Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>Chang’e-4 landed in the Von Kármán basaltic zone affected by Finsen ejecta from the South Pole-Aitken (SPA) “compositional anomaly” (SPACA), providing an opportunity to untangle the origin of the SPACA. We developed a mineral abundance unmixing model and built a spectral library composed of mineral mixtures of plagioclase, low-Ca pyroxene, high-Ca pyroxene, and olivine. Based on the mineral abundances returned by our model, the average plagioclase abundance (60.4 vol.%) of SPACA is beyond the high-plagioclase end of the mineralogical range of SPA impact melt differentiation products and would require an additional contribution from crustal materials. We suggest that either the crust was not entirely removed in the SPA-forming impact or the ejecta from post-SPA basins fed feldspathic materials back onto the SPA basin floor. Our unmixing analyses indicate that the surface regolith of the SPACA is a mixture of 70.2% crustal materials and 29.8% Fe- and incompatible-element-enriched materials.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The James Webb Space Telescope (JWST) will open a new window into the most distant universe and unveil the early growth of supermassive black holes (BHs) in the first galaxies. In preparation for deep JWST imaging surveys, it is crucial to understand the color selection of high-redshift accreting seed BHs. We model the spectral energy distribution of super-Eddington accreting BHs with millions of solar masses in metal-poor galaxies at <jats:italic>z</jats:italic> ≳ 8, applying postprocess line transfer calculations to radiation hydrodynamical simulation results. Exposures of 10 ks with the NIRCam and MIRI broadband filters are sufficient to detect the radiation flux from the seed BHs with bolometric luminosities of <jats:italic>L</jats:italic> <jats:sub>bol</jats:sub> ≃ 10<jats:sup>45</jats:sup> erg s<jats:sup>−1</jats:sup>. While the continuum colors are similar to those of typical low-<jats:italic>z</jats:italic> quasars, strong H<jats:italic>α</jats:italic> line emission with a rest-frame equivalent width EW<jats:sub>rest</jats:sub> ≃ 1300 Å is so prominent that the line flux affects the broadband colors significantly. The unique colors, for instance, F356W − F560W ≳ 1 at 7 &lt; <jats:italic>z</jats:italic> &lt; 8 and F444W − F770W ≳ 1 at 9 &lt; <jats:italic>z</jats:italic> &lt; 12, provide robust criteria for photometric selection of rapidly growing seed BHs. Moreover, NIRSpec observations of low-ionization emission lines can test whether the BH is fed via a dense accretion disk at super-Eddington rates.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report new VLA and e-MERLIN high-resolution and -sensitivity images of the triple radio continuum source in the Serpens star-forming region. These observations allowed us to perform a deep multifrequency, multiepoch study by exploring the innermost regions (≲100 au) of an intermediate-mass young stellar object for the first time, with a physical resolution of ∼15 au. The kinematic analysis of knots recently ejected by the protostar indicates that the jet is undergoing episodic variations in velocity. In addition, our multifrequency images reveal striking characteristics, e.g., a highly collimated ionized stream that would be launched at a radial distance of ∼0.4 au from the protostar and a narrow (∼28 au wide) ionized cavity that would be excited by the interaction of a wide-angle component with the surrounding toroid of infalling material. In light of these results, we propose the scenario in which both a highly collimated jet and a wide-angle wind coexist as the most plausible to explain our observations, either launched by the X-wind or X-plus-disk-wind mechanism.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Recent observations have shown that besides the characteristic multimillion degree component, the corona also contains a large amount of cool material called coronal rain, whose clumps are 10–100 times cooler and denser than the surroundings and are often organized in larger events, termed showers. Thermal instability (TI) within a coronal loop in a state of thermal nonequilibrium (TNE) is the leading mechanism behind the formation of coronal rain but no investigation on showers exists to date. In this study, we conduct a morphological and thermodynamic multiwavelength study of coronal rain showers observed in an active region (AR) off-limb with IRIS and the Solar Dynamics Observatory, spanning chromospheric to transition region and coronal temperatures. Rain showers were found to be widespread across the AR over the 5.45 hr observing time, with an average length, width, and duration of 27.37 ± 11.95 Mm, 2.14 ± 0.74 Mm, and 35.22 ± 20.35 minutes, respectively. We find a good correspondence between showers and the cooling coronal structures consistent with the TNE–TI scenario, thereby properly identifying coronal loops in the “coronal veil”, including the strong expansion at low heights and an almost zero expansion in the corona. This agrees with previous work suggesting that the observed zero expansion in the EUV is due to specific cross-field temperature distribution. We estimate the total number of showers to be 155 ± 40, leading to a TNE volume of 4.56 ± [3.71] × 10<jats:sup>28</jats:sup> cm<jats:sup>3</jats:sup>, i.e., on the same order of the AR volume. This suggests a prevalence of TNE over the AR indicating strongly stratified and high-frequency heating on average.