Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>The metallicity dependence of the wide binary fraction (WBF) is critical for studying the formation of wide binaries. While controversial results have been found in recent years, here we combine the wide binary catalog recognized from Gaia EDR3 and stellar parameters from LAMOST to investigate this topic. Taking the bias of the stellar temperature at given separations into account, we find that the relationship between the WBF and metallicity depends on the temperature for the thin disk at <jats:italic>s</jats:italic> &gt; 200 au. It changes from negative to positive as the temperature increases from 4000 to 7500 K. This temperature/mass dependence is not seen for the thick disk. Besides, the general tendency between the WBF and metallicity varies with the separation, consistent with previous results. It shows anticorrelation at small separations, <jats:italic>s</jats:italic> &lt; 200 au for the thin disk and <jats:italic>s</jats:italic> &lt; 600 au for the thick disk. Then it becomes an “arcuate” shape at larger separations (hundreds to thousands of astronomical units), peaking at [Fe/H] ≈0.1 for the thin disk and [Fe/H] ≈−0.5 for the thick disk. Finally it becomes roughly flat for the thin disk at 1000 &lt; <jats:italic>s</jats:italic> &lt; 10,000 au. Our work provides new observational evidence for theoretical studies on binary formation and evolution.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Supernovae emit large fluxes of neutrinos, which can be detected by detectors on Earth. Future multi-kiloton scale detectors will be sensitive to several neutrino interaction channels, with thousands of events expected if a supernova emerges in the galaxy neighborhood. There are a limited number of tools to study the interaction rates of supernova neutrinos, although a plethora of available supernova models exist. EstrellaNueva is an open-source software to calculate expected rates of supernova neutrinos in detectors using target materials with typical compositions, and additional compositions can be easily added. This software considers the flavor transformation of neutrinos in the supernova through the adiabatic Mikheyev–Smirnov–Wolfenstein effect, and their interaction in detectors through several channels. Most of the interaction cross sections, such as neutrino–electron and neutrino–proton elastic scattering, inverse beta decay, and coherent elastic neutrino–nucleus scattering, have been analytically implemented. This software provides a link between supernova simulations and the expected events in detectors by calculating fluences and event rates in order to ease any comparison between theory and observation. It provides a simple and standalone tool to explore many physics scenarios, offering an option to add analytical cross sections and define any target material.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We constrain the cosmic-ray (CR) population in the circumgalactic medium (CGM) of the Milky Way by comparing the observations of absorption lines of O <jats:sc>viii</jats:sc> ions with predictions from analytical models of the CGM: the precipitation (PP) and isothermal (IT) models. For a CGM in hydrostatic equilibrium, the introduction of CR suppresses thermal pressure and affects the O <jats:sc>viii</jats:sc> ion abundance. We explore the allowances given to the ratio of CR pressure to thermal pressure (<jats:italic>P</jats:italic> <jats:sub>CR</jats:sub>/<jats:italic>P</jats:italic> <jats:sub>th</jats:sub> = <jats:italic>η</jats:italic>), with varying boundary conditions, CGM mass content, photoionization by extragalactic ultraviolet background, and temperature fluctuations. We find that the allowed maximum values of <jats:italic>η</jats:italic> are <jats:italic>η</jats:italic> ≲ 10 in the PP model and <jats:italic>η</jats:italic> ≲ 6 in the IT model. We also explore the spatial variation of <jats:italic>η</jats:italic>: rising (<jats:italic>η</jats:italic> = <jats:italic>Ax</jats:italic>) or declining (<jats:italic>η</jats:italic> = <jats:italic>A</jats:italic>/<jats:italic>x</jats:italic>) with radius, where <jats:italic>A</jats:italic> is the normalization of the profiles. In particular, the models with a declining ratio of CR to thermal pressure fare better than those with a rising ratio with suitable temperature fluctuation (higher <jats:italic>σ</jats:italic> <jats:sub>lnT</jats:sub> for PP and lower for IT). The declining profiles allow <jats:italic>A</jats:italic> ≲ 8 and <jats:italic>A</jats:italic> ≲ 10 in the case of the IT and PP models, respectively, thereby accommodating a large value of <jats:italic>η</jats:italic> (≃200) in the central region but not in the outer regions. These limits, combined with the limits derived from the <jats:italic>γ</jats:italic>-ray and radio background, can be useful for building models of the Milky Way CGM including the CR population. However, the larger amount of CRs can be packed in the cold phase, which may be one way to circumvent these constraints.