Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>The shocked solar wind flows around the Earth’s magnetosphere in the magnetosheath downstream of the Earth’s bow shock. Within this region, faster flows of plasma, called magnetosheath jets, are frequently observed. These jets have been shown to sometimes exhibit supermagnetosonic speeds relative to the magnetosheath flow and to develop bow waves or shocks of their own. Such jet-driven bow waves have been observed to accelerate ions and electrons. We model electron acceleration by magnetosheath jet-driven bow waves using test-particle Monte Carlo simulations. Our simulations suggest that the energy increase of electrons with energies of a few hundred eV to 10 keV can be explained by a collapsing magnetic trap forming between the bow wave and the magnetopause with shock drift acceleration at the moving bow wave. Our simulations allow us to estimate the efficiency of acceleration as a function of different jet and magnetosheath parameters. Electron acceleration by jet-driven bow waves can increase the total acceleration in the parent shock environment, most likely also at shocks other than the Earth’s bow shock.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present Hubble Space Telescope WFC3/UVIS (F275W, F336W) and ACS/WFC optical (F435W, F555W, and F814W) observations of the nearby grand-design spiral galaxy M101 as part of the Legacy Extragalactic UV Survey (LEGUS). Compact sources detected in at least four bands were classified by both human experts and the convolutional neural network S<jats:sc>tarc</jats:sc>N<jats:sc>et</jats:sc>. Human experts classified the 2351 brightest sources, retrieving <jats:italic>N</jats:italic> <jats:sub> <jats:italic>c</jats:italic> </jats:sub> = 965 star clusters. S<jats:sc>tarc</jats:sc>N<jats:sc>et</jats:sc>, trained on LEGUS data not including M101, classified all 4725 sources detected in four bands, retrieving <jats:italic>N</jats:italic> <jats:sub> <jats:italic>c</jats:italic> </jats:sub> = 2270 star clusters. The combined catalog represents the most complete census to date of compact star clusters in M101. We find that for the 2351 sources with both a visual- and machine-learning classification S<jats:sc>tarc</jats:sc>N<jats:sc>et</jats:sc> is able to reproduce the human classifications at high levels of accuracy (∼80%–90%), which is equivalent to the level of agreement between human classifiers in LEGUS. The derived cluster age distribution implies a disruption rate of <jats:inline-formula> <jats:tex-math> <?CDATA ${dN}/d\tau \propto {\tau }^{-0.45\pm 0.14}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="italic">dN</mml:mi> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:mi>d</mml:mi> <mml:mi>τ</mml:mi> <mml:mo>∝</mml:mo> <mml:msup> <mml:mrow> <mml:mi>τ</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.45</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.14</mml:mn> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac7c07ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> over 10<jats:sup>7</jats:sup> &lt; <jats:italic>τ</jats:italic> &lt; 10<jats:sup>8.5</jats:sup> yr for cluster masses ≥10<jats:sup>3.55</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> for the central region of M101 and <jats:inline-formula> <jats:tex-math> <?CDATA ${dN}/d\tau \propto {\tau }^{-0.02\pm 0.15}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="italic">dN</mml:mi> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:mi>d</mml:mi> <mml:mi>τ</mml:mi> <mml:mo>∝</mml:mo> <mml:msup> <mml:mrow> <mml:mi>τ</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.02</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.15</mml:mn> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac7c07ieqn2.gif" xlink:type="simple" /> </jats:inline-formula> for cluster masses ≥10<jats:sup>3.38</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> in the northwest region of the galaxy. The trends we recover are weaker than those of other nearby spirals (e.g., M51) and starbursts, consistent with the M101 environment having a lower-density interstellar medium, and providing evidence in favor of environmentally dependent cluster disruption in the central, southeast, and northwest regions of M101.