Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>The observation of very-high-energy (VHE; &gt; 10 GeV) <jats:italic>γ</jats:italic>-ray emission from <jats:italic>γ</jats:italic>-ray bursts (GRBs), especially in the prompt phase, will provide critical information for understanding many aspects of their nature including the physical environment, the relativistic bulk motion, the mechanisms of particle acceleration of GRBs, and for studying Lorentz invariance violation, etc. For the afterglow phase, the highest-energy photons detected to date by the imaging atmospheric Cherenkov telescopes extend to the TeV regime. However, for the prompt phase, years of efforts in searching for the VHE emission has yielded no statistically significant detections. A wide field of view and large effective area above tens of GeV are essential for detecting the VHE emissions from GRBs in the prompt phase. The High Altitude Detection of Astronomical Radiation (HADAR) experiment has such merits. In this paper, we report the estimates of its expected annual GRB detection rate, which are obtained by combining the performance of the HADAR instrument with the theoretical calculations based on a phenomenological model to generate the pseudo-GRB population. The expected detectable gamma-ray signal from GRBs above the background is then obtained to give the detection rate. In the spectral model, an extra component is assigned to every GRB event in addition to the Band function. The results indicate that if the energy of the cutoff due to internal absorption is higher than 50 GeV, the detection rate for GRBs for the HADAR experiment is approximately two or three GRBs per year, which varies slightly depending upon the characteristics of the extra component.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Coronal holes (CHs) have subdued intensity and net blueshifts when compared to the quiet Sun (QS) at coronal temperatures. At transition region temperatures, such differences are obtained for regions with identical absolute photospheric magnetic flux density (∣B∣). In this work, we use spectroscopic measurements of the C <jats:sc>ii</jats:sc> 1334 Å line from the Interface Region Imaging Spectrograph, formed at chromospheric temperatures, to investigate the intensity, Doppler shift, line width, skew, and excess kurtosis variations with ∣B∣. We find the intensity, Doppler shift, and linewidths to increase with ∣B∣ for CHs and QS. The CHs show deficit in intensity and excess total widths over QS for regions with identical ∣B∣. For pixels with only upflows, CHs show excess upflows over QS, while for pixels with only downflows, CHs show excess downflows over QS that cease to exist at ∣B∣ ≤ 40. Finally, the spectral profiles are found to be more skewed and flatter than a Gaussian, with no difference between CHs and QS. These results are important in understanding the heating of the atmosphere in CH and QS, including solar wind formation, and provide further constraints on the modeling of the solar atmosphere.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The detection of disk-integrated polarization from Luhman 16 A and B in the <jats:italic>H</jats:italic> band, and subsequent modeling, has been interpreted in the framework of zonal cloud bands on these bodies. Recently, Tan and Showman investigated the 3D atmospheric circulation and cloud structures of brown dwarfs with general circulation models (GCMs), and their simulations yielded complex cloud distributions showing some aspects of zonal jets, but also complex vortices that cannot be captured by a simple model. Here we use these 3D GCMs specific to Luhman 16 A and B, along with the 3D Monte Carlo radiative transfer code ARTES, to calculate their polarization signals. We adopt the 3D temperature–pressure and cloud profiles from the GCMs as our input atmospheric structures. Our polarization calculations at 1.6 <jats:italic>μ</jats:italic>m agree well with the measured degree of linear polarization from both Luhman 16 A and B. Our calculations reproduce the measured polarization for both objects with cloud particle sizes between 0.5 and 1 <jats:italic>μ</jats:italic>m for Luhman 16 A and of 5 <jats:italic>μ</jats:italic>m for Luhman 16 B. We find that the degree of linear polarization can vary on hour-long timescales over the course of a rotation period. We also show that models with azimuthally symmetric band-like cloud geometries, typically used for interpreting polarimetry observations of brown dwarfs, overpredict the polarization signal if the cloud patterns do not include complex vortices within these bands. This exploratory work shows that GCMs are promising for modeling and interpreting polarization signals of brown dwarfs.