Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>A rare population of massive disk galaxies have been found to invade the red sequence dominated by early-type galaxies. The formation and origins of these red/quenched massive disk galaxies have recently gained great interest. The quenching mechanisms that are usually proposed, such as bar quenching and environment quenching, do not seem to be suitable for those bulgeless quenched disks in a low-density environment. In this paper, we use the TNG300 simulation to investigate the formation of massive quenched central disk galaxies. It is found that these galaxies contain less gas than their star-forming counterparts and harbor giant super massive black holes (SMBHs; above 10<jats:sup>8 </jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>). By tracing their formation history, we found that quenched disk galaxies formed early and preserved disk morphology for cosmological timescales. They have experienced less than one major merger on average, and mini-mergers (mass ratio &lt;1/10) have mainly contributed to the growth of their SMBHs. In the IllustrisTNG simulation, the black hole feedback mode switches from thermal to kinetic feedback when the black hole mass is more massive than ∼10<jats:sup>8 </jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, which is more efficient to eject gas outside of the galaxy and to suppress further cooling of the hot gaseous halo. We conclude that the dominant quenching mechanism in massive red/quenched disk galaxies is kinetic active galactic nuclei feedback.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present Atacama Large Millimeter/submillimeter Array observations of multiple <jats:sup>12</jats:sup>CO, <jats:sup>13</jats:sup>CO, and C<jats:sup>18</jats:sup>O lines and 2.9 mm and 1.3 mm continuum emission toward the nearby interacting luminous infrared galaxy NGC 3110, supplemented with similar spatial resolution H<jats:italic>α</jats:italic>, 1.4 GHz continuum, and <jats:italic>K</jats:italic>-band data. We estimate the typical CO-to-H<jats:sub>2</jats:sub> conversion factor of 1.7 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> (K km s<jats:sup>−1</jats:sup> pc<jats:sup>2</jats:sup>)<jats:sup>−1</jats:sup> within the disk using local thermal equilibrium-based and dust-based H<jats:sub>2</jats:sub> column densities, and measure the 1 kpc scale surface densities of the star formation rate (Σ<jats:sub>SFR</jats:sub>), super star clusters (Σ<jats:sub>SSC</jats:sub>), molecular gas mass, and star formation efficiency (SFE) toward the entire gas disk. These parameters show a peak in the southern part of the southern spiral arm (SFE ∼ 10<jats:sup>−8.2</jats:sup> yr<jats:sup>−1</jats:sup>, Σ<jats:sub>SFR</jats:sub> ∼ 10<jats:sup>−0.6</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> kpc<jats:sup>−2</jats:sup> yr<jats:sup>−1</jats:sup>, Σ<jats:sub>SSC</jats:sub> ∼ 6.0 kpc<jats:sup>−2</jats:sup>), which is likely attributable to the ongoing tidal interaction with the companion galaxy MCG-01-26-013, as well as toward the circumnuclear region. We also find that thermal free–free emission contributes to a significant fraction of the millimeter continuum emission at the position of the southern peak. These measurements imply that the peak of the southern arm is an active and young star-forming region, whereas the central part of NGC 3110 is a site of long-continued star formation. We suggest that during the early stage of the galaxy–galaxy interaction in which the mass ratio was high in NGC 3110, fragmentation along the main galaxy arms is an important driver of merger-induced star formation, and that massive gas inflow results in dusty nuclear starbursts.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The computational cost of fast non-LTE synthesis is one of the challenges that limits the development of 2D and 3D inversion codes. It also makes the interpretation of observations of lines formed in the chromosphere and transition region a slow and computationally costly process, which limits the inference of the physical properties on rather small fields of view. Having access to a fast way of computing the deviation from the LTE regime through the departure coefficients could largely alleviate this problem. We propose to build and train a graph network that quickly predicts the atomic level populations without solving the non-LTE problem. We find an optimal architecture for the graph network for predicting the departure coefficients of the levels of an atom from the physical conditions of a model atmosphere. A suitable data set with a representative