Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>The Large High Altitude Air Shower Observatory (LHAASO) detected 12 gamma-ray sources above 100 TeV, which are the possible origins of Galactic cosmic-rays. We summarize the neutrino measurements by IceCube and ANTARES in the vicinity of LHAASO sources to constrain the contribution of hadronic gamma-rays in these sources. We find that the current observations constrain hadronic gamma-rays to contribute no more than ∼60% of the gamma-rays from the Crab Nebula. Gamma-rays from two LHAASO sources, LHAASO J1825−1326 and LHAASO J1907+0626, are dominated by leptonic components up to ∼200 TeV, under the hypotheses in the analysis by IceCube. The uncertainties of the constraint on the hadronic gamma-ray emission are discussed. We also constrain the total 100 TeV gamma-ray emission from TeV pulsar wind nebulae by relying on the remarkable sensitivity of LHAASO at that energy.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We compose a 265-sight-line Milky Way C <jats:sc>iv</jats:sc> line-shape sample using the Hubble Space Telescope/Cosmic Origins Spectrograph archive, which is complementary to the existing Si <jats:sc>iv</jats:sc> samples. C <jats:sc>iv</jats:sc> has a higher ionization potential (47–64 eV) than Si <jats:sc>iv</jats:sc> (33–45 eV), so it also traces warm gas, which is roughly cospatial with Si <jats:sc>iv</jats:sc>. The spatial density distribution and kinematics of C <jats:sc>iv</jats:sc> are identical to those Si <jats:sc>iv</jats:sc> within ≈2<jats:italic>σ</jats:italic>. C <jats:sc>iv</jats:sc> is more sensitive to the warm gas density distribution at large radii with a higher element abundance. Applying the kinematical model to the C <jats:sc>iv</jats:sc> sample, we find two possible solutions of the density distribution, which are distinguished by the relative extension along the disk midplane and the normal-line direction. Both solutions can reproduce the existing sample and suggest a warm gas disk mass of <jats:inline-formula> <jats:tex-math> <?CDATA $\mathrm{log}M({M}_{\odot })\approx 8$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:mi>M</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> <mml:mo stretchy="false">)</mml:mo> <mml:mo>≈</mml:mo> <mml:mn>8</mml:mn> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac35cdieqn1.gif" xlink:type="simple" /> </jats:inline-formula> and an upper limit of <jats:inline-formula> <jats:tex-math> <?CDATA $\mathrm{log}M({M}_{\odot })\lt 9.3$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:mi>M</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> <mml:mo stretchy="false">)</mml:mo> <mml:mo>&lt;</mml:mo> <mml:mn>9.3</mml:mn> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac35cdieqn2.gif" xlink:type="simple" /> </jats:inline-formula> within 250 kpc, which is consistent with Si <jats:sc>iv</jats:sc>. There is a decrease in the C <jats:sc>iv</jats:sc>/Si <jats:sc>iv</jats:sc> column density ratio from the Galactic center to the outskirts by 0.2–0.3 dex, which may suggest a phase transition or different ionization mechanisms for C <jats:sc>iv</jats:sc> and Si <jats:sc>iv</jats:sc>. Also, we find that the difference between C <jats:sc>iv</jats:sc> and Si <jats:sc>iv</jats:sc> is an excellent tracer of small-scale features, and we find a typical size of 5°–10° for possible turbulence within individual clouds (≈1 kpc).</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present the results of an integrated laboratory and modeling investigation into the impact of stellar X-rays on cosmic dust. Carbonaceous grains were prepared in a cooled (&lt;200 K) supersonic expansion from aromatic molecular precursors, and were later irradiated with 970 eV X-rays. Silicate (enstatite) grains were prepared via laser ablation, thermally annealed, and later irradiated with 500 eV X-rays. Infrared spectra of the 3.4 <jats:italic>μ</jats:italic>m band of the carbon sample prepared with benzene revealed 84% ± 5% band area loss for an X-ray dose of 5.2 ×10<jats:sup>23</jats:sup> eV.cm<jats:sup>−2</jats:sup>. Infrared spectra of the 8–12 <jats:italic>μ</jats:italic>m Si–O band of the silicate sample revealed band area loss up to 63% ± 5% for doses of 2.3 × 10<jats:sup>23</jats:sup> eV.cm<jats:sup>−2</jats:sup>. A hybrid Monte Carlo particle trajectory approach was used to model the impact of X-rays and ensuing photoelectrons, Auger and collisionally ionized electrons through the bulk. As a result of X-ray ionization and ensuing Coulomb explosions on surface molecules, the calculated mass loss is 60% for the carbonaceous sample and 46% for the silicate sample, within a factor of 2 of the IR band loss, supporting an X-ray induced mass-loss mechanism. We apply the laboratory X-ray destruction rates to estimate the lifetimes of dust grains in protoplanetary disks surrounding 1 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> and 0.1 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> G and M stars. In both cases, X-ray destruction timescales are short (a few million years) at the disk surface, but are found to be much longer than typical disk lifetimes (≳10 Myr) over the disk bulk.