Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>In the core-accretion formation scenario of gas giants, most of the gas accreting onto a planet is processed through an accretion shock. In this series of papers we study this shock because it is key in setting the structure of the forming planet and thus its postformation luminosity, with dramatic observational consequences. We perform one-dimensional gray radiation-hydrodynamical simulations with nonequilibrium (two-temperature) radiation transport and up-to-date opacities. We survey the parameter space of accretion rate, planet mass, and planet radius and obtain postshock temperatures, pressures, and entropies, as well as global radiation efficiencies. We find that the shock temperature <jats:inline-formula> <jats:tex-math> <?CDATA ${T}_{\mathrm{shock}}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab245bieqn1.gif" xlink:type="simple" /> </jats:inline-formula> is usually given by the “free-streaming” limit. At low temperatures the dust opacity can make the shock hotter but not significantly so. We corroborate this with an original semianalytical derivation of <jats:inline-formula> <jats:tex-math> <?CDATA ${T}_{\mathrm{shock}}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab245bieqn2.gif" xlink:type="simple" /> </jats:inline-formula>. We also estimate the change in luminosity between the shock and the nebula. Neither <jats:inline-formula> <jats:tex-math> <?CDATA ${T}_{\mathrm{shock}}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab245bieqn3.gif" xlink:type="simple" /> </jats:inline-formula> nor the luminosity profile depend directly on the optical depth between the shock and the nebula. Rather, <jats:inline-formula> <jats:tex-math> <?CDATA ${T}_{\mathrm{shock}}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab245bieqn4.gif" xlink:type="simple" /> </jats:inline-formula> depends on the immediate preshock opacity, and the luminosity change on the equation of state. We find quite high immediate postshock entropies (<jats:inline-formula> <jats:tex-math> <?CDATA $S\approx 13$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab245bieqn5.gif" xlink:type="simple" /> </jats:inline-formula>–20 <jats:inline-formula> <jats:tex-math> <?CDATA ${k}_{{\rm{B}}}\,{{m}_{{\rm{H}}}}^{-1}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab245bieqn6.gif" xlink:type="simple" /> </jats:inline-formula>), which makes it seem unlikely that the shock can cool the planet. The global radiation efficiencies are high (<jats:inline-formula> <jats:tex-math> <?CDATA ${\eta }^{\mathrm{phys}}\gtrsim 97 \% $?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab245bieqn7.gif" xlink:type="simple" /> </jats:inline-formula>), but the remainder of the total incoming energy, which is brought into the planet, exceeds the internal luminosity of classical cold starts by orders of magnitude. Overall, these findings suggest that warm or hot starts are more plausible.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Line-intensity mapping, being an imperfect observation of the line-intensity field in a cosmological volume, will be subject to various anisotropies introduced in observation. Existing literature in the context of CO and [C <jats:sc>ii</jats:sc>] line-intensity mapping often predicts only the real-space, spherically averaged line-intensity power spectrum, with some works considering anisotropies while examining projection of interloper emission. We explicitly consider a simplified picture of redshift-space distortions and instrumental effects due to limited resolution, and how these distort an isotropic line-intensity signal in real space and introduce strong apparent anisotropies. The results suggest that while signal loss due to limited instrumental resolution is unavoidable, measuring the quadrupole power spectrum in addition to the monopole would still break parameter degeneracies present in monopole-only constraints, even without a measurement of the full anisotropic power spectrum.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We model the ultraviolet spectra of the Seyfert 1 galaxy NGC 5548 obtained with the <jats:italic>Hubble Space Telescope</jats:italic> during the 6 month reverberation mapping campaign in 2014. Our model of the emission from NGC 5548 corrects for overlying absorption and deblends the individual emission lines. Using the modeled spectra, we measure the response to continuum variations for the deblended and absorption-corrected individual broad emission lines, the velocity-dependent profiles of Ly<jats:italic>α</jats:italic> and C <jats:sc>iv</jats:sc>, and the narrow and broad intrinsic absorption features. We find that the time lags for the corrected emission lines are comparable to those for the original data. The velocity-binned lag profiles of Ly<jats:italic>α</jats:italic> and C <jats:sc>iv</jats:sc> have a double-peaked structure indicative of a truncated Keplerian disk. The narrow absorption lines show a delayed response to continuum variations corresponding to recombination in gas with a density of ∼10<jats:sup>5</jats:sup> cm<jats:sup>−3</jats:sup>. The high-ionization narrow absorption lines decorrelate from continuum variations during the same period as the broad emission lines. Analyzing the response of these absorption lines during this period shows that the ionizing flux is diminished in strength relative to the far-ultraviolet continuum. The broad absorption lines associated with the X-ray obscurer decrease in strength during this same time interval. The appearance of X-ray obscuration in ∼2012 corresponds with an increase in the luminosity of NGC 5548 following an extended low state. We suggest that the obscurer is a disk wind triggered by the brightening of NGC 5548 following the decrease in size of the broad-line region during the preceding low-luminosity state.</jats:p>