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<jats:title>Abstract</jats:title> <jats:p>Observations of core-collapse supernovae (CCSNe) reveal a wealth of information about the dynamics of the supernova ejecta and its composition but very little direct information about the progenitor. Constraining properties of the progenitor and the explosion requires coupling the observations with a theoretical model of the explosion. Here we begin with the CCSN simulations of Couch et al., which use a nonparametric treatment of the neutrino transport while also accounting for turbulence and convection. In this work we use the SuperNova Explosion Code to evolve the CCSN hydrodynamics to later times and compute bolometric light curves. Focusing on Type IIP SNe (SNe IIP), we then (1) directly compare the theoretical STIR explosions to observations and (2) assess how properties of the progenitor’s core can be estimated from optical photometry in the plateau phase alone. First, the distribution of plateau luminosities (<jats:italic>L</jats:italic> <jats:sub>50</jats:sub>) and ejecta velocities achieved by our simulations is similar to the observed distributions. Second, we fit our models to the light curves and velocity evolution of some well-observed SNe. Third, we recover well-known correlations, as well as the difficulty of connecting any one SN property to zero-age main-sequence mass. Finally, we show that there is a usable, linear correlation between iron core mass and <jats:italic>L</jats:italic> <jats:sub>50</jats:sub> such that optical photometry alone of SNe IIP can give us insights into the cores of massive stars. Illustrating this by application to a few SNe, we find iron core masses of 1.3–1.5 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> with typical errors of 0.05 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>. Data are publicly available online on Zenodo: doi:<jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="https://doi.org/10.5281/zenodo.6631964" xlink:type="simple">10.5281/zenodo.6631964</jats:ext-link>.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Using 2D particle-in-cell (PIC) simulations, the generation of electrostatic solitary waves (ESWs) and the associated plasma waves in symmetric magnetic reconnection are studied, and multiple kinds of ESWs with different propagating speeds are identified. Near the current sheet in the outflow region, there are two kinds of ESWs propagating away from the X line: their propagating speeds are about 0.73<jats:italic>V</jats:italic> <jats:sub>Te0</jats:sub> and 1.2<jats:italic>V</jats:italic> <jats:sub>Te0</jats:sub> (where <jats:italic>V</jats:italic> <jats:sub>Te0</jats:sub> is the initial electron thermal velocity), and their generation is associated with the Buneman instability and the electron two-stream instability, respectively. In the separatrix region, there is one kind of ESW propagating toward the X line with a propagating speed of about 1.2 <jats:italic>V</jats:italic> <jats:sub>Te0</jats:sub>, which is formed during the nonlinear evolution of the electron two-stream instability. We also run a case with a guide field, and there exist two kinds of ESWs: the ESWs propagating away from the X line can be generated near the separatrices with electron outflow, while the ESWs propagating toward the X line can be generated near the separatrices with electron inflow. The two kinds of ESWs are associated with the electron two-stream instability and the Buneman instability, respectively.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We examine the redshift evolution of density environments around 2163 radio galaxies with the stellar masses of ∼10<jats:sup>9</jats:sup>–10<jats:sup>12</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> between redshifts of <jats:italic>z</jats:italic> = 0.3–1.4, based on the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) and Faint Images of the Radio Sky at Twenty cm. We use the <jats:italic>k</jats:italic>-nearest neighbor method to measure the local galaxy number density around our radio galaxy sample. We find that the overdensities of the radio galaxies are weakly but significantly anticorrelated with redshift. This is consistent with the known result that the relative abundance of less-massive radio galaxies increases with redshift, because less-massive radio galaxies reside in relatively low-density regions. Massive radio galaxies with stellar masses of <jats:italic>M</jats:italic> <jats:sub>*</jats:sub> &gt; 10<jats:sup>11</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> are found in high density environments compared with the control sample galaxies with radio nondetection and matched stellar mass. Less-massive radio galaxies with <jats:italic>M</jats:italic> <jats:sub>*</jats:sub> &lt; 10<jats:sup>11</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> reside in average density environments. The fraction of the radio