cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Vortex creation, annihilation and nonlinear dynamics in atomic vapors
Creators: name: Azam, P.
name: Griffin, A.
name: Nazarenko, S.
name: Kaiser, R.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: We exploit new techniques for generating vortices and controlling their interactions in an optical beam in a nonlinear atomic vapor. A precise control of the vortex positions allows us to observe strong interactions leading to vortex dynamics involving annihilations. With this improved controlled nonlinear system, we get closer to the pure hydrodynamic regime than in previous experiments while a wavefront sensor offers us a direct access to the fluid's density and velocity. Finally, we developed a relative phase shift method which mimics a time evolution process without changing non-linear parameters. These observations are an important step toward the experimental implementation of 2D turbulent state
description: 6 pages, 6 figures
TOI-1670 b and c: An Inner Sub-Neptune with an Outer Warm Jupiter Unlikely to have Originated from High-Eccentricity Migration
Creators: name: Tran, Quang H.
name: Bowler, Brendan P.
name: Endl, Michael
name: Cochran, William D.
name: MacQueen, Phillip J.
name: Gandolfi, Davide
name: Persson, Carina M.
name: Fridlund, Malcolm
name: Palle, Enric
name: Nowak, Grzegorz
name: Deeg, Hans J.
name: Luque, Rafael
name: Livingston, John H.
name: Kabáth, Petr
name: Skarka, Marek
name: Šubjak, Ján
name: Howell, Steve B.
name: Albrecht, Simon H.
name: Collins, Karen A.
name: Esposito, Massimiliano
name: Van Eylen, Vincent
name: Grziwa, Sascha
name: Goffo, Elisa
name: Huang, Chelsea X.
name: Jenkins, Jon M.
name: Karjalainen, Marie
name: Karjalainen, Raine
name: Knudstrup, Emil
name: Korth, Judith
name: Lam, Kristine W. F.
name: Latham, David W.
name: Levine, Alan M.
name: Osborne, H. L. M.
name: Quinn, Samuel N.
name: Redfield, Seth
name: Ricker, George R.
name: Seager, S.
name: Serrano, Luisa Maria
name: Smith, Alexis M. S.
name: Twicken, Joseph D.
name: Winn, Joshua N.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: We report the discovery of two transiting planets around the bright ($V=9.9$ mag) main sequence F7 star TOI-1670 by the Transiting Exoplanet Survey Satellite. TOI-1670 b is a sub-Neptune ($R_\mathrm{b} = 2.06_{-0.15}^{+0.19}$ $R_\oplus$) on a 10.9-day orbit and TOI-1670 c is a warm Jupiter ($R_\mathrm{c} = 0.987_{-0.025}^{+0.025}$ $R_\mathrm{Jup}$) on a 40.7-day orbit. Using radial velocity observations gathered with the Tull coudé Spectrograph on the Harlan J. Smith telescope and HARPS-N on the Telescopio Nazionale Galileo, we find a planet mass of $M_\mathrm{c} = 0.63_{-0.08}^{+0.09}$ $M_\mathrm{Jup}$ for the outer warm Jupiter, implying a mean density of $ρ_c = 0.81_{-0.11}^{+0.13}$ g cm$^{-3}$. The inner sub-Neptune is undetected in our radial velocity data ($M_\mathrm{b} < 0.13$ $M_\mathrm{Jup}$ at the 99% confidence level). Multi-planet systems like TOI-1670 hosting an outer warm Jupiter on a nearly circular orbit ($e_\mathrm{c} = 0.09_{-0.04}^{+0.05}$) and one or more inner coplanar planets are more consistent with "gentle" formation mechanisms such as disk migration or $in$ $situ$ formation rather than high-eccentricity migration. Of the 11 known systems with a warm Jupiter and a smaller inner companion, 8 (73%) are near a low-order mean-motion resonance, which can be a signature of migration. TOI-1670 joins two other systems (27% of this subsample) with period commensurabilities greater than 3, a common feature of $in$ $situ$ formation or halted inward migration. TOI-1670 and the handful of similar systems support a diversity of formation pathways for warm Jupiters.
description: 23 pages, 9 figures, accepted for publication in AJ
The Extended Tidal Tails of NGC 7089 (M2)
Creators: name: Grillmair, Carl J.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Using photometry and proper motions from Gaia Early Data Release 3, we detect a 45 degree-long trailing stellar debris stream associated with the old, metal-poor globular cluster NGC 7089. With a width on the order of 100 pc, the extended stream appears to be as dynamically cold as the coldest known streams found to date. There is some evidence for an extended leading tail extending between 28 and 37 degrees from the cluster, though the greater distance of this tail, combined with proper motions that are virtually indistinguishable from those of foreground stars, make the detection much less certain. The proper motion profile and the path on the sky of the trailing tail are not well matched using a simple Galactic potential comprised purely of a disk, bulge, and spherical halo. However, the addition of a moving, massive (M = 1.88 x 10^(11) solar masses) Large Magellanic Cloud brings the model predictions into much better agreement with the observables. We provide tables of the most highly ranked candidate stream stars for follow-up by ongoing and future spectroscopic surveys.
