Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>The Advanced LIGO and Virgo detectors have now observed approximately 50 black hole binary mergers, from which we can begin to infer how rapidly astrophysical black holes spin. The LIGO-Virgo Collaboration (LVC) analysis of detections up to the end of the first half of the third observing run (O3a) appeared to uncover a distribution of spin magnitudes that peaks at ∼0.2. This is surprising: is there a black hole formation mechanism that prefers a particular, nonzero spin magnitude, or could this be the cumulative effect of multiple formation processes? We perform an independent analysis of the most recent gravitational-wave (GW) catalog, and find that (a) the support for the LVC spin magnitude is tenuous; in particular, adding or removing just one signal from the catalog can remove the statistical preference for this distribution; and (b) we find potential evidence for two spin subpopulations in the observed black holes: one with extremely low spins and one with larger spin magnitudes. We make the connection that these spin subpopulations could be correlated with the mass of the binary, with more massive binaries preferring larger spin magnitudes, and argue that this may provide evidence for hierarchical mergers in the second GW catalog.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Using a suite of 3D hydrodynamical simulations of star-forming molecular clouds, we investigate how the density probability distribution function (PDF) changes when including gravity, turbulence, magnetic fields, and protostellar outflows and heating. We find that the density PDF is not lognormal when outflows and self-gravity are considered. Self-gravity produces a power-law tail at high densities, and the inclusion of stellar feedback from protostellar outflows and heating produces significant time-varying deviations from a lognormal distribution at low densities. The simulation with outflows has an excess of diffuse gas compared to the simulations without outflows, exhibits an increased average sonic Mach number, and maintains a slower star formation rate (SFR) over the entire duration of the run. We study the mass transfer between the diffuse gas in the lognormal peak of the PDF, the collapsing gas in the power-law tail, and the stars. We find that the mass fraction in the power-law tail is constant, such that the stars form out of the power-law gas at the same rate at which the gas from the lognormal part replenishes the power law. We find that turbulence does not provide significant support in the dense gas associated with the power-law tail. When including outflows and magnetic fields in addition to driven turbulence, the rate of mass transfer from the lognormal to the power law, and then to the stars, becomes significantly slower, resulting in slower SFRs and longer depletion times.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report results of observations of the GGD 12-15 region, where cluster formation is actively taking place, using various molecular emission lines. The C<jats:sup>18</jats:sup>O (<jats:italic>J</jats:italic> = 1−0) emission line reveals a massive clump in the region with a mass of ∼2800 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> distributed over ∼2 pc. The distribution of the C<jats:sup>18</jats:sup>O (<jats:italic>J</jats:italic> = 3−2) emission is similar to that of a star cluster forming therein, with an elliptical shape of ∼1 pc in size. A bipolar molecular outflow driven by IRS 9Mc, a constituent star of the cluster, is blowing in the direction perpendicular to the elongated C<jats:sup>18</jats:sup>O (<jats:italic>J</jats:italic> = 3−2) distribution, covering the entire clump. There is a massive core with a radius of 0.3 pc and a mass of 530 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> in the center of the clump. There are two velocity components around the core, which are prominent in a position–velocity (PV) diagram along the major axis of the clump. In addition, a PV diagram along the minor axis of the clump, which is parallel to the outflow, shows a velocity gradient opposite to that of the outflow. The velocity structure strongly indicates the infalling motion of the clump. Comparison of the observational data with a simple model of infalling oblate clumps indicates that the clump is undergoing gravitational contraction with rotation.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Many astronomical surveys are limited by the brightness of the sources, and gravitational-wave searches are no exception. The detectability of gravitational waves from merging binaries is affected by the mass and spin of the constituent compact objects. To perform unbiased inference on the distribution of compact binaries, it is necessary to account for this selection effect, which is known as Malmquist bias. Since systematic error from selection effects grows with the number of events, it will be increasingly important over the coming years to accurately estimate the observational selection function for gravitational-wave astronomy. We employ density estimation methods to accurately and efficiently compute the compact binary coalescence selection function. We introduce a simple pre-processing method, which significantly reduces the complexity of the required machine-learning models. We demonstrate that our method has smaller statistical errors at comparable computational cost than the method currently most widely used allowing us to probe narrower distributions of spin magnitudes. The currently used method leaves 10%–50% of the interesting black hole spin models inaccessible; our new method can probe &gt;99% of the models and has a lower uncertainty for &gt;80% of the models.