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<jats:title>Abstract</jats:title> <jats:p>The 3D radial escape-velocity profile of galaxy clusters has been suggested to be a promising and competitive tool for constraining mass profiles and cosmological parameters in an accelerating universe. However, the observed line-of-sight escape profile is known to be suppressed compared to the underlying 3D radial (or tangential) escape profile. Past work has suggested that velocity anisotropy in the phase-space data is the root cause. Instead, we find that the observed suppression is from the statistical undersampling of the phase spaces and that the 3D radial escape edge can be accurately inferred from projected data. We build an analytical model for this suppression that only requires the number of observed galaxies <jats:italic>N</jats:italic> in the phase-space data within the sky-projected range 0.3 ≤ <jats:italic>r</jats:italic> <jats:sub>⊥</jats:sub>/<jats:italic>R</jats:italic> <jats:sub>200,critical</jats:sub> ≤ 1. The radially averaged suppression function is an inverse power law <jats:inline-formula> <jats:tex-math> <?CDATA $\langle {Z}_{{\rm{v}}}\rangle =1+{({N}_{0}/N)}^{\lambda }$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo stretchy="false">〈</mml:mo> <mml:msub> <mml:mrow> <mml:mi>Z</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">v</mml:mi> </mml:mrow> </mml:msub> <mml:mo stretchy="false">〉</mml:mo> <mml:mo>=</mml:mo> <mml:mn>1</mml:mn> <mml:mo>+</mml:mo> <mml:msup> <mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:msub> <mml:mrow> <mml:mi>N</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:mi>N</mml:mi> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> <mml:mrow> <mml:mi>λ</mml:mi> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac4786ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> with <jats:italic>N</jats:italic> <jats:sub>0</jats:sub> = 17.818 and <jats:italic>λ</jats:italic> = 0.362. We test our model with <jats:italic>N</jats:italic>-body simulations, using dark matter particles, subhalos, and semianalytic galaxies as the phase-space tracers, and find excellent agreement. We also assess the model for systematic biases from cosmology (Ω<jats:sub>Λ</jats:sub>, <jats:italic>H</jats:italic> <jats:sub>0</jats:sub>), cluster mass (<jats:italic>M</jats:italic> <jats:sub>200,critical</jats:sub>), and velocity anisotropy (<jats:italic>β</jats:italic>). We find that varying these parameters over large ranges can impart a maximal additional fractional change in 〈<jats:italic>Z</jats:italic> <jats:sub>v</jats:sub>〉 of 2.7%. These systematics are highly subdominant (by at least a factor of 13.7) to the suppression from <jats:italic>N</jats:italic>.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Galactic center black hole is a putative laboratory to test general relativity (GR) and constrain its alternatives. <jats:italic>f(R)</jats:italic> scalaron gravity is an interesting alternative to GR and has tremendous prospects for astrophysics and fundamental physics near the black hole. In this work, we search for breaking points of GR through estimation of pericenter shift of stellar orbits with semimajor axis <jats:italic>a</jats:italic> = (45–1000) au. The black hole spin is taken as the maximum <jats:italic>χ</jats:italic> = 0.99, and orbital eccentricity is taken as <jats:italic>e</jats:italic> = 0.9. We work with theoretical scalaron field amplitude and coupling, predicted by Kalita, and also consider the constraints reported by Hees et al. The scalaron mass is taken in the range (10<jats:sup>−22</jats:sup>–10<jats:sup>−17</jats:sup>) eV. It is found that GR suppresses scalaron gravity at all orbital radii for the theoretical values of scalaron field coupling predicted by Kalita. Breaking point arises only for higher scalaron coupling resulting from the Hees et al. observations within a few tens of au to <jats:italic>a</jats:italic> = 1000 au. We also estimate the pericenter shift with a power-law potential <jats:italic>V</jats:italic>(<jats:italic>r</jats:italic>) ∼ 1/<jats:italic>r</jats:italic> <jats:sup>2</jats:sup> arising in five-dimensional gravity and obtain allowed ranges of the five-dimensional Planck mass through existing bounds on the parameterized post-Newtonian parameters coming from the orbits of S-2, S-38, and S-55. The breaking point for GR arises for a five-dimensional Planck mass of about 10<jats:sup>4</jats:sup> GeV. Constraint on this parameter, expected from the astrometric capabilities of existing and upcoming large telescopes, is also presented.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The technique of normal-mode coupling is a powerful tool with which to seismically image non-axisymmetric phenomena in the Sun. Here we apply mode coupling in the Cartesian approximation to probe steady, near-surface flows in the Sun. Using Doppler cubes obtained from the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory, we perform inversions on mode-coupling measurements to show that the resulting divergence and radial vorticity maps at supergranular length scales (∼30 Mm) near the surface compare extremely well with those obtained using the local correlation tracking method. We find that the Pearson correlation coefficient is ≥0.9 for divergence flows, while ≥0.8 is obtained for the radial vorticity.