Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>We analyze three observations of GRS 1915+105 in 2017 by Insight–Hard X-ray Modulation Telescope when the source was in a spectrally soft state. We find strong absorption lines from highly ionized iron, which are due to absorption by disk wind outflowing at a velocity of ∼1000 km s<jats:sup>−1</jats:sup> along our line of sight. Two of the three observations show large amplitude oscillation in their light curves and the variation pattern corresponds to state <jats:italic>κ</jats:italic> of GRS 1915+105. From time-averaged and flux-resolved analysis, we find that the variation in the ionization state of the disk wind follows the X-ray continuum on timescales from hundreds of seconds to months. The radial location of the disk wind is consistent with thermal driving. The mass-loss rate due to the outflowing wind is comparable to the mass accretion rate in the inner disk, which demonstrates the important role of the disk wind in the disk accretion system.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Flux-rope-based magnetohydrodynamic modeling of coronal mass ejections (CMEs) is a promising tool for prediction of the CME arrival time and magnetic field at Earth. In this work, we introduce a constant-turn flux rope model and use it to simulate the 2012 July 12 16:48 CME in the inner heliosphere. We constrain the initial parameters of this CME using the graduated cylindrical shell (GCS) model and the reconnected flux in post-eruption arcades. We correctly reproduce all the magnetic field components of the CME at Earth, with an arrival time error of approximately 1 hr. We further estimate the average subjective uncertainties in the GCS fittings by comparing the GCS parameters of 56 CMEs reported in multiple studies and catalogs. We determined that the GCS estimates of the CME latitude, longitude, tilt, and speed have average uncertainties of 5.°74, 11.°23, 24.°71, and 11.4%, respectively. Using these, we have created 77 ensemble members for the 2012 July 12 CME. We found that 55% of our ensemble members correctly reproduce the sign of the magnetic field components at Earth. We also determined that the uncertainties in GCS fitting can widen the CME arrival time prediction window to about 12 hr for the 2012 July 12 CME. On investigating the forecast accuracy introduced by the uncertainties in individual GCS parameters, we conclude that the half-angle and aspect ratio have little impact on the predicted magnetic field of the 2012 July 12 CME, whereas the uncertainties in longitude and tilt can introduce relatively large spread in the magnetic field predicted at Earth.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Nonthermal, pickup ions (PUIs) represent an energetic component of the solar wind (SW). While a number of theoretical models have been proposed to describe the PUI flow, of major importance are in situ measurements providing us with the vital source of model validation. The Solar Wind Ion Composition Spectrometer (SWICS) instrument on board the Ulysses spacecraft was specifically designed for this purpose. Zhang et al. proposed a new, accurate method for the derivation of ion velocity distribution function in the SW frame on the basis of count rates collected by SWICS. We calculate the moments of these distribution functions for protons (H<jats:sup>+</jats:sup>) and He<jats:sup>+</jats:sup> ions along the Ulysses trajectory for a period of 2 months including the Halloween 2003 solar storm. This gives us the time distributions of PUI density and temperature. We compare these with the results obtained earlier for the same interval of time, in which the ion spectra are converted to the SW frame using the narrow-beam approximation. Substantial differences are identified, which are of importance for the interpretation of PUI distributions in the 3D, time-dependent heliosphere. We also choose one of the shocks crossed by Ulysses during this time interval and analyze the distribution functions and PUI bulk properties in front of and behind it. The results are compared with the test-particle calculations and diffusive shock acceleration theory.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Ultra-high-energy photons with energies exceeding 10<jats:sup>17</jats:sup> eV offer a wealth of connections to different aspects of cosmic-ray astrophysics as well as to gamma-ray and neutrino astronomy. The recent observations of photons with energies in the 10<jats:sup>15</jats:sup> eV range further motivate searches for even higher-energy photons. In this paper, we present a search for photons with energies exceeding 2 × 10<jats:sup>17</jats:sup> eV using about 5.5 yr of hybrid data from the low-energy extensions of the Pierre Auger Observatory. The upper limits on the integral photon flux derived here are the most stringent ones to date in the energy region between 10<jats:sup>17</jats:sup> and 10<jats:sup>18</jats:sup> eV.