Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>Type Ia supernovae (SNe Ia) may originate from a wide variety of explosion scenarios and progenitor channels. They exhibit a factor of ≈10 difference in brightness and thus a differentiation in the mass of <jats:sup>56</jats:sup>Ni → <jats:sup>56</jats:sup>Co → <jats:sup>56</jats:sup>Fe. We present a study on the fate of positrons within SNe Ia in order to evaluate their escape fractions and energy spectra. Our detailed Monte Carlo transport simulations for positrons and <jats:italic>γ</jats:italic>-rays include both <jats:italic>β</jats:italic> <jats:sup>+</jats:sup> decay of <jats:sup>56</jats:sup>Co and pair production. We simulate a wide variety of explosion scenarios, including the explosion of white dwarfs (WDs) close to the Chandrasekhar mass (<jats:italic>M</jats:italic> <jats:sub>Ch</jats:sub>), He-triggered explosions of sub-<jats:italic>M</jats:italic> <jats:sub>Ch</jats:sub> WDs, and dynamical mergers of two WDs. For each model, we study the influence of the size and morphology of the progenitor magnetic field between 1 and 10<jats:sup>13</jats:sup> G. Population synthesis based on the observed brightness distribution of SNe Ia was used to estimate the overall contributions to Galactic positrons due to escape from SNe Ia. We find that this is dominated by SNe Ia of normal brightness, where variations in the distribution of emitted positrons are small. We estimate a total SNe Ia contribution to Galactic positrons of &lt;2% and, depending on the magnetic field morphology, &lt;6–20% for <jats:italic>M</jats:italic> <jats:sub>Ch</jats:sub> and sub-<jats:italic>M</jats:italic> <jats:sub>Ch</jats:sub>, respectively.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Observations and numerical simulations have shown that outflows generally exist in the accretion process. We revisit the thermal equilibrium solutions of black hole accretion flows by including the role of outflows. Our study focuses on the comparison of the cooling rate of outflows with that of advection. Our results show that, except for the inner region, outflows can dominate over advection in a wide range of flows, which is in good agreement with previous numerical simulations. We argue that an advection-dominated inner region together with an outflow-dominated outer region should be a general radial distribution for both super-Eddington accretion flows and optically thin flows with low accretion rates.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Ly<jats:italic>α</jats:italic> tomography surveys have begun to produce 3D maps of the intergalactic medium opacity at <jats:italic>z</jats:italic> ∼ 2.5 with megaparsec resolution. These surveys provide an exciting new way to discover and characterize high-redshift overdensities, including the progenitors of today’s massive groups and clusters of galaxies, known as protogroups and protoclusters. We use the IllustrisTNG-300 hydrodynamical simulation to build mock maps that realistically mimic those observed in the Ly<jats:italic>α</jats:italic> Tomographic IMACS Survey. We introduce a novel method for delineating the boundaries of structures detected in 3D Ly<jats:italic>α</jats:italic> flux maps by applying the watershed algorithm. We provide estimators for the dark matter masses of these structures (at <jats:italic>z</jats:italic> ∼ 2.5), their descendant halo masses at <jats:italic>z</jats:italic> = 0, and the corresponding uncertainties. We also investigate the completeness of this method for the detection of protogroups and protoclusters. Compared to earlier work, we apply and characterize our method over a wider mass range that extends to massive protogroups. We also assess the widely used fluctuating Gunn–Peterson approximation applied to dark-matter-only simulations; we conclude that while it is adequate for estimating the Ly<jats:italic>α</jats:italic> absorption signal from moderate-to-massive protoclusters (≳10<jats:sup>14.2</jats:sup> <jats:italic>h</jats:italic> <jats:sup>−1</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>), it artificially merges a minority of lower-mass structures with more massive neighbors. Our methods will be applied to current and future Ly<jats:italic>α</jats:italic> tomography surveys to create catalogs of overdensities and study environment-dependent galactic evolution in the Cosmic Noon era.