Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>It has been demonstrated that planets belonging to the same close-in, compact multiple-planet system tend to exhibit a striking degree of uniformity in their sizes. A similar trend has also been found to hold for the masses of such planets, but considerations of such intra-system mass uniformity have generally been limited to statistical samples wherein a majority of systems have constituent planetary mass measurements obtained via analysis of transit timing variations (TTVs). Since systems with strong TTV signals typically lie in or near mean motion resonance, it remains to be seen whether intra-system mass uniformity is still readily emergent for nonresonant systems with non-TTV mass provenance. We thus present in this work a mass uniformity analysis of 17 non-TTV systems with masses measured via radial velocity measurements. Using the Gini index, a common statistic for economic inequality, as our primary metric for uniformity, we find that our sample of 17 non-TTV systems displays intra-system mass uniformity at a level of ∼2.5<jats:italic>σ</jats:italic> confidence. We provide additional discussion of possible statistical and astrophysical underpinnings for this result. We also demonstrate the existence of a correlation (<jats:italic>r</jats:italic> = 0.25) between characteristic solid surface density (Σ<jats:sub>0</jats:sub>) of the minimum-mass extrasolar nebula and system mass Gini index, suggesting that more-massive disks may generally form systems with more-unequal planetary masses.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Extremely large telescopes (ELTs) provide an opportunity to observe surface inhomogeneities for ultracool objects including M dwarfs, brown dwarfs (BDs), and gas giant planets via Doppler imaging and spectrophotometry techniques. These inhomogeneities can be caused by star spots, clouds, and vortices. Star spots and associated stellar flares play a significant role in habitability, either stifling life or catalyzing abiogenesis depending on the emission frequency, magnitude, and orientation. Clouds and vortices may be the source of spectral and photometric variability observed at the L/T transition of BDs and are expected in gas giant exoplanets. We develop a versatile analytical framework to model and infer surface inhomogeneities that can be applied to both spectroscopic and photometric data. This model is validated against a slew of numerical simulations. Using archival spectroscopic and photometric data, we infer starspot parameters (location, size, and contrast) and generate global surface maps for Luhman 16B (an early T dwarf and one of our solar system’s nearest neighbors at a distance of ≈2 pc). We confirm previous findings that Luhman 16B’s atmosphere is inhomogeneous with time-varying features. In addition, we provide tentative evidence of longer timescale atmospheric structures such as dark equatorial and bright midlatitude to polar spots. These findings are discussed in the context of atmospheric circulation and dynamics for ultracool dwarfs. Our analytical model will be valuable in assessing the feasibility of using ELTs to study surface inhomogeneities of gas giant exoplanets and other ultracool objects.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Using <jats:monospace>Athena++</jats:monospace>, we perform 3D radiation-hydrodynamic calculations of the radiative breakout of the shock wave in the outer envelope of a red supergiant (RSG) that has suffered core collapse and will become a Type IIP supernova. The intrinsically 3D structure of the fully convective RSG envelope yields key differences in the brightness and duration of the shock breakout (SBO) from that predicted in a 1D stellar model. First, the lower-density “halo” of material outside of the traditional photosphere in 3D models leads to a shock breakout at lower densities than 1D models. This would prolong the duration of the shock breakout flash at any given location on the surface to ≈1–2 hr. However, we find that the even larger impact is the intrinsically 3D effect associated with large-scale fluctuations in density that cause the shock to break out at different radii at different times. This substantially prolongs the SBO duration to ≈3–6 hr and implies a diversity of radiative temperatures, as different patches across the stellar surface are at different stages of their radiative breakout and cooling at any given time. These predicted durations are in better agreement with existing observations of SBO. The longer durations lower the predicted luminosities by a factor of 3–10 (<jats:italic>L</jats:italic> <jats:sub>bol</jats:sub> ∼ 10<jats:sup>44</jats:sup> erg s<jats:sup>−1</jats:sup>), and we derive the new scalings of brightness and duration with explosion energies and stellar properties. These intrinsically 3D properties eliminate the possibility of using observed rise times to measure the stellar radius via light-travel time effects.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The realization of fundamental relations between supermassive black holes and their host galaxies would have profound implications in astrophysics. To add further context to studies of their coevolution, an investigation is carried out to gain insight as to whether quasars and their hosts at earlier epochs follow the local relation between black hole mass (<jats:italic>M</jats:italic> <jats:sub>BH</jats:sub>) and stellar velocity dispersion (<jats:italic>σ</jats:italic> <jats:sub>*</jats:sub>). We use 584 Sloan Digital Sky Survey quasars at 0.2 &lt; <jats:italic>z</jats:italic> &lt; 0.8 with black hole measurements and properties of their hosts from the Hyper Suprime-Cam Subaru Strategic Program. An inference of <jats:italic>σ</jats:italic> <jats:sub>*</jats:sub> is achieved for each based on the total stellar mass (<jats:italic>M</jats:italic> <jats:sub>*</jats:sub>) and size of the host galaxy by using the galaxy mass fundamental plane for inactive galaxies at similar redshifts. In agreement with past studies, quasars occupy elevated positions from the local <jats:italic>M</jats:italic> <jats:sub>BH</jats:sub>−<jats:italic>σ</jats:italic> <jats:sub>*</jats:sub> relation which can be considered as a flattening of the relation. Based on a simulated sample, we demonstrate that an evolving intrinsic <jats:italic>M</jats:italic> <jats:sub>BH</jats:sub>−<jats:italic>σ</jats:italic> <jats:sub>*</jats:sub> relation can match the observations. However, we hypothesize that these changes are simply a consequence of a nonevolving intrinsic relationship between <jats:italic>M</jats:italic> <jats:sub>BH</jats:sub> and <jats:italic>M</jats:italic> <jats:sub>*</jats:sub>. Reassuringly, there is evidence of migration onto the local <jats:italic>M</jats:italic> <jats:sub>BH</jats:sub>−<jats:italic>σ</jats:italic> <jats:sub>*</jats:sub> for galaxies that are either massive, quiescent or compact. Thus, the bulges of quasar hosts at high redshift are growing and likely to align onto the mass scaling relation with their black holes at later times.