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We develop the power spectral density (PSD) model to explain the nature of the X-ray variability in IRAS 13224–3809, including the full effects of the X-ray reverberation due to the lamppost source. We utilize 16 XMM-Newton observations individually as well as group them into three different luminosity bins: low, medium, and high. The soft (0.3–1 keV) and hard (1.2–5 keV) PSD spectra are extracted and simultaneously fitted with the model. We find that the corona height changes from <jats:italic>h</jats:italic> ∼ 3 <jats:italic>r</jats:italic> <jats:sub>g</jats:sub> during the lowest luminosity state to ∼25 <jats:italic>r</jats:italic> <jats:sub>g</jats:sub> during the highest luminosity state. This provides further evidence that the source height from the reverberation data is significantly larger than what is constrained by the spectral analysis. Furthermore, as the corona height increases, the energy spectrum tends to be softer while the observed fractional excess variance, <jats:italic>F</jats:italic> <jats:sub>var</jats:sub>, reduces. We find that the PSD normalization is strongly correlated with <jats:italic>F</jats:italic> <jats:sub>var</jats:sub> and moderately correlated with the PSD bending index. Therefore, the normalization is dependent on the accretion rate that controls the intrinsic shape of the PSD. While the intrinsic variability of the disk is manifested by the reverberation signals, the disk and corona may evolve independently. Our results suggest that, as the source height increases, the disk itself generates less overall variability power but more high-frequency variability resulting in the PSD spectrum that flattens out (i.e., the inner disk becomes more active). Using the luminosity-bin data, the hint of the Lorentzian component is seen, with the peak appearing at lower frequencies with increasing luminosity.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Astropy Project supports and fosters the development of open-source and openly developed <jats:monospace>Python</jats:monospace> packages that provide commonly needed functionality to the astronomical community. A key element of the Astropy Project is the core package <jats:monospace>astropy</jats:monospace>, which serves as the foundation for more specialized projects and packages. In this article, we summarize key features in the core package as of the recent major release, version 5.0, and provide major updates on the Project. We then discuss supporting a broader ecosystem of interoperable packages, including connections with several astronomical observatories and missions. We also revisit the future outlook of the Astropy Project and the current status of Learn Astropy. We conclude by raising and discussing the current and future challenges facing the Project.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report spectroscopic confirmations of 15 Ly<jats:italic>α</jats:italic> galaxies at <jats:italic>z</jats:italic> ∼ 7, implying a spectroscopic confirmation rate of ∼80% on candidates selected from the Ly<jats:italic>α</jats:italic> Galaxies in the Epoch of Reionization (LAGER), which is the largest (24 deg<jats:sup>2</jats:sup>) survey aimed at finding Ly<jats:italic>α</jats:italic> emitters (LAEs) at <jats:italic>z</jats:italic> ∼ 7 and uses deep narrowband imaging from the Dark Energy Camera at CTIO. LAEs at high redshifts are sensitive probes of cosmic reionization, and narrowband imaging is a robust and effective method for selecting a large number of LAEs. In this work, we present results from the spectroscopic follow-up of LAE candidates in two LAGER fields, COSMOS and WIDE-12, using observations from Keck/LRIS. We report the successful detection of Ly<jats:italic>α</jats:italic> emission in 15 candidates. Three of these in COSMOS have matching confirmations from a previous spectroscopic follow-up and are part of the overdense region, LAGER-<jats:italic>z</jats:italic>7OD1. Two other candidates that were not detected with LRIS have prior spectroscopic confirmations from Magellan. Including these, we obtain a spectroscopic confirmation success rate of ∼80% for LAGER LAE candidates. Thorough checks were performed to reject the possibility of these detections being foreground emission resulting with a probability of, at most, one contaminant. We do not detect any other UV nebular lines in our LRIS spectra, apart from Ly<jats:italic>α</jats:italic>. We estimate a 2<jats:italic>σ</jats:italic> upper limit for the ratio of N <jats:sc>v</jats:sc>/Ly<jats:italic>α</jats:italic>, <jats:italic>f</jats:italic> <jats:sub>NV</jats:sub>/<jats:italic>f</jats:italic> <jats:sub>Ly<jats:italic>α</jats:italic> </jats:sub> ≲ 0.27. Including confirmations from this work, a total of 33 LAE sources from LAGER are now spectroscopically confirmed. LAGER has more than doubled the sample of spectroscopically confirmed LAE sources at <jats:italic>z</jats:italic> ∼ 7.