Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>Radiative transfer (RT) is a key component for investigating atmospheres of planetary bodies. With the 3D nature of exoplanet atmospheres being important in giving rise to their observable properties, accurate and fast 3D methods are required to be developed to meet future multidimensional and temporal data sets. We develop an open-source GPU RT code, gCMCRT, a Monte Carlo RT forward model for general use in planetary atmosphere RT problems. We aim to automate the post-processing pipeline, starting from direct global circulation model (GCM) output to synthetic spectra. We develop albedo, emission, and transmission spectra modes for 3D and 1D input structures. We include capability to use correlated-<jats:italic>k</jats:italic> and high-resolution opacity tables, the latter of which can be Doppler-shifted inside the model. We post-process results from several GCM groups, including ExoRad, SPARC/MITgcm THOR, UK Met Office UM, Exo-FMS, and the Rauscher model. Users can therefore take advantage of desktop and HPC GPU computing solutions. gCMCRT is well suited for post-processing large GCM model grids produced by members of the community and for high-resolution 3D investigations.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Stellar flares are characterized by sudden enhancement of electromagnetic radiation in stellar atmospheres. So far, much of our understanding of stellar flares has come from photometric observations, from which plasma motions in flare regions could not be detected. From the spectroscopic data of LAMOST DR7, we have found one stellar flare that is characterized by an impulsive increase followed by a gradual decrease in the H<jats:italic>α</jats:italic> line intensity on an M4-type star, and the total energy radiated through H<jats:italic>α</jats:italic> is estimated to be of the order of 10<jats:sup>33</jats:sup> erg. The H<jats:italic>α</jats:italic> line appears to have a Voigt profile during the flare, which is likely caused by Stark pressure broadening due to the dramatic increase in electron density and/or opacity broadening due to the occurrence of strong nonthermal heating. Obvious enhancement has been identified in the red wing of the H<jats:italic>α</jats:italic> line profile after the impulsive increase in the H<jats:italic>α</jats:italic> line intensity. The red-wing enhancement corresponds to plasma moving away from the Earth at a velocity of 100–200 km s<jats:sup>−1</jats:sup>. According to our current knowledge of solar flares, this red-wing enhancement may originate from: (1) flare-driven coronal rain, (2) chromospheric condensation, or (3) a filament/prominence eruption either with nonradial backward propagation or with strong magnetic suppression. The total mass of the moving plasma is estimated to be of the order of 10<jats:sup>15</jats:sup> kg.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Astrophysical jets, launched from the immediate vicinity of accreting black holes, carry away large amounts of power in a form of bulk kinetic energy of jet particles and electromagnetic flux. Here we consider a simple analytical model for relativistic jets at larger distances from their launching sites, assuming a cylindrical axisymmetric geometry with a radial velocity shear, and purely toroidal magnetic field. We argue that as long as the jet plasma is in magnetohydrostatic equilibrium, such outflows tend to be particle dominated, i.e., the ratio of the electromagnetic to particle energy flux, integrated over the jet cross-sectional area, is typically below unity, <jats:italic>σ</jats:italic> &lt; 1. At the same time, for particular magnetic and radial velocity profiles, magnetic pressure may still dominate over particle pressure for certain ranges of the jet radius, i.e., the local jet plasma parameter <jats:italic>β</jats:italic> <jats:sub>pl</jats:sub> &lt; 1, and this may be relevant in the context of particle acceleration and production of high-energy emission in such systems. The jet magnetization parameter can be elevated up to the modest values of <jats:inline-formula> <jats:tex-math> <?CDATA $\sigma \lesssim { \mathcal O }(10)$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>σ</mml:mi> <mml:mo>≲</mml:mo> <mml:mi mathvariant="italic"></mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:mn>10</mml:mn> <mml:mo stretchy="false">)</mml:mo> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac634aieqn1.gif" xlink:type="simple" /> </jats:inline-formula> only in the case of extreme gradients or discontinuities in the gaseous pressure, and a significantly suppressed velocity shear. Such configurations, which consist of a narrow, unmagnetized jet spine surrounded by an extended, force-free layer, may require an additional poloidal field component to stabilize them against current-driven oscillations, but even this will not substantially elevate their <jats:italic>σ</jats:italic> parameter.