Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>We present photometric and spectroscopic observations of Supernova 2020oi (SN 2020oi), a nearby (∼17 Mpc) type-Ic supernova (SN Ic) within the grand-design spiral M100. We undertake a comprehensive analysis to characterize the evolution of SN 2020oi and constrain its progenitor system. We detect flux in excess of the fireball rise model <jats:italic>δ</jats:italic> <jats:italic>t</jats:italic> ≈ 2.5 days from the date of explosion in multiband optical and UV photometry from the Las Cumbres Observatory and the Neil Gehrels Swift Observatory, respectively. The derived SN bolometric luminosity is consistent with an explosion with <jats:italic>M</jats:italic> <jats:sub>ej</jats:sub> = 0.81 ± 0.03 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, <jats:italic>E</jats:italic> <jats:sub> <jats:italic>k</jats:italic> </jats:sub> = 0.79 ± 0.09 × 10<jats:sup>51</jats:sup> erg s<jats:sup>−1</jats:sup>, and <jats:italic>M</jats:italic> <jats:sub>Ni56</jats:sub> = 0.08 ± 0.02 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>. Inspection of the event’s decline reveals the highest Δ<jats:italic>m</jats:italic> <jats:sub>15,bol</jats:sub> reported for a stripped-envelope event to date. Modeling of optical spectra near event peak indicates a partially mixed ejecta comparable in composition to the ejecta observed in SN 1994I, while the earliest spectrum shows signatures of a possible interaction with material of a distinct composition surrounding the SN progenitor. Further, Hubble Space Telescope pre-explosion imaging reveals a stellar cluster coincident with the event. From the cluster photometry, we derive the mass and age of the SN progenitor using stellar evolution models implemented in the <jats:monospace>BPASS</jats:monospace> library. Our results indicate that SN 2020oi occurred in a binary system from a progenitor of mass <jats:italic>M</jats:italic> <jats:sub>ZAMS</jats:sub> ≈ 9.5 ± 1.0 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, corresponding to an age of 27 ± 7 Myr. SN 2020oi is the dimmest SN Ic event to date for which an early-time flux excess has been observed, and the first in which an early excess is unlikely to be associated with shock cooling.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>To investigate the origins of the warm absorbers in active galactic nuclei (AGNs), we study the ionization-state structure of the radiation-driven fountain model in a low-mass AGN and calculate the predicted X-ray spectra utilizing the spectral synthesis code <jats:sans-serif>Cloudy</jats:sans-serif>. The spectra show many absorption and emission line features originating in the outflowing ionized gas. The O <jats:sc>viii</jats:sc> 0.654 keV lines are produced mainly in the polar region much closer to the supermassive black hole than the optical narrow-line regions. The absorption measure distribution of the ionization parameter (<jats:italic>ξ</jats:italic>) at a low inclination spreads over 4 orders of magnitude in <jats:italic>ξ</jats:italic>, indicating the multiphase ionization structure of the outflow, as actually observed in many type 1 AGNs. We compare our simulated spectra with the high energy resolution spectrum of the narrow-line Seyfert 1 galaxy NGC 4051. The model reproduces slowly outflowing (a few hundred kilometers per second) warm absorbers. However, the faster components with a few thousand kilometers per second observed in NGC 4051 are not reproduced. The simulation also underproduces the intensity and width of the O <jats:sc>viii</jats:sc> 0.654 keV line. These results suggest that the ionized gas launched from subparsec or smaller regions inside the torus, which is not included in the current fountain model, must be an important ingredient of the warm absorbers with a few thousand kilometers per second. The model also consistently explains the Chandra/HETG spectrum of the Seyfert 2 galaxy Circinus.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>This is the first paper in a series aimed at modeling the black hole (BH) mass function, from the stellar to the intermediate to the (super)massive regime. In the present work, we focus on stellar BHs and provide an ab initio computation of their mass function across cosmic times; we mainly consider the standard, and likely dominant, production channel of stellar-mass BHs constituted by isolated single/binary star evolution. Specifically, we exploit the state-of-the-art stellar and binary evolutionary code <jats:monospace>SEVN</jats:monospace>, and couple its outputs with redshift-dependent galaxy statistics and empirical scaling relations involving galaxy metallicity, star formation rate and stellar mass. The resulting relic mass function <jats:inline-formula> <jats:tex-math> <?CDATA ${dN}/{dVd}\mathrm{log}\,{m}_{\bullet }$?