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Microflares have been considered to be among the major energy input sources to form active solar corona. To investigate the response of the low atmosphere to events, we conducted an Atacama Large Millimeter/submillimeter Array (ALMA) observation at 3 mm, coordinated with Interface Region Imaging Spectrograph (IRIS) and Hinode observations, on 2017 March 19. During the observations, a soft X-ray loop-type microflare (active region transient brightening) was captured using the Hinode X-ray telescope in high temporal cadence. A brightening loop footpoint is located within narrow fields of view of ALMA, IRIS slit-jaw imager, and Hinode spectropolarimeter. Counterparts of the microflare at the footpoint were detected in Si <jats:sc>iv</jats:sc> and ALMA images, while the counterparts were less apparent in C <jats:sc>ii</jats:sc> and Mg <jats:sc>ii</jats:sc> <jats:italic>k</jats:italic> images. Their impulsive time profiles exhibit the Neupert effect pertaining to soft X-ray intensity evolution. The magnitude of thermal energy measured using ALMA was approximately 100 times smaller than that measured in the corona. These results suggest that impulsive counterparts can be detected in the transition region and upper chromosphere, where the plasma is thermally heated via impinging nonthermal particles. Our energy evaluation indicates a deficit of accelerated particles that impinge the footpoints for a small class of soft X-ray microflares. The footpoint counterparts consist of several brightening kernels, all of which are located in weak (void) magnetic areas formed in patchy distribution of strong magnetic flux at the photospheric level. The kernels provide a conceptual image in which the transient energy release occurs at multiple locations on the sheaths of magnetic flux bundles in the corona.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Ultralight bosons can be abundantly produced through superradiance process by a spinning black hole and form a bound state with hydrogen-like spectrum. We show that such a <jats:italic>gravitational atom</jats:italic> typically possesses anomalously large mass quadrupole and leads to significant orbital precession when it forms an eccentric binary with a second compact object. Dynamically formed black hole binaries or pulsar-black hole binaries are typically eccentric during their early inspirals. We show that the large orbital precession can generate distinct and observable signature in their gravitational wave or pulsar timing signals.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a Spitzer/IRAC survey of <jats:italic>H</jats:italic>-faint (<jats:italic>H</jats:italic> <jats:sub>160</jats:sub> ≳ 26.4, &lt; 5<jats:italic>σ</jats:italic>) sources in 101 lensing cluster fields. Across a CANDELS/Wide-like survey area of ∼648 arcmin<jats:sup>2</jats:sup> (effectively ∼221 arcmin<jats:sup>2</jats:sup> in the source plane), we have securely discovered 53 sources in the IRAC Channel-2 band (CH2, 4.5 <jats:italic>μ</jats:italic>m; median CH2 = 22.46 ± 0.11 AB mag) that lack robust HST/WFC3-IR F160W counterparts. The most remarkable source in our sample, namely ES-009 in the field of Abell 2813, is the brightest <jats:italic>H</jats:italic>-faint galaxy at 4.5 <jats:italic>μ</jats:italic>m known so far (CH2 = 20.48 ± 0.03 AB mag). We show that the <jats:italic>H</jats:italic>-faint sources in our sample are massive (median <jats:italic>M</jats:italic> <jats:sub>star</jats:sub> = 10<jats:sup>10.3±0.3</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>), star-forming (median star formation rate <jats:inline-formula> <jats:tex-math> <?CDATA $={100}_{-40}^{+60}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>100</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>40</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>60</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac2578ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> yr<jats:sup>−1</jats:sup>), and dust-obscured (<jats:italic>A</jats:italic> <jats:sub> <jats:italic>V</jats:italic> </jats:sub> = 2.6 ± 0.3) galaxies around a median photometric redshift of <jats:italic>z</jats:italic> = 3.9 ± 0.4. The stellar continua of 14 <jats:italic>H</jats:italic>-faint galaxies can be resolved in the CH2 band, suggesting a median circularized effective radius (<jats:italic>R</jats:italic> <jats:sub>e,circ</jats:sub>; lensing corrected) of 1.9 ± 0.2 kpc and &lt;1.5 kpc for the resolved and whole samples, respectively. This is consistent with the sizes of massive unobscured galaxies at <jats:italic>z</jats:italic> ∼ 