Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>Elemental abundances of extrinsic carbon stars provide insight into the poorly understood origin and evolution of elements in the early Galaxy. In this work, we present the results of a detailed spectroscopic analysis of four potential carbon star candidates from the Hamburg/ESO Survey (HES): HE 0457−1805, HE 0920−0506, HE 1241−0337, and HE 1327−2116. This analysis is based on the high-resolution spectra obtained with Mercator/HERMES (<jats:italic>R</jats:italic> ∼ 86,000) and SUBARU/HDS (<jats:italic>R</jats:italic> ∼ 50,000). Although the abundances of a few elements, such as Fe, C, and O, are available from medium-resolution spectra, we present the first ever detailed high-resolution spectroscopic analysis for these objects. The objects HE 0457−1805 and HE 1241−0337 are found to be CEMP-s stars, HE 0920−0506 a CH star, and HE 1327−2116 a CEMP-r/s star. The object HE 0457−1805 is a confirmed binary, whereas the binary status of the other objects is unknown. The locations of program stars on the diagram of absolute carbon abundance <jats:italic>A</jats:italic>(C) versus [Fe/H] point at their binary nature. We have examined various elemental abundance ratios of the program stars and confirmed the low-mass nature of their former AGB companions. We have shown that the i-process models could successfully reproduce the observed abundance pattern in HE 1327−2116. The analysis performed for HE 0457−1805, HE 0920−0506, and HE 1241−0337 based on the FRUITY parametric models confirmed that the surface chemical compositions of these three objects are influenced by pollution from low-mass AGB companions.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The GLASS-JWST Early Release Science (hereafter GLASS-JWST-ERS) Program will obtain and make publicly available the deepest extragalactic data of the ERS campaign. It is primarily designed to address two key science questions, namely, “what sources ionized the universe and when?” and “how do baryons cycle through galaxies?”, while also enabling a broad variety of first look scientific investigations. In primary mode, it will obtain NIRISS and NIRSpec spectroscopy of galaxies lensed by the foreground Hubble Frontier Field cluster, Abell 2744. In parallel, it will use NIRCam to observe two fields that are offset from the cluster center, where lensing magnification is negligible, and which can thus be effectively considered blank fields. In order to prepare the community for access to this unprecedented data, we describe the scientific rationale, the survey design (including target selection and observational setups), and present pre-commissioning estimates of the expected sensitivity. In addition, we describe the planned public releases of high-level data products, for use by the wider astronomical community.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>This paper constructs an analytic description for the late stages of giant planet formation. During this phase of evolution, the planet gains the majority of its final mass through gas accretion at a rapid rate. This work determines the density and velocity fields for material falling onto the central planet and its circumplanetary disk, and finds the corresponding column density of this infalling envelope. We derive a steady-state solution for the surface density of the disk as a function of its viscosity (including the limiting case where no disk accretion occurs). Planetary magnetic fields truncate the inner edge of the disk and determine the boundary conditions for mass accretion onto the planet from both direct infall and from the disk. The properties of the forming planet and its circumplanetary disk are determined, including the luminosity contributions from infall onto the planet and disk surfaces, and from disk viscosity. The radiative signature of the planet formation process is explored using a quasi-spherical treatment of the emergent spectral energy distributions. The analytic solutions developed herein show how the protoplanet properties (envelope density distribution, velocity field, column density, disk surface density, luminosity, and radiative signatures) vary with input parameters (instantaneous mass, orbital location, accretion rate, and planetary magnetic field strength).