. provide a large and uniformly measured sample of IR SBF distances which we directly compare with the distances to 25 SN Ia host galaxies. We divide the Hubble flow SNe Ia into subsamples that best match the divergent SN properties seen in the IR SBF hosts and Cepheid hosts. We further divide the SNe Ia into a sample with light-curve widths and host masses that are congruent to those found in the SBF-calibrated hosts. We refit the light-curve stretch and color correlations with luminosity, and use these revised parameters to calibrate a sample of "Hubble flow" SNe Ia with IR SBF calibrators. Relative to the Hubble flow sample, the average calibrator distance moduli vary by 0.03 mag depending on the SN Ia subsample examined and this adds a 1.8% systematic uncertainty to our Hubble constant estimate. Based on the IRSBF calibrators, H 0 = 74.6 ± 0.9(stat) ± 2.7(syst) km s-1 Mpc-1, which is consistent with the Hubble constant derived from SNe Ia calibrated from Cepheid variables. We conclude that IR SBFs provide reliable calibration of SNe Ia with a precision comparable to Cepheid calibrators, and with a significant saving in telescope time.

Keywords: cosmological parameters; hubble constant; type ia supernovae; distance indicators
First Sagittarius A* Event Horizon Telescope Results. VIII. Physical Interpretation of the Polarized Ring

In a companion paper, we present the first spatially resolved polarized image of Sagittarius A* on event horizon scales, captured using the Event Horizon Telescope, a global very long baseline interferometric array operating at a wavelength of 1.3 mm. Here we interpret this image using both simple analytic models and numerical general relativistic magnetohydrodynamic (GRMHD) simulations. The large spatially resolved linear polarization fraction (24%–28%, peaking at ∼40%) is the most stringent constraint on parameter space, disfavoring models that are too Faraday depolarized. Similar to our studies of M87*, polarimetric constraints reinforce a preference for GRMHD models with dynamically important magnetic fields. Although the spiral morphology of the polarization pattern is known to constrain the spin and inclination angle, the time-variable rotation measure (RM) of Sgr A* (equivalent to ≈46° ± 12° rotation at 228 GHz) limits its present utility as a constraint. If we attribute the RM to internal Faraday rotation, then the motion of accreting material is inferred to be counterclockwise, contrary to inferences based on historical polarized flares, and no model satisfies all polarimetric and total intensity constraints. On the other hand, if we attribute the mean RM to an external Faraday screen, then the motion of accreting material is inferred to be clockwise, and one model passes all applied total intensity and polarimetric constraints: a model with strong magnetic fields, a spin parameter of 0.94, and an inclination of 150°. We discuss how future 345 GHz and dynamical imaging will mitigate our present uncertainties and provide additional constraints on the black hole and its accretion flow.

Keywords: black holes; supermassive black holes; black hole physics; galactic center; radio interferometry; polarimetry; magnetohydrodynamics
COSMOS2020: Discovery of a Protocluster of Massive Quiescent Galaxies at z = 2.77

Protoclusters of galaxies have been found in the last quarter-century. However, most of them have been found through the overdensity of star-forming galaxies, and there have been no known structures identified by more than two spectroscopically confirmed quiescent galaxies at z > 2.5. In this letter, we report the discovery of an overdense structure of massive quiescent galaxies with the spectroscopic redshift z = 2.77 in the COSMOS field, QO-1000. We first photometrically identify this structure as a 4.2σ overdensity with 14 quiescent galaxies in 7 × 4 pMpc2 from the COSMOS2020 catalog. We then securely confirm the spectroscopic redshifts of four quiescent galaxies by detecting multiple Balmer absorption lines with Keck/MOSFIRE. All the spectroscopically confirmed members are massive ( $\mathrm{log}({M}_{\star }/{M}_{\odot })\gt 11.0$ ) and located in a narrow redshift range (2.76 < z < 2.79). Moreover, three of them are in the 1 × 1 pMpc2 in the transverse direction at the same redshift (z = 2.760-2.763). Such a concentration of four spectroscopically confirmed quiescent galaxies implies that QO-1000 is >68 times denser than the general field. In addition, we confirm that they form a red sequence in the J - K s color. This structure's halo mass is estimated as $\mathrm{log}({M}_{\mathrm{halo}}/{M}_{\odot })\gt 13.2$ from its stellar mass. Similar structures found in the IllustrisTNG simulation are expected to evolve into massive galaxy clusters with $\mathrm{log}({M}_{\mathrm{halo}}/{M}_{\odot })\geqslant 14.8$ at z = 0. These results suggest that QO-1000 is a more mature protocluster than the other known protoclusters. It is likely in a transition phase between star-forming protoclusters and quenched galaxy clusters.

