Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>The Last Journey is a large-volume, gravity-only, cosmological <jats:italic>N</jats:italic>-body simulation evolving more than 1.24 trillion particles in a periodic box with a side length of 5.025 Gpc. It was implemented using the HACC simulation and analysis framework on the BG/Q system Mira. The cosmological parameters are chosen to be consistent with the results from the Planck satellite. A range of analysis tools have been run in situ to enable a diverse set of science projects and, at the same time, keep the resulting data amount manageable. Analysis outputs have been generated starting at redshift <jats:italic>z</jats:italic> ∼ 10 to allow for construction of synthetic galaxy catalogs using a semianalytic modeling approach in postprocessing. As part of our in situ analysis pipeline, we employ a new method for tracking halo substructures, introducing the concept of subhalo cores. The production of multiwavelength synthetic sky maps is facilitated by generating particle light cones in situ, also beginning at <jats:italic>z</jats:italic> ∼ 10. We provide an overview of the simulation setup and generated data products; a first set of analysis results is presented. A subset of the data is publicly available.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Surveys of Wolf–Rayet (WR) stars in the Large Magellanic Cloud (LMC) have yielded a fairly complete catalog of 154 known stars. We have conducted a comprehensive, multiwavelength study of the interstellar/circumstellar environments of WR stars, using the Magellanic Cloud Emission Line Survey images in the H<jats:italic>α</jats:italic>, [O <jats:sc>iii</jats:sc>], and [S <jats:sc>ii</jats:sc>] lines; Spitzer Space Telescope 8 and 24 <jats:italic>μ</jats:italic>m images; Blanco 4 m Telescope H<jats:italic>α</jats:italic> CCD images; and Australian Telescope Compact Array + Parkes Telescope H <jats:sc>i</jats:sc> data cube of the LMC. We have also examined whether the WR stars are in OB associations, classified the H <jats:sc>ii</jats:sc> environments of WR stars, and used this information to qualitatively assess the WR stars’ evolutionary stages. The 30 Dor giant H <jats:sc>ii</jats:sc> region has active star formation and hosts young massive clusters, thus we have made statistical analyses for 30 Dor and the rest of the LMC both separately and altogether. Due to the presence of massive young clusters, the WR population in 30 Dor is quite different from that from elsewhere in the LMC. We find small bubbles (&lt;50 pc diameter) around ∼12% of WR stars in the LMC, most of which are WN stars and not in OB associations. The scarcity of small WR bubbles is discussed. Spectroscopic analyses of abundances are needed to determine whether the small WR bubbles contain interstellar medium or circumstellar medium. Implications of the statistics of interstellar environments and OB associations around WR stars are discussed. Multiwavelength images of each LMC WR star are presented.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>As relativistic plasma launches from a compact object at the center of a galaxy, the corresponding outflow should slow down with the increase of separation from the core due to energy dissipation along the path. However, some long-baseline observations of active galactic nucleus (AGN) jets show that the velocity of jets increases rather than decreases at a larger and larger separation from the core. The mechanism of such an acceleration of astrophysical jets has not been well understood so far, although much progress has been achieved on theoretical and observational perspectives. This paper illustrates the phenomenon of jet acceleration that emerged in some AGNs by the nonballistic model in which some nonconsecutive knots are produced by a continuous outflow at different distances from the central black hole; such knots appear to rotate along different radii at the same precession cone in the case of a precessing jet. The projection of the trajectories of such knots on the plane of the sky leads us to expect that jet components further from the core move at larger apparent velocities. The investigation provides a very simple scenario to the puzzling phenomena of astrophysical jets.