</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present Chandra X-ray observations of six previously identified Peter Pan objects, rare ∼40 Myr systems with evidence of primordial disk retention. We observe X-ray luminosities (0.8–3.0 keV) ranging from log <jats:italic>L</jats:italic> <jats:sub> <jats:italic>x</jats:italic> </jats:sub> ∼ 27.7–29.1. We find that our Peter Pan sample exhibits X-ray properties similar to that of weak-lined T Tauri stars and do not exhibit evidence of stellar accretion induced X-ray suppression. Our observed Peter Pan X-ray luminosities are consistent with that measured for field dM stars of similar spectral type and age, implying their long primordial disk lifetimes are likely not a consequence of unusually faint X-ray host stars. Our derived X-ray photoevaporative mass-loss rates predict our systems have passed the point of rapid gas dispersal and call into question the impact of this internal mechanism for primordial disk dispersal around dM stars. Our qualitative assessment of the surrounding Peter Pan environments also does not predict unusually low levels of external photoevaporation relative to other respective moving group members. Overall, our results suggest Peter Pan disks may be a consequence of the low far-UV flux incident on the disk in low-mass dM stars given their relatively lower levels of accretion over the course of their pre-main-sequence evolution.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In this work, we propose new statistical tools that are capable of characterizing the simultaneous dependence of dark matter and gas clustering on the scale and the density environment, and these are the environment-dependent wavelet power spectrum (env-WPS), the environment-dependent bias function (env-bias), and the environment-dependent wavelet cross-correlation function (env-WCC). These statistics are applied to the dark matter and baryonic gas density fields of the <jats:monospace>TNG100-1</jats:monospace> simulation at redshifts of <jats:italic>z</jats:italic>=3.0-0.0, and to <jats:monospace>Illustris-1</jats:monospace> and <jats:monospace>SIMBA</jats:monospace> at <jats:italic>z</jats:italic> = 0. The measurements of the env-WPSs suggest that the clustering strengths of both the dark matter and the gas increase with increasing density, while that of a Gaussian field shows no density dependence. By measuring the env-bias and env-WCC, we find that they vary significantly with the environment, scale, and redshift. A noteworthy feature is that at <jats:italic>z</jats:italic> = 0.0, the gas is less biased in denser environments of Δ ≳ 10 around 3 <jats:italic>h</jats:italic> Mpc<jats:sup>−1</jats:sup>, due to the gas reaccretion caused by the decreased AGN feedback strength at lower redshifts. We also find that the gas correlates more tightly with the dark matter in both the most dense and underdense environments than in other environments at all epochs. Even at <jats:italic>z</jats:italic> = 0, the env-WCC is greater than 0.9 in Δ ≳ 200 and Δ ≲ 0.1 at scales of <jats:italic>k</jats:italic> ≲ 10 <jats:italic>h</jats:italic> Mpc<jats:sup>−1</jats:sup>. In summary, our results support the local density environment having a non-negligible impact on the deviations between dark matter and gas distributions up to large scales.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The solar wind measured in situ by Parker Solar Probe in the very inner heliosphere is studied in combination with the remote-sensing observation of the coronal source region provided by the METIS coronagraph aboard Solar Orbiter. The coronal outflows observed near the ecliptic by Metis on 2021 January 17 at 16:30 UT, between 3.5 and 6.3 <jats:italic>R</jats:italic> <jats:sub>⊙</jats:sub> above the eastern solar limb, can be associated with the streams sampled by PSP at 0.11 and 0.26 au from the Sun, in two time intervals almost 5 days apart. The two plasma flows come from two distinct source regions, characterized by different magnetic field polarity and intensity at the coronal base. It follows that both the global and local properties of the two streams are different. Specifically, the solar wind emanating from the stronger magnetic field region has a lower bulk flux density, as expected, and is in a state of well-developed Alfvénic turbulence, with low intermittency. This is interpreted in terms of slab turbulence in the context of nearly incompressible magnetohydrodynamics. Conversely, the highly intermittent and poorly developed turbulent behavior of the solar wind from the weaker magnetic field region is presumably due to large magnetic deflections most likely attributed to the presence of switchbacks of interchange reconnection origin.