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Various profiles of matter distribution in galactic halos (such as the Navarro–Frenk–White, Burkert, Hernquist, Moore, Taylor–Silk models, and others) are considered here as the source term for the Einstein equations. We solve these equations and find exact solutions that represent the metric of a central black hole immersed in a galactic halo. Even though in the general case the solution is numerical, very accurate general analytical metrics, which include all the particular models, are found in the astrophysically relevant regime, when the mass of the galaxy is much smaller than the characteristic scale in the halo.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Collisionless shocks and plasma turbulence are crucial ingredients for a broad range of astrophysical systems. The shock–turbulence interaction, and in particular the transmission of fully developed turbulence across the quasi-perpendicular Earth’s bow shock, is here addressed using a combination of spacecraft observations and local numerical simulations. An alignment between the Wind (upstream) and Magnetospheric Multiscale (downstream) spacecraft is used to study the transmission of turbulent structures across the shock, revealing an increase of their magnetic helicity content in its downstream. Local kinetic simulations, in which the dynamics of turbulent structures are followed through their transmission across a perpendicular shock, confirm this scenario, revealing that the observed magnetic helicity increase is associated with the compression of turbulent structures at the shock front.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We show that the Southern Crab (aka Hen2–104) presents an auspicious opportunity to study the form and speed of the invisible winds that excavate and shock the lobes of various types of bipolar nebulae associated with close and highly evolved binary stars. A deep three-color image overlay of Hen2–104 reveals that the ionization state of its lobe edges, or “claws,” increases steadily from singly to doubly ionized values with increasing wall latitude. This “reverse” ionization pattern is unique among planetary nebulae (and similar objects) and incompatible with UV photoionization from a central source. We show that the most self-consistent explanation for the ionization pattern is shock ionization by a fast (∼600 km s<jats:sup>−1</jats:sup>) “tapered” stellar wind in which the speed and momentum flux of the wind increase with equatorial latitude. We present a hydrodynamic simulation that places the latitude-dependent form, the knotty walls, and the reverse ionization of the outer lobes of Hen2–104 into a unified context.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The important role played by magnetic reconnection in the early acceleration of coronal mass ejections (CMEs) has been widely discussed. However, as CMEs may have expansion speeds comparable to their propagation speeds in the corona, it is not clear whether and how reconnection contributes to the true acceleration and expansion separately. To address this question, we analyze the dynamics of a moderately fast CME on 2013 February 27, associated with a continuous acceleration of its front into the high corona, even though its speed had reached ∼700 km s<jats:sup>−1</jats:sup>, which is faster than the solar wind. The apparent acceleration of the CME is found to be due to its expansion in the radial direction. The true acceleration of the CME, i.e., the acceleration of its center, is then estimated by taking into account the expected deceleration caused by the drag force of the solar wind acting on a fast CME. It is found that the true acceleration and the radial expansion have similar magnitudes. We find that magnetic reconnection occurs after the eruption of the CME and continues during its propagation in the high corona, which contributes to its dynamic evolution. Comparison between the apparent acceleration related to the expansion and the true acceleration that compensates the drag shows that, for this case, magnetic reconnection contributes almost equally to the expansion and to the acceleration of the CME. The consequences of these measurements for the evolution of CMEs as they transit from the corona to the heliosphere are discussed.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Repeated mergers of stellar-mass black holes in dense star clusters can produce intermediate-mass black holes (IMBHs). In particular, nuclear star clusters at the centers of galaxies have deep enough potential wells to retain most of the black hole (BH) merger products, in spite of the significant recoil kicks due to anisotropic emission of gravitational radiation. These events can be detected in gravitational waves, which represent an unprecedented opportunity to reveal IMBHs. In this paper, we analyze the statistical results of a wide range of numerical simulations, which encompass different cluster metallicities, initial BH seed masses, and initial BH spins, and we compute the merger rate of IMBH binaries. We find that merger rates are in the range 0.01–10 Gpc<jats:sup>−3</jats:sup> yr<jats:sup>−1</jats:sup> depending on IMBH masses. We also compute the number of multiband detections in ground-based and space-based observatories. Our model predicts that a few merger events per year should be detectable with LISA, DECIGO, Einstein Telescope (ET), and LIGO for IMBHs with masses ≲1000 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, and a few tens of merger events per year with DECIGO, ET, and LIGO only.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Energetic electrons of Jovian origin have been observed for decades throughout the heliosphere, as far as 11 au, and as close as 0.5 au, from the Sun. The treatment of Jupiter as a continuously emitting point source of energetic electrons has made Jovian electrons a valuable tool in the study of energetic electron transport within the heliosphere. We present observations of Jovian electrons measured by the EPI-Hi instrument in the Integrated Science Investigation of the Sun instrument suite on Parker Solar Probe at distances within 0.5 au of the Sun. These are the closest measurements of Jovian electrons to the Sun, providing a new opportunity to study the propagation and transport of energetic electrons to the inner heliosphere. We also find periods of nominal connection between the spacecraft and Jupiter in which expected Jovian electron enhancements are absent. Several explanations for these absent events are explored, including stream interaction regions between Jupiter and Parker Solar Probe and the spacecraft lying on the opposite side of the heliospheric current sheet from Jupiter, both of which could impede the flow of the electrons. These observations provide an opportunity to gain a greater insight into electron transport through a previously unexplored region of the inner heliosphere.</jats:p>