description: 12 pages, 5 figures, 2 tables, accepted for publication in the Astrophysical Journal
The little robot, black holes, and spaghettification
Creators: name: Pinochet, Jorge
Publisher: name: arXiv
Year: 2022
Subjects: subject: Popular Physics (physics.pop-ph)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: The tidal forces generated by a black hole can be so powerful that they cause unlimited stretching, known as spaghettification. A detailed analysis of this phenomenon requires the use of Einstein's theory of general relativity. The aim of this paper is to offer an up-to-date and accessible analysis of spaghettification, in which the complex mathematics of Einstein's theory are replaced with the simpler and more intuitive concepts of Newtonian gravity. The article can serve as educational material for undergraduate modern physics or astronomy courses.
description: 10 pages, 9 figures
Abundance of LIGO/Virgo Black Holes from Microlensing Observations of Quasars with Reverberation Mapping Size Estimates
Creators: name: Esteban-Gutiérrez, A.
name: Mediavilla, E.
name: Jiménez-Vicente, J.
name: Agües-Paszkowsky, N.
name: Muñoz, J. A.
name: Heydenreich, S.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: Assuming a population of Black Holes (BHs) with masses in the range inferred by LIGO/Virgo from BH mergers, we use quasar microlensing observations to estimate their abundances. We consider a mixed population of stars and BHs and the presence of a smooth dark matter component. We adopt reverberation mapping estimates of the quasar size. According to a Bayesian analysis of the measured microlensing magnifications, a population of BHs with masses $\sim$ 30$M_{\odot}$ constitutes less than 0.4 % of the total matter at 68 % confidence level (less than 0.9 % at 90 % confidence). We have explored the whole mass range of LIGO/Virgo BHs finding that this upper limit ranges from 0.5 % to 0.4 % at 68 % C.L. (from 1.1 % to 0.9 % at 90 % C.L.) when the BHs mass change from 10 to 60$M_{\odot}$. We estimate a 16 % contribution from the stars, in agreement with previous studies based on a single mass population that do not consider explicitly the presence of BHs. These results are consistent with the estimates of BH abundances from the statistics of LIGO/Virgo mergers and rule out that PBHs (or any type of compact objects), in this mass range constitute a significant fraction of the dark matter.
description: 14 pages, 5 figures, 1 table
Surface Brightness Profile of Lyman-$α$ Halos out to 320 kpc in HETDEX
Creators: name: Niemeyer, Maja Lujan
name: Komatsu, Eiichiro
name: Byrohl, Chris
name: Davis, Dustin
name: Fabricius, Maximilian
name: Gebhardt, Karl
name: Hill, Gary J.
name: Wisotzki, Lutz
name: Bowman, William P.
name: Ciardullo, Robin
name: Farrow, Daniel J.
name: Finkelstein, Steven L.
name: Gawiser, Eric
name: Gronwall, Caryl
name: Jeong, Donghui
name: Landriau, Martin
name: Liu, Chenxu
name: Cooper, Erin Mentuch
name: Ouchi, Masami
name: Schneider, Donald P.
name: Zeimann, Gregory R.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We present the median-stacked Lyman-$α$ surface brightness profile of 968 spectroscopically selected Lyman-$α$ emitting galaxies (LAEs) at redshifts $1.980\,\mathrm{kpc}$, our profile is flatter than the MUSE model. The measured profile agrees at most radii with that of galaxies in the Byrohl et al. (2021) cosmological radiative transfer simulation at $z=3$. This suggests that the surface brightness of a Lyman-$α$ halo at $r\lesssim 100$ kpc is dominated by resonant scattering of Lyman-$α$ photons from star-forming regions in the central galaxy, whereas at $r > 100$ kpc it is dominated by photons from galaxies in surrounding dark matter halos.
description: 15 pages, 7 figures, accepted by The Astrophysical Journal
The interplay between structural, magnetic and electronic states in the pyrochlore iridate Eu2Ir2O7
Creators: name: Das, Manjil
name: Bhowal, Sayantika
name: Sannigrahi, Jhuma
name: Bandyopadhyay, Abhisek
name: Banerjee, Anupam
name: Cibin, Giannantonio
name: Khalyavin, Dmitry
name: Banerjee, Niladri
name: Adroja, Devashibhai
name: Dasgupta, Indra
name: Majumdar, Subham
Publisher: name: arXiv
Year: 2022
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We address the concomitant metal-insulator transition (MIT) and antiferromagnetic ordering in the novel pyrochlore iridate Eu2Ir2O7 by combining x-ray absorption spectroscopy, x-ray and neutron diffractions and density functional theory (DFT) based calculations. The temperature dependent powder x-ray diffraction clearly rules out any change in the lattice symmetry below the MIT, nevertheless a clear anomaly in the Ir-O-Ir bond angle and Ir-O bond length is evident at the onset of MIT. From the x-ray absorption near edge structure (XANES) spectroscopic study of Ir-L3 and L2 edges, the effective spin-orbit coupling is found to be intermediate, at least quite far from the strong atomic spin-orbit coupling limit. Powder neutron diffraction measurement is in line with an all-in-all-out magnetic structure of the Ir-tetrahedra in this compound, which is quite common among rare-earth pyrochlore iridates. The sharp change in the Ir-O-Ir bond angle around the MIT possibly arises from the exchange striction mechanism, which favors an enhanced electron correlation via weakening of Ir-Ir orbital overlap and an insulating phase below TMI . The theoretical calculations indicate an insulating state for shorter bond angle validating the experimental observation. Our DFT calculations show a possibility of intriguing topological phase below a critical value of the Ir-O distance, which is shorter than the experimentally observed bond length. Therefore, a topological state may be realized in bulk Eu2Ir2O7 sample if the Ir-O bond length can be reduced by the application of sufficient external pressure.
