Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>Using high-resolution H<jats:italic>α</jats:italic> data from the 1 m New Vacuum Solar Telescope, combined with multiband Atmospheric Imaging Assembly extreme ultraviolet observations and Helioseismic and Magnetic Imager light-of-sight magnetograms from the Solar Dynamical Observatory, we study a quiet-Sun filament eruption on 2019 November 1. During the erupting process, the filament was blocked by at least three sets of surrounding loops (L1–L3). The magnetic field direction of L2 is opposite to that of the top segment of the erupting filament. While the top segment contacted L2, a current sheet formed between L2 and the top segment. Then, magnetic reconnection took place, resulting in the destruction of L2 and the filament. On the other hand, the magnetic field direction of L1 is the same as that of the left leg of the erupting filament, and that of L3 is the same as that of the right leg. The left leg expanded eastward and met L1, then it stopped. The right leg expanded westward and collided with L3. It rebounded and finally stopped at the interaction region. These observations imply that the magnetic field directions of the surrounding magnetic structures are a key parameter for confining a filament eruption. While the field direction of a surrounding structure is the same as that of an eruptive filament, the filament is confined.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The postmerger gravitational wave (GW) emission from a binary neutron star merger is expected to provide exciting new constraints on the dense-matter equation of state (EoS). Such constraints rely, by and large, on the existence of quasi-universal relations, which relate the peak frequencies of the postmerger GW spectrum to properties of the neutron star structure in a model-independent way. In this work, we report on violations of existing quasi-universal relations between the peak spectral frequency, <jats:italic>f</jats:italic> <jats:sub>2</jats:sub>, and the stellar radius, for EoS models with backwards-bending slopes in their mass–radius relations (such that the radius increases at high masses). The violations are extreme, with variations in <jats:italic>f</jats:italic> <jats:sub>2</jats:sub> of up to ∼600 Hz between EoSs that predict the same radius for a 1.4 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> neutron star but that have significantly different radii at higher masses. Quasi-universality can be restored by adding in a second parameter to the fitting formulae that depends on the slope of the mass–radius curve. We further find strong evidence that quasi-universality is better maintained for the radii of very massive stars (with masses 2 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>). Both statements imply that <jats:italic>f</jats:italic> <jats:sub>2</jats:sub> is mainly sensitive to the high-density EoS. Combined with observations of the binary neutron star inspiral, these generalized quasi-universal relations can be used to simultaneously infer the characteristic radius and slope of the neutron star mass–radius relation.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Carbon dioxide is an important tracer of the chemistry and physics in the terrestrial planet-forming zone. Using a thermochemical model that has been tested against the mid-infrared water emission, we reinterpret the CO<jats:sub>2</jats:sub> emission as observed with Spitzer. We find that both water UV-shielding and extra chemical heating significantly reduce the total CO<jats:sub>2</jats:sub> column in the emitting layer. Water UV-shielding is the more efficient effect, reducing the CO<jats:sub>2</jats:sub> column by ∼2 orders of magnitude. These lower CO<jats:sub>2</jats:sub> abundances lead to CO<jats:sub>2</jats:sub>-to-H<jats:sub>2</jats:sub>O flux ratios that are closer to the observed values, but CO<jats:sub>2</jats:sub> emission is still too bright, especially in relative terms. Invoking the depletion of elemental oxygen outside of the water midplane ice line more strongly impacts the CO<jats:sub>2</jats:sub> emission than it does the H<jats:sub>2</jats:sub>O emission, bringing the CO<jats:sub>2</jats:sub>-to-H<jats:sub>2</jats:sub>O emission in line with the observed values. We conclude that the CO<jats:sub>2</jats:sub> emission observed with Spitzer-IRS is coming from a thin layer in the photosphere of the disk, similar to the strong water lines. Below this layer, we expect CO<jats:sub>2</jats:sub> not to be present except when replenished by a physical process. This would be visible in the <jats:sup>13</jats:sup>CO<jats:sub>2</jats:sub> spectrum as well as certain <jats:sup>12</jats:sup>CO<jats:sub>2</jats:sub> features that can be observed by JWST-MIRI.