Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>Ring structures are observed through (sub)millimeter dust continuum emission in various circumstellar disks from the early stages of class 0 and I to the late stage of class II young stellar objects (YSOs). In this paper, we study one of the possible scenarios for such ring formation, which is the coagulation of dust aggregates in the early stage. The dust grains grow in an inside-out manner because the growth timescale is roughly proportional to the orbital period. The boundary of the dust evolution can be regarded as the growth front, where the growth time is comparable to the disk age. Using radiative transfer calculations based on the dust coagulation model, we find that the growth front can be observed as a ring structure because the dust surface density changes sharply at this position. Furthermore, we confirm that the observed ring positions in YSOs with an age of ≲1 Myr are consistent with the growth front. The growth front could be important in creating the ring structure in particular for the early stage of disk evolution, such as class 0 and I sources.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>An optimal estimate for Stokes parameters is derived for the situation in X-ray astronomy where the instrument has a modulation factor that varies significantly with energy but the signals are very weak or mildly polarized. For such sources, the band of analysis may be broadened in order to obtain a significant polarization measurement. Optimal estimators are provided for the cases of binned and unbinned data and applied to data such as might be obtained for faint or weakly polarized sources observed using the Imaging X-ray Polarimetry Explorer. For a sample situation, the improvement in the minimum detectable polarization is 6%–7% using a count-weighted rms of the modulation factor, when compared to a count-weighted average. Improving the modulation factor, such as when using a neural network approach to Imaging X-ray Polarimetry Explorer event tracks, can provide additional improvement up to 10%–15%. The actual improvement depends on the spectral shape and the details of the instrument response functions.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present the Stage II results from the ongoing Satellites Around Galactic Analogs (SAGA) Survey. Upon completion, the SAGA Survey will spectroscopically identify satellite galaxies brighter than <jats:italic>M</jats:italic> <jats:sub> <jats:italic>r</jats:italic>,<jats:italic>o</jats:italic> </jats:sub> = −12.3 around 100 Milky Way (MW) analogs at <jats:italic>z</jats:italic> ∼ 0.01. In Stage II, we have more than quadrupled the sample size of Stage I, delivering results from 127 satellites around 36 MW analogs with an improved target selection strategy and deep photometric imaging catalogs from the Dark Energy Survey and the Legacy Surveys. We have obtained 25,372 galaxy redshifts, peaking around <jats:italic>z</jats:italic> = 0.2. These data significantly increase spectroscopic coverage for very low redshift objects in 17 &lt; <jats:italic>r</jats:italic> <jats:sub> <jats:italic>o</jats:italic> </jats:sub> &lt; 20.75 around SAGA hosts, creating a unique data set that places the Local Group in a wider context. The number of confirmed satellites per system ranges from zero to nine and correlates with host galaxy and brightest satellite luminosities. We find that the number and luminosities of MW satellites are consistent with being drawn from the same underlying distribution as SAGA systems. The majority of confirmed SAGA satellites are star-forming, and the quenched fraction increases as satellite stellar mass and projected radius from the host galaxy decrease. Overall, the satellite quenched fraction among SAGA systems is lower than that in the Local Group. We compare the luminosity functions and radial distributions of SAGA satellites with theoretical predictions based on cold dark matter simulations and an empirical galaxy–halo connection model and find that the results are broadly in agreement.