Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>This paper studied the faint, diffuse extended X-ray emission associated with the radio lobes and the hot gas in the intracluster medium (ICM) environment for a sample of radio galaxies. We used shallow (∼10 ks) archival Chandra observations for 60 radio galaxies (7 FR I and 53 FR II) with 0.0222 ≤ <jats:italic>z</jats:italic> ≤ 1.785 selected from the 298 extragalactic radio sources identified in the 3CR catalog. We used Bayesian statistics to look for any asymmetry in the extended X-ray emission between regions that contain the radio lobes and regions that contain the hot gas in the ICM. In the Chandra broad band (0.5–7.0 keV), which has the highest detected X-ray flux and the highest signal-to-noise ratio, we found that the nonthermal X-ray emission from the radio lobes dominates the thermal X-ray emission from the environment for ∼77% of the sources in our sample. We also found that the relative amount of on-jet axis nonthermal emission from the radio lobes tends to increase with redshift compared to the off-jet axis thermal emission from the environment. This suggests that the dominant X-ray mechanism for the nonthermal X-ray emission in the radio lobes is due to the inverse Compton upscattering of cosmic microwave background (CMB) seed photons by relativistic electrons in the radio lobes, a process for which the observed flux is roughly redshift independent due to the increasing CMB energy density with increasing redshift.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Nearby, low-metallicity dwarf starburst galaxies hosting active galactic nuclei (AGNs) offer the best local analogs to study the early evolution of galaxies and their supermassive black holes (BHs). Here we present a detailed multiwavelength investigation of star formation and BH activity in the low-metallicity dwarf–dwarf galaxy merger Mrk 709. Using Hubble Space Telescope H<jats:italic>α</jats:italic> and continuum imaging combined with Keck spectroscopy, we determine that the two dwarf galaxies are likely in the early stages of a merger (i.e., their first pass) and discover a spectacular ∼10 kpc long string of young massive star clusters (<jats:italic>t</jats:italic> ≲ 10 Myr; <jats:italic>M</jats:italic> <jats:sub>⋆</jats:sub> ≳ 10<jats:sup>5</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>) between the galaxies triggered by the interaction. We find that the southern galaxy, Mrk 709 S, is undergoing a clumpy mode of star formation resembling that seen in high-redshift galaxies, with multiple young clusters/clumps having stellar masses between 10<jats:sup>7</jats:sup> and 10<jats:sup>8</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>. Furthermore, we present additional evidence for a low-luminosity AGN in Mrk 709 S (first identified by Reines et al. using radio and X-ray observations), including the detection of the coronal [Fe <jats:sc>x</jats:sc>] optical emission line. The work presented here provides a unique glimpse into processes key to hierarchical galaxy formation and BH growth in the early universe.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The detection of larger complex organic molecules, such as molecules consisting of several functional groups or those which show conformational flexibility, in the interstellar medium could lead to insights into the availability of biomolecules in space. We present the rotational spectroscopic study of three amino alcohols: alaninol, valinol, and leucinol. The spectra were recorded over the 2–110 GHz region, which included the utilization of a newly developed instrument operating between 18–26 GHz. We report accurately determined line lists, rotational constants, centrifugal distortion constants, and nuclear quadrupole coupling constants for two conformers of alaninol, four conformers of valinol, and three conformers of leucinol, as well as for several singly substituted heavy-atom isotopologues, which also provide structural insights. Further, a number of spectra of vibrationally excited states were assigned, and the associated motions were revealed with anharmonic frequency calculations. Accurate predictions of rotational transitions into the millimeter-wave regime for all species were made, facilitating searches for these complex molecules by observational facilities such as ALMA. Their detection would establish a new family of interstellar molecules.