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We study the origin of gamma-rays from the supernova remnant (SNR) RX J1713.7-3946. Using an analytical model, we calculate the distribution of cosmic rays (CRs) around the SNRs. Motivated by the results of previous studies, we assume that the SNR is interacting with two-phase interstellar medium (ISM), where dense clumps are surrounded by tenuous interclump medium. We also assume that only higher-energy protons (≳TeV) can penetrate the dense clumps. We find that <jats:italic>π</jats:italic> <jats:sup>0</jats:sup>-decay gamma-rays produced by protons reproduce the observed gamma-ray spectrum peaked at ∼TeV. On the other hand, it has recently been indicated that the observed ISM column density (<jats:italic>N</jats:italic> <jats:sub> <jats:italic>p</jats:italic> </jats:sub>), the X-ray surface brightness (<jats:italic>I</jats:italic> <jats:sub> <jats:italic>X</jats:italic> </jats:sub>), and the gamma-ray surface brightness (<jats:italic>I</jats:italic> <jats:sub> <jats:italic>g</jats:italic> </jats:sub>) at grid points across the SNR form a plane in the three-dimensional (3D) space of (<jats:italic>N</jats:italic> <jats:sub> <jats:italic>p</jats:italic> </jats:sub>, <jats:italic>I</jats:italic> <jats:sub> <jats:italic>X</jats:italic> </jats:sub>, <jats:italic>I</jats:italic> <jats:sub> <jats:italic>g</jats:italic> </jats:sub>). We find that the planar configuration is naturally reproduced if the ISM or the CR electron-to-proton ratio is not spherically uniform. We show that the shift of the observed data in the 3D space could be used to identify which of the quantities, the ISM density, the CR electron-to-proton ratio, or the magnetic field, varies in the azimuthal direction of the SNR.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a catalog of 35 interplanetary coronal mass ejections (ICMEs) observed by the Juno spacecraft and at least one other spacecraft during its cruise phase to Jupiter. We identify events observed by MESSENGER, Venus Express, Wind, and STEREO with magnetic features that can be matched unambiguously with those observed by Juno. A multi-spacecraft study of ICME properties between 0.3 and 2.2 au is conducted: we first investigate the global expansion by tracking the variation in magnetic field strength with increasing heliocentric distance of individual ICME events, finding significant variability in magnetic field relationships for individual events in comparison with statistical trends. With the availability of plasma data at 1 au, the local expansion at 1 au can be compared with global expansion rates between 1 au and Juno. Despite following expected trends, the local and global expansion rates are only weakly correlated. Finally, for those events with clearly identifiable magnetic flux ropes, we investigate the orientation of the flux rope axis as they propagate; we find that 64% of events displayed a decrease in inclination with increasing heliocentric distance, and 40% of events undergo a significant change in orientation as they propagate toward Juno. The multi-spacecraft catalog produced in this study provides a valuable link between ICME observations in the inner heliosphere and beyond 1 au, thereby improving our understanding of ICME evolution.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Lower hybrid drift waves are commonly observed at plasma boundaries, playing an important role in plasma dynamics. Such waves have been widely investigated in the terrestrial magnetosphere but have never been reported in other planetary environments. Here, using the measurements from the Mars Atmosphere and Volatile EvolutioN mission, we present the first observation of electromagnetic lower hybrid drift waves at the edge of the current sheet on the dusk side of the Martian magnetotail, which should be locally excited rather than propagated from other regions. These plasma waves are associated with significant density gradients and magnetic field gradients. Based on the measured local plasma parameters and the sufficient condition for lower hybrid drift instability to be excited, we find that the proton density gradient is sharp enough to excite the lower hybrid drift instability. The analysis of the existence condition for lower hybrid drift instability indicates that these lower hybrid drift waves at the edge of the current sheet are generated through lower hybrid drift instability. The above results can improve our understanding of Mars’ magnetospheric dynamics.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The 3D-Drift And SHift (3D-DASH) program is a Hubble Space Telescope (HST) WFC3 F160W imaging and G141 grism survey of the equatorial COSMOS field. 