Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>Our understanding of the convective-engine paradigm driving core-collapse supernovae has been used for two decades to predict the remnant mass distribution from stellar collapse. These predictions improve as our understanding of this engine increases. In this paper, we review our current understanding of convection (in particular, the growth rate of convection) in stellar collapse and study its effect on the remnant mass distribution. We show how the depth of the mass gap between neutron stars and black holes can help probe this convective growth. We include a study of the effects of stochasticity in both the stellar structure and the convective seeds caused by stellar burning. We study the role of rotation and its effect on the pair-instability mass gap. Under the paradigm limiting stellar rotation to those stars in tight binaries, we determine the effect of rotation on the remnant mass distribution.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report on high-resolution observations of recurrent fan-like jets by the Goode Solar Telescope in multiple wavelengths inside a sunspot group. The dynamics behavior of the jets is derived from the H<jats:italic>α</jats:italic> line profiles. Quantitative values for one well-identified event have been obtained, showing a maximum projected velocity of 42 km s<jats:sup>−1</jats:sup> and a Doppler shift of the order of 20 km s<jats:sup>−1</jats:sup>. The footpoints/roots of the jets have a lifted center on the H<jats:italic>α</jats:italic> line profile compared to the quiet Sun, suggesting a long-lasting heating at these locations. The magnetic field between the small sunspots in the group shows a very high resolution pattern with parasitic polarities along the intergranular lanes accompanied by high-velocity converging flows (4 km s<jats:sup>−1</jats:sup>) in the photosphere. Magnetic cancellations between the opposite polarities are observed in the vicinity of the footpoints of the jets. Along the intergranular lanes horizontal magnetic field around 1000 G is generated impulsively. Overall, all the kinetic features at the different layers through the photosphere and chromosphere favor a convection-driven reconnection scenario for the recurrent fan-like jets and evidence a site of reconnection between the photosphere and chromosphere corresponding to the intergranular lanes.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The influences of the interplanetary magnetic field (IMF) on the induced magnetosphere of Venus are investigated using a global multispecies magnetohydrodynamics (MHD) model. The simulation results show that the induced magnetosphere is controlled by the IMF components perpendicular to the solar wind velocity (<jats:italic>B</jats:italic> <jats:sub> <jats:italic>Y</jats:italic> </jats:sub> and <jats:italic>B</jats:italic> <jats:sub> <jats:italic>Z</jats:italic> </jats:sub> in the Venus Solar Orbital coordinate), rather than the IMF magnitude (∣<jats:italic>B</jats:italic>∣). With the increase of <jats:inline-formula> <jats:tex-math> <?CDATA ${({B}_{Y}^{2}+{B}_{Z}^{2})}^{\tfrac{1}{2}}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:msubsup> <mml:mrow> <mml:mi>B</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>Y</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo>+</mml:mo> <mml:msubsup> <mml:mrow> <mml:mi>B</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>Z</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> <mml:mrow> <mml:mstyle displaystyle="false"> <mml:mfrac> <mml:mrow> <mml:mn>1</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:mfrac> </mml:mstyle> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac6ac5ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>, the induced magnetosphere becomes stronger in field strength and thicker in spatial scale, and the bow shock locates farther from the planet. The parallel IMF component (<jats:italic>B</jats:italic> <jats:sub> <jats:italic>X</jats:italic> </jats:sub>) has relatively small impacts on the magnetic barrier and the magnetotail, regardless of the various IMF magnitudes and orientations caused by different <jats:italic>B</jats:italic> <jats:sub> <jats:italic>X</jats:italic> </jats:sub>. The responses of the Venusian induced magnetosphere to the change of upstream IMF are also studied. The time-dependent MHD calculations show that the dayside magnetosphere responds quickly with a timescale of 10 s–10 minutes, depending on the considered magnetospheric region. For comparison, the timescale required for the adjustment of magnetotail as driven by an IMF rotation is derived to be ∼10–20 minutes.