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<jats:title>Abstract</jats:title> <jats:p>A giant planet embedded in a protoplanetary disk opens a gap by tidal interaction, and properties of the gap strongly depend on the planetary mass and disk parameters. Many numerical simulations of this process have been conducted, but detailed simulations and analysis of gap formation by a super-Jupiter-mass planet have not been thoroughly conducted. We performed two-dimensional numerical hydrodynamic simulations of the gap formation process by a super-Jupiter-mass planet and examined the eccentricity of the gap. When the planet is massive, the radial motion of gas is excited, causing the eccentricity of the gap’s outer edge to increase. Our simulations showed that the critical planetary mass for the eccentric gap was ∼ 3 <jats:italic>M</jats:italic> <jats:sub>J</jats:sub> in a disk with <jats:italic>α</jats:italic> = 4.0 × 10<jats:sup>−3</jats:sup> and <jats:italic>h</jats:italic>/<jats:italic>r</jats:italic> = 0.05, a finding that was consistent with that reported in a previous work. The critical planetary mass for the eccentric gap depends on the viscosity and the disk scale height. We found that the critical mass could be described by considering a dimensionless parameter related to the gap depth. The onset of gap eccentricity enhanced the surface density inside the gap, shallowing the gap more than the empirical relation derived in previous studies for a planet heavier than the critical mass. Therefore, our results suggest that the mass accretion rate, which strongly depends on the gas surface density in the gap, is also enhanced for super-Jupiter-mass planets. These results may substantially impact the formation and evolution processes of super-Jupiter-mass planets and population synthesis calculations.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We investigate the trapping of interstellar objects during the early stages of star and planet formation. Our results show a very wide range of possible values that will be narrowed down as the population of interstellar objects becomes better characterized. When assuming a background number density of 2 · 10<jats:sup>15</jats:sup> pc<jats:sup>−3</jats:sup> (based on 1I’s detection), a velocity dispersion of 30 km s<jats:sup>−1</jats:sup>, and an equilibrium size distribution, the number of interstellar objects captured by a molecular cloud and expected to be incorporated to each protoplanetary disk during its formation is O(10<jats:sup>9</jats:sup>) (50 cm–5 m), O(10<jats:sup>5</jats:sup>) (5–50 m), O(10<jats:sup>2</jats:sup>) (50–500 m), O(10<jats:sup>−2</jats:sup>) (500 m–5 km). After the disk has formed, the number of interstellar objects it can capture from the ISM during its lifetime is 6 · 10<jats:sup>11</jats:sup> (50 cm–5 m), 2 · 10<jats:sup>8</jats:sup> (5–50 m), 6 · 10<jats:sup>4</jats:sup> (50–500 m), 20 (500 m–5 km); in an open cluster where 1% of stars have undergone planet formation, these values increase by a factor of O(10<jats:sup>2</jats:sup>–10<jats:sup>3</jats:sup>). These trapped interstellar objects might be large enough to rapidly grow into larger planetesimals via the direct accretion of the subcm-sized dust grains in the protoplanetary disk before they drift in due to gas drag, helping overcome the meter-size barrier, acting as “seeds” for planet formation. They should be considered in future star and planet formation models, as well as in the potential spread of biological material across the Galaxy.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Suprathermal ions in the corona are thought to serve as seed particles for large gradual solar energetic particle (SEP) events associated with fast and wide coronal mass ejections (CMEs). A better understanding of the role of suprathermal particles as seed populations for SEP events can be made by using observations close to the Sun. We study a series of SEP events observed by the Integrated Science Investigation of the Sun (IS⊙IS) suite on board the Parker Solar Probe (PSP) from 2020 May 27 to June 2, during which PSP was at heliocentric distances between ∼0.4 and ∼0.2 au. These events were also observed by the Ahead Solar TErrestrial RElations Observatory (STEREO-A) near 1 au, but the particle intensity magnitude was much lower than that at PSP. We find that the SEPs should have spread in space as their source regions were distant from the nominal magnetic footpoints of both spacecraft and the parent CMEs were slow and narrow. We study the decay phase of the SEP events in the ∼1–2 MeV proton energy range at PSP and STEREO-A, and discuss their properties in terms of both continuous injections by successive solar eruptions and the distances where the measurements were made. This study indicates that seed particles can be continuously generated by eruptions associated with slow and narrow CMEs, spread over a large part of the inner heliosphere, and remain there for tens of hours, even if minimal particle intensity enhancements were measured near 1 au.