Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>We revisit the question of what mechanism is responsible for the spins of halos of dark matter. The answer to this question is of high importance for modeling galaxy intrinsic alignment, which can potentially contaminate current and future lensing data. In particular, we show that when the dark matter halos pass nearly each other in dense environments—namely halo assemblies—they swing and spin each other via exerting mutual tidal torques. We show that this has a significant contribution to the spin of dark matter halos comparable to that calculated by the so-called tidal torque theory. We use the results of the state-of-the-art simulation of Illutris to check the prediction of this theory against the simulation data.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Multi-wave band synchrotron linear polarization of gamma-ray burst (GRB) afterglows is studied under the assumption of an anisotropic turbulent magnetic field with a coherence length of the plasma skin-depth scale in the downstream of forward shocks. We find that for typical GRBs, in comparison to optical polarization, the degree of radio polarization shows a similar temporal evolution but a significantly smaller peak value. This results from differences in observed intensity image shapes between the radio and optical bands. We also show that the degree of the polarization spectrum undergoes a gradual variation from the low- to the high-polarization regime above the intensity of the spectral peak frequency, and that the difference in polarization angles in the two regimes is zero or 90°. Thus, simultaneous multi-wave band polarimetric observations of GRB afterglows would be a new determinative test of the plasma-scale magnetic field model. We also discuss theoretical implications from the recent detection of radio linear polarization in GRB 171205A with the Atacama Large Millimeter/submillimeter Array and other models of magnetic field configuration.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We reported the first glitch of PSR B2021+51 detected with the Shanghai Tian Ma Radio Telescope that occurred around MJD 58289.1 (2018 June 20). The spin frequency and its derivative suffered a jump of about 7.04 × 10<jats:sup>−10</jats:sup> Hz and 2.6 × 10<jats:sup>−18</jats:sup> s<jats:sup>−2</jats:sup>, respectively. The pulse width at the 10% intensity level (<jats:italic>W</jats:italic> <jats:sub>10</jats:sub>) of the mean pulse profile significantly decreased right before the glitch and then increased after the glitch, accompanied by an enhancement in the trailing peak of the normalized profile. The mean pulse profiles were decomposed into three Gaussian components, i.e., C1, C2, and C3 from left to right by peak phase. The width of C3 (<jats:italic>w</jats:italic> <jats:sub>3</jats:sub>) had an apparent maximum right before the glitch and its weighted mean value became slightly smaller than the pre-glitch value after the glitch, while the weighted mean values of both <jats:italic>w</jats:italic> <jats:sub>1</jats:sub> and <jats:italic>w</jats:italic> <jats:sub>2</jats:sub> had no apparent change. The significant decrease of the mean pulse width right before the glitch is mainly due to the movement of C3 toward C1 and C2, while the increase of the mean pulse width after the glitch results from the movement of C2 toward C3. Changes in the widths of mean pulse profiles and in the widths and phase separations of Gaussian components associated with the glitch convinced us of a connection between the changes in characteristics of the pulsar emission zone and the glitch activity. We discuss a possible interpretation invoking the movements of flux tubes in the emission zone.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Solar jets are ubiquitous phenomena in the solar atmosphere. They are important in mass and energy transport to the upper atmosphere and interplanetary space. Here, we report a detailed analysis of a small-scale chromospheric jet with high-resolution He <jats:sc>i</jats:sc> 10830 Å and TiO 7057 Å images observed by the 1.6 m aperture Goode Solar Telescope at the Big Bear Solar Observatory. The observation reveals the finest dark threads inside the jet are rooted in the intergranular lanes. Their width is equal to the telescope’s diffraction limit at 10830 Å (∼100 km). The jet is recurrent and its association with the emergence and convergence of magnetic flux is observed. Together with other important features like photospheric flow toward the magnetic polarity inversion line, a bald-patch magnetic configuration, and earlier excitation of helium atoms, we propose that the jet might be initiated by magnetic reconnection in a U-shaped loop configuration. The plasmoid configuration results from the possible buoyancy of the magnetic reconnection, which reoccurs in a second step with an overlying magnetic field line. Notably, the second-step magnetic reconnection produces not only bidirectional cool or hot flows but also a new U-shaped loop configuration. The feature may be used to explain the recurrent behavior of the jet, since the new U-shaped loop can be driven to reconnect again.