Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>We perform one-dimensional radiation-hydrodynamic simulations of energetic supernova (SN) ejecta colliding with a massive circumstellar medium (CSM) aimed at explaining SN 2016aps, likely the brightest SN observed to date. SN 2016aps was a superluminous Type IIn SN, which released as much as <jats:inline-formula> <jats:tex-math> <?CDATA $\gtrsim 5\times {10}^{51}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabd6ceieqn1.gif" xlink:type="simple" /> </jats:inline-formula> erg of thermal radiation. Our results suggest that the multiband light curve of SN 2016aps is well explained by the collision of a <jats:inline-formula> <jats:tex-math> <?CDATA $30\,{M}_{\odot }$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabd6ceieqn2.gif" xlink:type="simple" /> </jats:inline-formula> SN ejecta with the explosion energy of 10<jats:sup>52</jats:sup> erg and a <jats:inline-formula> <jats:tex-math> <?CDATA $\simeq 8\,{M}_{\odot }$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabd6ceieqn3.gif" xlink:type="simple" /> </jats:inline-formula> wind-like CSM with the outer radius of 10<jats:sup>16</jats:sup> cm, that is, a hypernova explosion embedded in a massive CSM. This finding indicates that very massive stars with initial masses larger than <jats:inline-formula> <jats:tex-math> <?CDATA $40\,{M}_{\odot }$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabd6ceieqn4.gif" xlink:type="simple" /> </jats:inline-formula>, which supposedly produce highly energetic SNe, occasionally eject their hydrogen-rich envelopes shortly before the core collapse. We suggest that the pulsational pair-instability SNe may provide a natural explanation for the massive CSM and the energetic explosion. We also provide the relations among the peak luminosity, the radiated energy and the rise time for interacting SNe with the kinetic energy of 10<jats:sup>52</jats:sup> erg, which can be used for interpreting SN 2016aps–like objects in future surveys.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We have carried out observations of CCH (<jats:italic>N</jats:italic> = 1 − 0), CH<jats:sub>3</jats:sub>CN (<jats:italic>J</jats:italic> = 5 − 4), and three <jats:sup>13</jats:sup>C isotopologues of HC<jats:sub>3</jats:sub>N (<jats:italic>J</jats:italic> = 10 − 9) toward three massive young stellar objects (MYSOs), G12.89+0.49, G16.86−2.16, and G28.28−0.36, with the Nobeyama 45 m radio telescope. Combined with previous results on HC<jats:sub>5</jats:sub>N, the column density ratios of <jats:italic>N</jats:italic>(CCH)/<jats:italic>N</jats:italic>(HC<jats:sub>5</jats:sub>N), hereafter the CCH/HC<jats:sub>5</jats:sub>N ratios, in the MYSOs are derived to be ∼15. This value is lower than that in a low-mass warm carbon chain chemistry (WCCC) source by more than one order of magnitude. We compare the observed CCH/HC<jats:sub>5</jats:sub>N ratios with hot-core model calculations. The observed ratios in the MYSOs can be best reproduced by models when the gas temperature is ∼85 K, which is higher than in L1527, a low-mass WCCC source (∼35 K). These results suggest that carbon-chain molecules detected around the MYSOs exist at least partially in higher temperature regions than those in low-mass WCCC sources. There is no significant difference in column density among the three <jats:sup>13</jats:sup>C isotopologues of HC<jats:sub>3</jats:sub>N in G12.89+0.49 and G16.86-2.16, while HCC<jats:sup>13</jats:sup>CN is more abundant than the others in G28.28–0.36. We discuss carbon-chain chemistry around the three MYSOs based on the CCH/HC<jats:sub>5</jats:sub>N ratio and the <jats:sup>13</jats:sup>C isotopic fractionation of HC<jats:sub>3</jats:sub>N.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Using a general circulation model (GCM), we investigate trends in simulated hot Jupiter atmospheres for a range of irradiation temperatures (1500–4000 K), surface gravities (10 and 40 m s<jats:sup>−2</jats:sup>), and cloud conditions. Our models include simplified temperature-dependent clouds with radiative feedback and show how different cloud compositions, vertical thicknesses, and opacities shape hot Jupiter atmospheres by potentially increasing planetary albedos, decreasing photospheric pressures and nightside temperatures, and in some cases producing strong dayside thermal inversions. With decreasing irradiation, clouds progressively form on the nightside and cooler western limb, followed by the eastern limb and central dayside. We find that clouds significantly modify the radiative transport and affect the observable properties of planets colder than <jats:italic>T</jats:italic> <jats:sub>irr</jats:sub> ≈ 3000 K (<jats:italic>T</jats:italic> <jats:sub>eq</jats:sub> ≈ 2100 K) depending on the clouds’ vertical extent. The precise strength of expected effects depends on the assumed parameters, but trends in predicted phase curves emerge from an ensemble of simulations. Clouds lead to larger phase-curve amplitudes and smaller phase-curve offsets at IR wavelengths, compared to cloud-free models. At optical wavelengths, we predict mostly westward phase-curve offsets at intermediate temperatures (<jats:italic>T</jats:italic> <jats:sub>irr</jats:sub> ≈ 2000–3500 K) with clouds confined to the nightside and western limb. If clouds are vertically compact (i.e., on the order of a pressure scale height in thickness), their distributions and effects become more complicated as different condensates form at different heights—some too deep to significantly affect the observable atmosphere. Our results have implications for interpreting the diversity of phase-curve observations of planets with <jats:italic>T</jats:italic> <jats:sub>irr</jats:sub> ≲ 3000 K.