Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>Using the CoDa II simulation, we study the Ly<jats:italic>α</jats:italic> transmissivity of the intergalactic medium (IGM) during reionization. At <jats:italic>z</jats:italic> &gt; 6, a typical galaxy without an active galactic nucleus fails to form a proximity zone around itself due to the overdensity of the surrounding IGM. The gravitational infall motion in the IGM makes the resonance absorption extend to the red side of Ly<jats:italic>α</jats:italic>, suppressing the transmission up to roughly the circular velocity of the galaxy. In some sight lines, an optically thin blob generated by a supernova in a neighboring galaxy results in a peak feature, which can be mistaken for a blue peak. Redward of the resonance absorption, the damping-wing opacity correlates with the global IGM neutral fraction and the UV magnitude of the source galaxy. Brighter galaxies tend to suffer lower opacity because they tend to reside in larger H <jats:sc>ii</jats:sc> regions, and the surrounding IGM transmits redder photons, which are less susceptible to attenuation, owing to stronger infall velocity. The H <jats:sc>ii</jats:sc> regions are highly nonspherical, causing both sight-line-to-sight-line and galaxy-to-galaxy variation in opacity. Also, self-shielded systems within H <jats:sc>ii</jats:sc> regions strongly attenuate the emission for certain sight lines. All these factors add to the transmissivity variation, requiring a large sample size to constrain the average transmission. The variation is largest for fainter galaxies at higher redshift. The 68% range of the transmissivity is similar to or greater than the median for galaxies with <jats:italic>M</jats:italic> <jats:sub>UV</jats:sub> ≥ −21 at <jats:italic>z</jats:italic> ≥ 7, implying that more than a hundred galaxies would be needed to measure the transmission to 10% accuracy.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We have observed a sample of nine Extended Green Objects (EGOs) at 1.3 and 5 cm with the Very Large Array (VLA) with subarcsecond resolution and ∼7–14 <jats:italic>μ</jats:italic>Jy beam<jats:sup>−1</jats:sup>-sensitivities in order to characterize centimeter continuum emission as it first appears in these massive protoclusters. We find an EGO-associated continu um emission—within 1″ of the extended 4.5 <jats:italic>μ</jats:italic>m emission—in every field, which is typically faint (order 10<jats:sup>1</jats:sup>–10<jats:sup>2</jats:sup> <jats:italic>μ</jats:italic>Jy) and compact (unresolved at 0″.3–0″.5). The derived spectral indices of our 36 total detections are consistent with a wide array of physical processes, including both non-thermal (19% of detections) and thermal free–free processes (e.g., ionized jets and compact H <jats:sc>ii</jats:sc> regions, 78% of sample) and warm dust (1 source). We also find an EGO-associated 6.7 GHz CH<jats:sub>3</jats:sub>OH and 22 GHz H<jats:sub>2</jats:sub>O maser emission in 100% of the sample and a NH<jats:sub>3</jats:sub> (3,3) masers in ∼45%; we do not detect any NH<jats:sub>3</jats:sub> (6,6) masers at ∼5.6 mJy beam<jats:sup>−1</jats:sup> sensitivity. We find statistically-significant correlations between <jats:italic>L</jats:italic> <jats:sub>radio</jats:sub> and <jats:italic>L</jats:italic> <jats:sub>bol</jats:sub> at two physical scales and three frequencies, consistent with thermal emission from ionized jets, but no correlation between <jats:inline-formula> <jats:tex-math> <?CDATA ${L}_{{{\rm{H}}}_{2}{\rm{O}}}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">H</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> <mml:mi mathvariant="normal">O</mml:mi> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac2c86ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> and <jats:italic>L</jats:italic> <jats:sub>radio</jats:sub> for our sample. From these data, we conclude that EGOs likely host multiple different centimeter continuum-producing processes simultaneously. Additionally, at our ∼1000 au resolution, we find that all EGOs except G18.89−0.47 contain 1 ∼ 2 massive sources based on the presence of CH<jats:sub>3</jats:sub>OH maser groups, which is consistent with our previous work suggesting that these are typical massive protoclusters, in which only one to a few of the young stellar objects are massive.