galaxies associated with the neighbors within a typical major merger scale, &lt;70 kpc, is higher than (comparable to) that of the control galaxies at <jats:italic>M</jats:italic> <jats:sub>*</jats:sub> &gt; 10<jats:sup>11</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> (<jats:italic>M</jats:italic> <jats:sub>*</jats:sub> &lt; 10<jats:sup>11</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>). We also find that the local densities around the radio galaxies are anticorrelated with the radio luminosities and black hole mass accretion rates at a fixed stellar mass. These findings suggest that massive radio galaxies have matured through galaxy mergers in the past, and have supermassive black holes whose mass accretion almost ceased at <jats:italic>z</jats:italic> &gt; 1.4, while less-massive radio galaxies undergo active accretion just at this epoch, as they have avoided such merger events.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Coronal mass ejections (CMEs) are associated with the eruption of magnetic flux ropes (MFRs), which usually appear as hot channels in active regions and coronal cavities in quiet-Sun regions. CMEs often exhibit a classical three-part structure in the lower corona when imaged with white-light coronagraphs, including a bright front, dark cavity, and bright core. For several decades, the bright core and dark cavity have been regarded as the erupted prominence and MFR, respectively. However, recent studies have clearly demonstrated that both the prominence and hot-channel MFR can be observed as the CME core. The current research presents a three-part CME resulting from the eruption of a coronal prominence cavity on 2010 October 7, with observations from two vantage perspectives, i.e., edge-on from the Earth and face-on from the Solar Terrestrial Relations Observatory (STEREO). Our observations illustrate two important results: (1) for the first time, the erupting coronal cavity is recorded as a channel-like structure in the extreme-ultraviolet passband, analogous to the hot-channel morphology, and is dubbed as the warm channel; and (2) both the prominence and warm-channel MFR (coronal cavity) in the extreme-ultraviolet passbands evolve into the CME core in the white-light coronagraphs of STEREO-A. The results suggest that we are working toward a unified explanation for the three-part structure of CMEs, in which both prominences and MFRs (hot or warm channels) are responsible for the bright core.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Ly<jats:italic>α</jats:italic> emission line is one of the main observables of galaxies at high redshift, but its output depends strongly on the neutral gas distribution and kinematics around the star-forming regions where UV photons are produced. We present observations of Ly<jats:italic>α</jats:italic> and 21 cm H <jats:sc>i</jats:sc> emission at comparable scales with the goal to qualitatively investigate how the neutral interstellar medium (ISM) properties impact Ly<jats:italic>α</jats:italic> transfer in galaxies. We have observed 21 cm H <jats:sc>i</jats:sc> at the highest possible angular resolution (≈3″ beam) with the Very Large Array in two local galaxies from the Lyman Alpha Reference Sample. We compare these data with Hubble Space Telescope Ly<jats:italic>α</jats:italic> imaging and spectroscopy, and Multi Unit Spectroscopic Explorer and Potsdam MultiAperture Spectrophotometer ionized gas observations. In LARS08, high-intensity Ly<jats:italic>α</jats:italic> emission is cospatial with high column density H <jats:sc>i</jats:sc> where the dust content is the lowest. The Ly<jats:italic>α</jats:italic> line is strongly redshifted, consistent with a velocity redistribution that allows Ly<jats:italic>α</jats:italic> escape from a high column density neutral medium with a low dust content. In eLARS01, high-intensity Ly<jats:italic>α</jats:italic> emission is located in regions of low column density H <jats:sc>i</jats:sc>, below the H <jats:sc>i</jats:sc> data sensitivity limit ( &lt; 2 × 10<jats:sup>20</jats:sup> cm<jats:sup>−2</jats:sup>). The perturbed ISM distribution with low column density gas in front of the Ly<jats:italic>α</jats:italic> emission region plays an important role in the escape. In both galaxies, the faint Ly<jats:italic>α</jats:italic> emission (∼1×10<jats:sup>−16</jats:sup> erg s<jats:sup>−1</jats:sup>cm<jats:sup>−2</jats:sup> arcsec<jats:sup>−2</jats:sup>) traces intermediate H<jats:italic>α</jats:italic> emission regions where H <jats:sc>i</jats:sc> is found, regardless of the dust content. Dust seems to modulate, but not prevent, the formation of a faint Ly<jats:italic>α</jats:italic> halo. This study suggests the existence of scaling relations between dust, H<jats:italic>α</jats:italic>, H <jats:sc>i</jats:sc>, and Ly<jats:italic>α</jats:italic> emission in galaxies.