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report the observation of nonstationary quasi-periodic pulsations (QPPs) in high-energy particles during the impulsive phase of an X4.8 flare on 2002 July 23 (SOL2002-07-23T00:35). The X4.8 flare was simultaneously measured by the Reuven Ramaty High Energy Solar Spectroscopic Imager, Nobeyama Radio Polarimeters, and Nobeyama Radioheliograph. The quasi-period of ∼50 ± 15 s, determined by the wavelet transform, is detected in the <jats:italic>γ</jats:italic>-ray line emission. Using the same method, a quasi-period of ∼90 ± 20 s is found in the <jats:italic>γ</jats:italic>-ray continuum, hard X-ray (HXR), and radio emissions during almost the same time. Our observations suggest that the flare QPPs should be associated with energetic ions and nonthermal electrons that are quasi-periodically accelerated by the repetitive magnetic reconnection. The different quasi-periods between the <jats:italic>γ</jats:italic>-ray line and continuum/HXR/radio emissions indicate an apparent difference in acceleration or propagation between energetic ions and nonthermal electrons of this solar flare.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Originally proposed as a cosmological probe of the large-scale structure, line intensity mapping (LIM) also offers a unique window into the astrophysics of galaxy evolution. Adding to the astrophysical explorations of the LIM technique that have traditionally focused on small, nonlinear scales, we present a novel method to study the global star formation law using forthcoming data from large-scale baryonic acoustic oscillation (BAO) intensity mapping. Using the amplitude of the percent-level but scale-dependent bias induced by baryon fraction fluctuations on BAO scales, we show that combining auto- and cross-correlation power spectra of two (or more) LIM signals allows to probe the star formation law power index <jats:inline-formula> <jats:tex-math> <?CDATA ${ \mathcal N }$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="italic"></mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjlac7138ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>. We examine the prospect for mapping H<jats:italic>α</jats:italic> and [O <jats:sc>iii</jats:sc>] lines across all scales, especially where imprints of the baryon fraction deviation exist, with space missions like SPHEREx. We show that although SPHEREx may only marginally probe <jats:inline-formula> <jats:tex-math> <?CDATA ${ \mathcal N }$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="italic"></mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjlac7138ieqn2.gif" xlink:type="simple" /> </jats:inline-formula> by accessing a modest number of large-scale modes in its 200 deg<jats:sup>2</jats:sup> deep survey, future infrared all-sky surveys reaching a comparable depth with an improved spectral resolution (<jats:italic>R</jats:italic> ≳ 400) are likely to constrain <jats:inline-formula> <jats:tex-math> <?CDATA ${ \mathcal N }$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="italic"></mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjlac7138ieqn3.gif" xlink:type="simple" /> </jats:inline-formula> to a precision of 10%–30%, sufficient for distinguishing models with varying feedback assumptions, out to <jats:italic>z</jats:italic> ∼ 4 using BAO intensity mapping. Leveraging this effect, large, cosmic-variance-limited LIM surveys in the far future can scrutinize the physical connection between galaxy evolution and the large-scale cosmological environment, while performing stringent tests of the standard cosmological model.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Recent ultrahigh-energy gamma-ray observations by the High Altitude Water Cherenkov Observatory up to 100 TeV and LHAASO observatories up to 1.4 PeV energies from the direction of Fermi Large Area Telescope 4FGL source 4FGL J2028.6 + 4110e (Cygnus Cocoon) are indicative of a hadronic origin over a leptonic process for their creation. The IceCube Neutrino Observatory has reported IceCube-201120A, a neutrino event coming from the same direction, suggesting that the Cygnus Cocoon may correspond to one of the most plausible sources of high-energy cosmic rays. The apparent relationship of the neutrino event with the observed ultrahigh-energy gamma rays from the Cygnus Cocoon is investigated in this work to study if it can be explained consistently in hadronic interactions of accelerated cosmic rays with ambient matter. Our findings reveal that leptonic mechanisms, together with pure hadronic mechanisms, make a considerable contribution to the understanding of the total electromagnetic spectrum as well as the observed neutrino event. The estimate of expected muon neutrino events from the Cygnus Cocoon agrees with the one muon neutrino event detected so far in IceCube multiyear observations. Thus, our results are indicative of the potential of the Cygnus Cocoon to be a Galactic cosmic-ray source capable of accelerating at least up to PeV energies.