description: 14 pages, 10 figures
A Comparative Analysis To Deal With Missing Spectral Information Caused By RFI In Cosmological HI 21CM Observations
Creators: name: Chakraborty, Arnab
name: Datta, Abhirup
name: Mazumder, Aishrila
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We investigate the effect of radio-frequency interference (RFI) excision in estimating the cosmological \hi\ 21 cm power spectrum. Flagging of RFI-contaminated channels results in a non-uniform sampling of the instrumental bandpass response. Hence, the Fourier transformation (FT) of visibilities from frequency to delay domain contaminates the higher foreground-free delay modes, and separating the spectrally fluctuating \hi\ signal from spectrally smooth foregrounds becomes challenging. We have done a comparative analysis between two algorithms, one-dimensional CLEAN and Least Square Spectral Analysis (LSSA), which have been used widely to solve this issue in the literature. We test these algorithms using the simulated SKA-1 low observations in the presence of different RFI flagging scenarios. We find that in the presence of random flagging of data, both algorithms perform well and can mitigate the foreground leakage issue. But, CLEAN fails to restrict the foreground leakage in the presence of periodic and periodic plus broadband RFI flagging and gives an extra bias to the estimated power spectrum. However, LSSA can restrict the foreground leakage for these RFI flagging scenarios and gives an unbiased estimate of the \hi\ 21 cm power spectrum. We have also applied these algorithms to the upgraded GMRT observation and found that both CLEAN and LSSA give consistent results in the presence of realistic random flagging scenarios for this observed data set. This comparative analysis demonstrates the effectiveness and robustness of these two algorithms in estimating the \hi\ 21 cm power spectrum from the data set affected by different RFI scenarios.
description: accepted for publication in APJ
A new goatfish of the genus Upeneus (Mullidae) from Australia and Vanuatu, with inter- and intraspecific comparisons
Creators: name: Uiblein, Franz
name: Gledhill, Daniel C.
Publisher: name: Taylor & Francis
Year: 2015
Subjects: subject: Biological Sciences
subject: Ecology
subject: FOS: Biological sciences
subject: Earth and Environmental Sciences
subject: Evolutionary Biology

description: A new goatfish, Upeneus torres sp. nov. (Mullidae), is described based on 27 specimens from Australia and Vanuatu using a diversified alpha-taxonomy approach that integrates species, population and size-related allometric differences. Based on large sets of comparative morphological and colour data, diagnoses and inter- and intraspecific comparisons are provided for similar and/or co-occurring species of the so-called japonicus species group, Upeneus torres sp. nov., U. australiae, U. guttatus, and U. japonicus. The new species can be distinguished from all congeneric species by the following combination of characters: seven spines in the first dorsal fin; 13–15 (typically 14) pectoral-fin rays, 22–25 total gill rakers, barbel length 24–28 %SL, and pectoral-fin length 24–26 %SL. Fish smaller than 65 mm SL (‘subadults’) of the new species differ from larger conspecifics (‘adults’) in shallower body, larger eyes, longer anal-fin base, and longer caudal fin. Similar size-related differences were also found for the three other species. Phenotypic population differences in the new species as well as in U. guttatus are reported that may reflect character displacement in the latter. The need to study size–depth–habitat relationships in more detail, the phylogeography of individual populations, and the overall diversity of the genus Upeneus from Australian waters is discussed.http://zoobank.org/urn:lsid:zoobank.org:pub:6F5C9E39-08DE-4183-A98A-3E11B8993C97
Parameter-Estimation Biases for Eccentric Supermassive Binary Black Holes in Pulsar Timing Arrays: Biases Caused by Ignored Pulsar Terms
Creators: name: Chen, Jie-Wen
name: Wang, Yan
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: The continuous nanohertz gravitational waves (GWs) from individual supermassive binary black holes (SMBBHs) can be encoded in the timing residuals of pulsar timing arrays (PTAs). For each pulsar, the residuals actually contain an Earth term and a pulsar term, but usually only the Earth term is considered as signal and the pulsar term is dropped, which leads to parameter-estimation biases (PEBs) for the SMBBHs, and currently there are no convenient evaluations of the PEBs. In this article, we formulate the PEBs for a SMBBH with an eccentric orbit. In our analyses, the unknown phases of pulsar terms are treated as random variables obeying the uniform distribution $U[0,2π)$, due to the fact that pulsar distances are generally poorly measured. Our analytical results are in accordance with the numerical work by Zhu et. al. (2016) at $1.5σ$ level, implying that our formulae are effective in estimating magnitudes of the PEBs. Additionally, we find that for two parameters -- Earth term phase $φ^E$ and orbital eccentricity $e$, their biases $Δφ^E$ and $Δe/e$ monotonically decrease as $e$ increases, which partly confirms a hypothesis in our previous work Chen & Zhang (2018). Furthermore, we also calculate the PEBs caused by the recently observed common-spectrum process (CSP), finding that if the strain amplitude of the continuous GW is significantly stronger ($3$ times larger, in our cases) than the stochastic GW background, the PEBs from pulsar terms are larger than those from the CSP. Our formulae of the PEBs can be conveniently applied in the future PTA data analyses.