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We perform comprehensive temporal and spectral analysis of the newly discovered X-ray transient MAXI J1803–298 using an AstroSat target of opportunity observation on 2021 May 11 during its outburst. The source was found to be in the hard-intermediate state. We detect type C quasi-periodic oscillations (QPOs) at the frequencies of ∼5.4 and ∼6.3 Hz along with a subharmonic at ∼2.8 Hz in the 3–15 keV band. The frequency and fractional rms amplitude of the QPO in the 15–30 keV band are found to be higher than those in the 3–15 keV band. We find soft lags of ∼3.8 and ∼6.8 ms for the respective QPOs at ∼5.4 and ∼6.3 Hz, whereas a soft lag of ∼4.7 ms is found at the subharmonic frequency. The increase in the soft lags at the QPO frequencies with energy is also observed in other black hole transients and attributed to the inclination dependence of the lags. The rms energy spectra indicate the power-law component to be more variable than the disk and reflection components. We find a broad iron line with an equivalent width of ∼0.17–0.19 keV and a reflection hump above ∼12 keV in the energy spectrum. Based on the X-ray spectroscopy and considering the distance to the source as 8 kpc, the estimated mass (∼8.5–16 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>) and spin (<jats:italic>a</jats:italic> ≳ 0.7) of the black hole suggest that the source is likely to be a stellar mass Kerr black hole X-ray binary.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The chemical diversity of low-mass protostellar sources has so far been recognized, and environmental effects are invoked as its origin. In this context, observations of isolated protostellar sources without the influence of nearby objects are of particular importance. Here, we report the chemical and physical structures of the low-mass Class 0 protostellar source IRAS 16544−1604 in the Bok globule CB 68, based on 1.3 mm Atacama Large Millimeter/submillimeter Array observations at a spatial resolution of ∼70 au that were conducted as part of the large program FAUST. Three interstellar saturated complex organic molecules (iCOMs), CH<jats:sub>3</jats:sub>OH, HCOOCH<jats:sub>3</jats:sub>, and CH<jats:sub>3</jats:sub>OCH<jats:sub>3</jats:sub>, are detected toward the protostar. The rotation temperature and the emitting region size for CH<jats:sub>3</jats:sub>OH are derived to be 131 ± 11 K and ∼10 au, respectively. The detection of iCOMs in close proximity to the protostar indicates that CB 68 harbors a hot corino. The kinematic structure of the C<jats:sup>18</jats:sup>O, CH<jats:sub>3</jats:sub>OH, and OCS lines is explained by an infalling–rotating envelope model, and the protostellar mass and the radius of the centrifugal barrier are estimated to be 0.08–0.30 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> and &lt;30 au, respectively. The small radius of the centrifugal barrier seems to be related to the small emitting region of iCOMs. In addition, we detect emission lines of c-C<jats:sub>3</jats:sub>H<jats:sub>2</jats:sub> and CCH associated with the protostar, revealing a warm carbon-chain chemistry on a 1000 au scale. We therefore find that the chemical structure of CB 68 is described by a hybrid chemistry. The molecular abundances are discussed in comparison with those in other hot corino sources and reported chemical models.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Changing-look active galactic nuclei (AGNs) present an important laboratory to understand the origin and physical properties of the broad-line region (BLR). We investigate follow-up optical spectroscopy spanning ∼500 days after the outburst of the changing-look AGN 1ES 1927+654. The emission lines displayed dramatic, systematic variations in intensity, velocity width, velocity shift, and symmetry. Analysis of optical spectra and multiband images indicates that the host galaxy contains a pseudobulge and a total stellar mass of <jats:inline-formula> <jats:tex-math> <?CDATA ${3.56}_{-0.35}^{+0.38}\times {10}^{9}\,{M}_{\odot }$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>3.56</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.35</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.38</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo>×</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>9</mml:mn> </mml:mrow> </mml:msup> <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="apjac714aieqn1.gif" xlink:type="simple" /> </jats:inline-formula>. Enhanced continuum radiation from the outburst produced an accretion disk wind, which condensed into BLR clouds in the region above and below the temporary eccentric disk. Broad Balmer lines emerged ∼100 days after the outburst, together with an unexpected, additional component of narrow-line emission. The newly formed BLR clouds then traveled along a similar eccentric orbit (<jats:italic>e</jats:italic> ≈ 0.6). The Balmer decrement of the BLR increased by a factor of ∼4–5 as a result of secular changes in