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Thin synchrotron-emitting filaments are increasingly seen in the intracluster medium (ICM). We present the first example of a direct interaction between a magnetic filament, a radio jet, and a dense ICM clump in the poor cluster A194. This enables the first exploration of the dynamics and possible histories of magnetic fields and cosmic rays in such filaments. Our observations are from the MeerKAT Galaxy Cluster Legacy Survey and the LOFAR Two-Meter Sky Survey. Prominent 220 kpc long filaments extend east of radio galaxy 3C40B, with very faint extensions to 300 kpc, and show signs of interaction with its northern jet. They curve around a bend in the jet and intersect the jet in Faraday depth space. The X-ray surface brightness drops across the filaments; this suggests that the relativistic particles and fields contribute significantly to the pressure balance and evacuate the thermal plasma in a ∼35 kpc cylinder. We explore whether the relativistic electrons could have streamed along the filaments from 3C40B, and present a plausible alternative whereby magnetized filaments are (a) generated by shear motions in the large-scale, post-merger ICM flow, (b) stretched by interactions with the jet and flows in the ICM, amplifying the embedded magnetic fields, and (c) perfused by re-energized relativistic electrons through betatron-type acceleration or diffusion of turbulently accelerated ICM cosmic-ray electrons. We use the Faraday depth measurements to reconstruct some of the 3D structures of the filameGnts and of 3C40A and B.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a reanalysis of reverberation mapping data from 2005 for the Seyfert galaxy NGC 4151, supplemented with additional data from the literature to constrain the continuum variations over a significantly longer baseline than the original monitoring program. Modeling of the continuum light curve and the velocity-resolved variations across the H<jats:italic>β</jats:italic> emission line constrains the geometry and kinematics of the broad line region (BLR). The BLR is well described by a very thick disk with similar opening angle (<jats:italic>θ</jats:italic> <jats:sub> <jats:italic>o</jats:italic> </jats:sub> ≈ 57°) and inclination angle (<jats:italic>θ</jats:italic> <jats:sub> <jats:italic>i</jats:italic> </jats:sub> ≈ 58°), suggesting that our sight line toward the innermost central engine skims just above the surface of the BLR. The inclination is consistent with constraints from geometric modeling of the narrow-line region, and the similarity between the inclination and opening angles is intriguing given previous studies of NGC 4151 that suggest BLR gas has been observed temporarily eclipsing the X-ray source. The BLR kinematics are dominated by eccentric bound orbits, with ∼10% of the orbits preferring near-circular motions. With the BLR geometry and kinematics constrained, the models provide an independent and direct black hole mass measurement of <jats:inline-formula> <jats:tex-math> <?CDATA $\mathrm{log}{M}_{\mathrm{BH}}/{M}_{\odot }={7.22}_{-0.10}^{+0.11}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>BH</mml:mi> </mml:mrow> </mml:msub> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>7.22</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.10</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.11</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac7c0aieqn1.gif" xlink:type="simple" /> </jats:inline-formula> or <jats:inline-formula> <jats:tex-math> <?CDATA ${M}_{\mathrm{BH}}={1.66}_{-0.34}^{+0.48}\times {10}^{7}$?> </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>BH</mml:mi> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>1.66</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.34</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.48</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo>×</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>7</mml:mn> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac7c0aieqn2.gif" xlink:type="simple" /> </jats:inline-formula> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, which is in good agreement with mass measurements from stellar dynamical modeling and gas dynamical modeling. NGC 4151 is one of the few nearby broad-lined Seyferts where the black hole mass may be measured via multiple independent techniques, and it provides an important test case for investigating potential systematics that could affect the black hole mass scales used in the local universe and for high-redshift quasars.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Magnetic holes are plasma structures that trap a large number of particles in a magnetic field that is weaker than the field in its surroundings. The unprecedented high time-resolution observations by NASA’s Magnetospheric Multiscale Mission enable us to study the particle dynamics in magnetic holes in the Earth’s magnetosheath in great detail. We reveal the local generation mechanism of whistler waves by a combination of Landau-resonant and cyclotron-resonant wave–particle interactions of electrons in response to the large-scale evolution of a magnetic hole. As the magnetic hole converges, a pair of counter-streaming electron beams form near the hole’s center as a consequence of the combined action of betatron and Fermi effects. The beams trigger the generation of slightly oblique whistler waves. Our conceptual prediction is supported by a remarkable agreement between our observations and numerical predictions from the Arbitrary Linear Plasma Solver. Our study shows that wave–particle interactions are fundamental to the evolution of magnetic holes in space and astrophysical plasmas.