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In this paper, we searched for the dust formation evidence of 66 supernovae (SNe) by using the blackbody model and the blackbody plus dust emission model to fit their early-time optical–near-infrared (NIR) spectral energy distributions (SEDs). We find that, while the blackbody model can fit most SEDs of the SNe in our sample, the model cannot fit the SEDs of some SNe in which the SEDs of two SNe (SNe 2010bq and 2012ca) show NIR excesses which can be attributed to the emission from the heated dust. We use the blackbody plus dust emission model to fit the SEDs showing NIR excesses, finding that both the graphite and silicate dust models can fit the SEDs, and the graphite model gets reasonable temperatures or better fits. Assuming that the dust is graphite, the best-fitting temperatures (masses) of the dust of SNe 2010bq and 2012ca are ∼1300–1800 K (∼0.1–3.4 ×10<jats:sup>−4</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>) and ∼600–1000 K (∼0.6–7.5 × 10<jats:sup>−3</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>), respectively. We compare the vaporization radii and the blackbody radii of the dust shells of the two SNe with the upper limits of the ejecta radii of the SNe at the first epochs, and demonstrate that the NIR excesses of the SEDs of the two SNe might be caused by the pre-existing dust.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report on the design and performance of the B<jats:sc>icep3</jats:sc> instrument and its first three-year data set collected from 2016 to 2018. B<jats:sc>icep3</jats:sc> is a 52 cm aperture refracting telescope designed to observe the polarization of the cosmic microwave background (CMB) on degree angular scales at 95 GHz. It started science observation at the South Pole in 2016 with 2400 antenna-coupled transition-edge sensor bolometers. The receiver first demonstrated new technologies such as large-diameter alumina optics, Zotefoam infrared filters, and flux-activated SQUIDs, allowing ∼10× higher optical throughput compared to the <jats:italic>Keck </jats:italic>design. B<jats:sc>icep3</jats:sc> achieved instrument noise equivalent temperatures of 9.2, 6.8, and 7.1 <jats:inline-formula> <jats:tex-math> <?CDATA $\mu {{\rm{K}}}_{{\rm\small{CMB}}}\sqrt{{\rm{s}}}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>μ</mml:mi> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">K</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathsize="small" mathvariant="normal">CMB</mml:mi> </mml:mrow> </mml:msub> <mml:msqrt> <mml:mrow> <mml:mi mathvariant="normal">s</mml:mi> </mml:mrow> </mml:msqrt> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac4886ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> and reached Stokes <jats:italic>Q</jats:italic> and <jats:italic>U</jats:italic> map depths of 5.9, 4.4, and 4.4 <jats:italic>μ</jats:italic>K arcmin in 2016, 2017, and 2018, respectively. The combined three-year data set achieved a polarization map depth of 2.8 <jats:italic>μ</jats:italic>K arcmin over an effective area of 585 square degrees, which is the deepest CMB polarization map made to date at 95 GHz.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a search for extreme emission line galaxies (EELGs) at <jats:italic>z</jats:italic> &lt; 1 in the COSMOS and North Ecliptic Pole (NEP) fields with imaging from Subaru/Hyper Suprime-Cam (HSC) and a combination of new and existing spectroscopy. We select EELGs on the basis of substantial excess flux in the <jats:italic>z</jats:italic> broad band, which is sensitive to H<jats:italic>α</jats:italic> at 0.3 ≲ <jats:italic>z</jats:italic> ≲ 0.42 and [O <jats:sc>iii</jats:sc>]<jats:italic>λ</jats:italic>5007 at 0.7 ≲ <jats:italic>z</jats:italic> ≲ 0.86. We identify 10,470 galaxies with <jats:italic>z</jats:italic>excesses in the COSMOS data set and 91,385 in the NEP field. We cross-reference the COSMOS EELG sample with the zCOSMOS and DEIMOS 10k spectral catalogs, finding 1395 spectroscopic matches. We made an additional 71 (46 unique) spectroscopic measurements with <jats:italic>Y</jats:italic> &lt; 23 using the HYDRA multiobject spectrograph on the WIYN 3.5 m telescope, and 204 spectroscopic measurements from the DEIMOS spectrograph on the Keck II telescope, providing a total of 1441/10,470 spectroscopic redshifts for the EELG sample in COSMOS (∼14%). We confirm that 1418 (∼98%) are H<jats:italic>α</jats:italic> or [O <jats:sc>iii</jats:sc>]<jats:italic>λ</jats:italic>5007 emitters in the above stated redshift ranges. We also identify 240 redshifted H<jats:italic>α</jats:italic> and [O <jats:sc>iii</jats:sc>]<jats:italic>λ</jats:italic>5007 emitters in the NEP using spectra taken with WIYN/HYDRA and Keck/DEIMOS. Using broadband-selection techniques in the <jats:italic>g</jats:italic> − <jats:italic>r</jats:italic> − <jats:italic>i</jats:italic> color space, we distinguish between H<jats:italic>α</jats:italic> and [O <jats:sc>iii</jats:sc>]<jats:italic>λ</jats:italic>5007 emitters with 98.6% accuracy. We test our EELG selection by constructing H<jats:italic>α</jats:italic> and [O <jats:sc>iii</jats:sc>]<jats:italic>λ</jats:italic>5007 luminosity functions and comparing to recent literature results. We conclude that broadband magnitudes from HSC, the Vera C. Rubin Observatory, and other deep optical multiband surveys can be used to select EELGs in a straightforward manner.