Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>Sunspots are known to be strong absorbers of solar oscillation modal power. The most convincing way to demonstrate this is done via Fourier–Hankel decomposition (FHD), where the local oscillation field is separated into in- and outgoing waves, showing the reduction in power. Due to the Helioseismic and Magnetic Imager’s high-cadence Doppler measurements, power absorption can be investigated at frequencies beyond the acoustic cutoff frequency. We perform an FHD on five sunspot regions and two quiet-Sun control regions and study the resulting absorption spectra <jats:italic>α</jats:italic> <jats:sub> <jats:italic>ℓ</jats:italic> </jats:sub>(<jats:italic>ν</jats:italic>), specifically at frequencies <jats:italic>ν</jats:italic> &gt; 5.3 mHz. We observe an unreported high-frequency absorption feature, which only appears in the presence of a sunspot. This feature is confined to phase speeds of one-skip waves whose origins coincide with the sunspot’s center, with <jats:italic>v</jats:italic> <jats:sub>ph</jats:sub> = 85.7 km s<jats:sup>−1</jats:sup> in this case. By employing a fit to the absorption spectra at a constant phase speed, we find that the peak absorption strength <jats:inline-formula> <jats:tex-math> <?CDATA ${\alpha }_{\max }$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabf55fieqn1.gif" xlink:type="simple" /> </jats:inline-formula> lies between 0.166 and 0.222 at a noise level of about 0.009 (5%). The well-known absorption along ridges at lower frequencies can reach up to <jats:inline-formula> <jats:tex-math> <?CDATA ${\alpha }_{\max }\approx 0.5$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabf55fieqn2.gif" xlink:type="simple" /> </jats:inline-formula>. Thus our finding in the absorption spectrum is weaker, but nevertheless significant. From first considerations regarding the energy budget of high-frequency waves, this observation can likely be explained by the reduction of emissivity within the sunspot. We derive a simple relation between emissivity and absorption. We conclude that sunspots yield a wave power absorption signature (for certain phase speeds only), which may help in understanding the effect of strong magnetic fields on convection and source excitation and potentially in understanding the general sunspot subsurface structure.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>This paper introduces Subhalo Mass-loss Analysis using Core Catalogs (SMACC). SMACC adds a mass model to substructure merger trees based on halo “core tracking.” Our approach avoids the need for running expensive subhalo finding algorithms and instead uses subhalo mass-loss modeling to assign masses to halo cores. We present details of the SMACC methodology and demonstrate its excellent performance in describing halo substructure and its evolution. Validation of the approach is carried out using cosmological simulations at significantly different resolutions. We apply SMACC to the 1.24-trillion-particle Last Journey simulation and construct core catalogs with the additional mass information. These catalogs can be readily used as input to semianalytic models or subhalo abundance matching approaches to determine approximate galaxy distributions, as well as for in-depth studies of small-scale structure evolution.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In order to connect galaxy clusters to their progenitor protoclusters, we must constrain the star formation histories within their member galaxies and the timescale of virial collapse. In this paper we characterize the complex star-forming properties of a <jats:italic>z</jats:italic> = 2.5 protocluster in the COSMOS field using ALMA dust continuum and new Very Large Array CO (1–0) observations of two filaments associated with the structure, sometimes referred to as the “Hyperion” protocluster. We focus in particular on the protocluster “core,” which has previously been suggested as the highest-redshift bona fide galaxy cluster traced by extended X-ray emission in a stacked Chandra/XMM image. We reanalyze these data and refute these claims, finding that at least 40% ± 17% of extended X-ray sources of similar luminosity and size at this redshift arise instead from inverse Compton scattering off recently extinguished radio