Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>There are many difficulties associated with forecasting high-energy solar particle events at Earth. One issue is understanding why some large solar eruptive events trigger ground-level enhancement (GLE) events and others do not. In this work we perform 3D test particle simulations of a set of historic GLEs to understand more about what causes these powerful events. Particular focus is given to studying how the heliospheric current sheet (HCS) affects high-energy proton transport through the heliosphere following an event. Analysis of ≥M7.0 flares between 1976 and 2020 shows that active regions located closer to the HCS (&lt;10°) are more likely to be associated with a GLE event. We found that modeled GLE events where the source region was close to the HCS also led to increased heliospheric transport in longitude and higher count rates (when the Earth was located in the drift direction). In a model that does not include perpendicular diffusion associated with turbulence, the HCS is the dominant mechanism affecting heliospheric particle transport for GLE 42 and 69, and varying other parameters (e.g., a narrow, 10°, or wider, 60°, injection width) causes little change. Overall in our model, the HCS is relevant in 71% of our analyzed GLEs, and including it more accurately reproduces observed intensities near Earth. Our simulations enable us to produce model profiles at Earth that can be compared to existing observations by the GOES satellites and neutron monitors, as well as for use in developing future forecasting models.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Airborne Infrared Spectrometer (AIR-Spec) was commissioned during the 2017 total solar eclipse, when it observed five infrared coronal emission lines from a Gulfstream V research jet owned by the National Science Foundation and operated by the National Center for Atmospheric Research. The second AIR-Spec research flight took place during the 2019 July 2 total solar eclipse across the south Pacific. The 2019 eclipse flight resulted in seven minutes of observations, during which the instrument measured all four of its target emission lines: S <jats:sc>xi</jats:sc> 1.393 <jats:italic>μ</jats:italic>m, Si <jats:sc>x</jats:sc> 1.431 <jats:italic>μ</jats:italic>m, S <jats:sc>xi</jats:sc> 1.921 <jats:italic>μ</jats:italic>m, and Fe <jats:sc>ix</jats:sc> 2.853 <jats:italic>μ</jats:italic>m. The 1.393 <jats:italic>μ</jats:italic>m S <jats:sc>xi</jats:sc> line was detected for the first time, and probable first detections were made of Si <jats:sc>xi</jats:sc> 1.934 <jats:italic>μ</jats:italic>m and Fe <jats:sc>x</jats:sc> 1.947 <jats:italic>μ</jats:italic>m. The 2017 AIR-Spec detection of Fe <jats:sc>ix</jats:sc> was confirmed and the first observations were made of the Fe <jats:sc>ix</jats:sc> line intensity as a function of solar radius. Telluric absorption features were used to calibrate the wavelength mapping, instrumental broadening, and throughput of the instrument. AIR-Spec underwent significant upgrades in preparation for the 2019 eclipse observation. The thermal background was reduced by a factor of 30, providing a 5.5× improvement in signal-to-noise ratio, and the postprocessed pointing stability was improved by a factor of 5 to &lt;10″ rms. In addition, two imaging artifacts were identified and resolved, improving the spectral resolution and making the 2019 data easier to interpret.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In neutral hydrogen (H <jats:sc>i</jats:sc>) intensity mapping (IM) survey, foreground contamination on cosmological signal is extremely severe, and systematic effects caused by radio telescopes further aggravate the difficulties in subtracting foreground. We investigate whether the deep-learning method, the 3D U-Net algorithm, can play a crucial role in foreground subtraction when considering the systematic effect caused by the telescope’s primary beam. We consider two beam models, i.e., the Gaussian beam and Cosine beam models. The traditional principal component analysis (PCA) method is employed as a preprocessing step for the U-Net method to reduce the map dynamic range. We find that in the case of the Gaussian beam, the PCA method can effectively clean the foreground. However, the PCA method cannot handle the systematic effect induced by the Cosine beam, and the additional U-Net method can improve the result significantly. To show how well the PCA and U-Net methods can recover the H <jats:sc>i</jats:sc> signal, we also derive the H <jats:sc>i</jats:sc> angular power spectrum and H <jats:sc>i</jats:sc> 2D power spectrum after performing foreground subtraction. It is found that in the case of Gaussian beam, the concordance with the original H <jats:sc>i</jats:sc> map using U-Net is better than that using PCA by 27.4%, and in the case of Cosine beam, the concordance using U-Net is better than that using PCA by 144.8%. Therefore, the U-Net–based foreground subtraction can efficiently eliminate the telescope primary beam effect and shed new light on recovering H <jats:sc>i</jats:sc> power spectrum for future H <jats:sc>i</jats:sc> IM experiments.