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We use deep Hubble Space Telescope imaging to derive a distance to the Virgo Cluster ultradiffuse galaxy (UDG) VCC 615 using the tip of the red giant branch (TRGB) distance estimator. We detect 5023 stars within the galaxy, down to a 50% completeness limit of F814W ≈ 28.0, using counts in the surrounding field to correct for contamination due to background sources and Virgo intracluster stars. We derive an extinction-corrected F814W tip magnitude of <jats:inline-formula> <jats:tex-math> <?CDATA ${m}_{\mathrm{tip},0}={27.19}_{-0.05}^{+0.07}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>m</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>tip</mml:mi> <mml:mo>,</mml:mo> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>27.19</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.05</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.07</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac35d9ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>, yielding a distance of <jats:inline-formula> <jats:tex-math> <?CDATA $d={17.7}_{-0.4}^{+0.6}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>d</mml:mi> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>17.7</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.4</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.6</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac35d9ieqn2.gif" xlink:type="simple" /> </jats:inline-formula> Mpc. This places VCC 615 on the far side of the Virgo Cluster (<jats:italic>d</jats:italic> <jats:sub>Virgo</jats:sub> = 16.5 Mpc), at a Virgocentric distance of 1.3 Mpc and near the virial radius of the main body of Virgo. Coupling this distance with the galaxy’s observed radial velocity, we find that VCC 615 is on an outbound trajectory, having survived a recent passage through the inner parts of the cluster. Indeed, our orbit modeling gives a 50% chance the galaxy passed inside the Virgo core (<jats:italic>r</jats:italic> &lt; 620 kpc) within the past gigayear, although very close passages directly through the cluster center (<jats:italic>r</jats:italic> &lt; 200 kpc) are unlikely. Given VCC 615's undisturbed morphology, we argue that the galaxy has experienced no recent and sudden transformation into a UDG due to the cluster potential, but rather is a long-lived UDG whose relatively wide orbit and large dynamical mass protect it from stripping and destruction by the Virgo cluster tides. Finally, we also describe the serendipitous discovery of a nearby Virgo dwarf galaxy projected 90″ (7.2 kpc) away from VCC 615.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The aim of the present study is to show the varying asymmetries during the decay of sunspot groups. The source of input data is the SOHO/MDI-Debrecen Database sunspot catalog that contains the magnetic polarity data for time interval 1996–2010. Several types of asymmetries were examined on the selected sample of 142 sunspot groups. The leading–following asymmetry increases in three phases during the decay and exhibits anticorrelation with size. It is also related to a hemispheric asymmetry: during the decay, the area asymmetry index has higher values in the southern hemisphere, which may be due to the higher activity level in the southern hemisphere in cycle 23. The total umbral area is inversely proportional to the umbra/penumbra ratio, but it is directly proportional to the umbral decay rate. During the decay, the umbra/penumbra (U/P) ratio decreases unambiguously in the trailing parts but in most cases in the leading parts as well. The U/P variation is a consequence of the different depths of umbral and penumbral fields.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The isotopic compositions of ruthenium (Ru) are measured from presolar silicon carbide (SiC) grains. In a popular scenario, the presolar SiC grains formed in the outskirt of an asymptotic giant branch (AGB) star, left the star as a stellar wind, and joined the presolar molecular cloud from which the solar system formed. The Ru isotopes formed inside the star, moved to the stellar surface during the AGB phase, and were locked into the SiC grains. Following this scenario, we analyze the Nucleosynthesis Grid (NuGrid) data, which provide the abundances of the Ru isotopes in the stellar wind for a set of stars in a wide range of initial masses and metallicities. We apply the C &gt; O (carbon abundance larger than the oxygen abundance) condition, which is commonly adopted for the condition of the SiC formation in the stellar wind. The NuGrid data confirm that SiC grains do not form in the winds of massive stars. The isotopic compositions of Ru in the winds of low-mass stars can explain the measurements. We find that lower-mass stars (1.65 <jats:italic>M</jats:italic> <jats:sub>☉</jats:sub> and 2 <jats:italic>M</jats:italic> <jats:sub>☉</jats:sub>) with low metallicity (<jats:italic>Z</jats:italic> = 0.0001) can explain most of the measured isotopic compositions of Ru. We confirm that the abundance of <jats:sup>99</jats:sup> Ru inside the presolar grain includes the contribution from the in situ decay of <jats:sup>99</jats:sup> Tc. We also verify our conclusion by comparing the isotopic compositions of Ru integrated over all the pulses with those calculated at individual pulses.