Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>We investigate how rapid stellar rotation commonly seen in A/F stars can influence planet habitability. Specifically, we model how rapid rotation influences a planet’s irradiation and determine the location of the habitable zone for stars in the mass range 1.3<jats:italic> M</jats:italic> <jats:sub>⊙</jats:sub> ≤ <jats:italic>M</jats:italic> <jats:sub>⋆</jats:sub> ≤ 2.2<jats:italic> M</jats:italic> <jats:sub>⊙</jats:sub>. Rapid stellar rotation can dramatically change a star’s luminosity and spectral energy distribution, and therefore can affect the habitability of any surrounding planets. Stars of mass <jats:italic>M</jats:italic> <jats:sub>⋆</jats:sub> ≳ 1.3 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> commonly rotate near their breakup speeds, which causes two effects relevant to planet habitability. First, these stars flatten into oblate spheroids with shorter polar radii and elongated equatorial radii. Second, rapid rotation induces a pole-to-equator temperature gradient on the surface of these stars. Using a 1D climate model, we calculate the inner and outer edges of the habitable zone of well-known rapid rotators and average theoretical stars in our stellar mass range. We find that, in general, rapid rotation causes the habitable zone to reside closer in than for a nonrotating equivalent star. We also find that gravity darkening dramatically reduces stellar UV emission, which combats the common assumption that high-mass stars emit too much UV light for habitable worlds. Overall, we determine that rapid stellar rotation has important consequences for the overall habitability of a system and must be accounted for both when modeling exoplanet environments and in observation of planets around high-mass stars.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a Monte Carlo–based population synthesis study of fast radio burst (FRB) dispersion and scattering focusing on the first catalog of sources detected with the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) project. We simulate intrinsic properties and propagation effects for a variety of FRB population models and compare the simulated distributions of dispersion measures and scattering timescales with the corresponding distributions from the CHIME/FRB catalog. Our simulations confirm the results of previous population studies, which suggested that the interstellar medium of the host galaxy alone (simulated based on the NE2001 model) cannot explain the observed scattering timescales of FRBs. We therefore consider additional sources of scattering, namely, the circumgalactic medium (CGM) of intervening galaxies and the circumburst medium whose properties are modeled based on typical Galactic plane environments. We find that a population of FRBs with scattering contributed by these media is marginally consistent with the CHIME/FRB catalog. In this scenario, our simulations favor a population of FRBs offset from their galaxy centers over a population that is distributed along the spiral arms. However, if the models proposing the CGM as a source of intense scattering are incorrect, then we conclude that FRBs may inhabit environments with more extreme properties than those inferred for pulsars in the Milky Way.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Ion cyclotron resonance is one of the fundamental energy-conversion processes through field–particle interaction in collisionless plasmas. However, the key evidence for ion cyclotron resonance (i.e., the coherence between electromagnetic fields and the ion phase-space density) and the resulting damping of ion cyclotron waves (ICWs) has not yet been directly observed. Investigating the high-quality measurements of space plasmas by the Magnetospheric Multiscale (MMS) satellites, we find that both the wave electromagnetic field vectors and the bulk velocity of the disturbed ion velocity distribution rotate around the background magnetic field. Moreover, we find that the absolute gyrophase angle difference between the center of the fluctuations in the ion velocity distribution functions and the wave electric field vectors falls in the range of (0, 90)°, consistent with an ongoing energy conversion from wave fields to particles. By invoking plasma kinetic theory, we demonstrate that the field–particle correlation for the damped ICWs in our theoretical model matches