sample of potential model atmospheres is used for training. This data set has been computed using existing non-LTE synthesis codes. The graph network has been integrated into existing synthesis and inversion codes for the particular case of Ca <jats:sc>ii</jats:sc>. We demonstrate orders-of-magnitude gain in computing speed. We analyze the generalization capabilities of the graph network and demonstrate that it produces good predicted departure coefficients for unseen models. We implement this approach in <jats:monospace>Hazel2</jats:monospace> and show how the inversions nicely compare with those obtained with standard non-LTE inversion codes. Our approximate method opens up the possibility of extracting physical information from the chromosphere on large fields of view with time evolution.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We consider the use of propagating kink waves, such as those observed by the Coronal Multi-channel Polarimeter, as a diagnostic technique. The transverse structuring of the plasma may be inferred by the frequency-dependent wave damping, which is attributed to resonant absorption. We include the effect of reflection of waves at the loop footpoints, which leads to the asymmetry parameter, describing the ratio of driven wave power at the footpoints becoming weakly constrained. The classical model of resonant absorption based on an exponential damping profile significantly overestimates the damping rate in coronal loops with low density contrast ratios. The use of the exponential profile in an analysis of observations therefore leads to underestimates for the density contrast ratio and associated parameters such as the heating rate following phase mixing.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Dust grains drift through the interstellar medium and are aligned with the magnetic field. Here we study the effect of grain alignment and motion on grain growth in molecular clouds (MCs). We first discuss the characteristic timescales of alignment of the grain axis of maximum inertia (<jats:inline-formula> <jats:tex-math> <?CDATA $\hat{{\boldsymbol{a}}}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mrow> <mml:mi mathvariant="bold-italic">a</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>ˆ</mml:mo> </mml:mrow> </mml:mover> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac5408ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> <jats:sub>1</jats:sub>) with its angular momentum (<jats:italic>J</jats:italic>; i.e., internal alignment) and alignment of <jats:italic>J</jats:italic> with the magnetic field (<jats:bold> <jats:italic>B</jats:italic> </jats:bold>; i.e., external alignment). We determine the maximum grain size with efficient internal (<jats:inline-formula> <jats:tex-math> <?CDATA ${a}_{\,\max ,{aJ}}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>a</mml:mi> </mml:mrow> <mml:mrow> <mml:mspace width="0.25em" /> <mml:mi>max</mml:mi> <mml:mo>,</mml:mo> <mml:mi mathvariant="italic">aJ</mml:mi> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac5408ieqn2.gif" xlink:type="simple" /> </jats:inline-formula>) and external (<jats:inline-formula> <jats:tex-math> <?CDATA ${a}_{\,\max ,{JB}}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>a</mml:mi> </mml:mrow> <mml:mrow> <mml:mspace width="0.25em" /> <mml:mi>max</mml:mi> <mml:mo>,</mml:mo> <mml:mi mathvariant="italic">JB</mml:mi> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac5408ieqn3.gif" xlink:type="simple" /> </jats:inline-formula>) alignment for composite grains. For the MC density of <jats:italic>n</jats:italic> <jats:sub>H</jats:sub> ∼ 10<jats:sup>3</jats:sup>–10<jats:sup>8</jats:sup> cm<jats:sup>−3</jats:sup>, we find that external alignment can occur for very large grains, but internal alignment only occurs for grains smaller than <jats:inline-formula> <jats:tex-math> <?CDATA ${a}_{\,\max ,{aJ}}\sim 2\,\mu {\rm{m}}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>a</mml:mi> </mml:mrow> <mml:mrow> <mml:mspace width="0.25em" /> <mml:mi>max</mml:mi> <mml:mo>,</mml:mo> <mml:mi mathvariant="italic">aJ</mml:mi> </mml:mrow> </mml:msub> <mml:mo>∼</mml:mo> <mml:mn>2</mml:mn> <mml:mspace width="0.25em" /> <mml:mi>μ</mml:mi> <mml:mi mathvariant="normal">m</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac5408ieqn4.gif" xlink:type="simple" /> </jats:inline-formula>. The presence of iron clusters within dust grains or suprathermal rotation increases <jats:inline-formula> <jats:tex-math> <?CDATA ${a}_{\,\max ,{aJ}}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>a</mml:mi> </mml:mrow> <mml:mrow> <mml:mspace