Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>Monitoring of vibrational eigenmodes of an elastic body excited by gravitational waves was one of the first concepts proposed for the detection of gravitational waves. At laboratory scale, these experiments became known as resonant bar detectors first developed by Joseph Weber in the 1960s. Due to the dimensions of these bars, the targeted signal frequencies were in the kHz range. Weber also pointed out that monitoring of vibrations of Earth or the Moon could reveal gravitational waves in the mHz band. His Lunar Surface Gravimeter experiment deployed on the Moon by the Apollo 17 crew had a technical failure, which greatly reduced the science scope of the experiment. In this article, we revisit the idea and propose a Lunar Gravitational-Wave Antenna (LGWA). We find that LGWA could become an important partner observatory for joint observations with the space-borne, laser-interferometric detector LISA and at the same time contribute an independent science case due to LGWA’s unique features. Technical challenges need to be overcome for the deployment of the experiment, and development of inertial vibration sensor technology lays out a future path for this exciting detector concept.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>This paper constructs a theoretical framework for calculating the distribution of masses for gas giant planets forming via the core accretion paradigm. Starting with known properties of circumstellar disks, we present models for the planetary mass distribution over the range 0.1<jats:italic>M</jats:italic> <jats:sub>J</jats:sub> ≤ <jats:italic>M</jats:italic> <jats:sub>p</jats:sub> &lt; 10<jats:italic>M</jats:italic> <jats:sub>J</jats:sub>. If the circumstellar disk lifetime is solely responsible for the end of planetary mass accretion, the observed (nearly) exponential distribution of disk lifetime would imprint an exponential falloff in the planetary mass function. This result is in apparent conflict with observations, which suggest that the mass distribution has a (nearly) power-law form of <jats:inline-formula> <jats:tex-math> <?CDATA ${dF}/{{dM}}_{{\rm{p}}}\sim {M}_{{\rm{p}}}^{-p}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabdd2bieqn1.gif" xlink:type="simple" /> </jats:inline-formula>, with an index of <jats:italic>p</jats:italic> ≈ 1.3, over the relevant planetary mass range (and for stellar masses ∼0.5–2<jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>). The mass accretion rate onto the planet depends on the fraction of the (circumstellar) disk accretion flow that enters the Hill sphere, and on the efficiency with which the planet captures the incoming material. Models for the planetary mass function that include distributions for these efficiencies, with uninformed priors, can produce nearly power-law behavior, consistent with current observations. The disk lifetimes, accretion rates, and other input parameters depend on the mass of the host star. We show how these variations lead to different forms for the planetary mass function for different stellar masses. Compared to stars with masses <jats:italic>M</jats:italic> <jats:sub>*</jats:sub> = 0.5–2<jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, stars with smaller masses are predicted to have a steeper planetary mass function (fewer large planets).</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The spectral energy distributions (SEDs) of some blazars exhibit an ultraviolet (UV) and/or soft X-ray excess that can be modeled with different radiation mechanisms. Polarization measurements of the UV/X-ray emission from blazars may provide new and unique information about the astrophysical environment of blazar jets, and could thus help to distinguish between different emission scenarios. In this paper, a new Monte Carlo code—Monte Carlo Applications for Partially Polarized Inverse External-Compton Scattering—for polarization-dependent Compton scattering is used to simulate the polarization signatures in a model where the UV/soft X-ray excess arises from the bulk Compton process. Predictions of the expected polarization signatures of Compton emission from the soft X-ray excess in the SED of AO 0235+164 and the UV excess in the SED of 3C 279 are made for upcoming and proposed polarimetry missions.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Sun produces highly dynamic and eruptive events that can drive shocks through the corona. These shocks can accelerate electrons, which result in plasma emission in the form of a type II radio burst. Despite the large number of type II radio burst observations, the precise origin of coronal shocks is still subject to investigation. Here, we present a well-observed solar eruptive event that occurred on 2015 October 16, focusing on a jet observed in the extreme ultraviolet by the Atmospheric Imaging Assembly (SDO/AIA), a streamer observed in white light by the Large Angle and Spectrometric Coronagraph (SOHO/LASCO), and a metric type II radio burst observed by the LOw Frequency Array (LOFAR). LOFAR interferometrically imaged the fundamental and harmonic sources of a type II radio burst and revealed that the sources did not appear to be cospatial, as would be expected from the plasma emission mechanism. We correct for the separation between the fundamental and harmonic using a model that accounts for scattering of radio waves by electron density fluctuations in a turbulent plasma. This allows us to show the type II radio sources were located ∼0.5<jats:italic>R</jats:italic> <jats:sub>⊙</jats:sub> above the jet and propagated at a speed of ∼1000 km s<jats:sup>−1</jats:sup>, which was significantly faster than the jet speed of ∼200 km s<jats:sup>−1</jats:sup>. This suggests that the type II burst was generated by a piston shock driven by the jet in the low corona.</jats:p>