galaxies rather than intracluster medium. Using ancillary COSMOS data, we also constrain the spectral energy distributions of the two filaments’ eight constituent galaxies from the rest-frame UV to radio. We do not find evidence for enhanced star formation efficiency in the core and conclude that the constituent galaxies are already massive (<jats:italic>M</jats:italic> <jats:sub>⋆</jats:sub> ≈ 10<jats:sup>11</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>), with molecular gas reservoirs &gt;10<jats:sup>10</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> that will be depleted within 200–400 Myr. Finally, we calculate the halo mass of the nested core at <jats:italic>z</jats:italic> = 2.5 and conclude that it will collapse into a cluster of (2–9) × 10<jats:sup>14</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, comparable to the size of the Coma Cluster at <jats:italic>z</jats:italic> = 0 and accounting for at least 50% of the total estimated halo mass of the extended “Hyperion” structure.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a detailed analysis of the single-slit optical spectrum of the flat-spectrum radio quasar (FSRQ) B2 0003+38A, taken by the Echellette Spectrograph and Imager (ESI) on the Keck II telescope. This classical low-redshift FSRQ (<jats:italic>z</jats:italic> = 0.22911, as measured from the stellar absorption lines) remains underexplored in its emission lines, though its broadband continuum properties from radio to X-ray are well studied. After removing the unresolved quasar nucleus and the starlight from the host galaxy, we obtain a spatially resolved 2D spectrum, which clearly shows three components, indicating a rotating disk, an extended emission-line region (EELR), and an outflow. The bulk of the EELR, with a characteristic mass <jats:italic>M</jats:italic> <jats:sub>EELR</jats:sub> ∼ 10<jats:sup>7</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, and redshifted by <jats:italic>v</jats:italic> <jats:sub>EELR</jats:sub> ≈ 120 km s<jats:sup>−1</jats:sup> with respect to the quasar systemic velocity, shows a one-sided structure stretching to a projected distance of <jats:italic>r</jats:italic> <jats:sub>EELR</jats:sub> ∼ 20 kpc from the nucleus. The rotation curve of the rotating disk is consistent with that of a typical galactic disk, suggesting that the FSRQ is hosted by a disk galaxy. This conclusion is in accordance with the facts that strong absorption in the H <jats:sc>i</jats:sc> 21 cm line was previously observed, and that Na <jats:sc>i</jats:sc> <jats:italic>λ</jats:italic> <jats:italic>λ</jats:italic>5891, 5897 and Ca <jats:sc>ii</jats:sc> <jats:italic>λ</jats:italic> <jats:italic>λ</jats:italic>3934, 3969 doublets are detected in the optical ESI spectrum. B2 0003+38A will become the first FSRQ discovered to be hosted by a gas-rich disk galaxy, if this is confirmed by follow-up deep imaging and/or integral field unit mapping with a high spatial resolution. These observations will also help unravel the origin of the EELR.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Accelerated He<jats:sup>+</jats:sup> pickup ions (PUIs) downstream of quasiperpendicular shocks are studied as a function of the fast-mode Mach number (M<jats:sub>f</jats:sub>) and shock obliquity (<jats:italic>θ</jats:italic> <jats:sub>Bn</jats:sub>). We analyze 10 quasiperpendicular shocks with Mach numbers in the range [1, 7] observed by the Magnetospheric MultiScale (MMS) mission, and compare upstream and downstream He<jats:sup>+</jats:sup> velocity distribution functions. For each shock event, we characterize the upstream PUI distribution and derive reduced 1D velocity distributions for the selected upstream and downstream intervals. We also compare the upstream-to-downstream ratio of spectral indices, computed from the He<jats:sup>+</jats:sup> perpendicular distributions, to M<jats:sub>f</jats:sub> and <jats:italic>θ</jats:italic> <jats:sub>Bn</jats:sub>. We find a positive correlation of this spectral index ratio and M<jats:sub>f</jats:sub>, which suggests that perpendicular energization of He<jats:sup>+</jats:sup> PUIs is enhanced as the shock becomes stronger. These results inform modeling efforts of PUIs and shock-acceleration processes, particularly those taking place at the termination shock.</jats:p>