Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>We employ a set of high resolution <jats:italic>N</jats:italic>-body simulations to study the merger rate of dark matter halos. We define a specific merger rate by normalizing the average number of mergers per halo with the logarithmic mass growth change of the hosts at the time of accretion. Based on the simulation results, we find that this specific merger rate, <jats:inline-formula> <jats:tex-math> <?CDATA ${{dN}}_{\mathrm{merge}}(\xi | M,z)/d\xi /d\mathrm{log}M(z)$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi mathvariant="italic">dN</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>merge</mml:mi> </mml:mrow> </mml:msub> <mml:mo stretchy="false">(</mml:mo> <mml:mi>ξ</mml:mi> <mml:mo stretchy="false">∣</mml:mo> <mml:mi>M</mml:mi> <mml:mo>,</mml:mo> <mml:mi>z</mml:mi> <mml:mo stretchy="false">)</mml:mo> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:mi>d</mml:mi> <mml:mi>ξ</mml:mi> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:mi>d</mml:mi> <mml:mi>log</mml:mi> <mml:mi>M</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:mi>z</mml:mi> <mml:mo stretchy="false">)</mml:mo> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac5aaaieqn1.gif" xlink:type="simple" /> </jats:inline-formula>, has a universal form, which is only a function of the mass ratio of merging halo pairs, <jats:italic>ξ</jats:italic>, and does not depend on the host halo mass, <jats:italic>M</jats:italic>, or redshift, <jats:italic>z</jats:italic>, over a wide range of masses (10<jats:sup>12</jats:sup> ≲ <jats:italic>M</jats:italic> ≲ 10<jats:sup>14</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> <jats:italic>h</jats:italic> <jats:sup>−1</jats:sup>) and merger ratios (<jats:italic>ξ</jats:italic> ≥ 1<jats:italic>e</jats:italic> − 2). We further test with simulations of different Ω<jats:sub> <jats:italic>m</jats:italic> </jats:sub> and <jats:italic>σ</jats:italic> <jats:sub>8</jats:sub>, and get the same specific merger rate. The universality of the specific merger rate shows that halos in the universe are built up self-similarly, with a universal composition in the mass contributions and an absolute merger rate that grows in proportion to the halo mass growth. As a result, the absolute merger rate relates with redshift and cosmology only through the halo mass variable, whose evolution can be readily obtained from the universal mass accretion history (MAH) model of Zhao et al. Last, we show that this universal specific merger rate immediately predicts an universal unevolved subhalo mass function that is independent on the redshift, MAH or the final halo mass, and vice versa.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present an extensive archival analysis of a sample of local galaxies, combining multiwavelength data from GALEX, Spitzer, and Herschel to investigate “blue-side” mid-infrared (MIR) and “red-side” far-infrared (FIR) color–color correlations within the observed infrared spectral energy distributions. Our sample largely consists of the KINGFISH galaxies, with the important addition of a select few including NGC 5236 (M83) and NGC 4449. With data from the far-ultraviolet (∼0.15 <jats:italic>μ</jats:italic>m) through 500 <jats:italic>μ</jats:italic>m convolved to common angular resolution, we measure the photometry of kiloparsec-scale star-forming regions 36″ × 36″ in size. Star formation rates (SFRs), stellar masses, and metallicity distributions are derived throughout our sample. Focusing on the <jats:italic>f</jats:italic> <jats:sub>70</jats:sub>/<jats:italic>f</jats:italic> <jats:sub>500</jats:sub> “FIR” and <jats:italic>f</jats:italic> <jats:sub>8</jats:sub>/<jats:italic>f</jats:italic> <jats:sub>24</jats:sub> “MIR” flux density ratios (colors), we find that a subsample of galaxies demonstrate a strong IR color–color correlation within their star-forming regions, while others demonstrate uncorrelated colors. This division is driven by two main effects: (1) the local strength of star formation (SF) and (2) the metal content of the interstellar medium (ISM). Galaxies uniformly dominated by high surface densities of SF (e.g., NGC 5236) demonstrate strong IR color–color correlations, while galaxies that exhibit lower levels of SF and mixed environments (e.g., NGC 5457) demonstrate weaker or no correlation—explained by the increasing effect of varying ISM heating and metal content on the IR colors, specifically in the MIR. We find large dispersion in the SFR–<jats:italic>L</jats:italic> <jats:sub>8</jats:sub> (8 <jats:italic>μ</jats:italic>m luminosity) relation that is traced by the metallicity distributions, consistent with extant studies, highlighting its problematic use as an SFR indicator across diverse systems/samples.