Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>We have used two methods to search for surviving companions of Type Ia supernova progenitors in three Balmer-dominated supernova remnants in the Large Magellanic Cloud: 0519–69.0, 0505–67.9 (DEM L71), and 0548–70.4. In the first method, we use the <jats:italic>Hubble Space Telescope</jats:italic> photometric measurements of stars to construct color–magnitude diagrams (CMDs) and compare positions of stars in the CMDs with those expected from theoretical post-impact evolution of surviving main-sequence or helium star companions. No obvious candidates of surviving companions are identified in this photometric search. Future models for surviving red giant companions or with different explosion mechanisms are needed for thorough comparisons with these observations in order to make more definitive conclusions. In the second method, we use Multi Unit Spectroscopic Explorer observations of 0519–69.0 and DEM L71 to carry out spectroscopic analyses of stars in order to use large peculiar radial velocities as diagnostics of surviving companions. We find a star in 0519–69.0 and a star in DEM L71 moving at radial velocities of 182 ± 0 km s<jats:sup>−1</jats:sup> and 213 ± 0 km s<jats:sup>−1</jats:sup>, respectively, more than 2.5<jats:italic>σ</jats:italic> from the mean radial velocity of the underlying stellar population, 264 and 270 km s<jats:sup>−1</jats:sup>, respectively. These stars need higher-quality spectra to investigate their abundances and rotation velocities to determine whether they are indeed surviving companions of the supernova progenitors.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The disk of HD 163296 shows ring and gap substructures in observations with the Atacama Large Millimeter/submillimeter Array. In addition, this is the only disk where the rings and gaps are spatially resolved in millimeter-wave polarization measurements. In this paper, we conduct radiative transfer modeling that includes self-scattering polarization to constrain the grain size and its distribution. We found that the grain size and dust scale height are the key parameters for reproducing the radial and azimuthal distributions of the observed polarization signature. Radial variation is mainly determined by grain size. The polarization fraction is high if the particle size is ∼<jats:italic>λ</jats:italic>/2<jats:italic>π</jats:italic>; it is low if the particle size is larger or smaller than this. In contrast, azimuthal variation in polarization is enhanced if the dust scale height is increased. Based on detailed modeling of the polarization of HD 163296, we found the following radial variations in the grain size and dust scale height. The maximum grain size was 140 <jats:italic>μ</jats:italic>m in the gaps and significantly larger or smaller in the rings. The dust scale height is less than one-third of the gas scale height inside the 70 au ring, and two-thirds of it outside. Furthermore, we constrained the gas turbulence to be <jats:italic>α</jats:italic> ≲ 1.5 × 10<jats:sup>−3</jats:sup> in the 50 au gap and <jats:italic>α</jats:italic> ∼ 0.015–0.3 in the 90 au gap. The transition in the turbulence strength at the boundary of the 70 au ring indicates the existence of a dead zone.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>As a natural consequence of the elementary processes of dust growth, we discovered that a new class of planets can be formed around supermassive black holes (SMBHs). We investigated a growth path from submicron sized icy dust monomers to Earth-sized bodies outside the “snow line,” located several parsecs from SMBHs in low luminosity active galactic nuclei (AGNs). In contrast to protoplanetary disks, the “radial drift barrier” does not prevent the formation of planetesimals. In the early phase of the evolution, low collision velocity between dust particles promotes sticking; therefore, the internal density of the dust aggregates decreases with growth. When the porous aggregate’s size reaches 0.1–1 cm, the collisional compression becomes effective, and the decrease in internal density stops. Once 10–100 m sized aggregates are formed, they are decoupled from gas turbulence, and the aggregate layer becomes gravitationally unstable, leading to the formation of planets by the fragmentation of the layer, with 10 times the mass of the Earth. The growth timescale depends on the turbulent strength of the circumnuclear disk and the black hole mass <jats:italic>M</jats:italic> <jats:sub>BH</jats:sub>, and it is comparable to the AGN’s lifetime (∼10<jats:sup>8</jats:sup> yr) for low mass (<jats:italic>M</jats:italic> <jats:sub>BH</jats:sub> ∼ 10<jats:sup>6</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>) SMBHs.