description: 29 pages, 4 figure, accepted by ApJ
New constraints on the neutron-star mass and radius relation from terrestrial nuclear experiments
Creators: name: Sotani, Hajime
name: Nishimura, Nobuya
name: Naito, Tomoya
Publisher: name: arXiv
Year: 2022
Subjects: subject: Nuclear Theory (nucl-th)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: The determination of the equation of state (EOS) for nuclear matter has been one of the biggest problems in nuclear astrophysics, because the EOS is essential for determining the properties of neutron stars. To constrain the density-dependence of the nuclear symmetry energy, several nuclear experiments, e.g., reported by the S$π$RIT and PREX-II collaborations, have recently been performed. However, since their uncertainties are still large, additional constraints such as astronomical observations must be crucial. In addition, it is interesting to see the effect of their reported value on neutron star properties. In this study, focusing on the relatively lower density region, we investigate the allowed area of the neutron-star mass and radius relation by assuming the constraints from S$π$RIT and PREX-II. Each region predicted by these experiments is still consistent with the allowed area constrained by the various astronomical observations. Our results show that terrestrial nuclear experiments must provide further constraints on the EOS for neutron stars, complementing astronomical observations.
description: 10 pages, 2 figures, accepted in PTEP
Photometric Signature of Ultra-Harmonic Resonances in Barred Galaxies
Creators: name: Krishnarao, Dhanesh
name: Pace, Zachary J.
name: D'Onghia, Elena
name: Aguerri, Alfonso L.
name: McClure, Rachel L.
name: Peterken, Thomas
name: Fernandez-Trincado, Jose G.
name: Merrifield, Michael
name: Masters, Karen L.
name: Garma-Oehmichen, Luis
name: Boardman, Nicholas Fraser
name: Bershady, Matthew
name: Drory, Niv
name: Lane, Richard R.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Bars may induce morphological features, such as rings, through their resonances. Previous studies suggested that the presence of 'dark-gaps', or regions of a galaxy where the difference between the surface brightness along the bar major axis and along the bar minor axis are maximal, can be attributed to the location of bar corotation. Here, using GALAKOS, a high-resolution N-body simulation of a barred galaxy, we test this photometric method's ability to identify the bar corotation resonance. Contrary to previous work, our results indicate that 'dark-gaps' are a clear sign of the location of the 4:1 ultra-harmonic resonance instead of bar corotation. Measurements of the bar corotation can indirectly be inferred using kinematic information, e.g., by measuring the shape of the rotation curve. We demonstrate our concept on a sample of 578 face-on barred galaxies with both imaging and integral field observations and find the sample likely consists primarily of fast bars.
description: 16 pages, 14 figures, Accepted for publication in ApJ
Carbon Abundances in Compact Galactic Planetary Nebulae: An Ultraviolet spectroscopic study with the Space Telescope Imaging Spectrograph (STIS)
Creators: name: Stanghellini, Letizia
name: Bushra, Rafia
name: Shaw, Richard A.
name: dell'Agli, Flavia
name: Garcia-Hernandez, D. A.
name: Ventura, Paolo
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We surveyed a sample of compact Galactic planetary nebulae (PNe) with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope (HST/STIS) to determine their gas-phase carbon abundances. Carbon abundances in PNe constrain the nature of their asymptotic giant branch (AGB) progenitors, as well as cosmic recycling. We measured carbon abundances, or limits thereof, of 11 compact Galactic PNe, notably increasing the sample of Galactic PNe whose carbon abundance based on HST ultraviolet spectra is available. Dust content of most targets has been studied elsewhere from Spitzer spectroscopy; given the compact nature of the nebulae, both UV and IR spectra can be directly compared to study gas- and dust-phase carbon. We found that carbon-poor (C/O<1) compact Galactic PNe have oxygen-rich dust type (ORD), while their carbon-enhanced counterparts (C/O>1) have carbon-rich dust (CRD), confirming the correlation between gas- and dust-phase carbon content which was known for Magellanic Cloud PNe. Based on models of expected final yields from AGB evolution we interpret the majority of the carbon-poor PNe in this study as the progeny of ~1.1-1.2 M$_{\odot}$ stars that experienced some extra-mixing on the red giant branch (RGB), they went through the AGB but did not go through the carbon star phase. Most PNe in this group have bipolar morphology, possibly due to the presence of a sub-solar companion. Carbon-enhanced PNe in our sample could be the progeny of stars in the ~1.5-2.5 M$_{\odot}$ range, depending on their original metallicity.
description: The Astrophysical Journal, in press
Comparing Implementations of Self-Interacting Dark Matter in the Gizmo and Arepo Codes
Creators: name: Meskhidze, Helen
name: Mercado, Francisco J.
name: Sameie, Omid
name: Robles, Victor H.
name: Bullock, James S.
name: Kaplinghat, Manoj
name: Weatherall, James O.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Self-interacting dark matter (SIDM) models have received great attention over the past decade as solutions to the small-scale puzzles of astrophysics. Though there are different implementations of dark matter (DM) self-interactions in N-body codes of structure formation, there has not been a systematic study to compare the predictions of these different implementations. We investigate the implementation of dark matter self-interactions in two simulation codes: Gizmo and Arepo. We begin with identical initial conditions for an isolated $10^{10}$ M$_\odot$ dark matter halo and investigate the evolution of the density and velocity dispersion profiles in Gizmo and Arepo for SIDM cross-section over mass of 1, 5, and 50 $\rm cm^2 g^{-1}$. Our tests are restricted to the core expansion phase where the core density decreases and core radius increases with time. We find better than 30% agreement between the codes for the density profile in this phase of evolution, with the agreement improving at higher resolution. We find that varying code-specific SIDM parameters changes the central halo density by less than 10% outside of the convergence radius. We argue that SIDM core formation is robust across the two different schemes and conclude that these codes can reliably differentiate between cross-sections of 1, 5, and 50 $\rm cm^2 g^{-1}$ but finer distinctions would require further investigation.
