Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>The interstellar medium (ISM) is turbulent over vast scales and in various phases. In this paper, we study turbulence with different tracers in four nearby star-forming regions: Orion, Ophiuchus, Perseus, and Taurus. We combine the APOGEE-2 and Gaia surveys to obtain the full six-dimensional measurements of positions and velocities of young stars in these regions. The velocity structure functions (VSFs) of the stars show a universal scaling of turbulence. We also obtain H<jats:italic>α</jats:italic> gas kinematics in these four regions from the Wisconsin H-Alpha Mapper. The VSFs of the H<jats:italic>α</jats:italic> are more diverse compared to those of stars. In regions with recent supernova activities, they show characteristics of local energy injections and higher amplitudes compared to the VSFs of stars and of CO from the literature. Such difference in amplitude of the VSFs can be explained by the different energy and momentum transport from supernovae into different phases of the ISM, thus resulting in higher levels of turbulence in the warm ionized phase traced by H<jats:italic>α</jats:italic>. In regions without recent supernova activities, the VSFs of young stars, H<jats:italic>α</jats:italic>, and CO are generally consistent, indicating well-coupled turbulence between different phases. Within individual regions, the brighter parts of the H<jats:italic>α</jats:italic> gas tend to have a higher level of turbulence than the low-emission parts. Our findings support a complex picture of the Milky Way ISM, where turbulence can be driven at different scales and inject energy unevenly into different phases.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>By assuming the photosphere located at the outmost edge of the ejecta, Arnett et al. (1980, 1982, 1989) presented the light curves of homologous explosions in supernovae analytically and numerically to include recombination effects. Actually as homologous expansion proceeds, the photosphere recedes deeper into the ejecta. In this situation, the photosphere radius increases at early times and decreases later on, which can be described by a simple method proposed by Liu et al. To study how the photosphere recession affects the luminosity evolution, we impose a boundary condition on the photosphere to determine the spatial and time distribution of the temperature of the ejecta, which is clarified to be reasonable. We find that the photosphere recession reduces the luminosity compared with the previous result without the recession, which can be tested with observations of Type-IIP supernovae.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Molecular hydrogen is the most abundant molecule in the galaxy and plays important roles in planets, their circumstellar environments, and many of their host stars. We have confirmed the presence of molecular hydrogen in the AU Mic system using high-resolution FUV spectra from HST-STIS during both quiescence and a flare. AU Mic is a ∼23 Myr M dwarf that hosts a debris disk and at least two planets. We estimate the temperature of the gas at 1000–2000 K, consistent with previous detections. Based on the radial velocities and widths of the H<jats:sub>2</jats:sub> line profiles and the response of the H<jats:sub>2</jats:sub> lines to a stellar flare, the H<jats:sub>2</jats:sub> line emission is likely produced in the star, rather than in the disk or the planet. However, the temperature of this gas is significantly below the temperature of the photosphere (∼3650 K) and the predicted temperature of its starspots (≳2650 K). We discuss the possibility of colder starspots or a cold layer in the photosphere of a pre-main-sequence M dwarf.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>An infrared <jats:italic>L</jats:italic>- and <jats:italic>M</jats:italic>-band spectral survey, performed toward the young planetary nebula NGC 7027 with the iSHELL instrument on NASA’s Infrared Telescope Facility (IRTF), has revealed more than 20 vibrational lines of the molecules HeH<jats:sup>+</jats:sup>, H<jats:sub>2</jats:sub>, and CH<jats:sup>+</jats:sup> and more than 50 spectral lines of atoms and atomic ions. The present paper focuses on the atomic line emissions, the molecular lines having been discussed in two previous publications. The atomic lines detected with high confidence in the 2.951–5.24 <jats:italic>μ</jats:italic>m region covered (incompletely) by this survey comprise (1) six collisionally excited lines of metal ions that had previously been identified in astrophysical nebulae but for which the present observations provide the most accurate wavelength determinations obtained to date; (2) a spectral line at 4.6895 <jats:italic>μ</jats:italic>m, not previously reported, for which the probable identification is the <jats:sup>4</jats:sup> <jats:italic>F</jats:italic> <jats:sub>7/2</jats:sub>–<jats:sup>4</jats:sup> <jats:italic>F</jats:italic> <jats:sub>9/2</jats:sub> fine-structure transition of [Zn <jats:sc>vi</jats:sc>]; (3) 39 recombination lines of H and He<jats:sup>+</jats:sup>, with upper states of principal quantum number up to 38 (H) or 24 (He<jats:sup>+</jats:sup>); (4) 10 recombination lines of the multielectron species He, C<jats:sup>2+</jats:sup>, and C<jats:sup>3+</jats:sup>.