cloud density. The drop in density at late times allowed the production of He <jats:sc>i</jats:sc> and He <jats:sc>ii</jats:sc> emission. The mass of the black hole cannot be derived from the broad emission lines because the BLR is not virialized. Instead, we use the stellar properties of the host galaxy to estimate <jats:inline-formula> <jats:tex-math> <?CDATA ${M}_{\mathrm{BH}}={1.38}_{-0.66}^{+1.25}\times {10}^{6}\,{M}_{\odot }$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>BH</mml:mi> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>1.38</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.66</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>1.25</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo>×</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>6</mml:mn> </mml:mrow> </mml:msup> <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="apjac714aieqn2.gif" xlink:type="simple" /> </jats:inline-formula>. The nucleus reached near or above its Eddington limit during the peak of the outburst. We discuss the nature of the changing-look AGN 1ES 1927+654 in the context of other tidal disruption events.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Radio wave scattering can cause severe reductions in detection sensitivity for surveys of Galactic and extragalactic fast (∼ms duration) transients. While Galactic sources like pulsars undergo scattering in the Milky Way interstellar medium (ISM), extragalactic fast radio bursts (FRBs) can also experience scattering in their host galaxies and other galaxies intervening in their lines of sight. We assess Galactic and extragalactic scattering horizons for fast radio transients using a combination of NE2001 to model the dispersion measure and scattering time (<jats:italic>τ</jats:italic>) contributed by the Galactic disk, and independently constructed electron density models for the Galactic halo and other galaxies’ ISMs and halos that account for different galaxy morphologies, masses, densities, and strengths of turbulence. For source redshifts 0.5 ≤ <jats:italic>z</jats:italic> <jats:sub>s</jats:sub> ≤ 1, an all-sky, isotropic FRB population has simulated values of <jats:italic>τ </jats:italic>(1 GHz) ranging from ∼1 <jats:italic>μ</jats:italic>s to ∼2 ms (90% confidence, observer frame) that are dominated by host galaxies, although <jats:italic>τ</jats:italic> can be ≫2 ms at low Galactic latitudes. A population at <jats:italic>z</jats:italic> <jats:sub>s</jats:sub> = 5 has 0.01 ≲ <jats:italic>τ</jats:italic> ≲ 300 ms at 1 GHz (90% confidence), dominated by intervening galaxies. About 20% of these high-redshift FRBs are predicted to have <jats:italic>τ</jats:italic> &gt; 5 ms at 1 GHz (observer frame), and ≳40% of FRBs between <jats:italic>z</jats:italic> <jats:sub>s</jats:sub> ∼ 0.5–5 have <jats:italic>τ</jats:italic> ≳ 1 ms for <jats:italic>ν</jats:italic> ≤ 800 MHz. Our scattering predictions may be conservative if scattering from circumsource environments is significant, which is possible under specific conditions. The percentage of FRBs selected against from scattering could also be substantially larger than we predict if circumgalactic turbulence causes more small-scale (≪1 au) density fluctuations than observed from nearby halos.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Astrophysical jets are often observed as bent or curved structures. We also know that the different jet sources may be binary in nature, which may lead to a regular, periodic motion of the jet nozzle, an orbital motion, or precession. Here we present the results of 2D (M)HD simulations in order to investigate how a precessing or orbiting jet nozzle affects the propagation of a high-speed jet. We have performed a parameter study of systems with different precession angles, different orbital periods or separations, and different magnetic field strengths. We find that these kinds of nozzles lead to curved jet propagation, which is determined by the main parameters that define the jet nozzle. We find C-shaped jets from orbiting nozzles and S-shaped jets from precessing nozzles. Over a long time and long distances, the initially curved jet motion bores a broad channel into the ambient gas that is filled with high-speed jet material whose lateral motion is damped, however. A strong (longitudinal) magnetic field can damp the jet curvature that is enforced by either precession or orbital motion of the jet sources. We have investigated the force balance across the jet and ambient medium and found that the lateral magnetic pressure and gas pressure gradients are almost balanced, but that a lack of gas pressure on the concave side of the curvature is leading to the lateral motion. Magnetic tension does not play a significant role. Our results are obtained in code units, but we provide scaling relations such that our results may be applied to young stars, microquasars, symbiotic stars, or active galactic nuclei.</jats:p>