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Many recent observational and theoretical studies suggest that globular clusters (GCs) host compact object populations large enough to play dominant roles in their overall dynamical evolution. Yet direct detection, particularly of black holes and neutron stars, remains rare and limited to special cases, such as when these objects reside in close binaries with bright companions. Here we examine the potential of microlensing detections to further constrain these dark populations. Based on state-of-the-art GC models from the <jats:monospace>CMC Cluster Catalog</jats:monospace>, we estimate the microlensing event rates for black holes, neutron stars, white dwarfs (WDs), and, for comparison, also for M dwarfs in Milky Way GCs, as well as the effects of different initial conditions on these rates. Among compact objects, we find that WDs dominate the microlensing rates, simply because they largely dominate by numbers. We show that microlensing detections are in general more likely in GCs with higher initial densities, especially in clusters that undergo core collapse. We also estimate microlensing rates in the specific cases of M22 and 47 Tuc using our best-fitting models for these GCs. Because their positions on the sky lie near the rich stellar backgrounds of the Galactic bulge and the Small Magellanic Cloud, respectively, these clusters are among the Galactic GCs best suited for dedicated microlensing surveys. The upcoming 10 yr survey with the Rubin Observatory may be ideal for detecting lensing events in GCs.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Observations indicate that the convective cores of stars must ingest a substantial amount of material from the overlying radiative zone, but the extent of this mixing and the mechanism that causes it remain uncertain. Recently, Anders et al. developed a theory of convective penetration and calibrated it with 3D numerical hydrodynamics simulations. Here we employ that theory to predict the extent of convective boundary mixing (CBM) in early-type main-sequence stars. We find that convective penetration produces enough mixing to explain core masses inferred from asteroseismology and eclipsing binary studies, and matches observed trends in mass and age. While there are remaining uncertainties in the theory, this agreement suggests that most CBM in early-type main-sequence stars arises from convective penetration. Finally, we provide a fitting formula for the extent of core convective penetration for main-sequence stars in the mass range from 1.1–60 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In this article, the central black hole (BH) mass in the distant tidal disruption event (TDE) of Swift J2058.4+0516, the second candidate of relativistic jet birth related to a TDE, is estimated. Swift J2058.4+0516 has quite different BH masses estimated through different indirect methods in the literature. Therefore, it is necessary and interesting to determine the central BH mass in Swift J2058.4+0516 by another independent method. Here, based on the theoretical TDE model applied to describe the long-term time-dependent X-ray variabilities of Swift J2058.4+0516, the central BH mass can be well determined to be around <jats:inline-formula> <jats:tex-math> <?CDATA ${1.05}_{-0.29}^{+0.39}\times {10}^{5}{M}_{\odot }$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>1.05</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.29</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.39</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo>×</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>5</mml:mn> </mml:mrow> </mml:msup> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac582cieqn1.gif" xlink:type="simple" /> </jats:inline-formula>, after considering the suggested intrinsic beaming effects from such relativistic jets tightly related to TDEs. Moreover, Swift J2058.4+0516 is a unique object in the space of BH masses versus energy transfer efficiencies of the reported TDE candidates, providing interesting clues to detect and/or anticipate candidates of relativistic TDEs that cause the birth of relativistic jets.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Based on the accurately calibrated interaction FSUGold, we show that including isovector-scalar <jats:italic>δ</jats:italic> meson and its coupling to isoscalar-scalar <jats:italic>σ</jats:italic> meson in the relativistic mean-field (RMF) model can soften the symmetry energy <jats:italic>E</jats:italic> <jats:sub>sym</jats:sub>(<jats:italic>n</jats:italic>) at intermediate densities while stiffening the <jats:italic>E</jats:italic> <jats:sub>sym</jats:sub>(<jats:italic>n</jats:italic>) at high densities. We find this new RMF model can be simultaneously compatible with (1) the constraints on the equation of state of symmetric nuclear matter at suprasaturation densities from flow data in heavy-ion collisions; (2) the neutron skin thickness of <jats:sup>208</jats:sup>Pb from the PREX-II experiment; (3) the largest mass of a neutron star (NS) reported so far from PSR J0740+6620; (4) the limit of Λ<jats:sub>1.4</jats:sub> ≤ 580 for the dimensionless tidal deformability of the canonical 1.4 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> NS from the gravitational-wave signal GW170817; (5) the mass–radius relation of PSR J0030+0451 and PSR J0740+6620 measured by NICER. The new model thus removes the tension between PREX-II and GW170817 observed in the conventional RMF model.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We analyze the energy dependence of the X-ray pulse profile and the phase-resolved spectra (PRS) of the Crab pulsar using observations from the Neutron star Interior Composition Explorer (NICER) and the Hard X-ray Modulation Telescope (Insight-HXMT). We parameterize the pulse profiles and quantify the evolution of these parameters in the broad energy band of 0.4–250 keV. A log-parabola function is used to fit the PRS in 2–250 keV, and the curvature of the spectrum, i.e., the evolution of the photon index with energy, as represented by the parameter <jats:italic>β</jats:italic> of the log-parabola model, also changes with phase. The relation of <jats:italic>β</jats:italic> and phase has two turning points slightly later than those of the pulse intensity profile, where the values of <jats:italic>β</jats:italic> are the lowest, suggesting that the energy-loss rate of the particles is the lowest in the corresponding regions. A three-segment broken-power-law model is also used to fit those PRS. The differences between the hard spectral index and the soft ones have a distribution similar to that of <jats:italic>β</jats:italic>, confirming the fitting results of the log-parabola model, while the broken energies are generally higher in the region bridging the two pulses. We find anticorrelations between the spectral indices and the curvature of the log-parabola model fitting and a similar anticorrelation between the spectral indices and broken energies of the broken-power-law model fitting, suggesting a scenario where the highest-energy particles are produced in regions where radiation energy loss is strongest.