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Planetary systems are thought to be born in protoplanetary disks. Isotope ratios are a powerful tool for investigating the material origin and evolution from molecular clouds to planetary systems via protoplanetary disks. However, it is challenging to measure the isotope (isotopologue) ratios, especially in protoplanetary disks, because the emission lines of major species are saturated. We developed a new method to overcome these challenges by using optically thin line wings induced by thermal broadening. As a first application of the method, we analyzed two carbon monoxide isotopologue lines, <jats:sup>12</jats:sup>CO 3–2 and <jats:sup>13</jats:sup>CO 3–2, from archival observations of a protoplanetary disk around TW Hya with the Atacama Large Millimeter/submillimeter Array. The <jats:sup>12</jats:sup>CO/<jats:sup>13</jats:sup>CO ratio was estimated to be 21 ± 5 at disk radii of 70–110 au, which is significantly smaller than the value observed in the local interstellar medium, ∼69. It implies that an isotope exchange reaction occurs in a low-temperature environment with C/O &gt; 1. In contrast, it is suggested that <jats:sup>12</jats:sup>CO/<jats:sup>13</jats:sup>CO is higher than ∼84 in the outer disk (<jats:italic>r</jats:italic> &gt; 130 au), which can be explained by the difference in the binding energy of the isotopologues on dust grains and the CO gas depletion processes. Our results imply that the gas-phase <jats:sup>12</jats:sup>CO/<jats:sup>13</jats:sup>CO can vary by a factor of &gt;4 even inside a protoplanetary disk and therefore can be used to trace material evolution in disks.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>During reionization, a fraction of galactic Ly<jats:italic>α</jats:italic> emission is scattered in the intergalactic medium (IGM) and appears as diffuse light extending megaparsecs from the source. We investigate how to probe the properties of the early galaxies and their surrounding IGM using this scattered light. We create a Monte Carlo algorithm to track individual photons and reproduce several test cases from previous literature. Then, we run our code on the simulated IGM of the CoDaII simulation. We find that the scattered light can leave an observable imprint on the emergent spectrum if collected over several square arcminutes. Scattering can redden the emission by increasing the path lengths of photons, but it can also make the photons bluer by upscattering them according to the peculiar motion of the scatterer. The photons emitted on the far blue side of the resonance appear more extended in both frequency and space compared to those emitted near the resonance. This provides a discriminating feature for the blueward emission, which cannot be constrained from the unscattered light coming directly from the source. The ionization state of the IGM also affects the scattered light spectrum. When the source is in a small H <jats:sc>ii</jats:sc> region, the emission goes through more scatterings in the surrounding H <jats:sc>i</jats:sc> region regardless of the initial frequency and ends up more redshifted and spatially extended. This can result in a weakening of the scattered light toward high <jats:italic>z</jats:italic> during reionization. Our results provide a framework for interpreting the scattered light to be measured by high-<jats:italic>z</jats:italic> integral-field-unit surveys.