width="0.25em" /> <mml:mi>max</mml:mi> <mml:mo>,</mml:mo> <mml:mi mathvariant="italic">aJ</mml:mi> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac5408ieqn5.gif" xlink:type="simple" /> </jats:inline-formula> to ∼10–50 <jats:italic>μ</jats:italic>m. We then study the growth of aligned grains drifting through the gas. Due to the motion of aligned grains across the magnetic field, gas accretion would increase the grain elongation rather than decrease, as expected from the growth of randomly oriented grains. Coagulation by grain collisions also increases grain elongation, leading to the increase of elongation with the grain size. The coagulation of aligned grains forms dust aggregates that contain elongated binaries comprising a pair of grains with parallel short axes. Grains within dust aggregates in 67P/Churyumov–Gerasimenko obtained by Rosetta have the grain elongation increasing with the grain radius, implying that such dust aggregates might form from aligned grains.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Recent observations from the MUSTANG2 instrument on the Green Bank Telescope have revealed evidence of enhanced long-wavelength emission in the dust spectral energy distribution (SED) in the Orion Molecular Cloud (OMC) 2/3 filament on 25″ (0.1 pc) scales. Here we present a measurement of the SED on larger spatial scales (map size 0.°5–3° or 3–20 pc), at somewhat lower resolution (120″, corresponding to 0.25 pc at 400 pc) using data from the Herschel satellite and Atacama Cosmology Telescope (ACT). We then extend the 120″-scale investigation to other regions covered in the Herschel Gould Belt Survey (HGBS), specifically the dense filaments in the southerly regions of Orion A, Orion B, and Serpens-S. Our data set in aggregate covers approximately 10 deg<jats:sup>2</jats:sup>, with continuum photometry spanning from 160 <jats:italic>μ</jats:italic>m to 3 mm. These OMC 2/3 data display excess emission at 3 mm, though less (10.9% excess) than what is seen at higher resolution. Strikingly, we find that the enhancement is present even more strongly in the other filaments we targeted, with an average excess of 42.4% and 30/46 slices showing an inconsistency with the modified blackbody to at least 4<jats:italic>σ</jats:italic>. Applying this analysis to the other targeted regions, we lay the groundwork for future high-resolution analyses. Additionally, we also consider a two-component dust model motivated by Planck results and an amorphous grain dust model. While both of these have been proposed to explain deviations in emission from a generic modified blackbody, we find that they have significant drawbacks, requiring many spectral points or lacking experimental data coverage.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present optical and near-infrared photometric and spectroscopic observations of the fast-declining Type Ia supernova (SN) 2015bo. SN 2015bo is underluminous (<jats:italic>M</jats:italic> <jats:sub> <jats:italic>B</jats:italic> </jats:sub> = −17.50 ± 0.15 mag) and has a fast-evolving light curve (Δm15(<jats:italic>B</jats:italic>) = 1.91 ± 0.01 mag and <jats:italic>s</jats:italic> <jats:sub>BV</jats:sub> = 0.48 ± 0.01). It has a unique morphology in the observed <jats:italic>V</jats:italic> − <jats:italic>r</jats:italic> color curve, where it is bluer than all other supernovae (SNe) in the comparison sample. A <jats:sup>56</jats:sup>Ni mass of 0.17 ± 0.03 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> was derived from the peak bolometric luminosity, which is consistent with its location on the luminosity–width relation. Spectroscopically, SN 2015bo is a cool SN in the Branch classification scheme. The velocity evolution measured from spectral features is consistent with 1991bg-like SNe. SN 2015bo has a SN twin (similar spectra) <jats:italic>and</jats:italic> sibling (same host galaxy), SN 1997cn. Distance moduli of <jats:italic>μ</jats:italic> = 34.33 ± 0.01 (stat) ±0.11 (sys) mag and <jats:italic>μ</jats:italic> = 34.34 ± 0.04 (stat) ± 0.12 (sys) mag are derived for SN 2015bo and SN 1997cn, respectively. These distances are consistent at the 0.06<jats:italic>σ</jats:italic> level with each other, and they are also consistent with distances derived using surface-brightness fluctuations and redshift-corrected cosmology. This suggests that fast-declining SNe could be accurate distance indicators, which should not be excluded from future cosmological analyses.