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a self-consistent model of the Milky Way to reproduce the observed distributions (spectral type, absolute <jats:italic>J</jats:italic>-band magnitude, effective temperature) and total velocity dispersion of brown dwarfs. For our model, we adopt parametric forms for the star formation history and initial-mass function, published evolutionary models, and theoretical age–velocity relations. Using standard Markov Chain Monte Carlo methods, we derive a power-law index of the initial-mass function of <jats:italic>α</jats:italic> = −0.71 ± 0.11, which is an improvement over previous studies. We consider a gamma-function form for the star formation history, though we find that this complex model is only slightly favored over a declining exponential. We find that a velocity variance that linearly increases with age and has an initial value of <jats:inline-formula> <jats:tex-math> <?CDATA ${\sigma }_{0}={9.0}_{-9.0}^{+11}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>σ</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>9.0</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>9.0</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>11</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac6de5ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> km s<jats:sup>−1</jats:sup> best reproduces the total velocity dispersions. Given the similarities to main-sequence stars, this suggests brown dwarfs likely form via similar processes, but we recognize that the sizable uncertainties on <jats:italic>σ</jats:italic> <jats:sub>0</jats:sub> preclude firm conclusions. To further refine these conclusions, we suggest that wide-field infrared imaging or low-resolution spectroscopic surveys, such as with the Nancy Grace Roman Space Telescope or Euclid, could provide large samples of brown dwarfs with robust spectral types that could probe the thickness of the thin disk. In this way, the number counts and population demographics could probe the same physical processes as with the kinematic measurements, however may provide larger samples and be subject to different selection biases.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The boundaries of solar coronal holes are difficult to uniquely define observationally but are sites of interest in part because the slow solar wind appears to originate there. The aim of this article is to explore the dynamics of interchange magnetic reconnection at different types of coronal hole boundaries—namely streamers and pseudostreamers—and their implications for the coronal structure. We describe synthetic observables derived from three-dimensional magnetohydrodynamic simulations of the atmosphere of the Sun in which coronal hole boundaries are disturbed by flows that mimic the solar supergranulation. Our analysis shows that interchange reconnection takes place much more readily at the pseudostreamer boundary of the coronal hole. As a result, the portion of the coronal hole boundary formed by the pseudostreamer remains much smoother, in contrast to the highly distorted helmet-streamer portion of the coronal hole boundary. Our results yield important new insights on coronal hole boundary regions, which are critical in coupling the corona to the heliosphere as the formation regions of the slow solar wind.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>State transitions in black hole X-ray binaries are likely caused by gas evaporation from a thin accretion disk into a hot corona. We present a height-integrated version of this process, which is suitable for analytical and numerical studies. With radius <jats:italic>r</jats:italic> scaled to Schwarzschild units and coronal mass accretion rate <jats:inline-formula> <jats:tex-math> <?CDATA ${\dot{m}}_{c}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mover accent="true"> <mml:mrow> <mml:mi>m</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>̇</mml:mo> </mml:mrow> </mml:mover> </mml:mrow> <mml:mrow> <mml:mi>c</mml:mi> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac6d5cieqn1.gif" xlink:type="simple" /> </jats:inline-formula> to Eddington units, the results of the model are independent of black hole mass. State transitions should thus be similar in X-ray binaries and an active galactic nucleus. The corona solution consists of two power-law segments separated at a break radius <jats:italic>r</jats:italic> <jats:sub> <jats:italic>b</jats:italic> </jats:sub> ∼ 10<jats:sup>3</jats:sup>(<jats:italic>α</jats:italic>/0.3)<jats:sup>−2</jats:sup>, where <jats:italic>α</jats:italic> is the viscosity parameter. Gas evaporates from the disk to the corona for <jats:italic>r</jats:italic> &gt; <jats:italic>r</jats:italic> <jats:sub> <jats:italic>b</jats:italic> </jats:sub>, and