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Gamma-ray bursts (GRBs) are the most luminous explosions in and can be detectable out to the edge of the universe. They have long been thought to be able to extend the Hubble diagram to very high redshifts. Several correlations between temporal or spectral properties and GRB luminosities have been proposed to make GRBs cosmological tools. However, those correlations cannot be properly standardized. In this paper, we select a long-GRB sample with X-ray plateau phases produced by electromagnetic dipole emissions from central newborn magnetars. A tight correlation is found between the plateau luminosity and the end time of the plateau in the X-ray afterglows out to the redshift <jats:italic>z</jats:italic> = 5.91. We standardize these long-GRB X-ray light curves to a universal behavior through this correlation, with a luminosity dispersion of 0.5 dex. The derived distance–redshift relation of GRBs is in agreement with the standard ΛCDM model both at low and high redshifts. The evidence for an accelerating universe from this GRB sample is 3<jats:italic>σ</jats:italic>, which is the highest statistical significance from GRBs to date.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Aiming to delineate the physical framework of blazars, we present an effective method to estimate four important parameters based on the idea proposed by Becker &amp; Kafatos, including the upper limit of central black hole mass <jats:italic>M</jats:italic>, the Doppler factor <jats:italic>δ</jats:italic>, the distance along the axis to the site of the <jats:italic>γ</jats:italic>-ray production <jats:italic>d</jats:italic> (which then can be transformed into the location of <jats:italic>γ</jats:italic>-ray-emitting region <jats:italic>R</jats:italic> <jats:sub> <jats:italic>γ</jats:italic> </jats:sub>) and the propagation angle with respect to the axis of the accretion disk Φ. To do so, we adopt an identical sample with 809 Fermi-LAT-detected blazars which had been compiled in Pei et al. These four derived parameters stepping onto the stage may shed new light on our knowledge regarding <jats:italic>γ</jats:italic>-ray blazars. With regard to the paper of Becker &amp; Kafatos, we obtain several new perspectives, mainly in (1) putting forward an updated demarcation between BL Lacs and FSRQs based on the relation between broad-line region luminosity and disk luminosity both measured in Eddington units, i.e., <jats:italic>L</jats:italic> <jats:sub>disk</jats:sub>/<jats:italic>L</jats:italic> <jats:sub>Edd</jats:sub> = 4.68 × 10<jats:sup>−3</jats:sup>, indicating that there are some differences between BL Lacs and FSRQs on the accretion power in the disk; (2) proposing that there is a so-called “appareling zone,” a potential transition field between BL Lacs and FSRQs where the changing-look blazars perhaps reside; (3) the location of <jats:italic>γ</jats:italic>-ray emission region is principally constrained outside the broad-line region, and for some BL Lacs are also away from the dusty molecular torus, which means the importance of emission components in the jet.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present observations of the dwarf galaxies GALFA Dw3 and GALFA Dw4 with the Advanced Camera for Surveys on the Hubble Space Telescope. These galaxies were initially discovered as optical counterparts to compact H <jats:sc>i</jats:sc> clouds in the GALFA survey. Both objects resolve into stellar populations which display old red giant branch (RGB), younger helium-burning, and massive main sequence stars. We use the tip of the RGB method to determine the distance to each galaxy, finding distances of <jats:inline-formula> <jats:tex-math> <?CDATA ${7.61}_{-0.29}^{+0.28}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>7.61</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.29</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.28</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac356cieqn1.gif" xlink:type="simple" /> </jats:inline-formula> Mpc and <jats:inline-formula> <jats:tex-math> <?CDATA ${3.10}_{-0.17}^{+0.16}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>3.10</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.17</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.16</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac356cieqn2.gif" xlink:type="simple" /> </jats:inline-formula> Mpc, respectively. With these distances we show that both galaxies are extremely isolated, with no other confirmed objects within ∼1.5 Mpc of either dwarf. GALFA Dw4 is also found to be unusually compact for a galaxy of its luminosity. GALFA Dw3 and Dw4 contain H <jats:sc>ii</jats:sc> regions with young star clusters and an overall irregular morphology; they show evidence of ongoing star formation through both ultraviolet and H<jats:italic>α</jats:italic> observations and are therefore classified as dwarf irregulars (dIrrs). The star formation histories of these two dwarfs show distinct differences: Dw3 shows signs of a recently ceased episode of active star formation across the entire dwarf, while Dw4 shows some evidence for current star formation in spatially limited H <jats:sc>ii</jats:sc> regions. Compact H <jats:sc>i</jats:sc> sources offer a promising method for identifying isolated field dwarfs in the Local Volume, including GALFA Dw3 and Dw4, with the potential to shed light on the driving mechanisms of dwarf galaxy formation and evolution.