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The possible existence of primordial black holes in the stellar-mass window has received considerable attention because their mergers may contribute to current and future gravitational-wave detections. Primordial black hole mergers, together with mergers of black holes originating from Population III stars, are expected to dominate at high redshifts (<jats:italic>z</jats:italic> ≳ 10). However, the primordial black hole merger rate density is expected to rise monotonically with redshift, while Population III mergers can only occur after the birth of the first stars. Next-generation gravitational-wave detectors such as the Cosmic Explorer (CE) and Einstein Telescope (ET) can access this distinctive feature in the merger rates as functions of redshift, allowing for direct measurement of the abundance of the two populations and hence for robust constraints on the abundance of primordial black holes. We simulate four months’ worth of data observed by a CE-ET detector network and perform hierarchical Bayesian analysis to recover the merger rate densities. We find that if the universe has no primordial black holes with masses of <jats:inline-formula> <jats:tex-math> <?CDATA ${ \mathcal O }(10{M}_{\odot })$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="italic"></mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:mn>10</mml:mn> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> <mml:mo stretchy="false">)</mml:mo> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjlac7aaeieqn1.gif" xlink:type="simple" /> </jats:inline-formula>, the projected upper limit on their abundance <jats:italic>f</jats:italic> <jats:sub>PBH</jats:sub> as a fraction of dark matter energy density may be as low as <jats:inline-formula> <jats:tex-math> <?CDATA ${f}_{\mathrm{PBH}}\sim { \mathcal O }({10}^{-5})$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>f</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>PBH</mml:mi> </mml:mrow> </mml:msub> <mml:mo>∼</mml:mo> <mml:mi mathvariant="italic"></mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>5</mml:mn> </mml:mrow> </mml:msup> <mml:mo stretchy="false">)</mml:mo> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjlac7aaeieqn2.gif" xlink:type="simple" /> </jats:inline-formula>, about two orders of magnitude lower than the current upper limits in this mass range. If instead <jats:italic>f</jats:italic> <jats:sub>PBH</jats:sub> ≳ 10<jats:sup>−4</jats:sup>, future gravitational-wave observations would exclude <jats:italic>f</jats:italic> <jats:sub>PBH</jats:sub> = 0 at the 95% credible interval.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report a Karl G. Jansky Very Large Array search for redshifted CO(1–0) emission from three H <jats:sc>i</jats:sc>-absorption-selected galaxies at <jats:italic>z</jats:italic> ≈ 2, identified earlier in their CO(3–2) or CO(4–3) emission. We detect CO(1–0) emission from DLA B1228-113 at <jats:italic>z</jats:italic> ≈ 2.1933 and DLA J0918+1636 at <jats:italic>z</jats:italic> ≈ 2.5848; these are the first detections of CO(1–0) emission in high-<jats:italic>z</jats:italic> H <jats:sc>i</jats:sc>-selected galaxies. We obtain high molecular gas masses, <jats:italic>M</jats:italic> <jats:sub>mol</jats:sub> ≈ 10<jats:sup>11</jats:sup> × (<jats:italic>α</jats:italic> <jats:sub>CO</jats:sub>/4.36) <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, for the two objects with CO(1–0) detections, which are a factor of ≈1.5–2 lower than earlier estimates. We determine the excitation of the mid<jats:italic>-J</jats:italic> CO rotational levels relative to the <jats:italic>J</jats:italic> = 1 level, <jats:italic>r</jats:italic> <jats:sub> <jats:italic>J</jats:italic>1</jats:sub>, in H <jats:sc>i</jats:sc>-selected galaxies for the first time, obtaining <jats:italic>r</jats:italic> <jats:sub>31</jats:sub> = 