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Low luminosity active galactic nuclei (LLAGN) probe accretion physics in the low Eddington regime can provide additional clues about galaxy evolution. AGN variability is ubiquitous and thus provides a reliable tool for finding AGN. We analyze the All-Sky Automated Survey for SuperNovae light curves of 1218 galaxies with <jats:italic>g</jats:italic> &lt; 14 mag and Sloan Digital Sky Survey spectra in search of AGN. We find 37 objects that are both variable and have AGN-like structure functions, which is about 3% of the sample. The majority of the variability selected AGN are LLAGN with Eddington ratios ranging from 10<jats:sup>−4</jats:sup> to 10<jats:sup>−2</jats:sup>. We thus estimate the fraction of LLAGN in the population of galaxies as 2% down to a median Eddington ratio of 2 × 10<jats:sup>−3</jats:sup>. Combining the BPT line ratio AGN diagnostics and the broad-line AGN, up to ∼60% of the AGN candidates are confirmed spectroscopically. The BPT diagnostics also classified 10%–30% of the candidates as star-forming galaxies rather than AGN.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The development of perturbations in the circumstellar disks of pre-main-sequence stars caused by clumpy accretion was investigated. Here we perform 3D smoothed particle hydrodynamics simulations of disks perturbed by a recent clump accretion event. These simulations are further explored by radiative transfer calculations to quantify the observational appearance of such disks. It was shown that the density waves in the disks were formed at the fall of the clump. After several revolutions they can transform into spirals and ring structures. Their images in millimeter wavelengths are very similar to those observed with Atacama Large Millimeter/submillimeter Array in some protoplanetary disks. We assume that clumpy accretion may be the source of such structures.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Based on the MWISP survey, we study high-<jats:italic>z</jats:italic> CO emission toward the tangent points, in which the distances of the molecular clouds (MCs) are well determined. In the region of <jats:italic>l</jats:italic> = 12°–26° and ∣<jats:italic>b</jats:italic>∣ ≲ 5.°1, a total of 321 MCs with ∣<jats:italic>z</jats:italic>∣ ≳ 110 pc are identified, of which nearly 30 extreme high-<jats:italic>z</jats:italic> MCs (EHMCs at ∣<jats:italic>z</jats:italic>∣ ≳ 260 pc) are concentrated in a narrow region of <jats:italic>R</jats:italic> <jats:sub>GC</jats:sub> ∼ 2.6–3.1 kpc. The EHMC concentrations, together with other high-<jats:italic>z</jats:italic> MCs at <jats:italic>R</jats:italic> <jats:sub>GC</jats:sub> ≲ 2.3–2.6 kpc, constitute molecular crater-wall structures surrounding the edges of the H <jats:sc>i</jats:sc> voids that are physically associated with the Fermi bubbles. Intriguingly, some large high-<jats:italic>z</jats:italic> MCs, which lie in the crater walls above and below the Galactic plane, show cometary structures with the head toward the plane, favoring the scenario that the entrained molecular gas moves with the multiphase flows from the plane to the high-<jats:italic>z</jats:italic> regions. We suggest that the Milky Way nuclear wind has a significant impact on the Galactic gaseous disk. The powerful nuclear wind at ∼3–6 Myr ago is likely responsible for the observational features: (1) the enhanced CO gas lying in the edges of the H <jats:sc>i</jats:sc> voids, (2) the deficiency of atomic and molecular gas within <jats:italic>R</jats:italic> <jats:sub>GC</jats:sub> ≲ 3 kpc, (3) the possible connection between the EHMC concentrations and the 3 kpc arm, and (4) the elongated high-<jats:italic>z</jats:italic> MCs with the tail pointing away from the Galactic plane.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We explore the possibility of detecting baryon acoustic oscillations (BAO) solely from gravitational wave (GW) observations of binary neutron star mergers with third-generation (3G) GW detectors such as the Cosmic Explorer and the Einstein Telescope. These measurements would provide a new independent probe of cosmology. The detection of the BAO peak with current-generation GW detectors (solely from GW observations) is not possible because i) unlike galaxies, the GW mergers are poorly localized, and ii) there are not enough merger events to probe the BAO length scale. With the 3G GW detector network, it is possible to observe <jats:inline-formula> <jats:tex-math> <?CDATA $\sim { \mathcal O }(1000)$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>∼</mml:mo> <mml:mi mathvariant="italic"></mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:mn>1000</mml:mn> <mml:mo stretchy="false">)</mml:mo> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac5e34ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> binary neutron star mergers per year that are localized well within one square degree in the sky for redshift <jats:italic>z</jats:italic> ≤ 0.3. We show that 3G observatories will enable precision measurements of the BAO feature in the large-scale two-point correlation function; the effect of BAO can be independently detected at different redshifts, with a log-evidence ratio of ∼23, 17, or 3, favoring a model with a BAO peak at redshift of 0.2, 0.25, or 0.3, respectively, using a redshift bin corresponding to a shell of thickness 150<jats:italic>h</jats:italic> <jats:sup>−1</jats:sup> Mpc.