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present an analysis of the internal velocity structures of the newly identified sub-0.1 pc coherent structures, <jats:italic>droplets</jats:italic>, in L1688 and B18. By fitting 2D linear velocity fields to the observed maps of velocity centroids, we determine the magnitudes of linear velocity gradients and examine the potential rotational motions that could lead to the observed velocity gradients. The results show that the droplets follow the same power-law relation between the velocity gradient and size found for larger-scale dense cores. Assuming that rotational motion giving rise to the observed velocity gradient in each core is a solid-body rotation of a rotating body with a uniform density, we derive the “net rotational motions” of the droplets. We find a ratio between rotational and gravitational energies, <jats:italic>β</jats:italic>, of ∼0.046 for the droplets, and when including both droplets and larger-scale dense cores, we find <jats:italic>β</jats:italic> ∼ 0.039. We then examine the alignment between the velocity gradient and the major axis of each droplet, using methods adapted from the histogram of relative orientations introduced by Soler et al. We find no definitive correlation between the directions of velocity gradients and the elongations of the cores. Lastly, we discuss physical processes other than rotation that may give rise to the observed velocity field.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present the distance-calibrated spectral energy distribution (SED) of TRAPPIST-1 using a new medium-resolution (<jats:italic>R</jats:italic> ∼ 6000) near-infrared (NIR) Folded-port InfraRed Echellette (FIRE) spectrum and its <jats:italic>Gaia</jats:italic> parallax. We report an updated bolometric luminosity (<jats:italic>L</jats:italic> <jats:sub>bol</jats:sub>) of −3.216 ± 0.016, along with semiempirical fundamental parameters: effective temperature <jats:italic>T</jats:italic> <jats:sub>eff</jats:sub> = 2628 ± 42 K, mass = 90 ± 8 <jats:italic>M</jats:italic> <jats:sub>Jup</jats:sub>, radius = 1.16 ± 0.03 <jats:italic>R</jats:italic> <jats:sub>Jup</jats:sub>, and log <jats:italic>g</jats:italic> = 5.21 ± 0.06 dex. Its kinematics point toward an older age, while spectral indices indicate youth; therefore, we compare the overall SED and NIR bands of TRAPPIST-1 to field-age, low-gravity, and low-metallicity dwarfs of similar <jats:italic>T</jats:italic> <jats:sub>eff</jats:sub> and <jats:italic>L</jats:italic> <jats:sub>bol</jats:sub>. We find field dwarfs of similar <jats:italic>T</jats:italic> <jats:sub>eff</jats:sub> and <jats:italic>L</jats:italic> <jats:sub>bol</jats:sub> best fit the overall and band-by-band features of TRAPPIST-1. Additionally, we present new Allers &amp; Liu spectral indices for the SpeX SXD and FIRE spectra of TRAPPIST-1, both classifying it as intermediate gravity. Examining <jats:italic>T</jats:italic> <jats:sub>eff</jats:sub>, <jats:italic>L</jats:italic> <jats:sub>bol</jats:sub>, and absolute <jats:italic>JHKW</jats:italic>1<jats:italic>W</jats:italic>2 magnitudes versus optical spectral type places TRAPPIST-1 in an ambiguous location containing both field and intermediate-gravity sources. Kinematics place TRAPPIST-1 within a subpopulation of intermediate-gravity sources lacking bona fide membership in a moving group with higher tangential and <jats:italic>UVW</jats:italic> velocities. We conclude that TRAPPIST-1 is a field-age source with subtle spectral features reminiscent of a low surface gravity object. To resolve the cause of TRAPPIST-1's intermediate-gravity indicators we speculate on two avenues that might be correlated to inflate the radius: (1) magnetic activity or (2) tidal interactions from planets. We find the M8 dwarf LHS 132 is an excellent match to TRAPPIST-1's spectral peculiarities along with the M9 <jats:italic>β</jats:italic> dwarf 2MASS J10220489+0200477, the L1 <jats:italic>β</jats:italic> 2MASS J10224821+5825453, and the L0 <jats:italic>β</jats:italic> 2MASS J23224684−3133231, which have distinct kinematics, making all four intriguing targets for future exoplanet studies.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Whether the spiral structure of galaxies is trailing or leading has been a subject of debate. We present a new spin parity catalog of 146 spiral galaxies that lists the following three pieces of information: whether the spiral structure observed on the sky is <jats:italic>S</jats:italic>-wise or <jats:italic>Z</jats:italic>-wise; which side of the minor axis of the galaxy is darker and redder, based on examination of Pan-STARRS and/or ESO/DSS2 red image archives; and which side of the major axis of the galaxy is approaching us based on the published literature. This paper confirms that all of the spiral galaxies in the catalog show a consistent relationship among these three parameters, without any confirmed counterexamples, which supports the generally accepted interpretation that all the spiral galaxies are trailing and that the darker/redder side of the galactic disk is closer to us. Although the results of this paper may not be surprising, they provide a rationale for analyzing the <jats:italic>S</jats:italic>/<jats:italic>Z</jats:italic> winding distribution of spiral galaxies, using the large and uniform image databases available now and in the near future, to study the spin vorticity distribution of galaxies in order to constrain the formation scenarios of galaxies and the large-scale structure of the universe.