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Using the extended halo-based group finder developed by Yang et al., which is able to deal with galaxies via spectroscopic and photometric redshifts simultaneously, we construct galaxy group and candidate protocluster catalogs in a wide redshift range (0 &lt; <jats:italic>z</jats:italic> &lt; 6) from the joint CFHT Large Area <jats:italic>U</jats:italic>-band Deep Survey and Hyper Suprime-Cam Subaru Strategic Program deep data set. Based on a selection of 5,607,052 galaxies with <jats:italic>i</jats:italic>-band magnitude <jats:italic>m</jats:italic> <jats:sub> <jats:italic>i</jats:italic> </jats:sub> &lt; 26 and a sky coverage of 34.41 deg<jats:sup>2</jats:sup>, we identify a total of 2,232,134 groups, of which 402,947 groups have at least three member galaxies. We have visually checked and discussed the general properties of these richest groups at redshift <jats:italic>z</jats:italic> &gt; 2.0. By checking the galaxy number distributions within a 5–7 <jats:italic>h</jats:italic> <jats:sup>−1</jats:sup>Mpc projected separation and a redshift difference Δ<jats:italic>z</jats:italic> ≤ 0.1 around those richest groups at redshift <jats:italic>z</jats:italic> &gt; 2, we identify lists of 761, 343, and 43 protocluster candidates in the redshift bins 2 ≤ <jats:italic>z</jats:italic> &lt; 3, 3 ≤ <jats:italic>z</jats:italic> &lt; 4, and <jats:italic>z</jats:italic> ≥ 4, respectively. In general, these catalogs of galaxy groups and protocluster candidates will provide useful environmental information in probing galaxy evolution along cosmic time.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Nonlocal gravity (NLG) is a classical nonlocal generalization of Einstein’s theory of gravitation that has been constructed in close analogy with the nonlocal electrodynamics of media. According to NLG, what appears as dark matter in astrophysics and cosmology is in reality the nonlocal aspect of the universal gravitational interaction. We focus here on two main features of the effective dark matter in NLG, namely, (a) the density of effective dark matter in NLG is always finite and therefore cusp-free, and (b) there is less effective dark matter in dwarf galaxies than is generally assumed in the standard particle dark matter paradigm. The corresponding astrophysical implications of NLG in connection with three ultra-diffuse galaxies AGC 114905, 242019, and 219533 are discussed.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In this VERTICO early science paper we explore in detail how environmental mechanisms, identified in H <jats:sc>i</jats:sc>, affect the resolved properties of molecular gas reservoirs in cluster galaxies. The molecular gas is probed using ALMA ACA (+TP) observations of <jats:sup>12</jats:sup>CO(2–1) in 51 spiral galaxies in the Virgo cluster (of which 49 are detected), all of which are included in the VIVA H <jats:sc>i</jats:sc> survey. The sample spans a stellar mass range of <jats:inline-formula> <jats:tex-math> <?CDATA $9\leqslant \mathrm{log}\,{M}_{\star }/{M}_{\odot }\leqslant 11$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>9</mml:mn> <mml:mo>≤</mml:mo> <mml:mi>log</mml:mi> <mml:mspace width="0.25em" /> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⋆</mml:mo> </mml:mrow> </mml:msub> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> <mml:mo>≤</mml:mo> <mml:mn>11</mml:mn> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac6e68ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>. We study molecular gas radial profiles, isodensity radii, and surface densities as a function of galaxy H <jats:sc>i</jats:sc> deficiency and morphology. There is a weak correlation between global H <jats:sc>i</jats:sc> and H<jats:sub>2</jats:sub> deficiencies, and resolved properties of molecular gas correlate with H <jats:sc>i</jats:sc> deficiency: galaxies that have large H <jats:sc>i</jats:sc> deficiencies have relatively steep and truncated molecular gas radial profiles, which is due to the removal of low-surface-density molecular gas on the outskirts. Therefore, while the environmental mechanisms observed in H <jats:sc>i</jats:sc> also affect molecular gas reservoirs, there is only a moderate reduction of the total amount of molecular gas.