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Recent gamma-ray observations have revealed inhomogeneous diffusion of cosmic rays (CRs) in the interstellar medium (ISM). This is expected, as the diffusion of CRs depends on the properties of turbulence, which can vary widely in the multiphase ISM. We focus on the mirror diffusion arising in highly compressible turbulence in molecular clouds (MCs) around supernova remnants (SNRs), where the magnetic mirroring effect results in significant suppression of diffusion of CRs near CR sources. Significant energy loss via proton–proton interactions due to slow diffusion flattens the low-energy CR spectrum, while the high-energy CR spectrum is steepened due to the strong dependence of mirror diffusion on CR energy. The resulting broken power-law spectrum of CRs matches well the gamma-ray spectrum observed from SNR/MC systems, e.g., IC443 and W44.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present an update of the open-source photochemical kinetics code VULCAN to include C–H–N–O–S networks and photochemistry. The additional new features are advection transport, condensation, various boundary conditions, and temperature-dependent UV cross sections. First, we validate our photochemical model for hot Jupiter atmospheres by performing an intercomparison of HD 189733b models between Moses et al., Venot et al., and VULCAN, to diagnose possible sources of discrepancy. Second, we set up a model of Jupiter extending from the deep troposphere to upper stratosphere to verify the kinetics for low temperature. Our model reproduces hydrocarbons consistent with observations, and the condensation scheme successfully predicts the locations of water and ammonia ice clouds. We show that vertical advection can regulate the local ammonia distribution in the deep atmosphere. Third, we validate the model for oxidizing atmospheres by simulating Earth and find agreement with observations. Last, VULCAN is applied to four representative cases of extrasolar giant planets: WASP-33b, HD 189733b, GJ 436b, and 51 Eridani b. We look into the effects of the C/O ratio and chemistry of titanium/vanadium species for WASP-33b, we revisit HD 189733b for the effects of sulfur and carbon condensation, the effects of internal heating and vertical mixing (<jats:italic>K</jats:italic> <jats:sub>zz</jats:sub>) are explored for GJ 436b, and we test updated planetary properties for 51 Eridani b with S<jats:sub>8</jats:sub> condensates. We find that sulfur can couple to carbon or nitrogen and impact other species, such as hydrogen, methane, and ammonia. The observable features of the synthetic spectra and trends in the photochemical haze precursors are discussed for each case.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The distribution of ejecta in young supernova remnants offers a powerful observational probe of their explosions and progenitors. Here we present a 3D reconstruction of the ejecta in SNR 0540-69.3, which is an O-rich remnant with a pulsar wind nebula located in the LMC. We use observations from the Very Large Telescope (VLT)/MUSE to study H<jats:italic>β</jats:italic>, [O <jats:sc>iii</jats:sc>] <jats:italic>λ</jats:italic> <jats:italic>λ</jats:italic>4959, 5007, H<jats:italic>α</jats:italic>, [S <jats:sc>ii</jats:sc>] <jats:italic>λ</jats:italic> <jats:italic>λ</jats:italic>6717, 6731, [Ar <jats:sc>iii</jats:sc>] <jats:italic>λ</jats:italic>7136, and [S <jats:sc>iii</jats:sc>] <jats:italic>λ</jats:italic>9069. This is complemented by 2D spectra from VLT/X-shooter, which also cover [O <jats:sc>ii</jats:sc>] <jats:italic>λ</jats:italic> <jats:italic>λ</jats:italic>3726, 3729, and [Fe <jats:sc>ii</jats:sc>] <jats:italic>λ</jats:italic>12567. We identify three main emission components: (i) clumpy rings in the inner nebula (≲1000 km s<jats:sup>−1</jats:sup>) with similar morphologies in all lines; (ii) faint extended [O <jats:sc>iii</jats:sc>] emission dominated by an irregular ring-like structure with radius ∼1600 km s<jats:sup>−1</jats:sup> and inclination ∼40°, but with maximal velocities reaching ∼3000 km s<jats:sup>−1</jats:sup>; and (iii) a blob of H<jats:italic>α</jats:italic> and H<jats:italic>β</jats:italic> located southeast of the pulsar at velocities ∼1500–3500 km s<jats:sup>−1</jats:sup>. We analyze the geometry using a clump-finding algorithm and use the clumps in the [O <jats:sc>iii</jats:sc>] ring to estimate an age of 1146 ± 116 yr. The observations favor an interpretation of the [O <jats:sc>iii</jats:sc>] ring as ejecta, while the origin of the H-blob is more uncertain. An alternative explanation is that it is the blown-off envelope of a binary companion. From the detection of Balmer lines in the innermost ejecta we confirm that SNR 0540 was a Type II supernova and that hydrogen was mixed down to low velocities in the explosion.