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We investigate the assembly history of massive disk galaxies and describe how they shape their morphology through cosmic time. Using SHARDS and HST data, we modeled the surface brightness distribution of 91 massive galaxies at redshift 0.14 &lt; <jats:italic>z</jats:italic> ≤ 1 in the wavelength range 0.5–1.6 <jats:italic>μ</jats:italic>m, deriving the uncontaminated spectral energy distributions of their bulges and disks separately. This spectrophotometric decomposition allows us to compare the stellar population properties of each component in individual galaxies. We find that the majority of massive galaxies (∼85%) build inside-out, growing their extended stellar disk around the central spheroid. Some bulges and disks could start forming at similar epochs, but these bulges grow more rapidly than their disks, assembling 80% of their mass in ∼0.7 and ∼3.5 Gyr, respectively. Moreover, we infer that both older bulges and older disks are more massive and compact than younger stellar structures. In particular, we find that bulges display a bimodal distribution of mass-weighted ages; i.e., they form in two waves. In contrast, our analysis of the disk components indicates that they form at <jats:italic>z</jats:italic> ∼ 1 for both first- and second-wave bulges. This translates to first-wave bulges taking longer to acquire a stellar disk (5.2 Gyr) compared to second-wave, less compact spheroids (0.7 Gyr). We do not find distinct properties (e.g., mass, star formation timescale, and mass surface density) for the disks in both types of galaxies. We conclude that the bulge mass and compactness mainly regulate the timing of the stellar disk growth, driving the morphological evolution of massive disk galaxies.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>A comet plasma tail is a product of the interaction between the solar wind and the comet’s coma, and has long been studied as a natural probe of the solar wind condition. We previously developed a method to derive the solar wind speed from dual-view observations of comet plasma tails. Here we improve the method to use single-view observations by assuming a radially propagating solar wind and apply it to two comets, C/2011 W3 (Lovejoy) and C/2012 S1 (ISON) observed by coronagraphs on board the Solar and Heliospheric Observatory and STEREO. We compare the results to the solar wind simulations and tomography and to the results from our previous dual-view method, and find they are generally consistent, especially when the comets were far away from the Sun or far away from the ecliptic plane and when the observer is high above the comet’s orbital plane. Meanwhile, we notice that this method may suffer from a large error for comets near the ecliptic plane and close to the Sun, where a nonradial component of the solar wind is significant. Using the observations from the first seven orbits of the Parker Solar Probe, we show that the solar wind deviates from a radial direction significantly within around 35 <jats:italic>R</jats:italic> <jats:sub>s</jats:sub>. We also notice that, when the nonradial solar wind component is presented, the error may be even larger if the observer is closer to the comet’s orbital plane. This method provides a potentially useful tool to estimate the solar wind speed around comets from only single-view imaging observations.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Duo to the large magnetic Reynolds number, the magnetic helicity originating from the solar interior can be carried away through the photosphere into the corona. However, the relationship between the accumulated magnetic helicity flux through the photosphere and the magnetic helicity in the corona is still unclear. By selecting 36 newly emerging active regions in the 23rd solar cycle, we apply optical flow methods to derive the accumulated magnetic helicity through the photosphere (<jats:italic>H</jats:italic> <jats:sub> <jats:italic>m</jats:italic> </jats:sub> <jats:sup> <jats:italic>p</jats:italic> </jats:sup>) by using the sequential longitudinal magnetograms, we use nonlinear force-free field extrapolation to obtain the 3D coronal magnetic field, and we adopt finite volume methods to calculate the instantaneous relative magnetic helicity in the corona (<jats:italic>H</jats:italic> <jats:sub> <jats:italic>m</jats:italic> </jats:sub> <jats:sup> <jats:italic>c</jats:italic> </jats:sup>) by using vector magnetograms. It is found that the local correlation tracking (LCT)–based <jats:italic>H</jats:italic> <jats:sub> <jats:italic>m</jats:italic> </jats:sub> <jats:sup> <jats:italic>p</jats:italic> </jats:sup> is larger than <jats:italic>H</jats:italic> <jats:sub> <jats:italic>m</jats:italic> </jats:sub> <jats:sup> <jats:italic>c</jats:italic> </jats:sup> in 1″, and that the Differential Affine Velocity Estimator–based <jats:italic>H</jats:italic> <jats:sub> <jats:italic>m</jats:italic> </jats:sub> <jats:sup> <jats:italic>p</jats:italic> </jats:sup> is