Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>We present a systematic analysis of the extended X-ray emission discovered around 35 FR II radio galaxies from the revised Third Cambridge Catalog (3CR) Chandra Snapshot Survey with redshifts between 0.05 and 0.9. We aimed to (i) test for the presence of extended X-ray emission around FR II radio galaxies, (ii) investigate whether the extended emission origin is due to inverse Compton (IC) scattering of seed photons arising from the cosmic microwave background (CMB) or thermal emission from an intracluster medium (ICM), and (iii) test the impact of this extended emission on hot-spot detection. We investigated the nature of the extended X-ray emission by studying its morphology and compared our results with low-frequency radio observations (i.e., ∼150 MHz) in the TGSS and LOFAR archives, as well as with optical images from Pan-STARRS. In addition, we optimized a search for X-ray counterparts of hot spots in 3CR FR II radio galaxies. We found statistically significant extended emission (&gt;3<jats:italic>σ</jats:italic> confidence level) along the radio axis of ∼90% and in the perpendicular direction of ∼60% of the galaxies in our sample. We confirmed the detection of seven hot spots in the 0.5–3 keV energy range. In the cases where the emission in the direction perpendicular to the radio axis is comparable to that along the radio axis, we suggest that the underlying radiative process is thermal emission from the ICM. Otherwise, the dominant radiative process is likely nonthermal IC/CMB emission from lobes. We found that nonthermal IC/CMB is the dominant process in ∼70% of the sources in our sample, while thermal emission from the ICM dominates in ∼15% of them.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Optical time-domain astronomy has grown rapidly in the past decade, but the dynamic infrared sky is rarely explored. Aiming to construct a sample of mid-infrared outbursts in nearby galaxies (MIRONG), we have conducted a systematical search of low-redshift (<jats:italic>z</jats:italic> &lt; 0.35) Sloan Digital Sky Survey spectroscopic galaxies that have experienced recent mid-infrared (MIR) flares using their Wide-field Infrared Survey Explorer (WISE) light curves. A total of 137 galaxies have been selected by requiring a brightening amplitude of 0.5 mag in at least one WISE band with respect to their quiescent phases. Only a small fraction (10.9%) has corresponding optical flares. Except for the four supernovae (SNe) in our sample, the MIR luminosities of the remaining sources (<jats:italic>L</jats:italic> <jats:sub>4.6 <jats:italic>μ</jats:italic>m</jats:sub> &gt; 10<jats:sup>42</jats:sup> erg s<jats:sup>−1</jats:sup>) are markedly brighter than known SNe, and their physical locations are very close to the galactic center (median &lt;0.″1). Only four galaxies are radio-loud, indicating that synchrotron radiation from relativistic jets could contribute to MIR variability. We propose that these MIR outbursts are dominated by the dust echoes of transient accretion onto supermassive black holes, such as tidal disruption events (TDEs) and turn-on (changing-look) active galactic nuclei. Moreover, the inferred peak MIR luminosity function is generally consistent with the X-ray and optical TDEs at the high end, albeit with large uncertainties. Our results suggest that a large population of transients has been overlooked by optical surveys, probably due to dust obscuration or intrinsically optical weakness. Thus, a search in the infrared band is crucial for us to obtain a panoramic picture of nuclear outburst. The multiwavelength follow-up observations of the MIRONG sample are in progress and will be presented in a series of subsequent papers.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We have measured trigonometric parallaxes for four H<jats:sub>2</jats:sub>O masers associated with distant massive young stars in the inner regions of the Galaxy using the Very Long Baseline Array as part of the BeSSeL Survey. G026.50 + 0.28 is located at the near end of the Galactic bar, perhaps at the origin of the Norma spiral arm. G020.77−0.05 is in the Galactic Center region and is likely associated with a far-side extension of the Scutum arm. G019.60−0.23 and G020.08−0.13 are likely associated and lie well past the Galactic Center. These sources appear to be in the Sagittarius spiral arm, but an association with the Perseus arm cannot be ruled out.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We have selected 43 southern massive star-forming regions to study the spatial distribution of HNCO 4<jats:sub>04</jats:sub>–3<jats:sub>03</jats:sub>, SiO 2–1, and HC<jats:sub>3</jats:sub>N 10–9 line emission and to investigate their spatial association with the dust emission. The morphology of HNCO 4<jats:sub>04</jats:sub>–3<jats:sub>03</jats:sub> and HC<jats:sub>3</jats:sub>N 10–9 agrees well with the dust emission. HC<jats:sub>3</jats:sub>N 10–9 tends to originate from more compact regions than HNCO 4<jats:sub>04</jats:sub>–3<jats:sub>03</jats:sub> and SiO 2–1. We divided our sources into three groups: those in the Central Molecular Zone (CMZ), those associated with bubbles (Bubble), and the remaining sources, which are termed “normal star-forming regions” (NMSFR). These three groups, subdivided into three different categories with respect to line widths, integrated intensities, and column densities, hint at the presence of different physical and chemical processes. We find that the dust temperature <jats:italic>T</jats:italic> <jats:sub>d</jats:sub>, and the abundance ratios <jats:italic>N</jats:italic> <jats:sub>HNCO</jats:sub>/<jats:italic>N</jats:italic> <jats:sub>SiO</jats:sub> and <jats:italic>N</jats:italic> <jats:sub>HNCO</jats:sub>/<jats:italic>N</jats:italic> <jats:sub>HC3N</jats:sub> show a decreasing trend toward the central dense regions of CMZ sources, while <jats:italic>N</jats:italic> <jats:sub>HC3N</jats:sub>/<jats:italic>N</jats:italic> <jats:sub>SiO</jats:sub> moves in the opposite direction. Moreover, a better agreement is found between <jats:italic>T</jats:italic> <jats:sub>d</jats:sub> and <jats:italic>N</jats:italic> <jats:sub>HC3N</jats:sub>/<jats:italic>N</jats:italic> <jats:sub>SiO</jats:sub> in Bubble and NMSFR category sources. Both outflow and inflow activities have been found in eight of the 16 bubble and NMSFR sources. The low outflow detection rate indicates either that in these sources the SiO 2–1 line wing emission is below our sensitivity limit or that the bulk of the SiO emission may be produced by the expansion of an H <jats:sc>ii</jats:sc> region or supernova remnant, which has pushed molecular gas away, forming a shock and yielding SiO.