3D-DASH extends the legacy of HST near-infrared imaging and spectroscopy to degree-scale swaths of the sky, enabling the identification and study of distant galaxies (<jats:italic>z</jats:italic> &gt; 2) that are rare or in short-lived phases of galaxy evolution at rest-frame optical wavelengths. Furthermore, when combined with existing ACS/F814W imaging, the program facilitates spatially resolved studies of the stellar populations and dust content of intermediate redshift (0.5 &lt; <jats:italic>z</jats:italic> &lt; 2) galaxies. Here we present the reduced F160W imaging mosaic available to the community. Observed with the efficient DASH technique, the mosaic comprises 1256 individual WFC3 pointings, corresponding to an area of 1.35 deg<jats:sup>2</jats:sup> (1.43 deg<jats:sup>2</jats:sup> in 1912 when including archival data). The median 5<jats:italic>σ</jats:italic> point-source limit in <jats:italic>H</jats:italic> <jats:sub>160</jats:sub> is 24.74 ± 0.20 mag. We also provide a point-spread function (PSF) generator tool to determine the PSF at any location within the 3D-DASH footprint. 3D-DASH is the widest HST/WFC3 imaging survey in the F160W filter to date, increasing the existing extragalactic survey area in the near-infrared at HST resolution by an order of magnitude.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Recent radio observations have obtained stringent constraints for annihilating dark matter. In this article, we use the radio continuum spectral data of the Large Magellanic Cloud to analyze the dark matter annihilation signals. We have discovered a slightly positive signal of dark matter annihilation with a 1.5<jats:italic>σ</jats:italic> statistical significance. The overall best-fit dark matter mass is <jats:italic>m</jats:italic> <jats:sub>DM</jats:sub> ≈ 90 GeV, annihilating via the <jats:inline-formula> <jats:tex-math> <?CDATA $b\bar{b}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>b</mml:mi> <mml:mover accent="true"> <mml:mrow> <mml:mi>b</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>¯</mml:mo> </mml:mrow> </mml:mover> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac71a9ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> channel. We have also constrained the 3<jats:italic>σ</jats:italic> lower limits of dark matter mass with the standard thermal dark matter annihilation cross section for the <jats:italic>e</jats:italic> <jats:sup>+</jats:sup> <jats:italic>e</jats:italic> <jats:sup>−</jats:sup>, <jats:italic>μ</jats:italic> <jats:sup>+</jats:sup> <jats:italic>μ</jats:italic> <jats:sup>−</jats:sup>, <jats:italic>τ</jats:italic> <jats:sup>+</jats:sup> <jats:italic>τ</jats:italic> <jats:sup>−</jats:sup>, and <jats:inline-formula> <jats:tex-math> <?CDATA $b\bar{b}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>b</mml:mi> <mml:mover accent="true"> <mml:mrow> <mml:mi>b</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>¯</mml:mo> </mml:mrow> </mml:mover> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac71a9ieqn2.gif" xlink:type="simple" /> </jats:inline-formula> channels.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present non-radiative, cosmological zoom-in simulations of galaxy-cluster formation with magnetic fields and (anisotropic) thermal conduction of one massive galaxy cluster with <jats:italic>M</jats:italic> <jats:sub>vir</jats:sub> ∼ 2 × 10<jats:sup>15</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> at <jats:italic>z</jats:italic> ∼ 0. We run the cluster on three resolution levels (1×, 10×, 25×), starting with an effective mass resolution of 2 × 10<jats:sup>8</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, subsequently increasing the particle number to reach 4 × 10<jats:sup>6</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>. The maximum spatial resolution obtained in the simulations is limited by the gravitational softening reaching <jats:italic>ϵ</jats:italic> = 1.0 kpc at the highest resolution level, allowing one to resolve the hierarchical assembly of the structures in fine detail. All simulations presented are carried out with the SPMHD code <jats:sc>gadget3</jats:sc> with an updated SPMHD prescription. The primary focus of this paper is to investigate magnetic field amplification in the intracluster medium. We show that the main amplification mechanism is the small-scale turbulent dynamo in the limit of reconnection diffusion. In our two highest resolution models we start to resolve the magnetic field amplification driven by the dynamo and we explicitly quantify this with the magnetic power spectra and the curvature of the magnetic field lines, consistent with dynamo theory. Furthermore, we investigate the ∇ · <jats:bold> <jats:italic>B</jats:italic> </jats:bold> = 0 constraint within our simulations and show that we achieve comparable results to state-of-the-art AMR or moving-mesh techniques, used in codes such as <jats:sc>enzo</jats:sc> and <jats:sc>arepo</jats:sc>. Our results show for the first time in a cosmological simulation of a galaxy cluster that dynamo action can be resolved with modern numerical Lagrangian magnetohydrodynamic methods, a study that is currently missing in the literature.</jats:p>