Ages of Main-Sequence Turn-Off Stars from the GALAH Survey
Creators: name: Chen, Xunzhou
name: Ge, Zhishuai
name: Chen, Yuqin
name: Bi, Shaolan
name: Yu, Jie
name: Yang, Wuming
name: Ferguson, Jason W.
name: Wu, Yaqian
name: Li, Yaguang
Publisher: name: arXiv
Year: 2022
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Main sequence turn-off (MSTO) stars are good tracers of Galactic populations since their ages can be reliably estimated from atmospheric parameters. Based on the GALAH survey, we use the Yale Rotation Evolution Code to determine ages of 2926 MSTO stars with mean age uncertainty $\sim$10\% considering the variation of C and O abundances. Ages of CO-poor stars are systematically affected by $\sim$10\% due to the C and O abundances, globally shifting to $\sim$0.5 Gyr older compared to the results using solar metal-mixture. Of the stars with \mbox{[Fe/H] $\sim$0.3-0.5} or \mbox{[O/Fe]~$\leq$~-0.25}, many have fractional age differences~$\geq$~20\%, and even reach up to 36\%. The age-metallicity relation appears to possibly exist two distinct sequences: a young sequence of stars with age mostly $$ 7 Gyr, overlapping at 5 Gyr $\leq$~age~$\leq$ 7 Gyr. Moreover, the trends of abundances to age ratios show two corresponding sequences, especially in [O/Fe]-age plane. We also find that [Y/Mg] is a good chemical clock in disk populations. The young sequence and the old sequence can not be separated based on chemistry or kinematics, therefore stellar age is an important parameter to distinguish these two sequences in our sample.
description: 15 pages, 13 figures, accepted for publication in ApJ
SolO/EUI Observations of Ubiquitous Fine-scale Bright Dots in an Emerging Flux Region: Comparison with a Bifrost MHD Simulation
Creators: name: Tiwari, Sanjiv K.
name: Hansteen, Viggo H.
name: De Pontieu, Bart
name: Panesar, Navdeep K.
name: Berghmans, David
Publisher: name: arXiv
Year: 2022
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We report on the presence of numerous tiny bright dots in and around an emerging flux region (an X-ray/coronal bright point) observed with SolO's EUI/\hri\ in 174 Å. These dots are roundish, have a diameter of 675$\pm$300 km, a lifetime of 50$\pm$35 seconds, and an intensity enhancement of 30\% $\pm$10\% above their immediate surroundings. About half of the dots remain isolated during their evolution and move randomly and slowly ($
description: 28 pages, 17 figues; accepted for publication in ApJ
Effects of an Immortal Stellar Population in AGN Disks
Creators: name: Jermyn, Adam S.
name: Dittmann, Alexander J.
name: McKernan, B.
name: Ford, K. E. S.
name: Cantiello, Matteo
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Stars are likely embedded in the gas disks of Active Galactic Nuclei (AGN). Theoretical models predict that in the inner regions of the disk these stars accrete rapidly, with fresh gas replenishing hydrogen in their cores faster than it is burned into helium, effectively stalling their evolution at hydrogen burning. We produce order-of-magnitude estimates of the number of such stars in a fiducial AGN disk. We find numbers of order $10^{2-4}$, confined to the inner $r_{\rm cap} \sim 3000 r_s \sim 0.03\rm pc$. These stars can profoundly alter the chemistry of AGN disks, enriching them in helium and depleting them in hydrogen, both by order-unity amounts. We further consider mergers between these stars and other disk objects, suggesting that star-star mergers result in rapid mass loss from the remnant to restore an equilibrium mass, while star-compact object mergers may result in exotic outcomes and even host binary black hole mergers within themselves. Finally, we examine how these stars react as the disk dissipates towards the end of its life, and find that they may return mass to the disk fast enough to extend its lifetime by a factor of several and/or may drive powerful outflows from the disk. Post-AGN, these stars rapidly lose mass and form a population of stellar mass black holes around $10M_{\odot}$. Due to the complex and uncertain interactions between embedded stars and the disk, their plausible ubiquity, and their order unity impact on disk structure and evolution, they must be included in realistic disk models.
description: 12 pages, 2 figures. Accepted in ApJ
A new goatfish of the genus Upeneus (Mullidae) from Australia and Vanuatu, with inter- and intraspecific comparisons
Creators: name: Uiblein, Franz
name: Gledhill, Daniel C.