more consistent with <jats:italic>H</jats:italic> <jats:sub> <jats:italic>m</jats:italic> </jats:sub> <jats:sup> <jats:italic>c</jats:italic> </jats:sup> than the LCT-based <jats:italic>H</jats:italic> <jats:sub> <jats:italic>m</jats:italic> </jats:sub> <jats:sup> <jats:italic>p</jats:italic> </jats:sup>. <jats:italic>H</jats:italic> <jats:sub> <jats:italic>m</jats:italic> </jats:sub> <jats:sup> <jats:italic>p</jats:italic> </jats:sup> is more consistent with <jats:italic>H</jats:italic> <jats:sub> <jats:italic>m</jats:italic> </jats:sub> <jats:sup> <jats:italic>c</jats:italic> </jats:sup> in evaluation from 2″ than from 1″. Moreover, <jats:inline-formula> <jats:tex-math> <?CDATA ${H}_{m}^{c}-{H}_{m}^{p}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>H</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>m</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>c</mml:mi> </mml:mrow> </mml:msubsup> <mml:mo>−</mml:mo> <mml:msubsup> <mml:mrow> <mml:mi>H</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>m</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>p</mml:mi> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac5593ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> systematically shows consistency with the Hemispheric Helicity Rule (over 55%), no matter which resolution and method are used. These estimations suggest that the consistency of <jats:italic>H</jats:italic> <jats:sub> <jats:italic>m</jats:italic> </jats:sub> <jats:sup> <jats:italic>c</jats:italic> </jats:sup> and <jats:italic>H</jats:italic> <jats:sub> <jats:italic>m</jats:italic> </jats:sub> <jats:sup> <jats:italic>p</jats:italic> </jats:sup> is partly dependent on the resolution of the magnetograms and the calculation methods.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Progenitors of core-collapse supernovae (SNe) can shed significant mass to circumstellar material (CSM) in the months to years preceding core collapse. The ensuing SN explosion launches ejecta that may subsequently collide with this CSM, producing shocks that can power emissions across the electromagnetic spectrum. In this work we explore the thermal signatures of dense CSM interaction when the CSM density profile is truncated at some outer radius. CSM with optical depth &gt;<jats:italic>c/v</jats:italic> (where <jats:italic>v</jats:italic> is the shock velocity) will produce primarily ∼blackbody optical/UV emission, whereas lower optical depth CSM will power bremsstrahlung X-ray emission. Focusing on the latter, we derive light curves and spectra of the resulting X-ray transients that include a detailed treatment of Comptonization. Due to strong photoelectric absorption, the X-ray light curve is dominated by the postinteraction phase that occurs after the shock reaches the CSM truncation radius. We treat this regime here for the first time. Using these results, we present the phase space of optical, UV, and X-ray transients as a function of CSM properties, and discuss detectability prospects. We find that ROSAT would not have been sensitive to CSM X-ray transients but that eROSITA is expected to detect many such events. Future wide-field UV missions such as the Ultraviolet Transient Astronomy Satellite will dramatically enhance sensitivity to large optical depth CSM configurations. Finally, we present a framework within which CSM properties may be directly inferred from observable features of X-ray transients. This can serve as an important tool for studying stellar mass loss using SN X-ray detections.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Assuming a population of black holes (BHs) with masses in the range inferred by LIGO/Virgo from BH mergers, we use quasar microlensing observations to estimate their abundances. We consider a mixed population of stars and BHs and the presence of a smooth dark matter component. We adopt reverberation mapping estimates of the quasar size. According to a Bayesian analysis of the measured microlensing magnifications, a population of BHs with masses ∼30<jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> constitutes less than 0.4% of the total matter at the 68% confidence level (less than 0.9% at the 90% confidence level). We have explored the whole mass range of LIGO/Virgo BHs, finding that this upper limit ranges from 0.5% to 0.4% at the 68% confidence level (from 1.1% to 0.9% at the 90% confidence level) when the BH masses change from 10 to 60<jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>. We estimate a 16% contribution from the stars, in agreement with previous studies based on a single-mass population that do not explicitly consider the presence of BHs. These results are consistent with the estimates of BH abundances from the statistics of LIGO/Virgo mergers, and rule out primordial BHs (or any other types of compact object) in this mass range constituting a significant fraction of the dark matter.