Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>Understanding the formation of stellar clusters requires following the interplay between gas and newly formed stars accurately. We therefore couple the magnetohydrodynamics code <jats:monospace>FLASH</jats:monospace> to the <jats:italic>N</jats:italic>-body code <jats:monospace>ph4</jats:monospace> and the stellar evolution code <jats:monospace>SeBa</jats:monospace> using the Astrophysical Multipurpose Software Environment (<jats:monospace>AMUSE</jats:monospace>) to model stellar dynamics, evolution, and collisional <jats:italic>N</jats:italic>-body dynamics and the formation of binary and higher-order multiple systems, while implementing stellar feedback in the form of radiation, stellar winds, and supernovae in <jats:monospace>FLASH</jats:monospace>. We here describe the algorithms used for each of these processes. We denote this integrated package Torch. We then use this novel numerical method to simulate the formation and early evolution of several examples of open clusters of ∼1000 stars formed from clouds with a mass range of 10<jats:sup>3</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> to 10<jats:sup>5</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>. Analyzing the effects of stellar feedback on the gas and stars of the natal clusters, we find that in these examples, the stellar clusters are resilient to disruption, even in the presence of intense feedback. This can even slightly increase the amount of dense, Jeans unstable gas by sweeping up shells; thus, a stellar wind strong enough to trap its own H <jats:sc>ii</jats:sc> region shows modest triggering of star formation. Our clusters are born moderately mass segregated, an effect enhanced by feedback, and retained after the ejection of their natal gas, in agreement with observations.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report the discovery of a young (only 30–40 Myr) snake-like structure (dubbed a stellar snake) in the solar neighborhood from Gaia DR2. The average distance of this structure is about 310 pc from us. Both the length and width are over 200 pc, but the thickness is only about 80 pc. The snake has one tail and two dissolving cores, which can be clearly distinguished in the 6D phase space. The whole structure includes thousands of members with a total mass of larger than 2000 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> in a uniform population. The population is so young that it cannot be well explained with the classical theory of tidal tails. We therefore suspect that the snake is hierarchically primordial, rather than the result of dynamically tidal stripping, even if the snake is probably expanding. The coherent 5D phase information and the ages suggest that the snake was probably born in the same environment as the filamentary structure of Beccari et al. If so, the snake could extend the sky region of the Vela OB2 association by a factor of ∼2 and supplement the census of its coeval structures. This finding is useful to understanding the history of the formation and evolution of the Vela OB2 complex. The age of the snake well matches with that of the Gould Belt. In the sky region of our interest, we detect one new open cluster, which is named Tian 1 in this work.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Radio emission from the high- and super-Eddington accreting active galactic nuclei (AGNs) has various origins: a persistent jet, the magnetized corona, and the wind-like outflows. It is still unclear which is the leading mechanism responsible for the observed radio emission and how the radio emission is related to other characteristic parameters such as the Eddington ratio and black hole mass. In this paper, we present the 5 GHz Very Large Array (VLA) observational results of a sample of 25 extremely high Eddington accreting supermassive black holes (EESBHs, the Eddington ratio <jats:italic>λ</jats:italic> <jats:sub>Edd</jats:sub> close to or above 1) in narrow-line Seyfert 1 galaxies, among which 22 sources are detected. Most of the EESBHs show a compact radio structure from a few hundred parsecs to 1 kpc scale. We estimated the lowest star formation rate surface density required for producing the observed radio emission and found that it is higher than the largest value previously detected in circumnuclear starburst galaxies, implying that the radio emission is from the AGN activity. Along with a comparison sample, we find an overall inverse <jats:inline-formula> <jats:tex-math> <?CDATA ${ \mathcal R }$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabb775ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>–<jats:italic>λ</jats:italic> <jats:sub>Edd</jats:sub> correlation ranging from sub- to super-Eddington ratios. The high-Eddington and mildly super-Eddington AGNs (−0.5 &lt; log <jats:inline-formula> <jats:tex-math> <?CDATA ${\lambda }_{\mathrm{Edd}}\lt 0.6$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabb775ieqn2.gif" xlink:type="simple" /> </jats:inline-formula>) have a radio-to-X-ray luminosity ratio <jats:italic>L</jats:italic> <jats:sub>R</jats:sub>/<jats:italic>L</jats:italic> <jats:sub>X</jats:sub> ∼ 10<jats:sup>−5</jats:sup>–10<jats:sup>−4</jats:sup> and a steep radio spectrum, supporting that the radio emission is from transient ejecta (outflows) of corona; however, the jet contribution cannot be entirely ruled out. Our highly super-Eddington sources (log <jats:inline-formula> <jats:tex-math> <?CDATA ${\lambda }_{\mathrm{Edd}}\gtrsim 0.6$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabb775ieqn3.gif" xlink:type="simple" /> </jats:inline-formula>) have a flatter radio spectrum, along with its low radio luminosity: <jats:inline-formula> <jats:tex-math> <?CDATA ${L}_{{\rm{R}}}/{L}_{{\rm{X}}}\sim {10}^{-5}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabb775ieqn4.gif" xlink:type="simple" /> </jats:inline-formula>; their radio emission is likely dominated by a magnetized corona, and a radiation-pressure-caused jet is also proposed in this paper.</jats:p>