Publisher: name: Taylor & Francis
Year: 2015
Subjects: subject: Biological Sciences
subject: Ecology
subject: FOS: Biological sciences
subject: Earth and Environmental Sciences
subject: Evolutionary Biology

description: A new goatfish, Upeneus torres sp. nov. (Mullidae), is described based on 27 specimens from Australia and Vanuatu using a diversified alpha-taxonomy approach that integrates species, population and size-related allometric differences. Based on large sets of comparative morphological and colour data, diagnoses and inter- and intraspecific comparisons are provided for similar and/or co-occurring species of the so-called japonicus species group, Upeneus torres sp. nov., U. australiae, U. guttatus, and U. japonicus. The new species can be distinguished from all congeneric species by the following combination of characters: seven spines in the first dorsal fin; 13–15 (typically 14) pectoral-fin rays, 22–25 total gill rakers, barbel length 24–28 %SL, and pectoral-fin length 24–26 %SL. Fish smaller than 65 mm SL (‘subadults’) of the new species differ from larger conspecifics (‘adults’) in shallower body, larger eyes, longer anal-fin base, and longer caudal fin. Similar size-related differences were also found for the three other species. Phenotypic population differences in the new species as well as in U. guttatus are reported that may reflect character displacement in the latter. The need to study size–depth–habitat relationships in more detail, the phylogeography of individual populations, and the overall diversity of the genus Upeneus from Australian waters is discussed.http://zoobank.org/urn:lsid:zoobank.org:pub:6F5C9E39-08DE-4183-A98A-3E11B8993C97
Continuous Habitable Zones: Using Bayesian Methods to Prioritize Characterization of Potentially Habitable Worlds
Creators: name: Ware, Austin
name: Young, Patrick
name: Truitt, Amanda
name: Spacek, Alexander
Publisher: name: arXiv
Year: 2022
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The number of potentially habitable planets continues to increase, but we lack the time and resources to characterize all of them. With $\sim$30 known potentially habitable planets and an ever-growing number of candidate and confirmed planets, a robust statistical framework for prioritizing characterization of these planets is desirable. Using the $\sim$2 Gy it took life on Earth to make a detectable impact on the atmosphere as a benchmark, we use a Bayesian statistical method to determine the probability that a given radius around a star has been continuously habitable for 2 Gy. We perform this analysis on 9 potentially habitable exoplanets with planetary radii $
description: 17 pages, 4 figures, 5 tables, accepted to ApJ
Effects of Gravitational Wave Radiation of Eccentric Neutron Star-White Dwarf Binaries on the Periodic Activity of Fast Radio Burst Sources
Creators: name: Lin, Yi-Qing
name: Chen, Hao-Yan
name: Gu, Wei-Min
name: Yi, Tuan
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We revisit the eccentric neutron star (NS)-white dwarf (WD) binary model for the periodic activity of fast radio burst (FRB) sources, by including the effects of gravitational wave (GW) radiation. In this model, the WD fills its Roche lobe at the periastron and mass transfer occurs from the WD to the NS. The accreted materials can be fragmented and arrive at the NS episodically, resulting in multiple bursts through curvature radiation. Consequently, the WD may be kicked away owing to the conservation of angular momentum. To initiate the next mass transfer, the WD has to refill its Roche lobe through GW radiation. In this scenario, whether the periodic activity can show up relies on three timescales, i.e., the orbital period $P_{\rm orb}$, the timescale $T_{\rm GW}$ for the Roche lobe to be refilled, and the time span $T_{\rm frag}$ for all the episodic events corresponding to each mass transfer process. Only when the two conditions $T_{\rm GW} \gtrsim P_{\rm orb}$ and $T_{\rm frag} < P_{\rm orb}$ are both satisfied, the periodic activity will manifest itself and the period should be equal to $P_{\rm orb}$. In this spirit, the periodic activity is more likely to show up for relatively long periods ($P_{\rm orb} \gtrsim$ several days). Thus, it is reasonable that FRBs 180916 and 121102, the only two sources having been claimed to manifest periodic activity, both correspond to relatively long periods.
description: 7 pages, 2 figures, accepted for pubilcation in ApJ
A new goatfish of the genus Upeneus (Mullidae) from Australia and Vanuatu, with inter- and intraspecific comparisons
Creators: name: Uiblein, Franz
name: Gledhill, Daniel C.