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a detailed multiwavelength follow-up of the nuclear radio flare VT J154843.06+220812.6, hereafter VT J1548. VT J1548 was selected as a ∼1 mJy radio flare in 3 GHz observations from the Very Large Array Sky Survey. It is located in the nucleus of a low-mass (<jats:inline-formula> <jats:tex-math> <?CDATA $\mathrm{log}{M}_{\mathrm{BH}}/{M}_{\odot }\sim 6$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>BH</mml:mi> </mml:mrow> </mml:msub> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> <mml:mo>∼</mml:mo> <mml:mn>6</mml:mn> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac5e29ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>) host galaxy with weak or no past active galactic nuclei (AGN) activity. VT J1548 is associated with a slow rising (multiple year), bright mid-IR flare in the Wide-field Infrared Survey Explorer survey, peaking at ∼10%<jats:italic>L</jats:italic> <jats:sub>edd.</jats:sub>. No associated optical transient is detected, although we cannot rule out a short, early optical flare given the limited data available. Constant late-time (∼3 yr post-flare) X-ray emission is detected at ∼10<jats:sup>42</jats:sup> erg s<jats:sup>−1</jats:sup>. The radio spectral energy distribution is consistent with synchrotron emission from an outflow incident on an asymmetric medium. A follow-up, optical spectrum shows transient, bright, high-ionization coronal line emission ([Fe <jats:sc>x</jats:sc> <jats:sc>i</jats:sc>] <jats:italic>λ</jats:italic>6375, [Fe <jats:sc>x</jats:sc> <jats:sc>i</jats:sc>] <jats:italic>λ</jats:italic>7894, [S <jats:sc>x</jats:sc> <jats:sc>i</jats:sc> <jats:sc>i</jats:sc>] <jats:italic>λ</jats:italic>7612). Transient broad H<jats:italic>α</jats:italic> is also detected but without corresponding broad H<jats:italic>β</jats:italic> emission, suggesting high nuclear extinction. We interpret this event as either a tidal disruption event or an extreme flare of an AGN, in both cases obscured by a dusty torus. Although these individual properties have been observed in previous transients, the combination is unprecedented. This event highlights the importance of searches across all wave bands for assembling a sample of nuclear flares that spans the range of observable properties and possible triggers.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The ultraluminous infrared galaxy IRAS 17208−0014 is a late-stage merger that hosts a buried active galactic nucleus (AGN). To investigate its nuclear structure, we performed high-spatial-resolution ( ∼ 0.″04 ∼ 32 pc) Atacama Large Millimeter/submillimeter Array (ALMA) observations in Band 9 (∼450 <jats:italic>μ</jats:italic>m or ∼660 GHz), along with near-infrared AKARI spectroscopy in 2.5–5.0 <jats:italic>μ</jats:italic>m. The Band 9 dust continuum peaks at the AGN location, and toward this position CO(<jats:italic>J</jats:italic> = 6 − 5) and CS(<jats:italic>J</jats:italic> = 14 − 13) are detected in absorption. Comparison with nonlocal thermal equilibrium calculations indicates that, within the central beam (<jats:italic>r</jats:italic> ∼ 20 pc), there exists a concentrated component that is dense (10<jats:sup>7</jats:sup> cm<jats:sup>−3</jats:sup>) and warm (&gt;200 K) and has a large column density (<jats:inline-formula> <jats:tex-math> <?CDATA ${N}_{{{\rm{H}}}_{2}}\gt {10}^{23}\,{\mathrm{cm}}^{-2}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>N</mml:mi> </mml:mrow> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">H</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> </mml:msub> <mml:mo>&gt;</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>23</mml:mn> </mml:mrow> </mml:msup> <mml:mspace width="0.25em" /> <mml:msup> <mml:mrow> <mml:mi>cm</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>2</mml:mn> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac57c2ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>). The AKARI spectrum shows deep and broad CO rovibrational absorption at 4.67 <jats:italic>μ</jats:italic>m. Its band profile is well reproduced with a similarly dense and large column but hotter (∼1000 K) gas. The region observed through absorption in the near-infrared is highly likely in the nuclear direction, as in the submillimeter, but with a narrower beam including a region closer to the nucleus. The central component is considered to possess a hot structure where vibrationally excited HCN emission originates. The most plausible heating source for the gas is X-rays from the AGN. The AKARI spectrum does not show other AGN signs in 2.5–4 <jats:italic>μ</jats:italic>m, but this absence may be usual for AGNs buried in a hot mid-infrared core. Further, based on our ALMA observations, we relate the various nuclear structures of IRAS 17208−0014 that have been proposed in the literature.</jats:p>