Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>Based on the photometric redshift catalog of Zou et al., we apply a fast clustering algorithm to identify 540,432 galaxy clusters at <jats:italic>z</jats:italic> ≲ 1 in the DESI legacy imaging surveys, which cover a sky area of about 20,000 deg<jats:sup>2</jats:sup>. Monte Carlo simulations indicate that the false-detection rate of our detecting method is about 3.1%. The total masses of galaxy clusters are derived using a calibrated richness–mass relation that is based on the observations of X-ray emission and the Sunyaev and Zel’dovich effect. The median redshift and mass of our detected clusters are about 0.53 and 1.23 × 10<jats:sup>14</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, respectively. Comparing with previous clusters identified using the data of the Sloan Digital Sky Survey; we can recognize most of them, especially those with high richness. Our catalog will be used for further statistical studies on galaxy clusters and environmental effects on galaxy evolution, etc.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Recently, GRAVITY on board the Very Large Telescope Interferometer (VLTI) first spatially resolved the structure of the quasar 3C 273 with an unprecedented resolution of ∼10 <jats:italic>μ</jats:italic>as. A new method of measuring parallax distances has been successfully applied to the quasar through joint analysis of spectroastrometry (SA) and reverberation mapping (RM) observation of its broad-line region (BLR). The uncertainty of this SA and RM (SARM) measurement is about 16% from real data, showing its great potential as a powerful tool for precision cosmology. In this paper, we carry out detailed analyses of mock data to study impacts of data qualities of SA observations on distance measurements and establish a quantitative relationship between statistical uncertainties of distances and relative errors of differential phases. We employ a circular disk model of the BLR for the SARM analysis. We show that SARM analyses of observations generally generate reliable quasar distances, even for relatively poor SA measurements with error bars of 40% at peaks of phases. Inclinations and opening angles of BLRs are the major parameters governing distance uncertainties. It is found that BLRs with inclinations ≳10° and opening angles ≲40° are the most reliable regimes from SARM analysis for distance measurements. Through analysis of a mock sample of AGNs generated by quasar luminosity functions, we find that if the GRAVITY/GRAVITY+ can achieve a phase error of 0.°1 per baseline for targets with magnitudes <jats:italic>K</jats:italic> ≲ 11.5, the SARM campaign can constrain <jats:italic>H</jats:italic> <jats:sub>0</jats:sub> to an uncertainty of 2% by observing 60 targets.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We analyze 4050 wide binary star systems involving a white dwarf (WD) and usually a main-sequence (MS) star, drawn from the large sample assembled by Tian et al. Using the modeling code BASE-9, we determine the system’s ages, the WD progenitors’ zero-age MS masses, the extinction values (<jats:italic>A</jats:italic> <jats:sub> <jats:italic>V</jats:italic> </jats:sub>), and the distance moduli. Discarding the cases with poor age convergences, we obtain ages for 3551 WDs, with a median age precision of <jats:italic>σ</jats:italic> <jats:sub> <jats:italic>τ</jats:italic> </jats:sub>/<jats:italic>τ</jats:italic> = 20%, and system ages typically in the range of 1–6 Gyr. We validated these ages against the very few known clusters and through cross validation of 236 WD-WD binaries. Under the assumption that the components are coeval in a binary system, this provides precise age constraints on the usually low-mass MS companions, mostly inaccessible by any other means.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Recent efforts coupling our Sun-to-Earth magnetohydrodynamics (MHD) model and lower-corona magnetofrictional (MF) model are described. Our Global Heliospheric MHD (GHM) model uses time-dependent three-component magnetic field data from the lower-corona MF model as time-dependent boundary values. The MF model uses data-assimilation techniques to introduce the vector magnetic field data from the Solar Dynamics Observatory/Helioseismic and Magnetic Imager, hence as a whole this simulation coupling structure is driven with actual observations. The GHM model employs a newly developed interface boundary treatment that is based on the concept of characteristics, and it properly treats the interface boundary sphere set at a height of the sub-Alfvénic lower corona (1.15 <jats:italic>R</jats:italic> <jats:sub>⊙</jats:sub> in this work). The coupled model framework numerically produces twisted nonpotential magnetic features and consequent eruption events in the solar corona in response to the time-dependent boundary values. The combination of our two originally independently developed models presented here is a model framework toward achieving further capabilities of modeling the nonlinear time-dependent nature of magnetic field and plasma, from small-scale solar active regions to large-scale solar wind structures. This work is a part of the Coronal Global Evolutionary Model project for enhancing our understanding of Sun–Earth physics to help improve space weather capabilities.