Publisher: name: Taylor & Francis
Year: 2014
Subjects: subject: Biological Sciences
subject: Ecology
subject: FOS: Biological sciences
subject: Earth and Environmental Sciences
subject: Evolutionary Biology

description: A new goatfish, Upeneus torres sp. nov. (Mullidae), is described based on 27 specimens from Australia and Vanuatu using a diversified alpha-taxonomy approach that integrates species, population and size-related allometric differences. Based on large sets of comparative morphological and colour data, diagnoses and inter- and intraspecific comparisons are provided for similar and/or co-occurring species of the so-called japonicus species group, Upeneus torres sp. nov., U. australiae, U. guttatus, and U. japonicus. The new species can be distinguished from all congeneric species by the following combination of characters: seven spines in the first dorsal fin; 13–15 (typically 14) pectoral-fin rays, 22–25 total gill rakers, barbel length 24–28 %SL, and pectoral-fin length 24–26 %SL. Fish smaller than 65 mm SL (‘subadults’) of the new species differ from larger conspecifics (‘adults’) in shallower body, larger eyes, longer anal-fin base, and longer caudal fin. Similar size-related differences were also found for the three other species. Phenotypic population differences in the new species as well as in U. guttatus are reported that may reflect character displacement in the latter. The need to study size–depth–habitat relationships in more detail, the phylogeography of individual populations, and the overall diversity of the genus Upeneus from Australian waters is discussed.http://zoobank.org/urn:lsid:zoobank.org:pub:6F5C9E39-08DE-4183-A98A-3E11B8993C97
Formation of Coronal Mass Ejection and Post-eruption Flow of Solar Wind on 2010 August 18 event
Creators: name: Slemzin, Vladimir
name: Goryaev, Farid
name: Rodkin, Denis
Publisher: name: arXiv
Year: 2022
Subjects: subject: Space Physics (physics.space-ph)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The state of the space environment plays a significant role for forecasting of geomagnetic storms produced by disturbances of the solar wind (SW). Coronal mass ejections (CMEs) passing through the heliosphere often have a prolonged (up to several days) trail with declining speed, which affects propagation of the subsequent SW streams. We studied the CME and the post-eruption plasma flows behind the CME rear in the event on 2010 August 18 observed in quadrature by several space-based instruments. Observations of the eruption in the corona with EUV telescopes and coronagraphs revealed several discrete outflows followed by a continuous structureless post-eruption stream. The interplanetary coronal mass ejection (ICME), associated with this CME, was registered by PLAsma and SupraThermal Ion Composition (PLASTIC) instrument aboard the Solar TErrestrial RElations Observatory (STEREO-A) between August 20, 16:14 UT and August 21, 13:14 UT, after which the SW disturbance was present over 3 days. Kinematic consideration with the use of the gravitational and Drag-Based models has shown that the discrete plasma flows can be associated with the ICME, whereas the post-eruption outflow was arrived in the declining part of the SW transient. We simulated the Fe-ion charge distributions of the ICME and post-CME parts of SW using the plasma temperature and density in the ejection region derived from the Differential Emission Measure analysis. The results demonstrate that in the studied event the post-ICME trailing region was associated with the post-eruption flow from the corona, rather then with the ambient SW entrained by the CME.
description: 13 pages, 4 figures
AT2020hur: A Possible Optical Counterpart of FRB 180916B
Creators: name: Li, Long
name: Li, Qiao-Chu
name: Zhong, Shu-Qing
name: Xia, Jie
name: Xie, Lang
name: Wang, Fa-Yin
name: Dai, Zi-Gao
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: The physical origin of fast radio bursts (FRBs) remains unclear. Finding multiwavelength counterparts of FRBs can be a breakthrough in understanding their nature. In this work, we perform a systematic search for astronomical transients (ATs) whose positions are consistent with FRBs. We find an unclassified optical transient AT2020hur ($α=01^{\mathrm{h}} 58^{\mathrm{m}} 00.750^{\mathrm{s}} \pm 1$ arcsec, $δ=65^{\circ} 43^{\prime} 00.30^{\prime \prime} \pm 1$ arcsec) that is spatially coincident with the repeating FRB 180916B ($α=01^{\mathrm{h}} 58^{\mathrm{m}} 00.7502^{\mathrm{s}} \pm 2.3$ mas, $δ=65^{\circ} 43^{\prime} 00.3152^{\prime \prime} \pm 2.3$ mas). The chance possibility for the AT2020hur-FRB 180916B association is about 0.04%, which corresponds to a significance of $3.5σ$. We develop a giant flare afterglow model to fit AT2020hur. Although the giant flare afterglow model can interpret the observations of AT2020hur, the derived kinetic energy of such a GF is at least three orders of magnitude larger than that of the typical GF, and there is a lot of fine tuning and coincidences required for this model. Another possible explanation is that AT2020hur might consist of two or more optical flares originating from the FRB source, e.g. fast optical bursts produced by the inverse Compton scattering of FRB emission. Besides, AT2020hur is located in one of the activity windows of FRB 180916B, which is an independent support for the association. This coincidence may be due to the reason that the optical counterpart is subject to the same periodic modulation as FRB 180916B, as implied by the prompt FRB counterparts. Future simultaneous observations of FRBs and their optical counterparts may help reveal their physical origin.
description: 17 pages, 6 figures, accepted for publication in ApJ
The X-ray coronae in NuSTAR bright active galactic nuclei
Creators: name: Kang, Jia-Lai
name: Wang, Jun-Xian
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present systematic and uniform analysis of NuSTAR data with 10-78 keV S/N > 50, of a sample of 60 SWIFT BAT selected AGNs, 10 of which are radio-loud. We measure their high energy cutoff Ecut or coronal temperature Te using three different spectral models to fit their NuSTAR spectra, and show a threshold in NuSTAR spectral S/N is essential for such measurements. High energy spectral breaks are detected in the majority of the sample, and for the rest strong constraints to Ecut or Te are obtained. Strikingly, we find extraordinarily large Ecut lower limits ( > 400 keV, up to > 800 keV) in 10 radio-quiet sources, whereas none in the radio-loud sample. Consequently and surprisingly, we find significantly larger mean Ecut/Te of radio-quiet sources compared with radio-loud ones. The reliability of these measurements are carefully inspected and verified with simulations. We find a strong positive correlation between Ecut and photon index Γ, which can not be attributed to the parameter degeneracy. The strong dependence of Ecut on Γ, which could fully account for the discrepancy of Ecut distribution between radio-loud and radio-quiet sources, indicates the X-ray coronae in AGNs with steeper hard X-ray spectra have on average higher temperature and thus smaller opacity. However, no prominent correlation is found between Ecut and λedd. In the l-Θ diagram, we find a considerable fraction of sources lie beyond the boundaries of forbidden regions due to runaway pair production, posing (stronger) challenges to various (flat) coronal geometries.
description: 17 pages, 9 figures, accepted by ApJ. Comments are welcome!