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a catalog of 4195 optically confirmed Sunyaev–Zel’dovich (SZ) selected galaxy clusters detected with signal-to-noise ratio &gt;4 in 13,211 deg<jats:sup>2</jats:sup> of sky surveyed by the Atacama Cosmology Telescope (ACT). Cluster candidates were selected by applying a multifrequency matched filter to 98 and 150 GHz maps constructed from ACT observations obtained from 2008 to 2018 and confirmed using deep, wide-area optical surveys. The clusters span the redshift range 0.04 &lt; <jats:italic>z</jats:italic> &lt; 1.91 (median <jats:italic>z</jats:italic> = 0.52). The catalog contains 222 <jats:italic>z</jats:italic> &gt; 1 clusters, and a total of 868 systems are new discoveries. Assuming an SZ signal versus mass-scaling relation calibrated from X-ray observations, the sample has a 90% completeness mass limit of <jats:italic>M</jats:italic> <jats:sub>500c</jats:sub> &gt; 3.8 × 10<jats:sup>14</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, evaluated at <jats:italic>z</jats:italic> = 0.5, for clusters detected at signal-to-noise ratio &gt;5 in maps filtered at an angular scale of 2.′4. The survey has a large overlap with deep optical weak-lensing surveys that are being used to calibrate the SZ signal mass-scaling relation, such as the Dark Energy Survey (4566 deg<jats:sup>2</jats:sup>), the Hyper Suprime-Cam Subaru Strategic Program (469 deg<jats:sup>2</jats:sup>), and the Kilo Degree Survey (825 deg<jats:sup>2</jats:sup>). We highlight some noteworthy objects in the sample, including potentially projected systems, clusters with strong lensing features, clusters with active central galaxies or star formation, and systems of multiple clusters that may be physically associated. The cluster catalog will be a useful resource for future cosmological analyses and studying the evolution of the intracluster medium and galaxies in massive clusters over the past 10 Gyr.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Hubble Space Telescope (HST) has been providing tremendous survey efficiency via its pure-parallel mode by observing another field in parallel with the primary instrument in operation for the primary observation. In this study, we present a new archival project, SuperBoRG, which aims at compiling data taken in extragalactic parallel programs of HST with the Wide Field Camera 3 in the past decade, including pure-parallel (BoRG, HIPPIES, and COS-GTO) and coordinated-parallel (CLASH and RELICS) programs. The total effective area reaches ∼0.41 deg<jats:sup>2</jats:sup> from 4.1 Ms, or 47 days, of observing time, which is the largest collection of optical-to-near-infrared imaging data of HST for extragalactic science. We reduce all data in a consistent manner with an updated version of our data reduction pipeline, including a new sky background subtraction step. When available, imaging data from the Spitzer Space Telescope are also included in photometric analyses. The data set consists of 316 independent sight lines and is highly effective for identification of high-<jats:italic>z</jats:italic> luminous sources (<jats:italic>M</jats:italic> <jats:sub>UV</jats:sub> ≲ −20 mag) at <jats:italic>z</jats:italic> ∼ 7–12, helping to minimize the effects of cosmic variance. As a demonstration, we present three new <jats:italic>z</jats:italic> ≳ 7 source candidates, including one luminous galaxy candidate at <jats:italic>z</jats:italic> <jats:sub>phot</jats:sub> ∼ 10.4 with <jats:italic>M</jats:italic> <jats:sub>UV</jats:sub> ∼ −21.9 mag; the best-fit spectral energy distribution implies a large amount of stellar mass (<jats:inline-formula> <jats:tex-math> <?CDATA $\mathrm{log}{M}_{* }/{M}_{\odot }$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjsabce67ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> ∼ 10) and moderate dust attenuation (<jats:italic>A</jats:italic> <jats:sub> <jats:italic>V</jats:italic> </jats:sub> ∼ 1.4 mag), though the possibility of it being a low-<jats:italic>z</jats:italic> interloper cannot be completely rejected (∼23%) with the current data set. The data set presented in this study is also suited for intermediate- and low-<jats:italic>z</jats:italic> science cases.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Event Horizon Telescope (EHT) is a very long-baseline interferometer built to image supermassive black holes on event-horizon scales. In this paper, we investigate candidate sites for an expanded EHT array with improved imaging capabilities. We use historical meteorology and radiative transfer analysis to evaluate site performance. Most of the existing sites in the EHT array have median zenith opacity less than 0.2 at 230 GHz during the March/April observing season. Seven of the existing EHT sites have 345 GHz opacity less than 0.5 during observing months. Out of more than 40 candidate new locations analyzed, approximately half have 230 GHz opacity comparable to the existing EHT sites, and at least 17 of the candidate sites would be comparably good for 345 GHz observing. A group of new sites with favorable transmittance and geographic placement leads to greatly enhanced imaging and science on horizon scales.</jats:p>