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Ever since a thick disk was proposed to explain the vertical distribution of the Milky Way disk stars, its origin has been a recurrent question. We aim to answer this question by inspecting 19 disk galaxies with stellar mass greater than 10<jats:sup>10</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> in recent cosmological high-resolution zoom-in simulations: <jats:sc>galactica</jats:sc> and <jats:sc>NewHorizon</jats:sc>. The thin and thick disks are reasonably reproduced by the simulations with scale heights and luminosity ratios as observed. We then spatially classify the thin and thick disks and find that the thick disk stars are older, metal-poorer, kinematically hotter, and higher in accreted star fraction, while both disks are dominated by the stars formed in situ. Half of the in situ stars in the thick disks are formed before the galaxies develop their disks, and the rest are formed in spatially and kinematically thinner disks and then thickened with time by heating. However, the 19 galaxies have various properties and evolutionary routes, highlighting the need for statistically large samples to draw general conclusions. We conclude from our simulations that the thin and thick disk components are not entirely distinct in terms of formation processes but rather markers of the evolution of galactic disks. Moreover, as the combined result of the thickening of the existing disk stars and the continued formation of young thin disk stars, the vertical distribution of stars does not change much after the disks settle, pointing to the modulation of both orbital diffusion and star formation by the same confounding factor: the proximity of galaxies to marginal stability.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In this work, we study the properties of molecular clouds in the second quadrant of the Milky Way Midplane, from <jats:italic>l</jats:italic> = 104.°75 to <jats:italic>l</jats:italic> = 119.°75, and <jats:italic>b</jats:italic> = −5.°25 to <jats:italic>b</jats:italic> = 5.°25, using the <jats:sup>12</jats:sup>CO, <jats:sup>13</jats:sup>CO, and C<jats:sup>18</jats:sup>O <jats:italic>J</jats:italic> = 1 − 0 emission line data from the Milky Way Imaging Scroll Painting project. We identify 857 and 300 clouds in the <jats:sup>12</jats:sup>CO and <jats:sup>13</jats:sup>CO spectral cubes, respectively, using the DENDROGRAM + SCIMES algorithms. The distances of the molecular clouds are estimated, and physical properties such as the mass, size, and surface densities of the clouds are tabulated. The molecular clouds in the Perseus Arm are about 30−50 times more massive, and 4−6 times larger than the clouds in the Local Arm. This result, however, is likely to be biased by distance selection effects. The surface densities of the clouds are enhanced in the Perseus Arm, with an average value of ∼100 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> pc<jats:sup>−2</jats:sup>. Here. we select the 40 most extended (&gt;0.35 arcdeg<jats:sup>2</jats:sup>) molecular clouds from the <jats:sup>12</jats:sup>CO catalog to build the H<jats:sub>2</jats:sub> column density probability distribution function (N-PDF). Some 78% of the N-PDFs of the selected molecular clouds are well fitted with log-normal functions with only small deviations at high densities, corresponding to star-forming regions with scales of ∼1–5 pc in the Local Arm, and ∼5–10 pc in the Perseus Arm. About 18% of the selected molecular clouds have power-law N-PDFs at high densities. In these molecular clouds, the majority of the regions fitted with the power law correspond to molecular clumps at sizes of ∼1 pc, or filaments at widths of ∼1 pc.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Plenty of crucial information about our universe is encoded in the cosmic large-scale structure (LSS). However, extractions of this information are usually hindered by the nonlinearities of the LSS, which can be largely alleviated by various techniques known as reconstruction. In realistic applications, the efficiencies of these methods are always degraded by many limiting factors, a quite important one being the shot noise induced by the finite number density of biased matter tracers (i.e., luminous galaxies or dark matter halos) in observations. In this work, we explore the gains of biased tracer reconstruction achieved from halo mass information, which can suppress the shot-noise component and dramatically improves the cross-correlation between tracer field and dark matter. To this end, we first closely study the clustering biases and the stochasticity properties of halo fields with various number densities under different weighting schemes, i.e., the uniform, mass, and optimal weightings. Then, we apply the biased tracer reconstruction method to these different weighted halo fields and investigate how linear bias and observational mass scatter affect the reconstruction performance. Our results demonstrate that halo masses are critical information for significantly improving the performance of biased tracer reconstruction, indicating great application potential for substantially promoting the precision of cosmological measurements (especially for baryon acoustic oscillations) in ambitious ongoing and future galaxy surveys.