Solute and gas geothermometry of geothermal wells: a geochemometrics study for evaluating the effectiveness of geothermometers to predict deep reservoir temperatures
Creators: name: García-López, Christian Guadalupe
name: Kailasa Pandarinath
name: Santoyo, Edgar
Publisher: name: Taylor & Francis
Year: 2014
Subjects: subject: 110309 Infectious Diseases
subject: FOS: Health sciences
subject: Biological Sciences
subject: Astronomy, Astrophysics, Space Science
subject: Ecology
subject: FOS: Biological sciences
subject: Chemistry
subject: Earth and Environmental Sciences
subject: Physiology
subject: Microbiology
subject: Medicine
subject: Physics

description: Deep reservoir temperatures of 10 important geothermal systems of the world were estimated by applying 13 solute (Na/K) and 21 gas geothermometers. The predicted temperatures were comprehensively evaluated and compared with measured bottom-hole temperatures using geochemometric techniques. The present study reveals (1) high prediction performances in most of the Na/K geothermometers for the majority of the geothermal fields with liquid-dominated reservoirs, whereas low prediction performances were indicated for the geothermal fields with vapour-dominated and high-temperature reservoirs; (2) the gas geothermometers, in comparison to Na/K, are more successful in predicting the subsurface temperatures in high-temperature geothermal systems; (3) the geothermal systems for which Na/K geothermometers have indicated a high prediction performance, the gas geothermometers have specified a low prediction performances, and vice versa; (4) both Na/K and gas geothermometers, generally, overestimated the reservoir temperatures for the majority of the low-enthalpy geothermal fields and underestimated for the majority of the high-enthalpy geothermal fields; (5) the reservoir temperature predictions of gas geothermometers have more scatter than those temperatures inferred from Na/K geothermometers; and (6) in general, Na/K geothermometers seem to be a more successful geochemical tool in predicting reliable reservoir temperatures than gas geothermometers.
The Metallicity Distribution Function in Outer Halo Fields of Simulated Elliptical Galaxies Compared to Observations of NGC 5128
Creators: name: Choi, Ena
name: Ostriker, Jeremiah P.
name: Hirschmann, Michaela
name: Somerville, Rachel S.
name: Naab, Thorsten
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Stellar metallicity distribution functions (MDF) have been measured for resolved stellar populations in the outer halos of many galaxies in nearby groups. Among them, the MDF of NGC 5128, the central giant elliptical in the Centaurus group, provides essential constraints for theories of massive galaxy formation and hierarchical assembly. To investigate the formation and chemical evolution history of the outer halo of giant elliptical galaxies, we examine the chemical properties of three zoom-in high resolution cosmological hydrodynamical simulations of an NGC 5128-like giant elliptical galaxy and compare their outer halo MDFs to the observed one of NGC 5128. Even though the simulated galaxies have different merging histories and age distributions, all predicted MDFs are in good qualitative agreement with the observed one. The median metallicity of the simulated galaxies is on average $\rm [M/H]=-0.41 \pm 0.06$ compared to the observed value of $\rm [M/H]=-0.38 \pm 0.02$ for NGC 5128, and the dispersion in metallicity is $\sim 0.77$ dex for both observed and simulated galaxies. We investigate the origin of the stars ending up in the outer halo field of simulated galaxies and show that most have an `accreted' origin, formed in other small galaxies and later accreted in mergers. Only $\sim 15$ percent of the stars are formed `in situ' within the main progenitor of galaxy and radially migrate outwards. We show that the contribution of metal-rich in situ stars is sub-dominant in the outer halos of our simulated galaxies, but can be prominent in the inner regions.
description: 16 pages, 9 figures, Accepted for publication in ApJ
Bayesian inference in single-line spectroscopic binaries with a visual orbit
Creators: name: Videla, Miguel
name: Mendez, Rene A.
name: Claveria, Ruben M.
name: Silva, Jorge F.
name: Orchard, Marcos E.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Computational Physics (physics.comp-ph)
subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: FOS: Physical sciences

description: We present a Bayesian inference methodology for the estimation of orbital parameters on single-line spectroscopic binaries with astrometric data, based on the No-U-Turn sampler Markov chain Monte Carlo algorithm. Our approach is designed to provide a precise and efficient estimation of the joint posterior distribution of the orbital parameters in the presence of partial and heterogeneous observations. This scheme allows us to directly incorporate prior information about the system - in the form of a trigonometric parallax, and an estimation of the mass of the primary component from its spectral type - to constrain the range of solutions, and to estimate orbital parameters that cannot be usually determined (e.g. the individual component masses), due to the lack of observations or imprecise measurements. Our methodology is tested by analyzing the posterior distributions of well-studied double-line spectroscopic binaries treated as single-line binaries by omitting the radial velocity data of the secondary object. Our results show that the system's mass ratio can be estimated with an uncertainty smaller than 10% using our approach. As a proof of concept, the proposed methodology is applied to twelve single-line spectroscopic binaries with astrometric data that lacked a joint astrometric-spectroscopic solution, for which we provide full orbital elements. Our sample-based methodology allows us also to study the impact of different posterior distributions in the corresponding observations space. This novel analysis provides a better understanding of the effect of the different sources of information on the shape and uncertainty of the orbit and radial velocity curve.
description: Accepted for publication to the Astronomical Journal.39 pages, 7 Tables, 18 Figures, two Appendices