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>This is the second paper of a series devoted to presenting an updated release of the BaSTI (a Bag of Stellar Tracks and Isochrones) stellar model and isochrone library. Following the publication of the updated solar-scaled library, here we present the library for an <jats:italic>α</jats:italic>-enhanced heavy element distribution. These new <jats:italic>α</jats:italic>-enhanced models account for all improvements and updates in the reference solar metal distribution and physics inputs, as in the new solar-scaled library. The models cover a mass range between 0.1 and 15 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, 18 metallicities between [Fe/H] = −3.20 and +0.06 with [<jats:italic>α</jats:italic>/Fe] = +0.4, and a He-to-metal enrichment ratio Δ<jats:italic>Y</jats:italic>/Δ<jats:italic>Z</jats:italic> = 1.31. For each metallicity, He-enhanced stellar models are also provided. The isochrones cover (typically) an age range between 20 Myr and 14.5 Gyr, including consistently the pre-main-sequence phase. The asteroseismic properties of the theoretical models have also been calculated. Models and isochrones have been compared with results from independent calculations, with the previous BaSTI release, and also with selected observations, to test the accuracy/reliability of these new calculations. All stellar evolution tracks, asteroseismic properties, and isochrones are publicly available at <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://basti-iac.oa-teramo.inaf.it" xlink:type="simple">http://basti-iac.oa-teramo.inaf.it</jats:ext-link>.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present the discovery of a low-redshift damped Ly<jats:italic>α</jats:italic> (DLA) system in the spectrum of background starburst galaxy SDSS J111323.88+293039.3 (<jats:italic>z</jats:italic> = 0.17514). The DLA is at an impact parameter of <jats:italic>ρ</jats:italic> = 36 kpc from the star-forming galaxy, SDSS J111324.08+293051.2 (<jats:italic>z</jats:italic> = 0.17077). We measure an H <jats:sc>i</jats:sc>  column density of <jats:italic>N</jats:italic>(H <jats:sc>i</jats:sc>) = 3.47 × 10<jats:sup>20</jats:sup> cm<jats:sup>−2</jats:sup> along with multiple low-ionization species such as N <jats:sc>i</jats:sc>, N <jats:sc>ii</jats:sc>, Si <jats:sc>ii</jats:sc>, C <jats:sc>ii</jats:sc>, and Si <jats:sc>iii</jats:sc>. We also make an estimate of the covering fraction to be 0.883, giving us a limiting size of the DLA to be <jats:italic>A</jats:italic> <jats:sub>DLA</jats:sub> ≥ 3.3 kpc<jats:sup>2</jats:sup>. Assuming a uniform column density over the entire DLA system, we estimate its mass to be <jats:italic>M</jats:italic> <jats:sub>DLA</jats:sub> ≥ 5.3 × 10<jats:sup>6</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>. The extended illuminator and the low redshift of this DLA give us the unique opportunity to characterize its nature and the connection to its host galaxy. We measure a velocity offset of +131 km s<jats:sup>−1</jats:sup> from the systemic velocity of the host for the DLA. This velocity is −84 km s<jats:sup>−1</jats:sup> from the projected rotation velocity of the host galaxy as measured using a newly constructed rotation curve. Based on the size of the host galaxy, the H <jats:sc>i</jats:sc>  column density, and the gas kinematics, we believe this DLA is tracing the warm neutral gas in the H <jats:sc>i</jats:sc>  disk of the foreground galaxy. Our detection adds to a small set of low-redshift DLAs that have confirmed host galaxies, and is the first to be found using an extended background source.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The neutron star equation of state is now being constrained from a diverse set of multi-messenger data, including gravitational waves from binary neutron star mergers, X-ray observations of the neutron star radius, and many types of laboratory nuclear experiments. These measurements are often mapped to a common domain for comparison with one another or are used to constrain the predictions of theoretical equations of state. We explore here the statistical biases that can arise when such multi-messenger data are compared or combined across different domains. We find that placing Bayesian priors individually in each domain of measurement can lead to biased constraints. We present a new prescription for defining Bayesian priors consistently across different experiments, which will allow for robust cross-domain comparisons. Using the first two binary neutron star mergers as an example, we show that a uniform prior in the tidal deformability can produce inflated evidence for large radii, while a uniform prior in the radius points toward smaller radii. Finally, using this new prescription, we provide a status update on multi-messenger constraints on the neutron star radius.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The identifications of Fe <jats:sc>vii</jats:sc> emission lines in the wavelength range 193–197 Å are discussed in the light of new measurements of laboratory spectra and atomic data calculations. This region is of importance to studies of solar spectra from the EUV Imaging Spectrometer (EIS) on board the Hinode spacecraft, which has its peak sensitivity at these wavelengths. Ten lines are measured, arising from seven fine structure levels in the 3<jats:italic>p</jats:italic> <jats:sup>5</jats:sup>3<jats:italic>d</jats:italic> <jats:sup>3</jats:sup> configuration. Two lines have not previously been reported and lead to new experimental energies for the <jats:inline-formula> <jats:tex-math> <?CDATA ${({a}^{2}D)}^{3}{F}_{\mathrm{2,3}}$?