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Solar eruptive events such as coronal mass ejections and eruptive flares are frequently associated with the emergence of magnetic flux from the convection zone into the corona. We use three-dimensional magnetohydrodynamic numerical simulations to study the interaction of coronal magnetic fields with emerging flux and determine the conditions that lead to eruptive activity. A simple parameter study is performed, varying the relative angle between emerging magnetic flux and a preexisting coronal dipole field. We find that in all cases the emergence results in a sheared magnetic arcade that transitions to a twisted coronal flux rope via low-lying magnetic reconnection. This structure, however, is constrained by its own outer field and so is noneruptive in the absence of reconnection with the overlying coronal field. The amount of this overlying reconnection is determined by the relative angle between the emerged and preexisting fields. The reconnection between emerging and preexisting fields is necessary to generate sufficient expansion of the emerging structure so that flare-like reconnection below the coronal flux rope becomes strong enough to trigger its release. Our results imply that the relative angle is the key parameter in determining whether the resultant active regions exhibit eruptive behavior and is thus a potentially useful candidate for predicting eruptions in newly emerging active regions. More generally, our results demonstrate that the detailed interaction between the convection zone/photosphere and the corona must be calculated self-consistently in order to model solar eruptions accurately.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present new Atacama Large Millimeter/submillimeter Array (ALMA) results obtained from spatially resolved CO <jats:italic>J</jats:italic> = 2–1 line (0.″4 resolution) and 870 <jats:italic>μ</jats:italic>m continuum (0.″2 resolution) observations of cluster galaxies in XMMXCS J2215.9-1738 at <jats:italic>z</jats:italic> = 1.46. Our sample comprises 17 galaxies within ∼0.5 Mpc (0.6<jats:italic>R</jats:italic> <jats:sub>200</jats:sub>) of the cluster center, all of which have previously been detected in the CO <jats:italic>J</jats:italic> = 2–1 line at a lower resolution. The effective radii of both the CO <jats:italic>J</jats:italic> = 2–1 line and 870 <jats:italic>μ</jats:italic>m dust continuum emissions are robustly measured for nine galaxies by modeling the visibilities. We find that the CO <jats:italic>J</jats:italic> = 2–1 line emission in all of the nine galaxies is more extended than the dust continuum emission by a factor of 2.8 ± 1.4. We investigate the spatially resolved Kennicutt–Schmidt (KS) relation in two regions within the interstellar medium of the galaxies. The relation for our sample reveals that the central region (0 &lt; <jats:italic>r</jats:italic> &lt; <jats:italic>R</jats:italic> <jats:sub> <jats:italic>e</jats:italic>,870<jats:italic>μ</jats:italic>m</jats:sub>) of galaxies tends to have a shorter gas depletion timescale, i.e., a higher star formation efficiency, compared to the extended region (<jats:italic>R</jats:italic> <jats:sub> <jats:italic>e</jats:italic>,870<jats:italic>μ</jats:italic>m</jats:sub> &lt; <jats:italic>r</jats:italic> &lt; <jats:italic>R</jats:italic> <jats:sub> <jats:italic>e</jats:italic>,CO</jats:sub>). Overall, our result suggests that star formation activities are concentrated inside the extended gas reservoir, possibly resulting in the formation of a bulge structure. We find consistency between the ALMA 870 <jats:italic>μ</jats:italic>m radii of star-forming members and the Hubble Space Telescope/1.6 <jats:italic>μ</jats:italic>m radii of passive members in a mass–size distribution, which suggests a transition from star-forming to passive members within ∼0.5 Gyr. In addition, no clear differences in the KS relation nor in the sizes are found between galaxies with and without a close companion.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Cassini data are consistent with a global electric field in Saturn's magnetosphere that points approximately antisunward. The inner radial extent of this field was initially established using Saturn orbit insertion data but measurements of ultrarelativistic electrons from that pass cast some doubt on whether the electric field reaches all the way to the A ring. It was not until the so-called ring-grazing and proximal orbits near the end of the mission in 2017 that relevant data were again obtained on magnetic field lines that connect to the region just outward of the main rings. Here we report on the energetic charged particle data during those orbits, showing that electron observations at a wide range of energies are consistent with an electric field that influences charged particle drift paths near the outer edge of the A ring. We include a very detailed analysis of Cassini's ultrarelativistic electron measurements (channel E7 in the text) and argue they provide no information about the electric field. This result further strengthens the case of several studies that have used the presence of the electric field to explain signatures of acceleration in the data.</jats:p>