> </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 mathvariant="italic">dVd</mml:mi> <mml:mi>log</mml:mi> <mml:mspace width="0.25em" /> <mml:msub> <mml:mrow> <mml:mi>m</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>•</mml:mo> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac34fbieqn1.gif" xlink:type="simple" /> </jats:inline-formula> as a function of the BH mass <jats:italic>m</jats:italic> <jats:sub>•</jats:sub> features a rather flat shape up to <jats:italic>m</jats:italic> <jats:sub>•</jats:sub> ≈ 50 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> and then a log-normal decline for larger masses, while its overall normalization at a given mass increases with decreasing redshift. We highlight the contribution to the local mass function from isolated stars evolving into BHs and from binary stellar systems ending up in single or binary BHs. We also include the distortion on the mass function induced by binary BH mergers, finding that it has a minor effect at the high-mass end. We estimate a local stellar BH relic mass density of <jats:italic>ρ</jats:italic> <jats:sub>•</jats:sub> ≈ 5 × 10<jats:sup>7</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> Mpc<jats:sup>−3</jats:sup>, which exceeds by more than two orders of magnitude that in supermassive BHs; this translates into an energy density parameter Ω<jats:sub>•</jats:sub> ≈ 4 × 10<jats:sup>−4</jats:sup>, implying that the total mass in stellar BHs amounts to ≲1% of the local baryonic matter. We show how our mass function for merging BH binaries compares with the recent estimates from gravitational wave observations by LIGO/Virgo, and discuss the possible implications for dynamical formation of BH binaries in dense environments like star clusters. We address the impact of adopting different binary stellar evolution codes (<jats:monospace>SEVN</jats:monospace> and <jats:monospace>COSMIC</jats:monospace>) on the mass function, and find the main differences to occur at the high-mass end, in connection with the numerical treatment of stellar binary evolution effects. We highlight that our results can provide a firm theoretical basis for a physically motivated light seed distribution at high redshift, to be implemented in semi-analytic and numerical models of BH formation and evolution. Finally, we stress that the present work can constitute a starting point to investigate the origin of heavy seeds and the growth of (super)massive BHs in high-redshift star-forming galaxies, that we will pursue in forthcoming papers.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Short-lived radioactive nuclei (half-life <jats:italic>τ</jats:italic> <jats:sub>1/2</jats:sub> ∼ 1 Myr) influence the formation of stars and planetary systems by providing sources of heating and ionization. Whereas many previous studies have focused on the possible nuclear enrichment of our own solar system, the goal of this paper is to estimate the distributions of short-lived radionuclides (SLRs) for the entire population of stars forming within a molecular cloud. Here we focus on the nuclear species <jats:sup>60</jats:sup>Fe and <jats:sup>26</jats:sup>Al, which have the largest impact due to their relatively high abundances. We construct molecular-cloud models and include nuclear contributions from both supernovae and stellar winds. The resulting distributions of SLRs are time dependent with widths of ∼3 orders of magnitude and mass fractions <jats:italic>ρ</jats:italic> <jats:sub>SLR</jats:sub>/<jats:italic>ρ</jats:italic> <jats:sub>*</jats:sub> ∼ 10<jats:sup>−11</jats:sup>–10<jats:sup>−8</jats:sup>. Over the range of scenarios explored herein, the SLR distributions show only modest variations with the choice of cloud structure (fractal dimension), star formation history, and cluster distribution. The most important variation arises from the diffusion length scale for the transport of SLRs within the cloud. The expected SLR distributions are wide enough to include values inferred for the abundances in our solar system, although most of the stars are predicted to have smaller enrichment levels. In addition, the ratio of <jats:sup>60</jats:sup>Fe/<jats:sup>26</jats:sup>Al is predicted to be greater than unity, on average, in contrast to solar system results. One explanation for this finding is the presence of an additional source for the <jats:sup>26</jats:sup>Al isotope.