condenses back for <jats:italic>r</jats:italic> &lt; <jats:italic>r</jats:italic> <jats:sub> <jats:italic>b</jats:italic> </jats:sub>. At <jats:italic>r</jats:italic> <jats:sub> <jats:italic>b</jats:italic> </jats:sub>, <jats:inline-formula> <jats:tex-math> <?CDATA ${\dot{m}}_{c}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mover accent="true"> <mml:mrow> <mml:mi>m</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>̇</mml:mo> </mml:mrow> </mml:mover> </mml:mrow> <mml:mrow> <mml:mi>c</mml:mi> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac6d5cieqn2.gif" xlink:type="simple" /> </jats:inline-formula> reaches its maximum, <jats:inline-formula> <jats:tex-math> <?CDATA ${\dot{m}}_{c,\max }\approx 0.02\,{(\alpha /0.3)}^{3}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mover accent="true"> <mml:mrow> <mml:mi>m</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>̇</mml:mo> </mml:mrow> </mml:mover> </mml:mrow> <mml:mrow> <mml:mi>c</mml:mi> <mml:mo>,</mml:mo> <mml:mi>max</mml:mi> </mml:mrow> </mml:msub> <mml:mo>≈</mml:mo> <mml:mn>0.02</mml:mn> <mml:mspace width="0.25em" /> <mml:msup> <mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:mi>α</mml:mi> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:mn>0.3</mml:mn> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac6d5cieqn3.gif" xlink:type="simple" /> </jats:inline-formula>. If at <jats:italic>r</jats:italic> ≫ <jats:italic>r</jats:italic> <jats:sub> <jats:italic>b</jats:italic> </jats:sub> the thin disk accretes with <jats:inline-formula> <jats:tex-math> <?CDATA ${\dot{m}}_{d}\lt {\dot{m}}_{c,\max }$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mover accent="true"> <mml:mrow> <mml:mi>m</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>̇</mml:mo> </mml:mrow> </mml:mover> </mml:mrow> <mml:mrow> <mml:mi>d</mml:mi> </mml:mrow> </mml:msub> <mml:mo>&lt;</mml:mo> <mml:msub> <mml:mrow> <mml:mover accent="true"> <mml:mrow> <mml:mi>m</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>̇</mml:mo> </mml:mrow> </mml:mover> </mml:mrow> <mml:mrow> <mml:mi>c</mml:mi> <mml:mo>,</mml:mo> <mml:mi>max</mml:mi> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac6d5cieqn4.gif" xlink:type="simple" /> </jats:inline-formula>, then the disk evaporates fully before reaching <jats:italic>r</jats:italic> <jats:sub> <jats:italic>b</jats:italic> </jats:sub>, giving the hard state. Otherwise, the disk survives at all radii, giving the thermal state. While the basic model considers only bremsstrahlung cooling and viscous heating, we also discuss a more realistic model that includes Compton cooling and direct coronal heating by energy transport from the disk. Solutions are again independent of black hole mass, and <jats:italic>r</jats:italic> <jats:sub> <jats:italic>b</jats:italic> </jats:sub> remains unchanged. This model predicts strong coronal winds for <jats:italic>r</jats:italic> &gt; <jats:italic>r</jats:italic> <jats:sub> <jats:italic>b</jats:italic> </jats:sub>, and a <jats:italic>T</jats:italic> ∼ 5 × 10<jats:sup>8</jats:sup> K Compton-cooled corona for <jats:italic>r</jats:italic> &lt; <jats:italic>r</jats:italic> <jats:sub> <jats:italic>b</jats:italic> </jats:sub>. Two-temperature effects are ignored, but may be important at small radii.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We conduct intensity mapping to probe for extended diffuse Ly<jats:italic>α</jats:italic> emission around Ly<jats:italic>α</jats:italic> emitters (LAEs) at <jats:italic>z</jats:italic> ∼2−7, exploiting very deep (∼26 mag at 5<jats:italic>σ</jats:italic>) and large-area (∼4.5 deg<jats:sup>2</jats:sup>) Subaru/Hyper Suprime-Cam narrowband (NB) images and large LAE catalogs consisting of a total of 1540 LAEs at <jats:italic>z</jats:italic> = 2.2, 3.3, 5.7, and 6.6 obtained by the HSC-SSP and CHORUS projects. We calculate the spatial correlations of these LAEs with ∼1–2 billion pixel flux values of the NB images, deriving the average Ly<jats:italic>α</jats:italic> surface brightness (SB<jats:sub>Ly<jats:italic>α</jats:italic> </jats:sub>) radial profiles around the LAEs. By carefully estimating systematics such as fluctuations of sky background and point-spread functions, we detect Ly<jats:italic>α</jats:italic> emission at 100–1000 comoving kpc around <jats:italic>z</jats:italic> = 3.3 and 5.7 LAEs at the 3.2<jats:italic>σ</jats:italic> and 3.7<jats:italic>σ</jats:italic> levels, respectively, and tentatively (=2.0<jats:italic>σ</jats:italic>) at <jats:italic>z</jats:italic> = 6.6. The emission is as diffuse as ∼10<jats:sup>−20</jats:sup>–10<jats:sup>−19</jats:sup> erg s<jats:sup>−1</jats:sup> cm<jats:sup>−2</jats:sup> arcsec<jats:sup>−2</jats:sup> and extended beyond the virial