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The <jats:sup>23</jats:sup>Na(<jats:italic>α</jats:italic>,<jats:italic> p</jats:italic>)<jats:sup>26</jats:sup>Mg reaction has been identified as having a significant impact on the nucleosynthesis of several nuclei between Ne and Ti in Type Ia supernovae, and of <jats:sup>23</jats:sup>Na and <jats:sup>26</jats:sup>Al in massive stars. The reaction has been subjected to renewed experimental interest recently, motivated by high uncertainties in early experimental data and in the statistical Hauser-Feshbach models used in reaction rate compilations. Early experiments were affected by target deterioration issues and unquantifiable uncertainties. Three new independent measurements instead are utilizing inverse kinematics and Rutherford scattering monitoring to resolve this. In this work we present directly measured angular distributions of the emitted protons to eliminate a discrepancy in the assumptions made in the recent reaction rate measurements, which results in cross sections differing by a factor of 3. We derive a new combined experimental reaction rate for the <jats:sup>23</jats:sup>Na(<jats:italic>α</jats:italic>, <jats:italic>p</jats:italic>)<jats:sup>26</jats:sup>Mg reaction with a total uncertainty of 30% at relevant temperatures. Using our new <jats:sup>23</jats:sup>Na(<jats:italic>α</jats:italic>, <jats:italic>p</jats:italic>)<jats:sup>26</jats:sup>Mg rate, the <jats:sup>26</jats:sup>Al and <jats:sup>23</jats:sup>Na production uncertainty is reduced to within 8%. In comparison, using the factor of 10 uncertainty previously recommended by the rate compilation STARLIB, <jats:sup>26</jats:sup>Al and <jats:sup>23</jats:sup>Na production was changing by more than a factor of 2. In Type Ia supernova conditions, the impact on production of <jats:sup>23</jats:sup>Na is constrained to within 15%.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present the systematic spectral analyses of gamma-ray bursts (GRBs) detected by the Fermi Gamma-Ray Burst Monitor during its first ten years of operation. This catalog contains two types of spectra: time-integrated spectral fits and spectral fits at the brightest time bin, from 2297 GRBs, resulting in a compendium of over 18,000 spectra. The four different spectral models used for fitting the spectra were selected based on their empirical importance to the shape of many GRBs. We describe in detail our procedure and criteria for the analyses, and present the bulk results in the form of parameter distributions both in the observer frame and in the GRB rest frame. 941 GRBs from the first four years have been refitted using the same methodology as that of the 1356 GRBs in years five through ten. The data files containing the complete results are available from the High-Energy Astrophysics Science Archive Research Center.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Radio active galactic nuclei (RAGNs) are mainly found in dense structures (i.e., clusters/groups) at redshifts of <jats:italic>z</jats:italic> &lt; 2 and are commonly used to detect protoclusters at higher redshift. Here, we attempt to study the host and environmental properties of two relatively faint (<jats:italic>L</jats:italic> <jats:sub>1.4 GHz</jats:sub> ∼ 10<jats:sup>25</jats:sup> W Hz<jats:sup>−1</jats:sup>) RAGNs in a known protocluster at <jats:italic>z</jats:italic> = 3.3 in the PCl J0227-0421 field, detected using the latest radio observation obtained as part of the Observations of Redshift Evolution in Large-Scale Environments (ORELSE) survey. Using new spectroscopic observations obtained from the Keck/Multi-Object Spectrometer for Infra-Red Exploration as part of the Charting Cluster Construction with the VIMOS Ultra-Deep Survey (VUDS) and ORELSE (C3VO) survey and previous spectroscopic data obtained as part of the VIMOS-Very Large Telescope Deep Survey and VUDS, we revise the three-dimensional overdensity field around this protocluster. The protocluster is embedded in a large-scale overdensity protostructure. This protostructure has an estimated total mass of ∼2.6 × 10<jats:sup>15</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> and contains several overdensity peaks. Both RAGNs are hosted by very bright and massive galaxies, while their hosts show extreme differences in color, indicating that they are of different ages and are in different evolutionary stages. Furthermore, we find that they are not in the most locally dense parts of the protostructure, but are fairly close to the centers of their parent overdensity peaks. We propose a scenario where merging might have already happened in both cases, which lowered the local density of their surrounding area and boosted their stellar mass. This work is the first time that two RAGNs at low luminosity have been found and studied within a high-redshift protostructure.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Submillimeter/far-IR spectroscopy was used to detect and quantify organic molecules sublimated after the ultraviolet photolysis (at 12 K) and warm-up (up to 300 K) of a methanol (CH<jats:sub>3</jats:sub>OH) ice sample. Eleven sublimated photoproducts were uniquely identified: carbon monoxide (CO), formaldehyde (H<jats:sub>2</jats:sub>CO), ketene (C<jats:sub>2</jats:sub>H<jats:sub>2</jats:sub>O), acetaldehyde (CH<jats:sub>3</jats:sub>CHO), ethylene oxide (CH<jats:sub>2</jats:sub>OCH<jats:sub>2</jats:sub>), vinyl alcohol (CH<jats:sub>2</jats:sub>CHOH), ethanol (CH<jats:sub>3</jats:sub>CH<jats:sub>2</jats:sub>OH), dimethyl ether (CH<jats:sub>3</jats:sub>OCH<jats:sub>3</jats:sub>), methyl formate (HCOOCH<jats:sub>3</jats:sub>), glycolaldehyde (HOCH<jats:sub>2</jats:sub>CHO), and acetone ((CH<jats:sub>3</jats:sub>)<jats:sub>2</jats:sub>CO). Two additional products were detected in the photolyzed ice by Fourier-transform infrared (FTIR) spectroscopy: carbon dioxide (CO<jats:sub>2</jats:sub>) and methane (CH<jats:sub>4</jats:sub>). The rotational temperatures and gas densities were calculated for the organics containing two or more C atoms via a rotation diagram analysis, and the gas-phase submillimeter/far-IR technique was used in tandem with mass spectrometry and FTIR spectroscopy of the ice during photolysis. The abundance ratios of the sublimated species (normalized to methanol) were compared to those observed in hot cores (Orion-KL, Sagittarius B2(N), and IRAS 16293-2422(B)) and in comets C/2014 Q2 (Lovejoy) and 67P/Churyumov–Gerasimenko.