4, indicating that <jats:italic>H</jats:italic>-faint galaxies represent the dusty tail of the distribution of a wider galaxy population. Comparing with the ALMA dust continuum sizes of similar galaxies reported previously, we conclude that the heavy dust obscuration in <jats:italic>H</jats:italic>-faint galaxies is related to the compactness of both stellar and dust continua (<jats:italic>R</jats:italic> <jats:sub>e,circ</jats:sub> ∼ 1 kpc). These <jats:italic>H</jats:italic>-faint galaxies make up <jats:inline-formula> <jats:tex-math> <?CDATA ${16}_{-7}^{+13}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>16</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>7</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>13</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac2578ieqn2.gif" xlink:type="simple" /> </jats:inline-formula>% of the galaxies in the stellar-mass range of 10<jats:sup>10</jats:sup> − 10<jats:sup>11.2</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> at <jats:italic>z</jats:italic> = 3 ∼ 5, contributing to <jats:inline-formula> <jats:tex-math> <?CDATA ${8}_{-4}^{+8}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>8</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>4</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>8</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac2578ieqn3.gif" xlink:type="simple" /> </jats:inline-formula>% of the cosmic star formation rate density in this epoch and likely tracing the early phase of massive galaxy formation.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Using a novel suite of cosmological simulations zooming in on a megaparsec-scale intergalactic sheet (pancake) at <jats:italic>z</jats:italic> ∼ (3–5), we conduct an in-depth study of the thermal properties and H <jats:sc>i</jats:sc> content of the warm-hot intergalactic medium (WHIM) at those redshifts. The simulations span nearly three orders of magnitude in gas cell mass, ∼(7.7 × 10<jats:sup>6</jats:sup>–1.5 × 10<jats:sup>4</jats:sup>)<jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, one of the highest-resolution simulations of such a large patch of the intergalactic medium (IGM) to date. At <jats:italic>z</jats:italic> ∼ 5, a strong accretion shock develops around the pancake. Gas in the postshock region proceeds to cool rapidly, triggering thermal instabilities and generating a multiphase medium. We find the mass, morphology, and distribution of H <jats:sc>i</jats:sc> in the WHIM to all be unconverged, even at our highest resolution. Interestingly, the lack of convergence is more severe for the less-dense, metal-poor intrapancake medium (IPM) in between filaments and far outside galaxies. With increased resolution, the IPM develops a shattered structure with most of the H <jats:sc>i</jats:sc> in kiloparsec-scale clouds. From our lowest-to-highest resolution, the covering fraction of metal-poor (<jats:italic>Z</jats:italic> &lt; 10<jats:sup>−3</jats:sup> <jats:italic>Z</jats:italic> <jats:sub>⊙</jats:sub>) Lyman-limit systems (<jats:italic>N</jats:italic> <jats:sub>H I</jats:sub> &gt; 10<jats:sup>17.2</jats:sup>cm<jats:sup>−2</jats:sup>) in the <jats:italic>z</jats:italic> ∼ 4 IPM increases from ∼(3–15)%, while that of metal-poor damped Ly<jats:italic>α</jats:italic> absorbers (<jats:italic>N</jats:italic> <jats:sub>H I</jats:sub> &gt; 10<jats:sup>20</jats:sup>cm<jats:sup>−2</jats:sup>) increases from ∼(0.2–0.6)%, with no sign of convergence. We find that a necessary condition for the formation of a multiphase shattered structure is resolving the cooling length, <jats:italic>l</jats:italic> <jats:sub>cool</jats:sub> = <jats:italic>c</jats:italic> <jats:sub>s</jats:sub> <jats:italic>t</jats:italic> <jats:sub>cool</jats:sub>, at <jats:italic>T</jats:italic> ∼ 10<jats:sup>5</jats:sup> K. If this is unresolved, gas “piles up” at <jats:italic>T</jats:italic> ≲ 10<jats:sup>5</jats:sup> K and further cooling becomes very inefficient. We conclude that state-of-the-art cosmological simulations are still unable to resolve the multiphase structure of the WHIM, with potentially far-reaching implications.