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a detailed weak-lensing and X-ray study of the Frontier Fields galaxy cluster Abell 370, one of the most massive known lenses on the sky, using wide-field <jats:italic>BR</jats:italic> <jats:sub>C</jats:sub> <jats:italic>z</jats:italic>′ Subaru/Suprime-Cam and Chandra X-ray observations. By combining two-dimensional (2D) shear and azimuthally averaged magnification constraints derived from Subaru data, we perform a lensing mass reconstruction in a free-form manner, which allows us to determine both the radial structure and 2D morphology of the cluster mass distribution. In a triaxial framework assuming a Navarro–Frenk–White density profile, we constrain the intrinsic structure and geometry of the cluster halo by forward modeling the reconstructed mass map. We obtain a halo mass <jats:italic>M</jats:italic> <jats:sub>200</jats:sub> = (1.54 ± 0.29) ×10<jats:sup>15</jats:sup> <jats:italic>h</jats:italic> <jats:sup>−1</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, a halo concentration <jats:italic>c</jats:italic> <jats:sub>200</jats:sub> = 5.27 ± 1.28, and a minor–major axis ratio <jats:italic>q</jats:italic> <jats:sub> <jats:italic>a</jats:italic> </jats:sub> = 0.62 ± 0.23 with uninformative priors. Using a prior on the line-of-sight alignment of the halo major axis derived from binary merger simulations constrained by multi-probe observations, we find that the data favor a more prolate geometry with lower mass and lower concentration. From triaxial lens modeling with the line-of-sight prior, we find a spherically enclosed gas mass fraction of <jats:italic>f</jats:italic> <jats:sub>gas</jats:sub> = (8.4 ± 1.0)% at 0.7 <jats:italic>h</jats:italic> <jats:sup>−1</jats:sup> Mpc ∼ 0.7<jats:italic>r</jats:italic> <jats:sub>500</jats:sub>. When compared to the hydrostatic mass estimate (<jats:italic>M</jats:italic> <jats:sub>HE</jats:sub>) from Chandra observations, our triaxial weak-lensing analysis yields spherically enclosed mass ratios of 1 − <jats:italic>b</jats:italic> ≡ <jats:italic>M</jats:italic> <jats:sub>HE</jats:sub>/<jats:italic>M</jats:italic> <jats:sub>WL</jats:sub> = 0.56 ± 0.09 and 0.51 ± 0.09 at 0.7 <jats:italic>h</jats:italic> <jats:sup>−1</jats:sup> Mpc with and without using the line-of-sight prior, respectively. Since the cluster is in a highly disturbed dynamical state, this represents the likely maximum level of hydrostatic bias in galaxy clusters.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present high-resolution, high-sensitivity upgraded Giant Metrewave Radio Telescope observations of the Coma cluster (A1656) at 250–500 MHz and 550–850 MHz. At 250–500 MHz, 135 sources have extensions &gt;0.′45 (with peak-to-local-noise ratio &gt;4). Of these, 24 sources are associated with Coma-member galaxies. In addition, we supplement this sample of 24 galaxies with 20 ram pressure stripped (RPS) galaxies from (Chen et al. 2020, eight are included in the original extended radio source sample) and an additional five are detected and extended. We present radio morphologies, radio spectra, spectral index maps, and equipartition properties for these two samples. In general, we find the equipartition properties lie within a narrow range (e.g., <jats:inline-formula> <jats:tex-math> <?CDATA ${P}_{\min }$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>P</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>min</mml:mi> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac7a9bieqn1.gif" xlink:type="simple" /> </jats:inline-formula> = 1–3 × 10<jats:sup>−</jats:sup> <jats:sup>13 </jats:sup>dynes cm<jats:sup>−2</jats:sup>). Only NGC 4874, one of the two brightest central Coma cluster galaxies, has a central energy density and pressure about five times higher and a radio source age about 50% lower than that of the other Coma galaxies. We find a diffuse tail of radio emission trailing the dominant galaxy of the merging NGC 4839 group that coincides with the <jats:italic>slingshot</jats:italic> tail seen in X-rays. The southwestern radio relic, B1253+275, has a large extent ≈32′ × 10′ (≃1.08 × 0.34 Mpc<jats:sup>2</jats:sup>). For NGC 4789, whose long radio tails merge into the relic and may be a source of its relativistic seed electrons, we find a transverse radio spectral gradient, a steepening from southwest to northeast across the width of the radio source. Finally, radio morphologies of the extended and RPS samples suggest that these galaxies are on their first infall into Coma on (predominantly) radial orbits.</jats:p>