well with our observations. Furthermore, the wave electric field vectors (<jats:inline-formula> <jats:tex-math> <?CDATA $\delta {{\boldsymbol{E}}}_{\mathrm{wave},\perp }^{{\prime} }$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>δ</mml:mi> <mml:msubsup> <mml:mrow> <mml:mi mathvariant="bold-italic">E</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>wave</mml:mi> <mml:mo>,</mml:mo> <mml:mo>⊥</mml:mo> </mml:mrow> <mml:mrow> <mml:mo accent="true">′</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac52a9ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>), ion current density (<jats:italic>δ</jats:italic> <jats:bold> <jats:italic>J</jats:italic> </jats:bold> <jats:sub>i,⊥</jats:sub>), and energy transfer rate (<jats:inline-formula> <jats:tex-math> <?CDATA $\delta {{\boldsymbol{J}}}_{{\rm{i}},\perp }\cdot \delta {{\boldsymbol{E}}}_{\mathrm{wave},\perp }^{{\prime} }$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>δ</mml:mi> <mml:msub> <mml:mrow> <mml:mi mathvariant="bold-italic">J</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">i</mml:mi> <mml:mo>,</mml:mo> <mml:mo>⊥</mml:mo> </mml:mrow> </mml:msub> <mml:mo>·</mml:mo> <mml:mi>δ</mml:mi> <mml:msubsup> <mml:mrow> <mml:mi mathvariant="bold-italic">E</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>wave</mml:mi> <mml:mo>,</mml:mo> <mml:mo>⊥</mml:mo> </mml:mrow> <mml:mrow> <mml:mo accent="true">′</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac52a9ieqn2.gif" xlink:type="simple" /> </jats:inline-formula>) exhibit quasiperiodic oscillations, and the integrated work done by the electromagnetic field on the ions is positive, indicating that ions are mainly energized by the perpendicular component of the electric field via cyclotron resonance. Therefore, our combined analysis of MMS observations and kinetic theory provides direct, thorough, and comprehensive evidence for ICW damping in space plasmas.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a new measurement of the Ly<jats:italic>α</jats:italic> luminosity function (LF) at redshift <jats:italic>z</jats:italic> = 6.9, finding moderate evolution from <jats:italic>z</jats:italic> = 5.7 that is consistent with a fully or largely ionized <jats:italic>z</jats:italic> ∼ 7 intergalactic medium. Our result is based on four fields of the LAGER (Lyman Alpha Galaxies in the Epoch of Reionization) project. Our survey volume of 6.1 × 10<jats:sup>6</jats:sup> Mpc<jats:sup>3</jats:sup> is double that of the next largest <jats:italic>z</jats:italic> ∼ 7 survey. We combine two new LAGER fields (WIDE12 and GAMA15A) with two previously reported LAGER fields (COSMOS and CDFS). In the new fields, we identify <jats:italic>N</jats:italic> = 95 new <jats:italic>z</jats:italic> = 6.9 Ly<jats:italic>α</jats:italic> emitter (LAEs) candidates, characterize our survey’s completeness and reliability, and compute Ly<jats:italic>α</jats:italic> LFs. The best-fit Schechter LF parameters for all four LAGER fields are in good general agreement. Two fields (COSMOS and WIDE12) show evidence for a bright-end excess above the Schechter function fit. We find that the Ly<jats:italic>α</jats:italic> luminosity density declines at the same rate as the UV continuum LF from <jats:italic>z</jats:italic> = 5.7 to 6.9. This is consistent with an intergalactic medium that was fully ionized as early as redshift <jats:italic>z</jats:italic> ∼ 7 or with a volume-averaged neutral hydrogen fraction of <jats:italic>x</jats:italic> <jats:sub>H I</jats:sub> &lt; 0.33 at 1<jats:italic>σ</jats:italic>.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We combine the Santa Cruz semianalytic model (SAM) for galaxy formation and evolution with the circumgalactic medium (CGM) model presented in Faerman et al. to explore the CGM properties of <jats:italic>L</jats:italic> <jats:sup>*</jats:sup> galaxies. We use the SAM to generate a sample of galaxies with halo masses similar to the Milky Way (MW) halo, <jats:italic>M</jats:italic> <jats:sub>vir</jats:sub> ≈ 10<jats:sup>12</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, and find that the CGM mass and mean metallicity in the sample are correlated. We use the CGM masses and metallicities of the SAM galaxies as inputs for the FSM20 model and vary the amount of nonthermal support. The density profiles in our models can be approximated by power-law functions with slopes in the range of 0.75 &lt; <jats:italic>a</jats:italic> <jats:sub> <jats:italic>n</jats:italic> </jats:sub> &lt; 1.25, with higher nonthermal pressure resulting in flatter distributions. We explore how the gas pressure, dispersion measure, O <jats:sc>VI</jats:sc>–O <jats:sc>VIII</jats:sc> column densities, and cooling rates behave with the gas distribution and total mass. We show that for CGM masses below ∼3 × 10<jats:sup>10</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> photoionization has a significant effect on the column densities of O <jats:sc>VI</jats:sc> and O <jats:sc>VIII</jats:sc>. The combination of different MW CGM observations favors models with similar fractions in thermal pressure, magnetic fields/cosmic rays, and turbulent support and with <jats:italic>M</jats:italic> <jats:sub>CGM</jats:sub> ∼ (3–10) × 10<jats:sup>10</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>. The MW O <jats:sc>VI</jats:sc> column requires <jats:italic>t</jats:italic> <jats:sub>cool</jats:sub>/<jats:italic>t</jats:italic> <jats:sub>dyn</jats:sub> ∼ 4, independent of the gas distribution. The AGN jet-driven heating rates in the SAM are enough to offset the CGM cooling, although exact balance is not required in star-forming galaxies. We provide predictions for the column densities of additional metal ions—N <jats:sc>V</jats:sc>, Ne <jats:sc>VIII</jats:sc>, and Mg <jats:sc>X</jats:sc>.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Messenger Interface Monte Carlo Mappings V (M<jats:sup>3</jats:sup>) is a photoionization code adopting the fully self-consistent Monte Carlo radiative transfer (MCRT) technique, which presents a major advance over previous photoionization models with simple geometries. M<jats:sup>3</jats:sup> is designed for modeling nebulae in arbitrary three-dimensional geometries. In this paper, we describe the MCRT technique and the microphysics implemented in M<jats:sup>3</jats:sup>, including photoionization, collisional ionization, free–free and free–bound recombination, and two-photon radiation. We put M<jats:sup>3</jats:sup> through the Lexington/Meudon benchmarks to test the reliability of the new code. We apply M<jats:sup>3</jats:sup> to three H <jats:sc>ii</jats:sc> region models with fiducial geometries, demonstrating that M<jats:sup>3</jats:sup> is capable of dealing with nebulae with complex geometries. M<jats:sup>3</jats:sup> is a promising tool for understanding emission-line behavior in the era of SDSS-V/LVM and James Webb Space Telescope, which will provide high-quality data of spatially resolved nearby H <jats:sc>ii</jats:sc> regions and highly turbulent local and high-redshift H <jats:sc>ii</jats:sc> regions.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Low-Frequency Array (LOFAR) Two-meter Sky Survey (LoTSS) is an ongoing survey aiming to observe the entire northern sky, providing an excellent opportunity to study the distribution and evolution of the large-scale structure of the universe. The source catalog from the public LoTSS first data release (DR1) covers 1% of the sky, and shows correlated noise or fluctuations of the flux density calibration on scales of a few degrees. We explore the LoTSS DR1 to understand the survey systematics and data quality of this first data release. We produce catalog mocks to estimate uncertainties, and measure the angular clustering statistics of LoTSS galaxies, which fit the Lambda cold dark matter cosmology reasonably well. We employ a Markov Chain Monte Carlo–based Bayesian analysis to recover the best galaxy biasing scheme and multicomponent source fraction for LoTSS DR1 above 1 mJy assuming different possible redshift templates. After masking some noisy and uneven patches and with suitable flux density cuts, the LOFAR survey appears qualified for large-scale cosmological studies. The upcoming data releases from LOFAR are expected to be deeper and wider, and will therefore provide improved cosmological measurements.