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Seeing pristine material from the donor star in a type Ia supernova (SN Ia) explosion can reveal the nature of the binary system. In this paper, we present photometric and spectroscopic observations of SN 2020esm, one of the best-studied SNe of the class of “super-Chandrasekhar” SNe Ia (SC SNe Ia), with data obtained −12 to +360 days relative to peak brightness, obtained from a variety of ground- and space-based telescopes. Initially misclassified as a type II supernova, SN 2020esm peaked at <jats:italic>M</jats:italic> <jats:sub> <jats:italic>B</jats:italic> </jats:sub> = −19.9 mag, declined slowly (Δ<jats:italic>m</jats:italic> <jats:sub>15</jats:sub>(<jats:italic>B</jats:italic>) = 0.92 mag), and had particularly blue UV and optical colors at early times. Photometrically and spectroscopically, SN 2020esm evolved similarly to other SC SNe Ia, showing the usual low ejecta velocities, weak intermediate-mass elements, and the enhanced fading at late times, but its early spectra are unique. Our first few spectra (corresponding to a phase of ≳10 days before peak) reveal a nearly pure carbon/oxygen atmosphere during the first days after explosion. This composition can only be produced by pristine material, relatively unaffected by nuclear burning. The lack of H and He may further indicate that SN 2020esm is the outcome of the merger of two carbon/oxygen white dwarfs. Modeling its bolometric light curve, we find an <jats:sup>56</jats:sup>Ni mass of <jats:inline-formula> <jats:tex-math> <?CDATA ${1.23}_{-0.14}^{+0.14}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>1.23</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.14</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.14</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac4780ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> <jats:italic>M</jats:italic> <jats:sub>☉</jats:sub> and an ejecta mass of <jats:inline-formula> <jats:tex-math> <?CDATA ${1.75}_{-0.20}^{+0.32}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>1.75</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.20</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.32</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac4780ieqn2.gif" xlink:type="simple" /> </jats:inline-formula> <jats:italic>M</jats:italic> <jats:sub>☉</jats:sub>, in excess of the Chandrasekhar mass. Finally, we discuss possible progenitor systems and explosion mechanisms of SN 2020esm and, in general, the SC SNe Ia class.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We have complemented existing observations of H <jats:sc>i</jats:sc> absorption with new observations of HCO<jats:sup>+</jats:sup>, C<jats:sub>2</jats:sub>H, HCN, and HNC absorption from the Atacama Large Millimeter/submillimeter Array and the Northern Extended Millimeter Array in the directions of 20 background radio continuum sources with 4° ≤ ∣<jats:italic>b</jats:italic>∣ ≤ 81° to constrain the atomic gas conditions that are suitable for the formation of diffuse molecular gas. We find that these molecular species form along sightlines where <jats:italic>A</jats:italic> <jats:sub> <jats:italic>V</jats:italic> </jats:sub> ≳ 0.25, consistent with the threshold for the H <jats:sc>i</jats:sc>-to-H<jats:sub>2</jats:sub> transition at solar metallicity. Moreover, we find that molecular gas is associated only with structures that have an H <jats:sc>i</jats:sc> optical depth &gt;0.1, a spin temperature &lt;80 K, and a turbulent Mach number ≳ 2. We also identify a broad, faint component to the HCO<jats:sup>+</jats:sup> absorption in a majority of sightlines. Compared to the velocities where strong, narrow HCO<jats:sup>+</jats:sup> absorption is observed, the H <jats:sc>i</jats:sc> at these velocities has a lower cold neutral medium fraction and negligible CO emission. The relative column densities and linewidths of the different molecular species observed here are similar to those observed in previous experiments over a range of Galactic latitudes, suggesting that gas in the solar neighborhood and gas in the Galactic plane are chemically similar. For a select sample of previously observed sightlines, we show that the absorption line profiles of HCO<jats:sup>+</jats:sup>, HCN, HNC, and C<jats:sub>2</jats:sub>H are stable over periods of ∼3 yr and ∼25 yr, likely indicating that molecular gas structures in these directions are at least ≳100 au in size.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We examine a sampling of 23 polar-coronal-hole jets. We first identified the jets in soft X-ray (SXR) images from the X-ray telescope (XRT) on the Hinode spacecraft, over 2014–2016. During this period, frequently the polar holes were small or largely obscured by foreground coronal haze, often making jets difficult to see. We selected 23 jets among those adequately visible during this period, and examined them further using Solar Dynamics Observatory’s (SDO) Atmospheric Imaging Assembly (AIA) 171, 193, 211, and 304 Å images. In SXRs, we track the lateral drift of the jet spire relative to the jet base’s jet bright point (JBP). In 22 of 23 jets, the spire either moves away from (18 cases) or is stationary relative to (4 cases) the JBP. The one exception where the spire moved toward the JBP may be a consequence of line-of-sight projection effects at the limb. From the AIA images, we clearly identify an erupting minifilament in 20 of the 23 jets, while the remainder are consistent with such an eruption having taken place. We also confirm that some jets can trigger the onset of nearby “sympathetic” jets, likely because eruption of the minifilament field of the first jet removes magnetic constraints on the base-field region of the second jet. The propensity for spire drift away from the JBP, the identification of the erupting minifilament in the majority of jets, and the magnetic-field topological changes that lead to sympathetic jets, all support or are consistent with the minifilament-eruption model for jets.</jats:p>