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report on the presence of numerous tiny bright dots in and around an emerging flux region (an X-ray/coronal bright point) observed with SolO’s EUI/HRI<jats:sub>EUV</jats:sub> in 174 Å. These dots are roundish and have a diameter of 675 ± 300 km, a lifetime of 50 ± 35 s, and an intensity enhancement of 30% ± 10% above their immediate surroundings. About half of the dots remain isolated during their evolution and move randomly and slowly (&lt;10 km s<jats:sup>−1</jats:sup>). The other half show extensions, appearing as a small loop or surge/jet, with intensity propagations below 30 km s<jats:sup>−1</jats:sup>. Many of the bigger and brighter HRI<jats:sub>EUV</jats:sub> dots are discernible in the SDO/AIA 171 Å channel, have significant emissivity in the temperature range of 1–2 MK, and are often located at polarity inversion lines observed in SDO/HMI LOS magnetograms. Although not as pervasive as in observations, a Bifrost MHD simulation of an emerging flux region does show dots in synthetic Fe <jats:sc>ix</jats:sc>/<jats:sc>x</jats:sc> images. These dots in the simulation show distinct Doppler signatures—blueshifts and redshifts coexist, or a redshift of the order of 10 km s<jats:sup>−1</jats:sup> is followed by a blueshift of similar or higher magnitude. The synthetic images of O <jats:sc>v</jats:sc>/<jats:sc>vi</jats:sc> and Si <jats:sc>iv</jats:sc> lines, which represent transition region radiation, also show the dots that are observed in Fe <jats:sc>ix</jats:sc>/<jats:sc>x</jats:sc> images, often expanded in size, or extended as a loop, and always with stronger Doppler velocities (up to 100 km s<jats:sup>−1</jats:sup>) than that in Fe <jats:sc>ix</jats:sc>/<jats:sc>x</jats:sc> lines. Our observation and simulation results, together with the field geometry of dots in the simulation, suggest that most dots in emerging flux regions form in the lower solar atmosphere (at ≈ 1 Mm) by magnetic reconnection between emerging and preexisting/emerged magnetic field. Some dots might be manifestations of magnetoacoustic shocks through the line formation region of Fe <jats:sc>ix</jats:sc>/<jats:sc>x</jats:sc> emission.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We explore the possibility that radio-loud gamma-ray bursts (GRBs) result from the collapse of massive stars in interacting binary systems, while radio-quiet GRBs are produced by the collapse of single massive stars. A binary collapsar system can have the necessary angular momentum and energy budget to explain the longer prompt gamma-ray durations and higher isotropic energies seen in the the radio-loud subsample of long GRBs. Additionally, binary systems can lead to rich and extended circumstellar environments that allow for the presence of the long-lived radio afterglows seen in the radio-loud systems. Finally, the relative fraction of stars in binary systems versus single-star systems appears consistent with the fraction of radio-loud versus radio-quiet GRBs.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We investigate the effect of radio-frequency interference (RFI) excision in estimating the cosmological H <jats:sc>i</jats:sc> 21 cm power spectrum. Flagging of RFI-contaminated channels results in a nonuniform sampling of the instrumental bandpass response. Hence, the Fourier transformation of visibilities from frequency to delay domain contaminates the higher foreground-free delay modes, and separating the spectrally fluctuating H <jats:sc>i</jats:sc> signal from spectrally smooth foregrounds becomes challenging. We have done a comparative analysis between two algorithms, one-dimensional CLEAN and least-squares spectral analysis (LSSA), which have been used widely to solve this issue in the literature. We test these algorithms using the simulated SKA-1 Low observations in the presence of different RFI flagging scenarios. We find that, in the presence of random flagging of data, both algorithms perform well and can mitigate the foreground leakage issue. But CLEAN fails to restrict the foreground leakage in the presence of periodic and periodic plus broadband RFI flagging and gives an extra bias to the estimated power spectrum. However, LSSA can restrict the foreground leakage for these RFI flagging scenarios and gives an unbiased estimate of the H <jats:sc>i</jats:sc> 21 cm power spectrum. We have also applied these algorithms to observations with the upgraded GMRT and found that both CLEAN and LSSA give consistent results in the presence of realistic random flagging scenarios for this observed data set. This comparative analysis demonstrates the effectiveness and robustness of these two algorithms in estimating the H <jats:sc>i</jats:sc> 21 cm power spectrum from data sets affected by different RFI scenarios.</jats:p>