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present high-resolution (≲160 au) Atacama Large Millimeter/submillimeter Array (ALMA) 1.3 mm observations of the high-mass prestellar core candidate G11.92−0.61 MM2, which reveal that this source is in fact a protobinary system with a projected separation of 505 au. The binary components, MM2E and MM2W, are compact (radii &lt;140 au) sources within the partially optically thick dust emission with <jats:italic>α</jats:italic> <jats:sub>0.9 cm−1.3 mm</jats:sub> = 2.47–2.94. The 1.3 mm brightness temperatures, <jats:italic>T</jats:italic> <jats:sub>b</jats:sub> = 68.4/64.6 K for MM2E/MM2W, imply internal heating and minimum luminosities <jats:italic>L</jats:italic> <jats:sub>*</jats:sub> &gt; 24.7 <jats:italic>L</jats:italic> <jats:sub>⊙</jats:sub> for MM2E and <jats:italic>L</jats:italic> <jats:sub>*</jats:sub> &gt; 12.6 <jats:italic>L</jats:italic> <jats:sub>⊙</jats:sub> for MM2W. The compact sources are connected by a “bridge” of lower-surface-brightness dust emission and lie within more extended emission that may correspond to a circumbinary disk. The circumprotostellar gas mass, estimated from ∼0.″2 resolution VLA 0.9 cm observations assuming optically thin emission, is 6.8 ± 0.9 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>. No line emission is detected toward MM2E and MM2W in our high-resolution 1.3 mm ALMA observations. The only line detected is <jats:sup>13</jats:sup>CO <jats:italic>J</jats:italic> = 2–1, in absorption against the 1.3 mm continuum, which likely traces a layer of cooler molecular material surrounding the protostars. We also report the discovery of a highly asymmetric bipolar molecular outflow that appears to be driven by MM2E and/or MM2W in new deep, ∼0.″5 resolution (1685 au) ALMA 0.82 mm observations. This outflow, traced by low-excitation CH<jats:sub>3</jats:sub>OH emission, indicates ongoing accretion onto the protobinary system. Overall, the super-Alfvénic models of Mignon-Risse et al. agree well with the observed properties of the MM2E/MM2W protobinary, suggesting that this system may be forming in an environment with a weak magnetic field.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Current sheets (CSs), long stretching structures of magnetic reconnection above solar flare loops, are usually observed to oscillate; their origins, however, are still puzzled at present. Based on a high-resolution 2.5D MHD simulation of magnetic reconnection, we explore the formation mechanism of CS oscillations. We find that large-amplitude transverse waves are excited by the Kelvin–Helmholtz instability at the highly turbulent cusp-shaped region. The perturbations propagate upward along the CS with a phase speed close to local Alfvén speed thus resulting in the CS oscillations we observe. Though the perturbations damp after propagating for a long distance, the CS oscillations are still detectable. In terms of detected CS oscillations, with a combination of differential emission measure techniques, we propose a new method for measuring the magnetic field strength of the CS and its distribution in height.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The successive addition of H atoms to CO in the solid phase has been hitherto regarded as the primary route to form methanol in dark molecular clouds. However, recent Monte Carlo simulations of interstellar ices alternatively suggested the radical-molecule H-atom abstraction reaction CH<jats:sub>3</jats:sub>O + H<jats:sub>2</jats:sub>CO → CH<jats:sub>3</jats:sub>OH + HCO, in addition to CH<jats:sub>3</jats:sub>O + H → CH<jats:sub>3</jats:sub>OH, as a very promising and possibly dominating (70%–90%) final step to form CH<jats:sub>3</jats:sub>OH in those environments. Here, we compare the contributions of these two steps leading to methanol by experimentally investigating hydrogenation reactions on H<jats:sub>2</jats:sub>CO and D<jats:sub>2</jats:sub>CO ices, which ensures comparable starting points between the two scenarios. The experiments are performed under ultrahigh vacuum conditions and astronomically relevant temperatures, with H:H<jats:sub>2</jats:sub>CO (or D<jats:sub>2</jats:sub>CO) flux ratios of 10:1 and 30:1. The radical-molecule route in the partially deuterated scenario, CHD<jats:sub>2</jats:sub>O + D<jats:sub>2</jats:sub>CO → CHD<jats:sub>2</jats:sub>OD + DCO, is significantly hampered by the isotope effect in the D-abstraction process, and can thus be used as an artifice to probe the efficiency of this step. We observe a significantly smaller yield of D<jats:sub>2</jats:sub>CO + H products in comparison to H<jats:sub>2</jats:sub>CO + H, implying that the CH<jats:sub>3</jats:sub>O-induced abstraction route must play an important role in the formation of methanol in interstellar ices. Reflection-absorption infrared spectroscopy and temperature-programmed desorption-quadrupole mass spectrometry analyses are used to quantify the species in the ice. Both analytical techniques indicate constant contributions of ∼80% for the abstraction route in the 10–16 K interval, which agrees well with the Monte Carlo calculations. Additional H<jats:sub>2</jats:sub>CO + D experiments confirm these conclusions.</jats:p>