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>A spectral-energy distribution (SED) model for Type Ia supernovae (SNe Ia) is a critical tool for measuring precise and accurate distances across a large redshift range and constraining cosmological parameters. We present an improved model framework, SALT3, which has several advantages over current models—including the leading SALT2 model (SALT2.4). While SALT3 has a similar philosophy, it differs from SALT2 by having improved estimation of uncertainties, better separation of color and light-curve stretch, and a publicly available training code. We present the application of our training method on a cross-calibrated compilation of 1083 SNe with 1207 spectra. Our compilation is 2.5× larger than the SALT2 training sample and has greatly reduced calibration uncertainties. The resulting trained SALT3.K21 model has an extended wavelength range 2000–11,000 Å (1800 Å redder) and reduced uncertainties compared to SALT2, enabling accurate use of low-<jats:italic>z I</jats:italic> and <jats:italic>iz</jats:italic> photometric bands. Including these previously discarded bands, SALT3.K21 reduces the Hubble scatter of the low-<jats:italic>z</jats:italic> Foundation and CfA3 samples by 15% and 10%, respectively. To check for potential systematic uncertainties, we compare distances of low (0.01 &lt; <jats:italic>z</jats:italic> &lt; 0.2) and high (0.4 &lt; <jats:italic>z</jats:italic> &lt; 0.6) redshift SNe in the training compilation, finding an insignificant 3 ± 14 mmag shift between SALT2.4 and SALT3.K21. While the SALT3.K21 model was trained on optical data, our method can be used to build a model for rest-frame NIR samples from the Roman Space Telescope. Our open-source training code, public training data, model, and documentation are available at <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="https://saltshaker.readthedocs.io/en/latest/" xlink:type="simple">https://saltshaker.readthedocs.io/en/latest/</jats:ext-link>, and the model is integrated into the <jats:monospace>sncosmo</jats:monospace> and <jats:monospace>SNANA</jats:monospace> software packages.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We investigate the nonradial oscillations of newly born neutron stars (NSs) and strange quark stars (SQSs). This is done with the relativistic nuclear field theory with hyperon degrees of freedom employed to describe the equation of state (EoS) for the stellar matter in NSs, and with both the MIT bag model and the Nambu–Jona-Lasinio model adopted to construct the configurations of the SQSs. We find that the gravitational-mode (<jats:italic>g</jats:italic>-mode) eigenfrequencies of newly born SQSs are significantly lower than those of NSs, which is independent of models implemented to describe the EoS for the strange quark matter. Meanwhile, the eigenfrequencies of the other modes of nonradial oscillations, e.g., fundamental (<jats:italic>f</jats:italic>)- and pressure (<jats:italic>p</jats:italic>)-modes, are much larger than those of the <jats:italic>g</jats:italic>-mode, and are related to the stiffness of the EoSs. In light of the first direct observation of gravitational waves (GWs), it is promising to employ GWs to identify the QCD phase transition in high-density strong-interaction matter.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We introduce a novel method for reconstructing the projected matter distributions of galaxy clusters with weak-lensing (WL) data based on a convolutional neural network (CNN). Training data sets are generated with ray-tracing through cosmological simulations. We control the noise level of the galaxy shear catalog such that it mimics the typical properties of the existing ground-based WL observations of galaxy clusters. We find that the mass reconstruction by our multilayered CNN with the architecture of alternating convolution and trans-convolution filters significantly outperforms the traditional reconstruction methods. The CNN method provides better pixel-to-pixel correlations with the truth, restores more accurate positions of the mass peaks, and more efficiently suppresses artifacts near the field edges. In addition, the CNN mass reconstruction lifts the mass-sheet degeneracy when applied to our projected cluster mass estimation from sufficiently large fields. This implies that this CNN algorithm can be used to measure the cluster masses in a model-independent way for future wide-field WL surveys.