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present an analysis of a densely repeating sample of bursts from the first repeating fast radio burst, FRB 121102. We reanalyzed the data used by Gourdji et al. and detected 93 additional bursts using our single-pulse search pipeline. In total, we detected 133 bursts in three hours of data at a center frequency of 1.4 GHz using the Arecibo telescope, and develop robust modeling strategies to constrain the spectro-temporal properties of all of the bursts in the sample. Most of the burst profiles show a scattering tail, and burst spectra are well modeled by a Gaussian with a median width of 230 MHz. We find a lack of emission below 1300 MHz, consistent with previous studies of FRB 121102. We also find that the peak of the log-normal distribution of wait times decreases from 207 to 75 s using our larger sample of bursts, as compared to that of Gourdji et al. Our observations do not favor either Poissonian or Weibull distributions for the burst rate distribution. We searched for periodicity in the bursts using multiple techniques, but did not detect any significant period. The cumulative burst energy distribution exhibits a broken power-law shape, with the lower- and higher-energy slopes of −0.4 ± 0.1 and −1.8 ± 0.2, with the break at (2.3 ± 0.2) × 10<jats:sup>37</jats:sup> erg. We provide our burst fitting routines as a Python package <jats:sc>burstfit</jats:sc> <jats:xref ref-type="fn" rid="apjac2577fn1"> <jats:sup>4</jats:sup> </jats:xref> <jats:fn id="apjac2577fn1"> <jats:label> <jats:sup>4</jats:sup> </jats:label> <jats:p> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="https://github.com/thepetabyteproject/burstfit" xlink:type="simple">https://github.com/thepetabyteproject/burstfit</jats:ext-link> </jats:p> </jats:fn> that can be used to model the spectrogram of any complex fast radio burst or pulsar pulse using robust fitting techniques. All of the other analysis scripts and results are publicly available.<jats:xref ref-type="fn" rid="apjac2577fn2"> <jats:sup>5</jats:sup> </jats:xref> <jats:fn id="apjac2577fn2"> <jats:label> <jats:sup>5</jats:sup> </jats:label> <jats:p> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="https://github.com/thepetabyteproject/FRB121102" xlink:type="simple">https://github.com/thepetabyteproject/FRB121102</jats:ext-link> </jats:p> </jats:fn> </jats:p>

<jats:title>Abstract</jats:title> <jats:p>Instabilities described by linear theory characterize an important form of wave–particle interaction in the solar wind. We diagnose unstable behavior of solar wind plasma between 0.3 and 1 au via the Nyquist criterion, applying it to fits of ∼1.5M proton and <jats:italic>α</jats:italic> particle Velocity Distribution Functions (VDFs) observed by Helios I and II. The variation of the fraction of unstable intervals with radial distance from the Sun is linear, signaling a gradual decline in the activity of unstable modes. When calculated as functions of the solar wind velocity and Coulomb number, we obtain more extreme, exponential trends in the regions where collisions appear to have a notable influence on the VDF. Instability growth rates demonstrate similar behavior, and significantly decrease with Coulomb number. We find that for a nonnegligible fraction of observations, the proton beam or secondary component might not be detected, due to instrument resolution limitations, and demonstrate that the impact of this issue does not affect the main conclusions of this work.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Kinematic weak lensing describes the distortion of a galaxy’s projected velocity field due to lensing shear, an effect recently reported for the first time by Gurri et al. based on a sample of 18 galaxies at <jats:italic>z</jats:italic> ∼ 0.1. In this paper, we develop a new formalism that combines the shape information from imaging surveys with the kinematic information from resolved spectroscopy to better constrain the lensing distortion of source galaxies and to potentially address systematic errors that affect conventional weak-lensing analyses. Using a Bayesian forward model applied to mock galaxy observations, we model distortions in the source galaxy’s velocity field simultaneously with the apparent shear-induced offset between the kinematic and photometric major axes. We show that this combination dramatically reduces the statistical uncertainty on the inferred shear, yielding statistical error gains of a factor of 2–6 compared to kinematics alone. While we have not accounted for errors from intrinsic kinematic irregularities, our approach opens kinematic lensing studies to higher redshifts where resolved spectroscopy is more challenging. For example, we show that ground-based integral-field spectroscopy of background galaxies at <jats:italic>z</jats:italic> ∼ 0.7 can deliver gravitational shear measurements with signal-to-noise ratio of ∼1 <jats:italic>per source galaxy</jats:italic> at 1 arcminute separations from a galaxy cluster at <jats:italic>z</jats:italic> ∼ 0.3. This suggests that even modest samples observed with existing instruments could deliver improved galaxy cluster mass measurements and well-sampled probes of their halo mass profiles to large radii.</jats:p>