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The late-time evolution of the neutrino event rate from supernovae is evaluated for Super-Kamiokande using simulated results of proto-neutron star (PNS) cooling. In the present work, we extend the result of Suwa et al., who studied the dependence of the neutrino event rate on the PNS mass, but focus on the impact of the nuclear equation of state (EOS). We find that the neutrino event rate depends on both the high-density and low-density EOS, where the former determines the radius of the PNS and the latter affects its surface temperature. Based on the present evaluation of the neutrino event rate, we propose a new analysis method to extract the time variability of the neutrino average energy taking into account the statistical error in the observation.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>A rotating black hole can be clouded by light bosons via superradiance and thus acquire an atom-like structure. If such a gravitational atom system is accompanied by a pulsar, the pulsar can trigger transitions between energy levels of the gravitational atom, and these transitions can be detected by pulsar timing. We show that in such pulsar–black hole systems, fine and hyperfine structure transitions are more likely to be probed than the Bohr transition. Also, the calculation of these fine and hyperfine structure transitions are under better analytic control. Thus, these fine and hyperfine structure transitions are more ideal probes in the search for gravitational collider signals in pulsar–black hole systems.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Observations indicate that the star formation rate (SFR) of nuclear rings varies considerably with time and is sometimes asymmetric rather than being uniform across a ring. To understand what controls temporal and spatial distributions of ring star formation, we run semiglobal, hydrodynamic simulations of nuclear rings subject to time-varying and/or asymmetric mass inflow rates. These controlled variations in the inflow lead to variations in the star formation, while the ring orbital period (18 Myr) and radius (600 pc) remain approximately constant. We find that both the mass inflow rate and supernova feedback affect the ring SFR. An oscillating inflow rate with period Δ<jats:italic>τ</jats:italic> <jats:sub>in</jats:sub> and amplitude 20 causes large-amplitude (a factor of ≳5), quasi-periodic variations of the SFR when Δ<jats:italic>τ</jats:italic> <jats:sub>in</jats:sub> ≳ 50 Myr. We find that the time-varying interstellar medium (ISM) weight and midplane pressure track each other closely, establishing an instantaneous vertical equilibrium. The measured time-varying depletion time is consistent with the prediction from self-regulation theory provided the time delay between star formation and supernova feedback is taken into account. The supernova feedback is responsible only for small-amplitude (a factor of ∼2) fluctuations of the SFR with a timescale ≲40 Myr. Asymmetry in the inflow rate does not necessarily lead to asymmetric star formation in nuclear rings. Only when the inflow rate from one dust lane is suddenly increased by a large factor do the rings undergo a transient period of lopsided star formation.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>On the main sequence, low-mass and solar-like stars are observed to spin down over time, and magnetized stellar winds are thought to be predominantly responsible for this significant angular momentum loss. Previous studies have demonstrated that the wind torque can be predicted via formulations dependent on stellar properties, such as magnetic field strength and geometry, stellar radius and mass, wind mass-loss rate, and stellar rotation rate. Although these stars are observed to experience surface differential rotation, torque formulations so far have assumed solid-body rotation. Surface differential rotation is expected to affect the rotation of the wind and thus the angular momentum loss. To investigate how differential rotation affects the torque, we use the PLUTO code to perform 2.5D magnetohydrodynamic, axisymmetric simulations of stellar winds, using a colatitude-dependent surface differential rotation profile that is solar-like (i.e., rotation is slower at the poles than the equator). We demonstrate that the torque is determined by the average rotation rate in the wind so that the net torque is less than that predicted by assuming solid-body rotation at the equatorial rate. The magnitude of the effect is essentially proportional to the magnitude of the surface differential rotation, for example, resulting in a torque for the Sun that is ∼20% smaller than predicted by the solid-body assumption. We derive and fit a semianalytic formulation that predicts the torque as a function of the equatorial spin rate, magnitude of differential rotation, and wind magnetization (depending on the dipolar magnetic field strength and mass-loss rate, combined).</jats:p>