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The structure of a dwarf galaxy is an important probe of the effects of stellar feedback and environment. Using an unprecedented sample of 223 low-mass satellites from the ongoing Exploration of Local Volume Satellites survey, we explore the structures of dwarf satellites in the mass range 10<jats:sup>5.5</jats:sup> &lt; <jats:italic>M</jats:italic> <jats:sub>⋆</jats:sub> &lt; 10<jats:sup>8.5</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>. We survey satellites around 80% of the massive, <jats:italic>M</jats:italic> <jats:sub> <jats:italic>K</jats:italic> </jats:sub> &lt; − 22.4 mag, hosts in the Local Volume (LV). Our sample of dwarf satellites is complete to luminosities of <jats:italic>M</jats:italic> <jats:sub>V</jats:sub> &lt;−9 mag and surface brightness <jats:italic>μ</jats:italic> <jats:sub>0,<jats:italic>V</jats:italic> </jats:sub> &lt; 26.5 mag arcsec<jats:sup>−2</jats:sup> within at least ∼200 projected kpc of the hosts. For this sample, we find a median satellite luminosity of <jats:italic>M</jats:italic> <jats:sub> <jats:italic>V</jats:italic> </jats:sub> = −12.4 mag, median size of <jats:italic>r</jats:italic> <jats:sub> <jats:italic>e</jats:italic> </jats:sub> = 560 pc, median ellipticity of <jats:italic>ϵ</jats:italic> = 0.30, and median Sérsic index of <jats:italic>n</jats:italic> = 0.72. We separate the satellites into late- and early-type (29.6% and 70.4%, respectively). The mass–size relations are very similar between them within ∼5%, which indicates that the quenching and transformation of a late-type dwarf into an early-type one involves only very mild size evolution. Considering the distribution of apparent ellipticities, we infer the intrinsic shapes of the early- and late-type samples. Combining with literature samples, we find that both types of dwarfs are described roughly as oblate spheroids that get more spherical at fainter luminosities, but early-types are always rounder at fixed luminosity. Finally, we compare the LV satellites with dwarf samples from the cores of the Virgo and Fornax clusters. We find that the cluster satellites show similar scaling relations to the LV early-type dwarfs but are roughly 10% larger at fixed mass, which we interpret as being due to tidal heating in the cluster environments. The dwarf structure results presented here are a useful reference for simulations of dwarf galaxy formation and the transformation of dwarf irregulars into spheroidals.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The ejecta velocities of Type Ia supernovae (SNe Ia), as measured by the Si <jats:sc>ii</jats:sc> <jats:italic>λ</jats:italic>6355 line, have been shown to correlate with other supernova properties, including color and standardized luminosity. We investigate these results using the Foundation Supernova Survey, with a spectroscopic data release presented here, and photometry analyzed with the SALT2 light-curve fitter. We find that the Foundation data do not show significant evidence for an offset in color between SNe Ia with high and normal photospheric velocities, with Δ<jats:italic>c</jats:italic> = 0.004 ± 0.015. Our SALT2 analysis does show evidence for redder high-velocity SNe Ia in other samples, including objects from the Carnegie Supernova Project, with a combined sample yielding Δ<jats:italic>c</jats:italic> = 0.018 ± 0.008. When split on velocity, the Foundation SNe Ia also do not show a significant difference in Hubble diagram residual, Δ<jats:italic>HR</jats:italic> = 0.015 ± 0.049 mag. Intriguingly, we find that SN Ia ejecta velocity information may be gleaned from photometry, particularly in redder optical bands. For high-redshift SNe Ia, these rest-frame red wavelengths will be observed by the Nancy Grace Roman Space Telescope. Our results are in line with previous work that suggests SN Ia host-galaxy stellar mass is correlated with ejecta velocity: high-velocity SNe Ia are found nearly exclusively in high-stellar-mass hosts. However, host-galaxy properties alone do not explain velocity-dependent differences in supernova colors and luminosities across samples. Measuring and understanding the connection between intrinsic explosion properties and supernova environments, across cosmic time, will be important for precision cosmology with SNe Ia.</jats:p>