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The transport of energetic charged particles (e.g., cosmic rays) in turbulent magnetic fields is usually characterized in terms of the diffusion parallel and perpendicular to a large-scale (or mean) magnetic field. The nonlinear guiding center theory has been a prominent perpendicular diffusion theory. A recent version of this theory, based on the random ballistic spreading of magnetic field lines and a backtracking correction (RBD/BC), has shown good agreement with test particle simulations for a two-component magnetic turbulence model. The aim of the present study is to test the generality of the improved theory by applying it to the noisy reduced magnetohydrodynamic (NRMHD) turbulence model, determining perpendicular diffusion coefficients that are compared with those from the field line random walk (FLRW) and unified nonlinear (UNLT) theories and our test particle simulations. The synthetic NRMHD turbulence model creates special conditions for energetic particle transport, with no magnetic fluctuations at higher parallel wavenumbers so there is no resonant parallel scattering if the particle Larmor radius <jats:italic>R</jats:italic> <jats:sub>L</jats:sub> is even slightly smaller than the minimum resonant scale. This leads to nonmonotonic variation in the parallel mean free path <jats:italic>λ</jats:italic> <jats:sub>∥</jats:sub> with <jats:italic>R</jats:italic> <jats:sub>L</jats:sub>. Among the theories considered, only RBD/BC matches simulations within a factor of 2 over the range of parameters considered. This accuracy is obtained even though the theory depends on <jats:italic>λ</jats:italic> <jats:sub>∥</jats:sub> and has no explicit dependence on <jats:italic>R</jats:italic> <jats:sub>L</jats:sub>. In addition, the UNLT theory often provides accurate results, and even the FLRW limit provides a very simple and reasonable approximation in many cases.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Free-form strong-lensing (SL) mass reconstructions typically suffer from overfitting, which manifests itself as false-positive small-scale fluctuations. We present a new free-form MAximum-entropy ReconStruction (<jats:monospace>MARS</jats:monospace>) method without the assumption that light traces mass (LTM). The <jats:monospace>MARS</jats:monospace> algorithm enables us to achieve excellent convergence in source positions (∼0.″001), minimize spurious small-scale fluctuations, and provide a quasi-unique solution independently of initial conditions. Our method is tested with the publicly available synthetic SL data <jats:monospace>FF-SIMS</jats:monospace>. The comparison with the truth shows that the mass reconstruction quality is on par with those of the best-performing LTM methods published in the literature, which have been demonstrated to outperform existing free-form methods. In terms of the radial mass profile reconstruction, we achieve &lt;1% agreement with the truth for the regions constrained by multiple images. Finally, we apply <jats:monospace>MARS</jats:monospace> to A1689 and find that the cluster mass in the SL regime is dominated by the primary halo centered on the brightest cluster galaxy and the weaker secondary halo is also coincident with the bright cluster member ∼160 kpc northeast. Within the SL field, the A1689 radial profile is well described by a Navarro–Frenk–White profile with <jats:italic>c</jats:italic> <jats:sub>200</jats:sub> = 5.53 ± 0.77 and <jats:inline-formula> <jats:tex-math> <?CDATA ${r}_{s}={538}_{-100}^{+90}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>r</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>s</mml:mi> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>538</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>100</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>90</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac69dfieqn1.gif" xlink:type="simple" /> </jats:inline-formula> kpc, and we find no evidence that A1689 is overconcentrated.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We use a recent census of the Milky Way (MW) satellite galaxy population to constrain the lifetime of particle dark matter (DM). We consider two-body decaying dark matter (DDM) in which a heavy DM particle decays with lifetime <jats:italic>τ</jats:italic> comparable to the age of the universe to a lighter DM particle (with mass splitting <jats:italic>ϵ</jats:italic>) and to a dark radiation species. These decays impart a characteristic “kick velocity,” <jats:italic>V</jats:italic> <jats:sub>kick</jats:sub> = <jats:italic>ϵ</jats:italic> <jats:italic>c</jats:italic>, on the DM daughter particles, significantly depleting the DM content of low-mass subhalos and making them more