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report the first unambiguous detection and mass measurement of an isolated stellar-mass black hole (BH). We used the Hubble Space Telescope (HST) to carry out precise astrometry of the source star of the long-duration (<jats:italic>t</jats:italic> <jats:sub>E</jats:sub> ≃ 270 days), high-magnification microlensing event MOA-2011-BLG-191/OGLE-2011-BLG-0462 (hereafter designated as MOA-11-191/OGLE-11-462), in the direction of the Galactic bulge. HST imaging, conducted at eight epochs over an interval of 6 yr, reveals a clear relativistic astrometric deflection of the background star’s apparent position. Ground-based photometry of MOA-11-191/OGLE-11-462 shows a parallactic signature of the effect of Earth’s motion on the microlensing light curve. Combining the HST astrometry with the ground-based light curve and the derived parallax, we obtain a lens mass of 7.1 ± 1.3 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> and a distance of 1.58 ± 0.18 kpc. We show that the lens emits no detectable light, which, along with having a mass higher than is possible for a white dwarf or neutron star, confirms its BH nature. Our analysis also provides an absolute proper motion for the BH. The proper motion is offset from the mean motion of Galactic disk stars at similar distances by an amount corresponding to a transverse space velocity of ∼45 km s<jats:sup>−1</jats:sup>, suggesting that the BH received a “natal kick” from its supernova explosion. Previous mass determinations for stellar-mass BHs have come from radial velocity measurements of Galactic X-ray binaries and from gravitational radiation emitted by merging BHs in binary systems in external galaxies. Our mass measurement is the first for an isolated stellar-mass BH using any technique.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present the Local Volume Complete Cluster Survey (LoVoCCS; we pronounce it as “low-vox” or “law-vox,” with stress on the second syllable), an NSF’s National Optical-Infrared Astronomy Research Laboratory survey program that uses the Dark Energy Camera to map the dark matter distribution and galaxy population in 107 nearby (0.03 &lt; <jats:italic>z</jats:italic> &lt; 0.12) X-ray luminous ([0.1–2.4 keV] <jats:italic>L</jats:italic> <jats:sub>X500</jats:sub> &gt; 10<jats:sup>44</jats:sup> erg s<jats:sup>−1</jats:sup>) galaxy clusters that are not obscured by the Milky Way. The survey will reach Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) Year 1–2 depth (for galaxies <jats:italic>r</jats:italic> = 24.5, <jats:italic>i</jats:italic> = 24.0, signal-to-noise ratio (S/N) &gt; 20; <jats:italic>u</jats:italic> = 24.7, <jats:italic>g</jats:italic> = 25.3, <jats:italic>z</jats:italic> = 23.8, S/N &gt; 10) and conclude in ∼2023 (coincident with the beginning of LSST science operations), and will serve as a zeroth-year template for LSST transient studies. We process the data using the LSST Science Pipelines that include state-of-the-art algorithms and analyze the results using our own pipelines, and therefore the catalogs and analysis tools will be compatible with the LSST. We demonstrate the use and performance of our pipeline using three X-ray luminous and observation-time complete LoVoCCS clusters: A3911, A3921, and A85. A3911 and A3921 have not been well studied previously by weak lensing, and we obtain similar lensing analysis results for A85 to previous studies. (We mainly use A3911 to show our pipeline and give more examples in the Appendix.)</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We investigated the detection rates and early-warning parameters of binary neutron star (BNS) populations with decihertz gravitational-wave observatories in a realistic detecting strategy. Assuming the operation time of B-DECIGO is 4 yr, we classified the detectable BNSs based on parameter precision into three categories: (a) sources that merge within 1 yr, which could be localized with an uncertainty of ΔΩ ∼ 10<jats:sup>0</jats:sup> deg<jats:sup>2</jats:sup>; (b) sources that merge in 1–4 yr, which take up three-quarters of the total events and yield the most precise angular resolution with ΔΩ ∼ 10<jats:sup>−2</jats:sup> deg<jats:sup>2</jats:sup> and time-of-merger accuracy with Δ<jats:italic>t</jats:italic> <jats:sub> <jats:italic>c</jats:italic> </jats:sub> ∼ 10<jats:sup>−1</jats:sup> s; and (c) sources that do not merge during the 4 yr mission window, which enable possible early warnings, with ΔΩ ∼ 10<jats:sup>−1</jats:sup> deg<jats:sup>2</jats:sup> and Δ<jats:italic>t</jats:italic> <jats:sub> <jats:italic>c</jats:italic> </jats:sub> ∼ 10<jats:sup>0</jats:sup> s. Furthermore, we compared the pros and cons of B-DECIGO with the third-generation ground-based detectors, and explored the prospects of detections using three other decihertz observatories and four BNS population models. In realistic observing scenarios, we found that decihertz detectors could even provide early-warning alerts to a source decades before its merger while their localizations are still as accurate as ground-based facilities. Finally we found a decrease of events when considering the confusion noise, but this could be partially solved by a proper noise subtraction.