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report new branching fraction measurements for 199 UV and optical transitions of Hf <jats:sc>ii</jats:sc>. These transitions range in wavelength (wavenumber) from 2068 to 6584 Å (48,322–15,183 cm<jats:sup>−1</jats:sup>) and originate in 17 odd-parity upper levels ranging in energy from 38,578 to 53,227 cm<jats:sup>−1</jats:sup>. The branching fractions are combined with radiative lifetimes reported in an earlier study to produce a set of transition probabilities and log(<jats:italic>gf</jats:italic>) values with accuracy ranging from 5% to 25%. Comparison is made to transition probabilities from the literature where such data exist. We use these new transition probabilities to derive improved Hf abundances in two metal-poor stars. HD 196944 is enhanced in s-process elements, and we derive log <jats:italic>ε</jats:italic> (Hf) = −0.72 ± 0.03 (<jats:italic>σ</jats:italic> = 0.09) from 12 Hf <jats:sc>ii</jats:sc> lines. HD 222925 is enhanced in r-process elements, and we derive log <jats:italic>ε</jats:italic> (Hf) = 0.32 ± 0.03 (<jats:italic>σ</jats:italic> = 0.11) from 20 Hf <jats:sc>ii</jats:sc> lines. These measurements greatly expand the number of potentially useful Hf <jats:sc>ii</jats:sc> lines for analysis in UV and optical spectra.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Quasars behind the Galactic plane (GPQs) are important astrometric references and useful probes of Milky Way gas. However, the search for GPQs is difficult due to large extinctions and high source densities in the Galactic plane. Existing selection methods for quasars developed using high Galactic latitude (high-<jats:italic>b</jats:italic>) data cannot be applied to the Galactic plane directly because the photometric data obtained from high-<jats:italic>b</jats:italic> regions and the Galactic plane follow different probability distributions. To alleviate this data set shift problem for quasar candidate selection, we adopt a transfer-learning framework at both the data and algorithm levels. At the data level, to make a training set in which a data set shift is modeled, we synthesize quasars and galaxies behind the Galactic plane based on SDSS sources and the Galactic dust map. At the algorithm level, to reduce the effect of class imbalance, we transform the three-class classification problem for stars, galaxies, and quasars into two binary classification tasks. We apply the XGBoost algorithm to Pan-STARRS1 (PS1) and AllWISE photometry for classification and an additional cut on Gaia proper motion to remove stellar contaminants. We obtain a reliable GPQ candidate catalog with 160,946 sources located at ∣<jats:italic>b</jats:italic>∣ ≤ 20° in the PS1-AllWISE footprint. Photometric redshifts of GPQ candidates achieved with the XGBoost regression algorithm show that our selection method can identify quasars in a wide redshift range (0 &lt; <jats:italic>z</jats:italic> ≲ 5). This study extends the systematic searches for quasars to the dense stellar fields and shows the feasibility of using astronomical knowledge to improve data mining under complex conditions in the big-data era.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Various properties of Jovian Trojan asteroids such as composition, rotation periods, and photometric amplitudes, or the rate of binarity in the population, can provide information and constraints on the evolution of the group and of the solar system itself. Here we present new photometric properties of 45 Jovian Trojans from the K2 mission of the Kepler space telescope, and present phase-folded light curves for 44 targets, including (11351) Leucus, one of the targets of the Lucy mission. We extend our sample to 101 asteroids with previous K2 Trojan measurements, then compare their combined amplitude and frequency distributions to other ground-based and space data. We show that there is a dichotomy in the periods of Trojans with a separation at ∼100 hr. We find that 25% of the sample are slow rotators (<jats:italic>P</jats:italic> ≥ 30 hr), an excess that can be attributed to binary objects. We also show that 32 systems can be classified as potential detached binary systems. Finally, we calculate density and rotation constraints for the asteroids. Both the spin barrier and fits to strengthless ellipsoid models indicate low densities and thus compositions similar to populations of comets and trans-Neptunian objects throughout the sample. This supports the scenario of outer solar system origin for Jovian Trojans.</jats:p>