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a linear stability analysis of the fast-pairwise neutrino flavor conversion based on a result of our latest axisymmetric core-collapse supernova (CCSN) simulation with full Boltzmann neutrino transport. In the CCSN simulation, coherent asymmetric neutrino emissions of electron-type neutrinos (<jats:italic>ν</jats:italic> <jats:sub>e</jats:sub>) and their antiparticles (<jats:inline-formula> <jats:tex-math> <?CDATA ${\bar{\nu }}_{{\rm{e}}}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab4cf2ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>), in which the asymmetries of <jats:italic>ν</jats:italic> <jats:sub>e</jats:sub> and <jats:inline-formula> <jats:tex-math> <?CDATA ${\bar{\nu }}_{{\rm{e}}}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab4cf2ieqn2.gif" xlink:type="simple" /> </jats:inline-formula> are anticorrelated with each other, occur at almost the same time as the onset of aspherical shock expansion. We find that the asymmetric neutrino emissions play a crucial role on occurrences of fast flavor conversions. The linear analysis shows that unstable modes appear in both pre- and post-shock flows; for the latter, they appear only in the hemisphere of higher <jats:inline-formula> <jats:tex-math> <?CDATA ${\bar{\nu }}_{{\rm{e}}}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab4cf2ieqn3.gif" xlink:type="simple" /> </jats:inline-formula> emissions (the same hemisphere with stronger shock expansion). We analyze the characteristics of electron–lepton number (ELN) crossing in depth by closely inspecting the angular distributions of neutrinos in momentum space. The ELN crossing happens in various ways, and the property depends on the radius: in the vicinity of neutron star, <jats:inline-formula> <jats:tex-math> <?CDATA ${\bar{\nu }}_{{\rm{e}}}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab4cf2ieqn4.gif" xlink:type="simple" /> </jats:inline-formula> (<jats:italic>ν</jats:italic> <jats:sub>e</jats:sub>) dominates over <jats:italic>ν</jats:italic> <jats:sub>e</jats:sub> (<jats:inline-formula> <jats:tex-math> <?CDATA ${\bar{\nu }}_{{\rm{e}}}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjab4cf2ieqn5.gif" xlink:type="simple" /> </jats:inline-formula>) in the forward (backward) direction; at the larger radius, the ELN crossing occurs in the opposite way. We also find that the non-radial ELN crossing occurs at the boundary between no ELN crossing and the radial one, which is an effect of genuine multi-dimensional transport. Our findings indicate that the collective neutrino oscillation may occur more commonly in CCSNe and suggest that the CCSN community needs to accommodate these oscillations self-consistently in the modeling of CCSNe.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Early-time observations of Type Ia supernovae (SNe Ia) are essential to constrain the properties of their progenitors. In this paper, we present high-quality light curves of 127 SNe Ia discovered by the Zwicky Transient Facility (ZTF) in 2018. We describe our method to perform forced point-spread function photometry, which can be applied to other types of extragalactic transients. With a planned cadence of six observations per night (three <jats:italic>g</jats:italic> + three <jats:italic>r</jats:italic>), all of the 127 SNe Ia are detected in both <jats:italic>g</jats:italic> and <jats:italic>r</jats:italic> bands more than 10 days (in the rest frame) prior to the epoch of <jats:italic>g</jats:italic>-band maximum light. The redshifts of these objects range from <jats:italic>z</jats:italic> = 0.0181 to 0.165; the median redshift is 0.074. Among the 127 SNe, 50 are detected at least 14 days prior to maximum light (in the rest frame), with a subset of nine objects being detected more than 17 days before <jats:italic>g</jats:italic>-band peak. This is the largest sample of young SNe Ia collected to date; it can be used to study the shape and color evolution of the rising light curves in unprecedented detail. We discuss six peculiar events in this sample: one 02cx-like event ZTF18abclfee (SN 2018crl), one Ia-CSM SN ZTF18aaykjei (SN 2018cxk), and four objects with possible super-Chandrasekhar mass progenitors: ZTF18abhpgje (SN 2018eul), ZTF18abdpvnd (SN 2018dvf), ZTF18aawpcel (SN 2018cir), and ZTF18abddmrf (SN 2018dsx).</jats:p>