> </jats:tex-math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabd39bieqn1.gif" xlink:type="simple" /> </jats:inline-formula> levels. Updated experimental energies are obtained for the remaining levels. The new atomic model is used to compute theoretical values for the two density diagnostic ratios <jats:italic>λ</jats:italic>196.21/<jats:italic>λ</jats:italic>195.39 and <jats:italic>λ</jats:italic>196.21/<jats:italic>λ</jats:italic>196.06, and densities are derived from EIS spectra of coronal loop footpoints.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), we have recorded ∼10<jats:sup>5</jats:sup> single pulses from PSR J1022+1001. We studied the polarization properties, their energy distribution, and their times of arrival. This is only possible with the high sensitivity available using FAST. There is no indication that PSR J1022+1001 exhibits giant pulse, nulling, or traditional mode changing phenomena. The energy in the leading and trailing components of the integrated profile is shown to be correlated. The degree of both linear and circular polarization increases with the pulse flux density for individual pulses. Our data indicates that pulse jitter leads to an excess noise in the timing residuals of 67 ns when scaled to one hour, which is consistent with Liu et al. We have unsuccessfully trialed various methods to improve timing precision through the selection of specific single pulses. Our work demonstrates that FAST can detect individual pulses from pulsars that are observed in order to detect and study gravitational waves. This capability enables detailed studies, and parameterization, of the noise processes that affect the sensitivity of a pulsar timing array.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report SOFIA/GREAT observations of high-<jats:italic>J</jats:italic> CO lines and [C <jats:sc>ii</jats:sc>] observations of the super star cluster candidate H72.97-69.39 in the Large Magellanic Cloud (LMC), which is in its very early formation stage. We use our observations to determine if shocks are heating the gas or if photon-dominated regions (PDRs) are being heated by local far-UV radiation. We use a PDR model and a shock model to determine whether the CO and [C <jats:sc>ii</jats:sc>] lines arise from PDRs or shocks. We can reproduce the observed high-<jats:italic>J</jats:italic> CO and [C <jats:sc>ii</jats:sc>] emission with a clumpy PDR model with the following properties: a density of 10<jats:sup>4.7</jats:sup> cm<jats:sup>−3</jats:sup>, a mass of 10<jats:sup>4</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, and UV radiation of 10<jats:sup>3.5</jats:sup> in units of Draine field. Comparison with the ALMA beam-filling factor suggests a higher density within the uncertainty of the fit. We find the lower-limit [C <jats:sc>ii</jats:sc>]/total infrared (TIR) ratio (<jats:italic>ϵ</jats:italic>) traced by [C <jats:sc>ii</jats:sc>]/TIR to be 0.026%, lower than other known young star-forming regions in the LMC. Our shock models may explain the CO (16−15) and CO (11−10) emission lines with shock velocity of 8–11 km s<jats:sup>−1</jats:sup>, pre-shock density of 10<jats:sup>4</jats:sup>–10<jats:sup>5</jats:sup> cm<jats:sup>−3</jats:sup>, and <jats:italic>G</jats:italic> <jats:sub>UV</jats:sub> = 0 in units of Draine field. However, the [C <jats:sc>ii</jats:sc>] line emission cannot be explained by a shock model, thus it is originating in a different gas component. Observations of [O <jats:sc>i</jats:sc>] 63 <jats:italic>μ</jats:italic>m predicted to be 1.1 × 10<jats:sup>−13</jats:sup> W m<jats:sup>−2</jats:sup> by PDR models and 7.8 × 10<jats:sup>−15</jats:sup> W m<jats:sup>−2</jats:sup> by shock models will help distinguish between the PDR and shock scenarios.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>A mass paucity of compact objects in the range of ∼2–5 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> has been suggested by X-ray binary observations, namely, the “lower mass gap.” Gravitational wave detections have unlocked another mass measurement method, and aLIGO/Virgo has observed some candidates in the gap. We revisit the numerical simulations on the core-collapse supernovae (CCSNe) for ∼20–40 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> progenitor stars with different initial explosion energies. As a result, the lower explosion energy naturally causes more efficient fallback accretion for low-metallicity progenitors, and then the newborn black holes (BHs) in the center of the CCSNe can escape from the gap, but neutron stars cannot easily collapse into BHs in the gap; nevertheless, the final remnants of the solar-metallicity progenitors stick to the gap. If we consider that only drastic CCSNe can be observed and that those with lower explosion energies are universal, the lower mass gap can be reasonably built. The width and depth of the gap are mainly determined by the typical CCSN initial explosion energy and metallicity. One can expect that the future multimessenger observations of compact objects delineate the shape of the gap, which might constrain the properties of the CCSNe and their progenitors.</jats:p>