Keywords: galaxy evolution; high-redshift galaxy clusters; galaxy environments; galaxy quenching; quenched galaxies
Generation of Solenoidal Modes and Magnetic Fields in Turbulence Driven by Compressive Driving

We perform numerical simulations of hydrodynamic (HD) and magnetohydrodynamic (MHD) turbulence driven by compressive driving, to study the generation of solenoidal velocity components and the small-scale magnetic field. We mainly focus on the effects of mean magnetic field (B0) and the sonic Mach number (Ms). The dependence of solenoidal ratio (I.e., ratio of solenoidal to kinetic energies) and magnetic energy density on Ms in compressively driven turbulence is already established, but that on B0 is not yet. We also consider two different driving schemes in terms of the correlation timescale of forcing vectors: a finite-correlated driving and a delta-correlated driving. Our findings are as follows. First, when we fix the value of B0, the solenoidal ratio after saturation increases as ${M}_{s}$ increases. A similar trend is observed for generation of magnetic field when B0 is small. Second, when we fix the value of ${M}_{s}$ , HD and MHD simulations result in similar solenoidal ratios when B0 is not strong (say, MA ≳ 5, where MA is Alfvén Mach number). However, the ratio increases when MA ≲ 5. Roughly speaking, the magnetic energy density after saturation is a linearly increasing function of B0 irrespective of Ms. Third, generation of the solenoidal velocity component is not sensitive to numerical resolution, but that of magnetic energy density is mildly sensitive. Finally, when initial conditions are same, the finite-correlated driving always produces more solenoidal velocity and small-scale magnetic field components than the delta-correlated driving. We additionally analyze the vorticity equation to understand why higher ${M}_{s}$ and B0 yield a larger quantity of the solenoidal velocity component.

Keywords: magnetohydrodynamics; interplanetary turbulence; interstellar medium; interstellar magnetic fields; magnetohydrodynamical simulations; intracluster medium
Evolution of the Gas Density in a Simulated Star-forming Cloud with Stellar Feedback

Star formation involves gravity, turbulence, magnetic fields, and feedback from new stars through jets, radiation and winds. The evolution of the density probability distribution function (ρ-PDF) is directly related to the star formation rate (SFR), forming the basis of several star formation models. We utilize two runs from the STARFORGE simulation suite that follow the evolution of molecular clouds, while resolving individual stars and including all gas and feedback physics. The two runs have different initial conditions, one is a periodic box with driven turbulence (Box), while the other is an isolated cloud without turbulent driving (Sphere). We find that the ρ-PDF for both runs is initially well-fit by a log-normal (LN) plus a power-law (PL) function. However, as the SFR peaks, the PDF for the Sphere run becomes well-fit by just a wide LN. Conversely, the Box run PDF remains well-fit by a LN+PL function for the entirety of the run.

Keywords: computational astronomy; star formation; interstellar medium; interstellar clouds
X-Ray Photoabsorption of Density-sensitive Metastable States in Ne VII, Fe XXII, and Fe XXIII

Metastable states of ions can be sufficiently populated in absorbing and emitting astrophysical media, enabling spectroscopic plasma-density diagnostics. Long-lived states appear in many isoelectronic sequences with an even number of electrons, and can be fed at large rates by various photonic and electronic mechanisms. Here, we experimentally investigate beryllium-like and carbon-like ions of neon and iron that have been predicted to exhibit detectable features in astrophysical soft X-ray absorption spectra. An ion population generated and excited by electron impact is subjected to highly monochromatic X-rays from a synchrotron beamline, allowing us to identify Kα transitions from metastable states. We compare their energies and natural line widths with state-of-the-art theory and benchmark level population calculations at electron densities of 1010.5 cm-3.

Keywords: atomic physics; plasma astrophysics; spectroscopy; laboratory astrophysics; ionization; line positions; line intensities; atomic data benchmarking