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Properties of the inner heliosheath (IHS) plasma are inferred from energetic neutral atom (ENA) observations by ∼1 au spacecraft. However, the Compton–Getting effect due to the plasma velocity relative to the spacecraft is rarely taken into account, even though the plasma speed is a significant fraction of the ENA speed. In this study, we transform Interstellar Boundary Explorer (IBEX) ENA spectra to the IHS plasma frame using flow profiles from a 3D heliosphere simulation. We find that proton spectra in the plasma frame are steeper by ∼30% to 5% at ∼0.5 to 6 keV, respectively, compared to ENAs in the spacecraft frame. While radial plasma flows contribute most to the Compton–Getting effect, transverse flows at mid/high latitudes and the heliosphere flanks account for up to ∼30% of the frame transformation for IBEX-Hi at ∼0.7 keV and up to ∼60% for IBEX-Lo at ∼0.1 keV. We determine that the majority of IHS proton fluxes derived from IBEX-Hi measurements in 2009–2016 are statistically consistent with power-law distributions, with mean proton index ∼2.1 and standard deviation ∼0.4. We find significantly fewer spectral breaks in IBEX observations compared to early analyses, which we determine were a product of the “ion gun” background prevalent in ∼2009–2012 before corrections made by McComas et al. in subsequent data releases. We recommend that future analyses of the IHS plasma utilizing ENA measurements take into account the Compton–Getting effect including radial and transverse flows, particularly IBEX and Interstellar Mapping and Acceleration Probe measurements below ∼10 keV.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We explore several ways to dissect brightest cluster galaxies (BCGs) and their surrounding intracluster light (ICL) using a surface brightness (SB) cut, a luminosity cut, excess light above a de Vaucouleurs profile, or a double Sérsic decomposition. Assuming that all light above <jats:inline-formula> <jats:tex-math> <?CDATA $M\lt -21.85\,g^{\prime} \ \mathrm{mag}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjsabcda6ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> is attributable to the ICL, we find that an average fraction of <jats:inline-formula> <jats:tex-math> <?CDATA ${f}_{\mathrm{ICL}}^{\mathrm{MT}}=71\pm 22 \% $?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjsabcda6ieqn2.gif" xlink:type="simple" /> </jats:inline-formula> of all diffuse light centered on the BCG belongs to the ICL. Likewise, if we assume that all light fainter than <jats:inline-formula> <jats:tex-math> <?CDATA $\mathrm{SB}\gt 27\,{\rm{g}}^{\prime} $?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjsabcda6ieqn3.gif" xlink:type="simple" /> </jats:inline-formula> mag arcsec<jats:sup>−2</jats:sup> belongs to the ICL, the average ICL fraction is <jats:inline-formula> <jats:tex-math> <?CDATA ${f}_{\mathrm{ICL}}^{\mathrm{SB}27}=34\pm 19 \% $?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjsabcda6ieqn4.gif" xlink:type="simple" /> </jats:inline-formula>. After fitting a de Vaucouleurs profile to the inner parts of the SB profile, we detect excess light at large radii, corresponding to an average ICL fraction of <jats:inline-formula> <jats:tex-math> <?CDATA ${f}_{\mathrm{ICL}}^{\mathrm{DV}}=48\pm 20 \% $?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjsabcda6ieqn5.gif" xlink:type="simple" /> </jats:inline-formula>. Finally, by decomposing the SB profile into two Sérsic functions, we find an average ICL fraction of <jats:inline-formula> <jats:tex-math> <?CDATA ${f}_{\mathrm{ICL}}^{{\rm{S}}\times }\,=\,52\pm 21 \% $?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjsabcda6ieqn6.gif" xlink:type="simple" /> </jats:inline-formula> associated with the outer Sérsic component. Our measured ICL and BCG+ICL luminosities agree well with predictions from high-resolution simulations where the outer Sérsic component traces the unrelaxed, accreted stellar material. BCG and ICL properties defined in this way are correlated with cluster parameters to study the coevolution of BCGs, ICL, and their host clusters. We find positive correlations between BCG+ICL brightness and cluster mass, cluster velocity dispersion, cluster radius, and integrated satellite brightness, confirming that BCG/ICL growth is indeed coupled with cluster growth. On average, the ICL is better aligned than the BCG with the host cluster in terms of position angle, ellipticity, and centering. That makes it a potential dark-matter tracer.</jats:p>