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The CALorimetric Electron Telescope (CALET) on the International Space Station consists of a high-energy cosmic-ray CALorimeter (CAL) and a lower-energy CALET Gamma-ray Burst Monitor (CGBM). CAL is sensitive to electrons up to 20 TeV, cosmic-ray nuclei from <jats:italic>Z</jats:italic> = 1 through <jats:italic>Z</jats:italic> ∼ 40, and gamma rays over the range 1 GeV–10 TeV. CGBM observes gamma rays from 7 keV to 20 MeV. The combined CAL-CGBM instrument has conducted a search for gamma-ray bursts (GRBs) since 2015 October. We report here on the results of a search for X-ray/gamma-ray counterparts to gravitational-wave events reported during the LIGO/Virgo observing run O3. No events have been detected that pass all acceptance criteria. We describe the components, performance, and triggering algorithms of the CGBM—the two Hard X-ray Monitors consisting of LaBr<jats:sub>3</jats:sub>(Ce) scintillators sensitive to 7 keV–1 MeV gamma rays and a Soft Gamma-ray Monitor BGO scintillator sensitive to 40 keV–20 MeV—and the high-energy CAL consisting of a charge detection module, imaging calorimeter, and the fully active total absorption calorimeter. The analysis procedure is described and upper limits to the time-averaged fluxes are presented.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present the results of a search for core-collapse supernova neutrinos, using long-term KamLAND data from 2002 March 9 to 2020 April 25. We focus on the electron antineutrinos emitted from supernovae in the energy range of 1.8–111 MeV. Supernovae will make a neutrino event cluster with the duration of ∼10 s in the KamLAND data. We find no neutrino clusters and give the upper limit on the supernova rate to be 0.15 yr<jats:sup>−1</jats:sup> with a 90% confidence level. The detectable range, which corresponds to a &gt;95% detection probability, is 40–59 kpc and 65–81 kpc for core-collapse supernovae and failed core-collapse supernovae, respectively. This paper proposes to convert the supernova rate obtained by the neutrino observation to the Galactic star formation rate. Assuming a modified Salpeter-type initial mass function, the upper limit on the Galactic star formation rate is &lt;(17.5–22.7) <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> yr<jats:sup>−1</jats:sup> with a 90% confidence level.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The LIGO and Virgo gravitational-wave detectors have uncovered binary black hole systems with definitively nonzero spins, as well as systems with significant spin residing in the more massive black hole of the pair. We investigate the ability of isolated binary evolution in forming such highly spinning, asymmetric-mass systems through both accretion onto the first-born black hole and tidal spin-up of the second-born black hole using a rapid population synthesis approach with detailed considerations of spin-up through tidal interactions. Even with the most optimistic assumptions regarding the efficiency at which an accreting star receives material from a donor, we find that it is difficult to form systems with significant mass asymmetry and moderate or high spins in the primary black hole component. Assuming efficient angular momentum transport within massive stars and Eddington-limited accretion onto black holes, we find that &gt;1.5% of systems in the underlying binary black hole population have a primary black hole spin greater than 0.2 and a mass asymmetry of greater than 2:1 in our most optimistic models, with most models finding that this criteria is only met in ∼0.01% of systems. The production of systems with significant mass asymmetries and spin in the primary black hole component is thus an unlikely byproduct of isolated evolution unless highly super-Eddington accretion is invoked or angular momentum transport in massive stars is less efficient than typically assumed.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a new approach for observationally constraining where the tails of Jellyfish (JF) galaxies in groups and clusters first appear and how long they remain visible for with respect to the moment of their orbital pericenter. This is accomplished by measuring the distribution of their tail directions, with respect to their host centers, and their distribution in a projected velocity–radius phase-space diagram. We then model these observed distributions using a fast and flexible approach, where JF tails are painted onto dark matter halos, according to a simple parameterized prescription, before a Bayesian analysis is performed to estimate the parameters. We demonstrate the effectiveness of our approach using observational mocks, then apply it to a known observational sample of 106 JF galaxies, with radio-continuum tails located inside 68 hosts such as groups and clusters. We find that, typically, the radio-continuum tails become visible on first infall, when the galaxy reaches roughly three-quarters of <jats:italic>r</jats:italic> <jats:sub>200</jats:sub>, and the tails remain visible for a few hundred Myr after pericenter passage. Lower-mass galaxies in more massive hosts tend to form visible tails further out and their tails disappear more quickly after pericenter. We argue that this indicates that they are more sensitive to ram pressure stripping. With upcoming large-area surveys of JF galaxies in progress, this is a promising new method for constraining the environmental conditions in which visible JF tails exist.</jats:p>