radius of a dark matter halo with a mass of 10<jats:sup>11</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>. While the observed SB<jats:sub>Ly<jats:italic>α</jats:italic> </jats:sub> profiles have similar amplitudes at <jats:italic>z</jats:italic> = 2.2–6.6 within the uncertainties, the intrinsic SB<jats:sub>Ly<jats:italic>α</jats:italic> </jats:sub> profiles (corrected for the cosmological dimming effect) increase toward high redshifts. This trend may be explained by increasing hydrogen gas density due to the evolution of the cosmic volume. Comparisons with theoretical models suggest that extended Ly<jats:italic>α</jats:italic> emission around an LAE is powered by resonantly scattered Ly<jats:italic>α</jats:italic> photons in the CGM and IGM that originate from the inner part of the LAE and/or neighboring galaxies around the LAE.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a multiband study of FRB 20180916B, a repeating source with a 16.3 day periodicity. We report the detection of four, one, and seven bursts from observations spanning 3 days using the upgraded Giant Metrewave Radio Telescope (300–500 MHz), the Canadian Hydrogen Intensity Mapping Experiment (400–800 MHz) and the Green Bank Telescope (600–1000 MHz), respectively. We report the first ever detection of the source in the 800–1000 MHz range along with one of the widest instantaneous bandwidth detections (200 MHz) at lower frequencies. We identify 30 <jats:italic>μ</jats:italic>s wide structures in one of the bursts at 800 MHz, making it the lowest frequency detection of such structures for this fast radio burst thus far. There is also a clear indication of high activity of the source at a higher frequency during earlier phases of the activity cycle. We identify a gradual decrease in the rotation measure over two years and no significant variations in the dispersion measure. We derive useful conclusions about progenitor scenarios, energy distribution, emission mechanisms, and variation of the downward drift rate of emission with frequency. Our results reinforce that multiband observations are an effective approach to study repeaters, and even one-off events, to better understand their varying activity and spectral anomalies.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Small-scale magnetic flux ropes (SMFRs) have been identified at a large range of heliospheric distances from the Sun. Their features are somewhat similar to those of larger-scale flux rope structures such as magnetic clouds (MCs), while their occurrence rate is far higher. In this work, we examined the orientations of a large number of SMFRs that were identified at 1 au by fitting to the force-free model. We find that, while most of the SMFRs lie mostly close to the ecliptic plane, as previously known, their azimuthal orientations relative to the Sun–Earth line are found largely at two specific angles (slightly less than 45° and 225°). This latter feature in turn leads to a strong statistical trend in which the axis of SMFRs lies at a large tilt angle relative to (most often nearly orthogonal to) the corresponding background interplanetary magnetic field directions in the ecliptic plane. This feature is different from previous reports on SMFRs—and in stark contrast to the cases of MCs. This is an important observational constraint that should be considered for understanding SMFR generation and propagation.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Inference is crucial in modern astronomical research, where hidden astrophysical features and patterns are often estimated from indirect and noisy measurements. Inferring the posterior of hidden features, conditioned on the observed measurements, is essential for understanding the uncertainty of results and downstream scientific interpretations. Traditional approaches for posterior estimation include sampling-based methods and variational inference (VI). However, sampling-based methods are typically slow for high-dimensional inverse problems, while VI often lacks estimation accuracy. In this paper, we propose <jats:italic>α</jats:italic>-deep probabilistic inference, a deep learning framework that first learns an approximate posterior using <jats:italic>α</jats:italic>-divergence VI paired with a generative neural network, and then produces more accurate posterior samples through importance reweighting of the network samples. It inherits strengths from both sampling and VI methods: it is fast, accurate, and more scalable to high-dimensional problems than conventional sampling-based approaches. We apply our approach to two high-impact astronomical inference problems using real data: exoplanet astrometry and black hole feature extraction.</jats:p>