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>High-mass stars play an important role in the interstellar medium, but much remains to be known about their formation. Class I methanol masers may be unique tracers of an early stage of high-mass star formation, and a better understanding of such masers will allow them to be used as more effective probes of the high-mass star-forming process. We present an investigation of the long-term variability of Class I methanol masers at 44 GHz toward the high-mass star-forming region DR21(OH). We compare observations taken in 2017 to observations from 2012, and also to 2001 data from the literature. A total of 57 maser spots were found in the 2017 data, with center velocities ranging between −8.65 to +2.56 km s<jats:sup>−1</jats:sup>. The masers are arranged in a western and an eastern lobe with two arcs in each lobe that look like bow shocks, consistent with previous observations. The general trend is an increase in intensity from 2001 to 2012, and a decrease from 2012 to 2017. Variability appears to be more prevalent in the inner arc of the western lobe than in the outer arc. We speculate that this may be a consequence of episodic accretion, in which a later accretion event has resulted in ejection of material whose shock reached the inner arc at some point in time after 2001. We conclude that class I methanol masers are variable on long timescales (of the order of 5–10 yr).</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We train convolutional neural networks to correct the output of fast and approximate <jats:italic>N</jats:italic>-body simulations at the field level. Our model, Neural Enhanced COLA (NECOLA), takes as input a snapshot generated by the computationally efficient COLA code and corrects the positions of the cold dark matter particles to match the results of full <jats:italic>N</jats:italic>-body Quijote simulations. We quantify the accuracy of the network using several summary statistics, and find that NECOLA can reproduce the results of the full <jats:italic>N</jats:italic>-body simulations with subpercent accuracy down to <jats:italic>k</jats:italic> ≃ 1 <jats:italic>h</jats:italic>Mpc<jats:sup>−1</jats:sup>. Furthermore, the model that was trained on simulations with a fixed value of the cosmological parameters is also able to correct the output of COLA simulations with different values of Ω<jats:sub>m</jats:sub>, Ω<jats:sub>b</jats:sub>, <jats:italic>h</jats:italic>, <jats:italic>n</jats:italic> <jats:sub> <jats:italic>s</jats:italic> </jats:sub>, <jats:italic>σ</jats:italic> <jats:sub>8</jats:sub>, <jats:italic>w</jats:italic>, and <jats:italic>M</jats:italic> <jats:sub> <jats:italic>ν</jats:italic> </jats:sub> with very high accuracy: the power spectrum and the cross-correlation coefficients are within ≃1% down to <jats:italic>k</jats:italic> = 1 <jats:italic>h</jats:italic>Mpc<jats:sup>−1</jats:sup>. Our results indicate that the correction to the power spectrum from fast/approximate simulations or field-level perturbation theory is rather universal. Our model represents a first step toward the development of a fast field-level emulator to sample not only primordial mode amplitudes and phases, but also the parameter space defined by the values of the cosmological parameters.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present the detection of a broad 8 <jats:italic>μ</jats:italic>m feature in newly formed dust around the carbon-rich Wolf-Rayet (WC) binary WR 125 from <jats:italic>N</jats:italic>-band low-resolution (NL; <jats:italic>R</jats:italic> ∼ 250) spectroscopy between 7.3 and 13.6 <jats:italic>μ</jats:italic>m and <jats:italic>N</jats:italic>-band (11.7 <jats:italic>μ</jats:italic>m) and <jats:italic>Q</jats:italic>-band (18.8 <jats:italic>μ</jats:italic>m) imaging with Subaru/COMICS in 2019 October. WR 125 is a colliding-wind binary (WC7 + O9) that exhibited renewed dust formation starting in 2018, ∼28 yr after its first dust formation episode had been observed. We also compare our infrared photometry with historical observations and revise the dust formation period of WR 125 to 28.1 yr. Archival infrared spectra of five dusty WC stars, WR 48a, WR 98a, WR 104, WR 112, and WR 118, obtained with Infrared Space Observatory/Short-Wavelength Spectrometer are reanalyzed and compared with the WR 125 spectrum to search for a similar feature. We analyze the dusty WC spectra using two different extinction curves to investigate the impact of interstellar extinction correction on the presence and/or properties of the 8 <jats:italic>μ</jats:italic>m feature. All of the dusty WC spectra dereddened with the two different extinction curves show a broad feature around 8 <jats:italic>μ</jats:italic>m (FWHM ∼ 1–2 <jats:italic>μ</jats:italic>m). We suggest that these 8 <jats:italic>μ</jats:italic>m features seen in the dusty WC spectra are related to the Class C unidentified infrared features.</jats:p>