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Recently there have been reports of finding a lower bound on the neutrino mass parameter (Σ<jats:italic>m</jats:italic> <jats:sub> <jats:italic>ν</jats:italic> </jats:sub>) when using the Atacama Cosmology Telescope (ACT) and SPTpol data; however, these bounds on the Σ<jats:italic>m</jats:italic> <jats:sub> <jats:italic>ν</jats:italic> </jats:sub> are still weaker for most cases around the 1<jats:italic>σ</jats:italic> level. In this context, here in this work, we study the consequences of using an enlarged four parameter dynamical dark energy equation of state on the neutrino mass parameter as well as on the Hubble and S8 tensions. The four parameter dark energy equation of state incorporates a generic nonlinear monotonic evolution of the dark energy equation of state, where the four parameters are the early and the present value of the equation of state, the transition scale factor, and the sharpness of the transition. We report that with lensing-marginalized Planck + BAO + Pantheon and prior on absolute magnitude <jats:italic>M</jats:italic> <jats:sub> <jats:italic>B</jats:italic> </jats:sub>, and KIDS/Viking <jats:italic>S</jats:italic> <jats:sub>8</jats:sub> prior, the model favors a nonzero value for the neutrino mass parameter at most at the 1<jats:italic>σ</jats:italic> level (<jats:inline-formula> <jats:tex-math> <?CDATA ${\rm{\Sigma }}{m}_{\nu }={0.1847}_{-0.165}^{+0.0698}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="normal">Σ</mml:mi> <mml:msub> <mml:mrow> <mml:mi>m</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>ν</mml:mi> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>0.1847</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.165</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.0698</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac7a33ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> eV). In this case this model also brings down the Hubble tension to a 2.5<jats:italic>σ</jats:italic> level and the S8 tension to a ∼1.5<jats:italic>σ</jats:italic> level. This model also provides tighter constraints on the value of the dark energy equation of state at present epoch <jats:italic>w</jats:italic> <jats:sub>0</jats:sub> (<jats:inline-formula> <jats:tex-math> <?CDATA ${w}_{0}=-{0.9901}_{-0.0766}^{+0.0561}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>w</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mo>−</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>0.9901</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.0766</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.0561</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac7a33ieqn2.gif" xlink:type="simple" /> </jats:inline-formula>) in comparison to the Chevalier-Polarski and Linder-like parameterization.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The presence of an early-formed giant planet in the protoplanetary disk has mixed influence on the growth of other planetary embryos. Gravitational perturbation from the planet can increase the relative velocities of planetesimals at the mean motion resonances to very high values and impede accretion at those locations. However, gas drag can also align the orbital pericenters of equal-size planetesimals in certain disk locations and make them dynamically quiet and “accretion-friendly” locations for planetesimals of similar sizes. Following the previous paper, where we investigated the effect of a Jupiter-like planet on an external planetesimal disk, we generalize our findings to extrasolar planetary systems by varying the planet parameters. In particular, we focus on the dependence of the planetesimal relative velocities on the mass and eccentricity of the existing planet. We found that the velocity dispersion of identical-mass particles increases monotonically with increasing planet mass. Meanwhile, the dependence of the relative velocity between different-mass planetesimals on their mass ratio becomes weaker as the planet mass increases. While the relative velocities generally increase with increasing planet eccentricity, the velocity dispersion of lower-mass particles (<jats:italic>m</jats:italic> ≲ 10<jats:sup>18</jats:sup> g) is almost independent of planet eccentricity owing to their strong coupling to gas. We find that the erosion limits are met for a wider range of parameters (planet mass/eccentricity, planetesimal mass ratio) when the planetesimal size decreases. Our results could provide some clues for the formation of Saturn’s core, as well as the architecture of some exoplanetary systems with multiple cold giant planets.