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We revisit the dependence of the covering factor (CF) of dust torus on physical properties of active galactic nuclei (AGNs) by taking into account an AGN polar dust emission. The CF is converted from a ratio of infrared (IR) luminosity contributed from AGN dust torus (<jats:inline-formula> <jats:tex-math> <?CDATA ${L}_{\mathrm{IR}}^{\mathrm{torus}}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabe94aieqn1.gif" xlink:type="simple" /> </jats:inline-formula>) and AGN bolometric luminosity (<jats:italic>L</jats:italic> <jats:sub>bol</jats:sub>), by assuming a nonlinear relation between luminosity ratio and intrinsic CF. We select 37,181 type 1 quasars at <jats:italic>z</jats:italic> &lt; 0.7 from the Sloan Digital Sky Survey Data Release 16 quasar catalog. Their <jats:italic>L</jats:italic> <jats:sub>bol</jats:sub>, black hole mass (<jats:italic>M</jats:italic> <jats:sub>BH</jats:sub>), and Eddington ratio (<jats:italic>λ</jats:italic> <jats:sub>Edd</jats:sub>) are derived by spectral fitting with <jats:monospace>QSFit</jats:monospace>. We conduct spectral energy distribution decomposition by using <jats:monospace>X-CIGALE</jats:monospace> with a clumpy torus and polar dust model to estimate <jats:inline-formula> <jats:tex-math> <?CDATA ${L}_{\mathrm{IR}}^{\mathrm{torus}}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabe94aieqn2.gif" xlink:type="simple" /> </jats:inline-formula> without being affected by the contribution of stellar and AGN polar dust to IR emission. For 5752 quasars whose physical quantities are securely determined, we perform a correlation analysis on CF and (i) <jats:italic>L</jats:italic> <jats:sub>bol</jats:sub>, (ii) <jats:italic>M</jats:italic> <jats:sub>BH</jats:sub>, and (iii) <jats:italic>λ</jats:italic> <jats:sub>Edd</jats:sub>. As a result, anticorrelations for CF–<jats:italic>L</jats:italic> <jats:sub>bol</jats:sub>, CF–<jats:italic>M</jats:italic> <jats:sub>BH</jats:sub>, and CF–<jats:italic>λ</jats:italic> <jats:sub>Edd</jats:sub> are confirmed. We find that incorporating the AGN polar dust emission makes those anticorrelations stronger compared to those without considering it. This indicates that polar dust wind probably driven by AGN radiative pressure is one of the key components to regulate obscuring material of AGNs.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>NGC 2617 attracted a lot of attention after the detection of changes in its spectral type; the geometry and kinematics of the broad-line region (BLR) are still ambiguous. In this paper, we present the high cadence (∼2 days) reverberation mapping campaign of NGC 2617 from 2019 October to 2020 May undertaken at the Lijiang 2.4 m telescope. For the first time, the velocity-resolved reverberation signature of the object was successfully detected. Both H<jats:italic>α</jats:italic> and H<jats:italic>β</jats:italic> show an asymmetrical profile with a peak in the velocity-resolved time lags. For both of the lines, the lag of the line core is longer than those of the relevant wings, and the peak of the velocity-resolved lags is slightly blueshifted. These characteristics are not consistent with the theoretical prediction of the inflow, outflow or Keplerian disk model. Our observations give the time lags of H<jats:italic>α</jats:italic>, H<jats:italic>β</jats:italic>, H<jats:italic>γ</jats:italic>, and He <jats:sc>i</jats:sc>, with a ratio of <jats:italic>τ</jats:italic> <jats:sub>H<jats:italic>α</jats:italic> </jats:sub>: <jats:italic>τ</jats:italic> <jats:sub>H<jats:italic>β</jats:italic> </jats:sub>: <jats:italic>τ</jats:italic> <jats:sub>H<jats:italic>γ</jats:italic> </jats:sub>: <jats:italic>τ</jats:italic> <jats:sub>He I</jats:sub> = 1.27:1.00:0.89:0.20, which indicates a stratified structure in the BLR of the object. It is the first time that the lags of H<jats:italic>α</jats:italic> and He <jats:sc>i</jats:sc> are obtained. Assuming a virial factor of <jats:italic>f</jats:italic> = 5.5 for the dispersion width of the line, the masses of the black holes derived from H<jats:italic>α</jats:italic> and H<jats:italic>β</jats:italic> are <jats:inline-formula> <jats:tex-math> <?CDATA ${23.8}_{-2.7}^{+5.4}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabefe0ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> and <jats:inline-formula> <jats:tex-math> <?CDATA ${21.1}_{-4.4}^{+3.8}\times {10}^{6}{M}_{\odot }$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabefe0ieqn2.gif" xlink:type="simple" /> </jats:inline-formula>, respectively. Our observed results indicate the complexity of the BLR of NGC 2617.