susceptible to tidal disruption. We fit the suppression of the present-day DDM subhalo mass function (SHMF) as a function of <jats:italic>τ</jats:italic> and <jats:italic>V</jats:italic> <jats:sub>kick</jats:sub> using a suite of high-resolution zoom-in simulations of MW-mass halos, and we validate this model on new DDM simulations of systems specifically chosen to resemble the MW. We implement our DDM SHMF predictions in a forward model that incorporates inhomogeneities in the spatial distribution and detectability of MW satellites and uncertainties in the mapping between galaxies and DM halos, the properties of the MW system, and the disruption of subhalos by the MW disk using an empirical model for the galaxy–halo connection. By comparing to the observed MW satellite population, we conservatively exclude DDM models with <jats:italic>τ</jats:italic> &lt; 18 Gyr (29 Gyr) for <jats:italic>V</jats:italic> <jats:sub>kick</jats:sub> = 20 kms<jats:sup>−1</jats:sup> (40 kms<jats:sup>−1</jats:sup>) at 95% confidence. These constraints are among the most stringent and robust small-scale structure limits on the DM particle lifetime and strongly disfavor DDM models that have been proposed to alleviate the Hubble and <jats:italic>S</jats:italic> <jats:sub>8</jats:sub> tensions.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>It is difficult to distinguish the hadronic process from the leptonic one in <jats:italic>γ</jats:italic>-ray observation, which is however crucial in revealing the origin of cosmic rays. As an endeavor in this regard, we focus in this work on the complex <jats:italic>γ</jats:italic>-ray emitting region, which partially overlaps with the unidentified TeV source HESS J1858+020 and includes supernova remnant (SNR) G35.6−0.4 and H <jats:sc>ii</jats:sc> region G35.6−0.5. We reanalyze CO line, H <jats:sc>i</jats:sc>, and Fermi-LAT GeV <jats:italic>γ</jats:italic>-ray emission data of this region. The analysis of the molecular and H <jats:sc>i</jats:sc> data suggests that SNR G35.6−0.4 and H <jats:sc>ii</jats:sc> region G35.6−0.5 are located at different distances. The analysis of the GeV <jats:italic>γ</jats:italic>-rays shows that GeV emission arises from two point sources: one (SrcA) coincident with the SNR, and the other (SrcB) coincident with both HESS J1858+020 and H <jats:sc>ii</jats:sc> region G35.6−0.5. The GeV emission of SrcA can be explained by the hadronic process in the SNR–molecular cloud association scenario. The GeV-band spectrum of SrcB and the TeV-band spectrum of HESS J1858+020 can be smoothly connected by a power-law function, with an index of ∼2.2. The connected spectrum is well explained with a hadronic emission, with the cutoff energy of protons above 1 PeV. It thus indicates that there is a potential PeVatron in the H <jats:sc>ii</jats:sc> region and should be further verified with ultrahigh-energy observations with, e.g., LHAASO.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report on a long-lasting, elevated gamma-ray flux state from VER J0521+211 observed by VERITAS, MAGIC, and Fermi-LAT in 2013 and 2014. The peak integral flux above 200 GeV measured with the nightly binned light curve is (8.8 ± 0.4) × 10<jats:sup>−7</jats:sup> photons m<jats:sup>−2</jats:sup> s<jats:sup>−1</jats:sup>, or ∼37% of the Crab Nebula flux. Multiwavelength observations from X-ray, UV, and optical instruments are also presented. A moderate correlation between the X-ray and TeV gamma-ray fluxes was observed, and the X-ray spectrum appeared harder when the flux was higher. Using the gamma-ray spectrum and four models of the extragalactic background light (EBL), a conservative 95% confidence upper limit on the redshift of the source was found to be <jats:italic>z</jats:italic> ≤ 0.31. Unlike the gamma-ray and X-ray bands, the optical flux did not increase significantly during the studied period compared to the archival low-state flux. The spectral variability from optical to X-ray bands suggests that the synchrotron peak of the spectral energy distribution (SED) may become broader during flaring states, which can be adequately described with a one-zone synchrotron self-Compton model varying the high-energy end of the underlying particle spectrum. The synchrotron peak frequency of the SED and the radio morphology of the jet from the MOJAVE program are consistent with the source being an intermediate-frequency-peaked BL Lac object.</jats:p>