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a study of the relationship between black hole accretion rate (BHAR) and star formation rate (SFR) in a sample of giant elliptical galaxies. These galaxies, which live at the centers of galaxy groups and clusters, have star formation and black hole activity that is primarily fueled by gas condensing out of the hot intracluster medium. For a sample of 46 galaxies spanning five orders of magnitude in BHAR and SFR, we find a mean ratio of <jats:inline-formula> <jats:tex-math> <?CDATA ${\mathrm{log}}_{10}(\mathrm{BHAR}/\mathrm{SFR})=-1.45\pm 0.2$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabd47fieqn1.gif" xlink:type="simple" /> </jats:inline-formula>, independent of the methodology used to constrain both SFR and BHAR. This ratio is significantly higher than most previously published values for field galaxies. We investigate whether these high BHAR/SFR ratios are driven by high BHAR, low SFR, or a different accretion efficiency in radio galaxies. The data suggest that the high BHAR/SFR ratios are primarily driven by boosted black hole accretion in spheroidal galaxies compared to their disk counterparts. We propose that the angular momentum of the cool gas is the primary driver in suppressing BHAR in lower-mass galaxies, with massive galaxies accreting gas that has condensed out of the hot phase on nearly radial trajectories. Additionally, we demonstrate that the relationship between specific BHAR and SFR (sBHAR and sSFR) has much less scatter over six orders of magnitude in both parameters, due to competing dependence on morphology between the <jats:italic>M</jats:italic> <jats:sub>BH</jats:sub>–<jats:italic>M</jats:italic> <jats:sub>*</jats:sub> and BHAR–SFR relations. In general, active galaxies selected by typical techniques have sBHAR/sSFR ∼ 10, while galactic nuclei with no clear AGN signatures have sBHAR/sSFR ∼ 1, consistent with a universal <jats:italic>M</jats:italic> <jats:sub>BH</jats:sub>–<jats:italic>M</jats:italic> <jats:sub>spheroid</jats:sub> relation.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Strongly driven magnetic reconnection occurs in astrophysical events and also in laboratory experiments with laser-produced plasma. We have performed 2.5D particle-in-cell simulations of collisions of two high-energy–density plasmas resulting in strongly driven magnetic reconnection that demonstrates significant non-thermal ion acceleration. Such acceleration is significant only when the plasma beta is sufficiently low that the Alfvén speed at the reconnection inflow exceeds the thermal speed. Under these conditions, the most energetic ions are primarily accelerated by the Hall electric field in the reconnection outflow, especially at the trailing edge of an emerging plasmoid in the outflow. Laboratory experiments in the near future should be able to confirm these predictions and their applicability to astrophysical situations.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We analyze the gas mass distribution, the gas kinematics, and the young stellar objects of the California Molecular Cloud L1482 filament. The mean Gaia DR2 YSO distance is <jats:inline-formula> <jats:tex-math> <?CDATA ${511}_{-16}^{+17}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabd47cieqn1.gif" xlink:type="simple" /> </jats:inline-formula> pc. In terms of the gas, the line-mass (M/L) profiles are symmetric scale-free power laws consistent with cylindrical geometry. We calculate the gravitational potential and field profiles based on these. Our IRAM 30 m multi-tracer position–velocity diagrams highlight twisting and turning structures. We measure the C<jats:sup>18</jats:sup>O velocity profile perpendicular to the southern filament ridgeline. The profile is regular, confined (projected <jats:italic>r</jats:italic> ≲ 0.4 pc), antisymmetric, and, to first order, linear, with a break at <jats:italic>r</jats:italic> ∼ 0.25 pc. We use a simple solid-body rotation toy model to interpret it. We show that the centripetal force, compared to gravity, increases toward the break; when the ratio of forces approaches unity, the profile turns over, just before the implied filament breakup. The timescales of the inner (outer) gradients are ∼0.7 (6.0) Myr. The timescales and relative roles of gravity to rotation indicate that the structure is stable, long lived (∼a few times 6 Myr), and undergoing outside-in evolution. This filament has practically no star formation, a perpendicular Planck plane-of-the-sky magnetic field morphology, and 2D “zig-zag” morphology, which together with the rotation profile lead to the suggestion that the 3D shape is a “corkscrew” filament. These results, together with results in other regions, suggest evolution toward higher densities as rotating filaments shed angular momentum. Thus, magnetic fields may be an essential feature of high-mass (<jats:italic>M</jats:italic> ∼ 10<jats:sup>5</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>) cloud filament evolution toward cluster formation.</jats:p>