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Single AGB stars are not normally expected to be X-ray emitters due to the lack of a corona capable of powering a hot plasma. Therefore, the detection of X-ray emission in AGB stars by the ROSAT, Chandra, and XMM-Newton observatories has been interpreted as evidence for binarity. The number of X-ray-emitting AGB stars is, however, very small, and statistically sound conclusions shall be considered tentative. In this paper we aim at increasing the number of X-ray-emitting AGB stars and at providing a consistent analysis of their X-ray emission to be compared to their UV and optical properties. The XMM-Newton 4XMM-DR9 catalog has been searched for X-ray counterparts of various types of AGB stars: nearby (i.e., listed in Hipparcos), mass-losing, and S- and C-types. Seventeen X-ray counterparts of AGB stars have been found in the 4XMM-DR9. Nine of them have pointed XMM-Newton observations, whereas eight are genuine serendipitous discoveries. Together with the AGB stars detected by ROSAT, this increases the number of X-ray AGB stars to 26. Most of their X-ray spectra can be fit by the emission from an optically thin single-temperature thermal plasma with temperatures typically larger than 10<jats:sup>7</jats:sup> K. There is no obvious correlation between the X-ray and bolometric luminosity of these stars, but the X-ray luminosity generally increases with the amount of far-UV excess. The high temperature of some X-ray-emitting plasma in AGB stars and the correlation of their X-ray luminosity with the far-UV emission supports the origin of this X-ray emission from accretion disks around unseen companions.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Waiting-time distributions of solar flares and coronal mass ejections (CMEs) exhibit power-law-like distribution functions with slopes in the range of <jats:italic>α</jats:italic> <jats:sub> <jats:italic>τ</jats:italic> </jats:sub> ≈ 1.4–3.2, as observed in annual data sets during four solar cycles (1974–2012). We find a close correlation between the waiting-time power-law slope <jats:italic>α</jats:italic> <jats:sub> <jats:italic>τ</jats:italic> </jats:sub> and the sunspot number (SN), i.e., <jats:italic>α</jats:italic> <jats:sub> <jats:italic>τ</jats:italic> </jats:sub> = 1.38 + 0.01 × SN. The waiting-time distribution can be fitted with a Pareto-type function of the form <jats:italic>N</jats:italic>(<jats:italic>τ</jats:italic>) = <jats:italic>N</jats:italic> <jats:sub>0</jats:sub> <jats:inline-formula> <jats:tex-math> <?CDATA ${({\tau }_{0}+\tau )}^{-{\alpha }_{\tau }}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabef69ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>, where the offset <jats:italic>τ</jats:italic> <jats:sub>0</jats:sub> depends on the instrumental sensitivity, the detection threshold of events, and pulse pileup effects. The time-dependent power-law slope <jats:italic>α</jats:italic> <jats:sub> <jats:italic>τ</jats:italic> </jats:sub>(<jats:italic>t</jats:italic>) of waiting-time distributions depends only on the global solar magnetic flux (quantified by the sunspot number) or flaring rate, which is not predicted by self-organized criticality or magnetohydrodynamic turbulence models. Power-law slopes of <jats:italic>α</jats:italic> <jats:sub> <jats:italic>τ</jats:italic> </jats:sub> ≈ 1.2–1.6 were also found in solar wind switchback events, as observed with the Parker Solar Probe during the solar minimum, while steeper slopes are predicted during the solar maximum. We find that the annual variability of switchback events in the heliospheric solar wind and solar flare and CME rates (originating in the photosphere and lower corona) are highly correlated.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present X-ray and multiband optical observations of the afterglow and host galaxy of GRB 180418A, discovered by Swift/BAT and Fermi/GBM. We present a reanalysis of the GBM and BAT data deriving durations of the prompt emission of <jats:italic>T</jats:italic> <jats:sub>90</jats:sub> ≈ 2.56 and 1.90 s, respectively. Modeling the Fermi/GBM catalog of 1405 bursts (2008–2014) in the hardness–<jats:italic>T</jats:italic> <jats:sub>90</jats:sub> plane, we obtain a probability of ≈60% that GRB 180418A is a short-hard burst. From a combination of Swift/XRT and Chandra observations, the X-ray afterglow is detected to ≈38.5 days after the burst and exhibits a single power-law decline with <jats:italic>F</jats:italic> <jats:sub>X</jats:sub> ∝ <jats:italic>t</jats:italic> <jats:sup>−0.98</jats:sup>. Late-time Gemini observations reveal a faint <jats:italic>r</jats:italic> ≈ 25.69 mag host galaxy at an angular offset of ≈0.