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The role of H <jats:sc>i</jats:sc> content in galaxy interactions is still under debate. To study the H <jats:sc>i</jats:sc> content of galaxy pairs at different merging stages, we compile a sample of 66 major-merger galaxy pairs and 433 control galaxies from the Sloan Digital Sky Survey IV (SDSS-IV) MaNGA IFU survey. In this study, we adopt kinematic asymmetry as a new effective indicator to describe the merging stage of galaxy pairs. With archival data from the HI-MaNGA survey and new observations from the Five-hundred-meter Aperture Spherical radio Telescope (FAST), we investigate the differences in H <jats:sc>i</jats:sc> gas fraction (<jats:italic>f</jats:italic> <jats:sub>H I</jats:sub>), star formation rate (SFR), and H <jats:sc>i</jats:sc> star formation efficiency (SFE<jats:sub>H I</jats:sub>) between the pair and control samples. Our results suggest that the H <jats:sc>i</jats:sc> gas fraction of major-merger pairs on average is marginally decreased by ∼15% relative to isolated galaxies, implying mild H <jats:sc>i</jats:sc> depletion during galaxy interactions. Compared to isolated galaxies, pre-passage paired galaxies have similar <jats:italic>f</jats:italic> <jats:sub>H I</jats:sub>, SFR, and SFE<jats:sub>H I</jats:sub>, while pairs during the pericentric passage have weakly decreased <jats:italic>f</jats:italic> <jats:sub>H I</jats:sub> (−0.10 ± 0.05 dex), significantly enhanced SFR (0.42 ± 0.11 dex), and SFE<jats:sub>H I</jats:sub> (0.48 ± 0.12 dex). When approaching the apocenter, paired galaxies show marginally decreased <jats:italic>f</jats:italic> <jats:sub>H I</jats:sub> (−0.05 ± 0.04 dex), comparable SFR (0.04 ± 0.06 dex), and SFE<jats:sub>H I</jats:sub> (0.08 ± 0.08 dex). We propose that the marginally detected H <jats:sc>i</jats:sc> depletion may originate from the gas consumption in fueling the enhanced H<jats:sub>2</jats:sub> reservoir of galaxy pairs. In addition, new FAST observations also reveal a H <jats:sc>i</jats:sc> absorber (<jats:italic>N</jats:italic> <jats:sub>H I</jats:sub> ∼ 4.7 × 10<jats:sup>21</jats:sup> cm<jats:sup>−2</jats:sup>), which may suggest gas infalling and the triggering of active galactic nuclei activity.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present the multi-epoch monitoring with NuSTAR and XMM-Newton of NGC 1358, a nearby Seyfert 2 galaxy whose properties made it a promising candidate X-ray changing-look active galactic nucleus (AGN), i.e., a source whose column density could transition from its 2017 Compton-thick (having LOS hydrogen column density <jats:italic>N</jats:italic> <jats:sub>H,LOS</jats:sub> &gt; 10<jats:sup>24</jats:sup> cm<jats:sup>−2</jats:sup>) state to a Compton-thin (<jats:italic>N</jats:italic> <jats:sub>H,LOS</jats:sub> &lt; 10<jats:sup>24</jats:sup> cm<jats:sup>−2</jats:sup>) one. The multi-epoch X-ray monitoring confirmed the presence of significant <jats:italic>N</jats:italic> <jats:sub>H,LOS</jats:sub> variability over timescales of weeks to years, and allowed us to confirm the <jats:italic>changing-look</jats:italic> nature of NGC 1358, which has most recently been observed in a Compton-thin status. Multi-epoch monitoring with NuSTAR and XMM-Newton is demonstrated to be highly effective in simultaneously constraining three otherwise highly degenerate parameters: the torus average column density and covering factor, and the inclination angle between the torus axis and the observer. We find a tentative anticorrelation between column density and luminosity, which can be understood under the framework of chaotic cold accretion clouds driving recursive AGN feedback. The monitoring campaign of NGC 1358 has proven the efficiency of our newly developed method to select candidate <jats:italic>N</jats:italic> <jats:sub>H,LOS</jats:sub>-variable, heavily obscured AGN, which we plan to soon extend to a larger sample to better characterize the properties of the obscuring material surrounding accreting supermassive black holes, as well as to constrain AGN feeding models.</jats:p>