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present new observational evidence for one of the most important three wave interactions, called the electrostatic decay instability (ESD) <jats:inline-formula> <jats:tex-math> <?CDATA $L\to {L}^{{\prime} }+S$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabee74ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> in the source regions of complex solar type III radio bursts (<jats:italic>L</jats:italic> is the electron beam-excited Langmuir wave, and <jats:inline-formula> <jats:tex-math> <?CDATA ${L}^{{\prime} }$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabee74ieqn2.gif" xlink:type="simple" /> </jats:inline-formula> and <jats:italic>S</jats:italic> are the ESD excited daughter Langmuir and ion sound waves, respectively). The STEREO in situ wave observations in the source regions of complex type III bursts show that Langmuir waves often occur as one-dimensional magnetic field aligned beat-type wave packets, with peak intensities well in excess of the threshold for excitation of ESD, and with spectra containing (a) two closely spaced narrow peaks (<jats:italic>L</jats:italic> and <jats:inline-formula> <jats:tex-math> <?CDATA ${L}^{{\prime} }$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabee74ieqn3.gif" xlink:type="simple" /> </jats:inline-formula>) corresponding probably to the beating modes responsible for the beat patterns at frequencies very close to the local electron plasma frequency, <jats:italic>f</jats:italic> <jats:sub> <jats:italic>pe</jats:italic> </jats:sub>, and (b) narrow peaks at ion sound frequencies, <jats:italic>f</jats:italic> <jats:sub> <jats:italic>S</jats:italic> </jats:sub>, which are very close to beat frequencies. Using the FFT and higher order spectral techniques, we show that the frequency, wavevector and phase resonance conditions required for excitation of ESD are well satisfied for these wave packets, and the speeds of electron beams derived from the resonance conditions agree reasonably well with those derived from the drift rates of the associated type III events. We also show that the merging of (<jats:italic>L</jats:italic>) and (<jats:inline-formula> <jats:tex-math> <?CDATA ${L}^{{\prime} }$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabee74ieqn4.gif" xlink:type="simple" /> </jats:inline-formula>) most probably is the excitation mechanism of the second harmonic radio emission <jats:inline-formula> <jats:tex-math> <?CDATA ${T}_{2{f}_{{pe}}}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabee74ieqn5.gif" xlink:type="simple" /> </jats:inline-formula> of these type III bursts.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Red giants show a large number of absorption lines in both optical and near-infrared wavelengths. Still, the characteristics of the lines in different wave passbands are not necessarily the same. We searched for lines of Mg <jats:sc>i</jats:sc>, Si <jats:sc>i</jats:sc>, Ca <jats:sc>i</jats:sc>, Ti <jats:sc>i</jats:sc>, Cr <jats:sc>i</jats:sc>, and Ni <jats:sc>i</jats:sc> in the <jats:inline-formula> <jats:tex-math> <?CDATA $z^{\prime} $?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabf0b1ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>, <jats:italic>Y</jats:italic>, and <jats:italic>J</jats:italic> bands (0.91–1.33 <jats:italic>μ</jats:italic>m), that are useful for precise abundance analyses, from two different compilations of lines, namely, the third release of Vienna Atomic Line Database (VALD3) and the catalog published by Meléndez &amp; Barbuy in 1999 (MB99). We selected sufficiently strong lines that are not severely blended and ended up with 191 lines (165 and 141 lines from VALD3 and MB99, respectively), in total, for the six elements. Combining our line lists with high-resolution (<jats:italic>λ</jats:italic>/Δ<jats:italic>λ</jats:italic> = 28,000) and high signal-to-noise ratio (&gt;500) spectra taken with the WINERED spectrograph, we measured the abundances of the six elements in addition to Fe <jats:sc>i</jats:sc> of two prototype red giants, i.e., Arcturus and <jats:italic>μ</jats:italic> Leo. The resultant abundances show reasonable agreement with the values in the literature within ∼0.2 dex, indicating that the available oscillator strengths are acceptable, although the abundances based on the two line lists show systematic differences by 0.1–0.2 dex. Furthermore, to improve the precision, solid estimation of the microturbulence (or the microturbulences if they are different for different elements) is necessary as far as the classical hydrostatic atmosphere models are used for the analysis.</jats:p>