″16. At the likely redshift range of <jats:italic>z</jats:italic> ≈ 1–2.25, we find that the X-ray afterglow luminosity of GRB 180418A is intermediate between short and long gamma-ray bursts (GRBs) at all epochs during which there are contemporaneous data and that GRB 180418A lies closer to the <jats:italic>E</jats:italic> <jats:sub> <jats:italic>γ</jats:italic>,peak</jats:sub>–<jats:italic>E</jats:italic> <jats:sub> <jats:italic>γ</jats:italic>,iso</jats:sub> correlation for short GRBs. Modeling the multiwavelength afterglow with the standard synchrotron model, we derive the burst explosion properties and find a jet opening angle of <jats:italic>θ</jats:italic> <jats:sub>j</jats:sub> ≳ 9°–14°. If GRB 180418A is a short GRB that originated from a neutron star merger, it has one of the brightest and longest-lived afterglows along with an extremely faint host galaxy. If, instead, the event is a long GRB that originated from a massive star collapse, it has among the lowest-luminosity afterglows and lies in a peculiar space in terms of the hardness–<jats:italic>T</jats:italic> <jats:sub>90</jats:sub> and <jats:italic>E</jats:italic> <jats:sub> <jats:italic>γ</jats:italic>,peak</jats:sub>–<jats:italic>E</jats:italic> <jats:sub> <jats:italic>γ</jats:italic>,iso</jats:sub> planes.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Infrared interferometry has led to a paradigm shift in our understanding of the dusty structure in the central parsecs of active galactic nuclei (AGNs). The dust is now thought to comprise a hot (∼1000 K) equatorial disk, some of which is blown into a cooler (∼300 K) polar dusty wind by radiation pressure. In this paper, we utilize the new near-IR interferometer GRAVITY on the Very Large Telescope Interferometer (VLTI) to study a Type 1.2 AGNs hosted in the nearby Seyfert galaxy ESO 323-G77. By modeling the squared visibility and closure phase, we find that the hot dust is equatorially extended, consistent with the idea of a disk, and shows signs of asymmetry in the same direction. Furthermore, the data is fully consistent with the hot dust size determined by <jats:italic>K</jats:italic>-band reverberation mapping as well as the predicted size from a CAT3D-WIND model created in previous work using the spectral energy distribution of ESO 323-G77 and observations in the mid-IR from VLTI/MID-infrared Interferometric instrument).</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Using EUV images and line-of-sight magnetograms from Solar Dynamics Observatory, we examine eight emerging bipolar magnetic regions (BMRs) in central-disk coronal holes for whether the emerging magnetic arch made any noticeable coronal jets directly, via reconnection with ambient open field as modeled by Yokoyama &amp; Shibata. During emergence, each BMR produced no obvious EUV coronal jet of normal brightness, but each produced one or more faint EUV coronal jets that are discernible in AIA 193 Å images. The spires of these jets are much fainter and usually narrower than for typical EUV jets that have been observed to be produced by minifilament eruptions in quiet regions and coronal holes. For each of 26 faint jets from the eight emerging BMRs, we examine whether the faint spire was evidently made a la Yokoyama &amp; Shibata. We find that (1) 16 of these faint spires evidently originate from sites of converging opposite-polarity magnetic flux and show base brightenings like those in minifilament-eruption-driven coronal jets, (2) the 10 other faint spires <jats:italic>maybe</jats:italic> were made by a burst of the external-magnetic-arcade-building reconnection of the emerging magnetic arch with the ambient open field, with reconnection directly driven by the arch's emergence, but (3) <jats:italic>none</jats:italic> were unambiguously made by such emergence-driven reconnection. Thus, for these eight emerging BMRs, the observations indicate that emergence-driven external reconnection of the emerging magnetic arch with ambient open field <jats:italic>at most</jats:italic> produces a jet spire that is much fainter than in previously reported, much more obvious coronal jets driven by minifilament eruptions.</jats:p>