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The broad high-energy spectral component in blazars is usually attributed to various inverse Compton scattering processes in the relativistic jet, but has not been clearly identified in most cases due to degeneracies in physical models. AP Librae, a low-synchrotron-peaking BL Lac object (LBL) detected in 2015 by H.E.S.S. at very high energies (VHE; &gt;0.5 TeV), has an extremely broad high-energy spectrum, covering ∼9 decades in energy. Standard synchrotron self-Compton models generally fail to reproduce the VHE emission, which has led to the suggestion that it might arise not from the blazar core, but on kiloparsec scales from inverse Compton (IC) scattering of cosmic microwave background (CMB) photons by a still-relativistic jet (IC/CMB). IC/CMB models for the TeV emission of AP Librae in prior works have implied a high level of infrared emission from the kiloparsec-scale jet. With newly obtained Hubble Space Telescope (HST) imaging, we obtain a deep upper limit on the kiloparsec-scale jet emission at 1.6 <jats:italic>μ</jats:italic>m, well below the expected level. High-resolution Atacama Large Millimeter/submillimeter Array imaging in bands 3–9 reveals a residual dust-disk signature after core subtraction, with a clearly thermal spectrum, and an extent (∼500 pc) that matches with a nonjet residual emission seen after point-spread function subtraction in our 1.6 <jats:italic>μ</jats:italic>m HST imaging. We find that the unusually broad GeV and VHE emission in AP Librae can be reproduced through the combined IC scattering of photons from the CMB and the dust disk, respectively, by electrons in both the blazar core and subkiloparsec jet.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>This work presents the first steps to modeling synthetic rovibrational spectra for all molecules of astrophysical interest using a new approach implemented in the Prometheus code. The goal is to create a new comprehensive source of first-principles molecular spectra, thus bridging the gap for missing data to help drive future high-resolution studies. Our primary application domain is for molecules identified as signatures of life in planetary atmospheres (biosignatures), but our approach is general and can be applied to other systems. In this work we evaluate the accuracy of our method by studying four diatomic molecules, H<jats:sub>2</jats:sub>, O<jats:sub>2</jats:sub>, N<jats:sub>2</jats:sub>, and CO, all of which have well-known spectra. Prometheus uses the transition-optimised shifted Hermite (TOSH) theory to account for anharmonicity for the fundamental <jats:italic>ν</jats:italic> = 0 → <jats:italic>ν</jats:italic> = 1 band, along with thermal-profile modeling for the rotational transitions. To this end, we expand TOSH theory to enable the modeling of rotational constants. We show that our simple model achieves results that are a better approximation of the real spectra than those produced through an harmonic approach. We compare our results with high-resolution HITRAN and ExoMol spectral data. We find that modeling accuracy tends to diminish for rovibrational transition away from the band origin, thus highlighting the need for the theory to be further adapted.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present the statistical analysis of the spectral response of solar radio type III bursts over the wide frequency range between 20 kHz and 410 MHz. For this purpose, we have used observations that were carried out using both spaced-based (Wind/Waves) and ground-based (Nançay Decameter Array and Nançay Radioheliograph) facilities. In order to compare the flux densities observed by the different instruments, we have carefully calibrated the data and displayed them in solar flux units. The main result of our study is that type III bursts, in the metric to hectometric wavelength range, statistically exhibit a clear maximum of their median radio flux density around 2 MHz. Although this result was already reported by inspecting the spectral profiles of type III bursts in the frequency range 20 kHz–20 MHz, our study extends such analysis for the first time to metric radio frequencies (i.e., from 20 kHz to 410 MHz) and confirms the maximum spectral response around 2 MHz. In addition, using a simple empirical model we show that the median radio flux <jats:italic>S</jats:italic> of the studied data set obeys the polynomial form <jats:italic>Y</jats:italic> = 0.04<jats:italic>X</jats:italic> <jats:sup>3</jats:sup> − 1.63<jats:italic>X</jats:italic> <jats:sup>2</jats:sup> + 16.30<jats:italic>X</jats:italic> − 41.24, with <jats:inline-formula> <jats:tex-math> <?CDATA $X=\mathrm{ln}({F}_{\mathrm{MHz}})$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>X</mml:mi> <mml:mo>=</mml:mo> <mml:mi>ln</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:msub> <mml:mrow> <mml:mi>F</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>MHz</mml:mi> </mml:mrow> </mml:msub> <mml:mo stretchy="false">)</mml:mo> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac34edieqn1.gif" xlink:type="simple" /> </jats:inline-formula> and with <jats:inline-formula> <jats:tex-math> <?CDATA $Y=\mathrm{ln}({S}_{\mathrm{SFU}})$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>Y</mml:mi> <mml:mo>=</mml:mo> <mml:mi>ln</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:msub> <mml:mrow> <mml:mi>S</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>SFU</mml:mi> </mml:mrow> </mml:msub> <mml:mo stretchy="false">)</mml:mo> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac34edieqn2.gif" xlink:type="simple" /> </jats:inline-formula>. Using the Sittler and Guhathakurtha model for coronal streamers, we have found that the maximum of radio power therefore falls in the range 4 to 10 <jats:italic>R</jats:italic> <jats:sub>⊙</jats:sub>, depending on whether the type III emissions are assumed to be at the fundamental or the harmonic.