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The origin of the Uranian satellite system remains uncertain. The four major satellites have nearly circular, coplanar orbits, and the ratio of the satellite system to planetary mass resembles Jupiter’s satellite system, suggesting the Uranian system was similarly formed within a disk produced by gas coaccretion. However, Uranus is a retrograde rotator with a high obliquity. The satellites orbit in its highly tilted equatorial plane in the same sense as the planet’s retrograde rotation, a configuration that cannot be explained by coaccretion alone. In this work, we investigate the first stages of the coaccretion + giant-impact scenario proposed by Morbidelli et al. (2012) for the origin of the Uranian system. In this model, a satellite system formed by coaccretion is destabilized by a giant impact that tilts the planet. The primordial satellites collide and disrupt, creating an outer debris disk that can reorient to the planet’s new equatorial plane and accrete into Uranus’ four major satellites. The needed reorientation out to distances comparable to outermost Oberon requires that the impact creates an inner disk with ≥1% of Uranus’ mass. We here simulate giant impacts that appropriately tilt the planet and leave the system with an angular momentum comparable to that of the current system. We find that such impacts do not produce inner debris disks massive enough to realign the outer debris disk to the post-impact equatorial plane. Although our results are inconsistent with the apparent requirements of a coaccretion + giant-impact model, we suggest alternatives that merit further exploration.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Main-sequence turnoff (MSTO) stars are good tracers of Galactic populations since their ages can be reliably estimated from atmospheric parameters. Based on the GALAH survey, we use the Yale rotation evolution code to determine the ages of 2926 MSTO stars with a mean age uncertainty of ∼10% considering the variation of C and O abundances. The ages of CO-poor stars are systematically affected by ∼10% due to the C and O abundances, globally shifting to ∼0.5 Gyr older compared to the results using solar metal mixture. Of the stars with [Fe/H] ∼ 0.3–0.5 or [O/Fe] ≤ −0.25, many have fractional age differences of ≥20%, and even reach up to 36%. The age–metallicity relation appears to possibly indicate the existence of two distinct sequences: a young sequence of stars with ages mostly &lt;7 Gyr, and a relatively older sequence of stars with ages mostly &gt;7 Gyr, overlapping at 5 Gyr ≤ age ≤ 7 Gyr. Moreover, the trends of abundances-to-age ratios show two corresponding sequences, especially in the [O/Fe]–age plane. We also find that [Y/Mg] is a good chemical clock in disk populations. The young sequence and the old sequence cannot be separated based on chemistry or kinematics; therefore, stellar age is an important parameter to distinguish these two sequences in our sample.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The possibility that primordial black holes (PBHs) form some part of dark matter has been considered for a long time but poorly constrained over a wide mass range. Fast radio bursts (FRBs) are bright radio transients with millisecond duration. Their lensing effect has been proposed to be one of the cleanest probes for constraining the presence of PBHs in the stellar-mass window. In this paper, we first apply the normalized cross-correlation algorithm to search and identify candidates for lensed FRBs in the latest public FRB observations, i.e., 593 FRBs, which mainly consist of the first Canadian Hydrogen Intensity Mapping Experiment FRB catalog, and then derive constraints on the abundance of PBHs from the null search result of the lensing signature. For a monochromatic mass distribution, the fraction of dark matter made up of PBHs could be constrained to ≤87% for ≥500 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> at the 95% confidence level by assuming signal-to-noise ratios dependent on the flux ratio threshold for each FRB and that apparently one-off events are intrinsic single bursts. This result would be improved by a factor of 3 when a conventional constant flux ratio threshold is considered. Moreover, we derive constraints on PBHs with a log-normal mass function naturally predicted by some popular inflation models and often investigated with gravitational-wave detections. We find that, in this mass distribution scenario, the constraint from the current public FRB observations is relatively weaker than the one from gravitational-wave detections. It is foreseen that upcoming complementary multimessenger observations will yield considerable constraints on the possibilities of PBHs in this intriguing mass window.</jats:p>