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Sub-Neptunes (planets with radii between 2 and 4 <jats:italic>R</jats:italic> <jats:sub>⊕</jats:sub>) are abundant around M-dwarf stars, yet the atmospheric dynamics of these planets is relatively unexplored. In this paper, we aim to provide a basic underpinning of the dry dynamics of general low-mean-molecular-weight, temperate sub-Neptune atmospheres. We use the ExoFMS general circulation model (GCM) with an idealized gray-gas radiation scheme to simulate planetary atmospheres with different levels of instellation and rotation rates, using the atmosphere of K2-18b as our control. We find that the atmospheres of tidally locked (TL), temperate sub-Neptunes have weak horizontal temperature gradients owing to their slow rotation rates and hydrogen-dominated composition. The zonal wind structure is dominated by high-latitude cyclostrophic jets driven by the conservation of angular momentum. At low pressures we observe superrotating equatorial jets, which we propose are driven by a Rossby–Kelvin instability similar to the type seen in simulations of idealized atmospheres with axisymmetric forcing. By viewing the flow in TL coordinates, we find the predominant overturning circulation to be between the day side and night side, and we derive scaling relations linking the TL stream function and vertical velocities to instellation. Comparing our results to the only other GCM study of K2-18b, we find significant qualitative differences in dynamics, highlighting the need for further collaboration and investigation into the effects of different dynamical cores and physical parameterizations. This paper provides a baseline for studying the dry dynamics of temperate sub-Neptunes, which will be built on in part II with the introduction of moist effects.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>New X-ray and optical observations shed light on the remarkable X-ray filament of the gamma-ray pulsar PSR J2030+4415. Images of the associated H<jats:italic>α</jats:italic> bow shock’s evolution over the past decade compared with its velocity structure provide an improved kinematic distance of ∼0.5 kpc. These velocities also imply that the pulsar spin axis lies ∼15° from the proper motion axis, which is close to the plane of the sky. The multi-bubble shock structure indicates that the bow shock standoff was compressed to a small value ∼20–30 yr ago when the pulsar broke through the bow shock to its present bubble. This compression allowed multi-TeV pulsar <jats:italic>e</jats:italic> <jats:sup>±</jats:sup> to escape to the external interstellar medium (ISM), lighting up an external magnetic field structure as the filament. The narrow filament indicates excellent initial confinement and the full 15′ (2.2 pc = 7 lt-yr) projected length of the filament indicates rapid <jats:italic>e</jats:italic> <jats:sup>±</jats:sup> propagation to its end. Spectral variation along the filament suggests that the injected particle energy evolved during the breakthrough event.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present the results of a Very Large Array H <jats:sc>i</jats:sc> imaging survey aimed at understanding why some galaxies develop long extraplanar H<jats:italic>α</jats:italic> tails, becoming extreme jellyfish galaxies. The observations are centered on five extreme jellyfish galaxies optically selected from the WINGS and OMEGAWINGS surveys and confirmed to have long H<jats:italic>α</jats:italic> tails through MUSE observations. Each galaxy is located in a different cluster. In the observations, there are in total 88 other spiral galaxies within the field of view (40′ × 40′) and observed bandwidth (6500 km s<jats:sup>−1</jats:sup>). We detect 13 of these 88 spirals, plus one uncataloged spiral, with H <jats:sc>i</jats:sc> masses ranging from 1 to 7 × 10<jats:sup>9</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>. Many of these detections have extended H <jats:sc>i</jats:sc> disks, two show direct evidence for ram pressure stripping, and others are possibly affected by tidal forces and/or ram pressure stripping. We stack the 75 nondetected spiral galaxies and find an average H <jats:sc>i</jats:sc> mass of 1.9 × 10<jats:sup>8</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, which, given their average stellar mass, implies that they are very H <jats:sc>i</jats:sc> deficient. Comparing the extreme jellyfish galaxies to the other disk galaxies, we find that they are at smaller projected distance from the cluster center, and have a higher stellar mass and higher relative velocity than all other H <jats:sc>i</jats:sc> detections and most nondetections. We conclude that the high stellar mass allows extreme jellyfish galaxies to fall deeply into the cluster before being stripped, and the surrounding ICM pressure gives rise to their spectacular star-forming tails.</jats:p>