1.00 ± 0.20 and <jats:italic>r</jats:italic> <jats:sub>41</jats:sub> = 1.03 ± 0.23 for DLA J0918+1636, and <jats:italic>r</jats:italic> <jats:sub>31</jats:sub> = 0.86 ± 0.21 for DLA B1228-113. These values are consistent with thermal excitation of the <jats:italic>J</jats:italic> = 3 and <jats:italic>J</jats:italic> = 4 levels. The excitation of the <jats:italic>J</jats:italic> = 3 level in the H <jats:sc>i</jats:sc>-selected galaxies is similar to that seen in massive main-sequence and submillimeter galaxies at <jats:italic>z</jats:italic>≳2, but higher than that in main-sequence galaxies at <jats:italic>z</jats:italic> ≈ 1.5; the higher excitation of the galaxies at <jats:italic>z</jats:italic> ≳ 2 is likely to be due to their higher star formation rate (SFR) surface density. We use Hubble Space Telescope Wide Field Camera 3 imaging to detect the rest-frame near-ultraviolet (NUV) emission of DLA B1228-113, obtaining an NUV SFR of 4.44 ± 0.47 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> yr<jats:sup>−1</jats:sup>, significantly lower than that obtained from the total infrared luminosity, indicating significant dust extinction in the <jats:italic>z</jats:italic> ≈ 2.1933 galaxy.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Neutrinos are the most elusive particles in the universe, capable of traveling nearly unimpeded across it. Despite the vast amount of data collected, a long-standing and unsolved issue is still the association of high-energy neutrinos with the astrophysical sources that originate them. Among the candidate sources of neutrinos, there are blazars, a class of extragalactic sources powered by supermassive black holes that feed highly relativistic jets, pointed toward Earth. Previous studies appear controversial, with several efforts claiming a tentative link between high-energy neutrino events and individual blazars, and others putting into question such relation. In this work, we show that blazars are unambiguously associated with high-energy astrophysical neutrinos at an unprecedented level of confidence, i.e., a chance probability of 6 × 10<jats:sup>−7</jats:sup>. Our statistical analysis provides the observational evidence that blazars are astrophysical neutrino factories and hence, extragalactic cosmic-ray accelerators.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Cometary activity may be driven by ices with very low sublimation temperatures, such as carbon monoxide ice, which can sublimate at distances well beyond 20 au. This point is emphasized by the discovery of the Oort cloud comet C/2014 UN<jats:sub>271</jats:sub> (Bernardinelli–Bernstein) and its observed activity out to ∼26 au. Through observations of this comet’s optical brightness and behavior, we can potentially discern the drivers of activity in the outer solar system. We present a study of the activity of comet Bernardinelli–Bernstein with broad-band optical photometry taken at 19–20 au from the Sun (2021 June to 2022 February) as part of the LCO Outbursting Objects Key (LOOK) Project. Our analysis shows that the comet’s optical brightness during this period was initially dominated by cometary outbursts, stochastic events that ejected ∼10<jats:sup>7</jats:sup> to ∼10<jats:sup>8</jats:sup> kg of material on short (&lt;1 day) timescales. We present evidence for three such outbursts occurring in 2021 June and September. The nominal nuclear volumes excavated by these events are similar to the 10–100 m pit-shaped voids on the surfaces of short-period comet nuclei, as imaged by spacecraft. Two out of three Oort cloud comets observed at large pre-perihelion distances exhibit outburst behavior near 20 au, suggesting such events may be common in this population. In addition, quiescent CO-driven activity may account for the brightness of the comet in 2022 January to February, but that variations in the cometary active area (i.e., the amount of sublimating ice) with heliocentric distance are also possible.