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Radio relics in the outskirts of galaxy clusters imply the diffusive shock acceleration (DSA) of electrons at merger-driven shocks with Mach number <jats:italic>M</jats:italic> <jats:sub> <jats:italic>s</jats:italic> </jats:sub> ≲ 3–4 in the intracluster medium (ICM). Recent studies have suggested that electron preacceleration and injection, prerequisite steps for DSA, could occur at supercritical shocks with <jats:italic>M</jats:italic> <jats:sub> <jats:italic>s</jats:italic> </jats:sub> ≳ 2.3 in the ICM, thanks to the generation of multiscale waves by microinstabilities such as the Alfvén ion cyclotron (AIC) instability, the electron firehose instability (EFI), and the whistler instability (WI). On the other hand, some relics are observed to have subcritical shocks with <jats:italic>M</jats:italic> <jats:sub> <jats:italic>s</jats:italic> </jats:sub> ≲ 2.3, leaving DSA at such weak shocks as an outstanding problem. Reacceleration of preexisting nonthermal electrons has been contemplated as one of possible solutions for that puzzle. To explore this idea, we perform particle-in-cell simulations for weak quasi-perpendicular shocks in high-<jats:italic>β</jats:italic> (<jats:italic>β</jats:italic> = <jats:italic>P</jats:italic> <jats:sub>gas</jats:sub>/<jats:italic>P</jats:italic> <jats:sub> <jats:italic>B</jats:italic> </jats:sub>) plasmas with power-law suprathermal electrons in addition to Maxwellian thermal electrons. We find that suprathermal electrons enhance the excitation of electron-scale waves via the EFI and WI. However, they do not affect the ion reflection and the ensuing generation of ion-scale waves via the AIC instability. The presence of ion-scale waves is the key for the preacceleration of electrons up to the injection momentum; thus, the shock criticality condition for electron injection to DSA is preserved. Based on the results, we conclude that preexisting nonthermal electrons in the preshock region alone would not resolve the issue of electron preacceleration at subcritical ICM shocks.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Ion–Weibel instability (IWI) is an important mechanism of generating a magnetic field in supernova remnants; it plays a key role in the generation of high-energy cosmic rays. Computational efficiency has been a bottleneck in numerical exploration of the large-scale evolution of IWI. Here I report a new hybrid particle-in-cell (PIC) method that can quickly simulate IWI. The method is based on a new model that describes the relation of the ion current and its magnetic field under the electron screening. The new method’s computational efficiency is nearly two orders of magnitude higher than that of the PIC method. This method is suitable for the full-scale simulation of the IWI in laser-plasma experiments and supernova remnants.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Double white dwarf (DWD) binaries are important for studies of common-envelope (CE) evolution, Type Ia supernova progenitors and Galactic sources of low-frequency gravitational waves. PTF J0533+0209 is a DWD system with a short orbital period of <jats:italic>P</jats:italic> <jats:sub>orb</jats:sub> ∼ 20 minutes and thus a so-called LISA verification source. The formation of this system and other DWDs is still under debate. In this paper, we discuss the possible formation scenarios of this binary and argue that it is not likely to have formed through CE evolution. Applying a new magnetic-braking prescription, we use the <jats:monospace>MESA</jats:monospace> code to model the formation of this system through stable mass transfer. We find a model that can well reproduce the observed WD masses and orbital period but not the effective temperature and hydrogen abundance of the low-mass He WD component. We discuss the possibility of using H flashes to mitigate this discrepancy. Finally, we discuss the future evolution of this system into an AM CVn binary such as those that will be detected by spaceborne GW observatories like LISA, TianQin, and Taiji.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>It is commonly believed that blazar jets are relativistic magnetized plasma outflows from supermassive black holes. One key question is how the jets dissipate magnetic energy to accelerate particles and drive powerful multiwavelength flares. Relativistic magnetic reconnection has been proposed as the primary plasma physical process in the blazar emission region. Recent numerical simulations have shown strong acceleration of nonthermal particles that may lead to multiwavelength flares. Nevertheless, previous works have not directly evaluated <jats:italic>γ</jats:italic>-ray signatures from first-principles simulations. In this paper, we employ combined particle-in-cell and polarized radiation transfer simulations to study multiwavelength radiation and optical polarization signatures under the leptonic scenario from relativistic magnetic reconnection. We find harder-when-brighter trends in optical and Fermi-LAT <jats:italic>γ</jats:italic>-ray bands as well as closely correlated optical and <jats:italic>γ</jats:italic>-ray flares. The swings in optical polarization angle are also accompanied by <jats:italic>γ</jats:italic>-ray flares with trivial time delays. Intriguingly, we find highly variable synchrotron self-Compton signatures due to inhomogeneous particle distributions during plasmoid mergers. This feature may result in fast <jats:italic>γ</jats:italic>-ray flares or orphan <jats:italic>γ</jats:italic>-ray flares under the leptonic scenario, complementary to the frequently considered minijet scenario. It may also imply neutrino emission with low secondary synchrotron flux under the hadronic scenario, if plasmoid mergers can accelerate protons to very high energy.</jats:p>