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present <jats:monospace>nimbus</jats:monospace>: a hierarchical Bayesian framework to infer the intrinsic luminosity parameters of kilonovae (KNe) associated with gravitational-wave (GW) events, based purely on nondetections. This framework makes use of GW 3D distance information and electromagnetic upper limits from multiple surveys for multiple events and self-consistently accounts for the finite sky coverage and probability of astrophysical origin. The framework is agnostic to the brightness evolution assumed and can account for multiple electromagnetic passbands simultaneously. Our analyses highlight the importance of accounting for model selection effects, especially in the context of nondetections. We show our methodology using a simple, two-parameter linear brightness model, taking the follow-up of GW190425 with the Zwicky Transient Facility as a single-event test case for two different prior choices of model parameters: (i) uniform/uninformative priors and (ii) astrophysical priors based on surrogate models of Monte Carlo radiative-transfer simulations of KNe. We present results under the assumption that the KN is within the searched region to demonstrate functionality and the importance of prior choice. Our results show consistency with <jats:monospace>simsurvey</jats:monospace>—an astronomical survey simulation tool used previously in the literature to constrain the population of KNe. While our results based on uniform priors strongly constrain the parameter space, those based on astrophysical priors are largely uninformative, highlighting the need for deeper constraints. Future studies with multiple events having electromagnetic follow-up from multiple surveys should make it possible to constrain the KN population further.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In this paper, a novel bimodal model to predict a complete sunspot cycle based on comprehensive precursor information is proposed. We compare the traditional 13 month moving average with the Gaussian filter and find that the latter has less missing information and can better describe the overall trend of the raw data. Unlike the previous models that usually only use one precursor, here we combine the implicit and geometric information of the solar cycle (peak and skewness of the previous cycle and start value of the predicted cycle) with the traditional precursor method based on the geomagnetic index and adopt a multivariate linear approach with a higher goodness of fit (&gt;0.85) in the fitting. Verifications for cycles 22–24 demonstrate that the model has good performance in predicting the peak and peak occurrence time. It also successfully predicts the complete bimodal structure for cycle 22 and cycle 24, showing a certain ability to predict whether the next solar cycle is unimodal or bimodal. It shows that cycle 25 is a single-peak structure and that the peak will come in 2024 October with a peak of 145.3.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Molecular emission was imaged with ALMA from numerous components near and within bright H<jats:sub>2</jats:sub>-emitting knots and absorbing dust globules in the Crab Nebula. These observations provide a critical test of how energetic photons and particles produced in a young supernova remnant interact with gas, cleanly differentiating between competing models. The four fields targeted show contrasting properties but within them, seventeen distinct molecular clouds are identified with CO emission; a few also show emission from HCO<jats:sup>+</jats:sup>, SiO, and/or SO. These observations are compared with Cloudy models of these knots. It has been suggested that the Crab filaments present an exotic environment in which H<jats:sub>2</jats:sub> emission comes from a mostly neutral zone probably heated by cosmic rays produced in the supernova surrounding a cool core of molecular gas. Our model is consistent with the observed CO <jats:italic>J</jats:italic> = 3 − 2 line strength. These molecular line emitting knots in the Crab Nebula present a novel phase of the ISM representative of many important astrophysical environments.</jats:p>