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present high-cadence optical and ultraviolet light curves of the normal Type Ia supernova (SN) 2021aefx, which shows an early bump during the first two days of observation. This bump may be a signature of interaction between the exploding white dwarf and a nondegenerate binary companion, or it may be intrinsic to the white dwarf explosion mechanism. In the case of the former, the short duration of the bump implies a relatively compact main-sequence companion star, although this conclusion is viewing-angle dependent. Our best-fit companion-shocking and double-detonation models both overpredict the UV luminosity during the bump, and existing nickel-shell models do not match the strength and timescale of the bump. We also present nebular spectra of SN 2021aefx, which do not show the hydrogen or helium emission expected from a nondegenerate companion, as well as a radio nondetection that rules out all symbiotic progenitor systems and most accretion disk winds. Our analysis places strong but conflicting constraints on the progenitor of SN 2021aefx; no current model can explain all of our observations.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We study the sensitivity of the <jats:italic>z</jats:italic> = 0.1 Ly<jats:italic>α</jats:italic> forest observables, such as the column density distribution function (CDD), flux PDF, flux power spectrum, and line-width distribution, to subgrid models of active galactic nucleus (AGN) feedback using the Illustris and IllustrisTNG (TNG) cosmological simulations. The two simulations share an identical ultraviolet background (UVB) prescription and similar cosmological parameters, but TNG features an entirely reworked AGN feedback model. Due to changes in the AGN radio-mode model, the original Illustris simulations have a factor of 2–3 fewer Ly<jats:italic>α</jats:italic> absorbers than TNG at column densities <jats:italic>N</jats:italic> <jats:sub>H <jats:sc>i</jats:sc> </jats:sub> &lt; 10<jats:sup>15.5</jats:sup> cm<jats:sup>−2</jats:sup>. We compare the simulated forest statistics to UV data from the Cosmic Origins Spectrograph (COS) and find that neither simulation can reproduce the slope of the absorber distribution. Both Illustris and TNG also produce significantly smaller line-width distributions than observed in the COS data. We show that TNG is in much better agreement with the observed <jats:italic>z</jats:italic> = 0.1 flux power spectrum than Illustris. We explore which statistics can disentangle the effects of AGN feedback from alternative UVB models by rescaling the UVB of Illustris to produce a CDD match to TNG. While this UVB rescaling is degenerate with the effect of AGN feedback on the CDD, the amplitude and shape of the flux PDF and 1D flux power spectrum change in a way distinct from the scaling of the UVB. Our study suggests that the <jats:italic>z</jats:italic> = 0.1 Ly<jats:italic>α</jats:italic> forest observables can be used as a diagnostic of AGN feedback models.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Coronal bright points (CBPs) are ubiquitous structures in the solar atmosphere composed of hot small-scale loops observed in extreme-ultraviolet (EUV) or X-rays in the quiet Sun and coronal holes. They are key elements to understanding the heating of the corona; nonetheless, basic questions regarding their heating mechanisms, the chromosphere underneath, or the effects of flux emergence in these structures remain open. We have used the Bifrost code to carry out a 2D experiment in which a coronal-hole magnetic null-point configuration evolves perturbed by realistic granulation. To compare with observations, synthetic SDO/AIA, Solar Orbiter EUI-HRI, and IRIS images have been computed. The experiment shows the self-consistent creation of a CBP through the action of stochastic granular motions alone, mediated by magnetic reconnection in the corona. The reconnection is intermittent and oscillatory, and it leads to coronal and transition-region temperature loops that are identifiable in our EUV/UV observables. During the CBP lifetime, convergence and cancellation at the surface of its underlying opposite polarities takes place. The chromosphere below the CBP shows a number of peculiar features concerning its density and the spicules in it. The final stage of the CBP is eruptive: Magnetic flux emergence at the granular scale disrupts the CBP topology, leading to different ejections, such as UV bursts, surges, and EUV coronal jets. Apart from explaining observed CBP features, our results pave the way for further studies combining simulations and coordinated observations in different atmospheric layers.</jats:p>