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Using spectroscopic observations from the Sloan Digital Sky Survey Mapping Nearby Galaxies at Apache Point Observatory Data Release 15, we study the relationships between the ratio of total to visible mass and various parameters characterizing the evolution and environment of the galaxies in this survey. Measuring the rotation curve with the relative velocities of the H<jats:italic>α</jats:italic> emission line across a galaxy’s surface, we estimate each galaxy’s total mass. We develop a statistical model to describe the observed distribution in the ratio of total to visible mass, from which we extract the most probable value of this mass ratio for a given sample of galaxies. We present the relationships between the ratio of total to visible mass and several characteristics describing galactic evolution, such as luminosity, gas-phase metallicity, distance to the nearest neighbor, and position on the color–magnitude diagram. We find that faint galaxies with low metallicities, typically in the blue cloud, have the highest ratios of total to visible mass. This mass ratio is significantly reduced when we include the H <jats:sc>i</jats:sc> mass in the total visible mass, implying that feedback mechanisms are not as strong in low-mass galaxies as previously thought. Those galaxies that exhibit the second-highest ratios of total to visible mass are the brightest with high metallicities, typically members of the red sequence or green valley. Active galactic nucleus activity is likely both the quenching mechanism and the feedback that drives the mass ratio higher in these massive galaxies. Finally, we introduce a parameterization that predicts a galaxy’s ratio of total to visible mass based only on its photometry and luminosity.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We analyze the normal (<jats:italic>N</jats:italic>) component of the heliospheric magnetic field observed by the Interplanetary Monitoring Platform and the Advanced Composition Explorer spacecraft for the period 1973–2020. Parameters characterizing the frequency spectrum are calculated with a novel technique, which is based on calculating variances at incremental lags to yield the integral of a turbulence spectrum. We compare this technique with the standard second-order structure function to show their similarity in the inertial range, and use the latter to calculate correlation functions. We find that the yearly average for magnetic field magnitude and the variance attained their lowest values since spacecraft observations began for the period that includes the 2020 solar minimum, 4.2 nT and 3.3 nT<jats:sup>2</jats:sup>, respectively. The ratio of the magnitude of fluctuations of the <jats:italic>N</jats:italic> component to the field magnitude shows little variation, with an average value of 0.43 ± 0.04. The average value of the spectral index of the energy range for the whole data set is −1.0 ± 0.1, and shows some solar-cycle dependence. The average value for the inertial range is an almost constant −1.69 ± 0.04. While the break between the energy and the inertial range is difficult to determine accurately to search for a solar-cycle dependence, an indirect indication of such a dependence follows when the ratio of spectral levels in the energy and in the inertial range is calculated. The e-folding correlation length has an average value of 1.1 ± 0.3 Mkm, with a clear solar-cycle dependence.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The mechanisms and pathways of magnetic energy conversion are an important subject for many laboratory, space, and astrophysical systems. Here, we present a perspective on magnetic energy conversion in magnetohydrodynamics through magnetic field curvature relaxation (CR) and perpendicular expansion (PE) due to magnetic pressure gradients, and quantify their relative importance in two representative cases, namely 3D magnetic reconnection and 3D kink-driven instability in an astrophysical jet. We find that the CR and PE processes have different temporal and spatial evolutions in these systems. The relative importance of the two processes tends to reverse as the system enters the nonlinear stage from the instability growth stage. Overall, the two processes make comparable contributions to magnetic energy conversion, with the PE process somewhat stronger than the CR process. We further explore how these energy conversion terms can be related to particle energization in these systems.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Observations of H <jats:sc>i</jats:sc> Lyman <jats:italic>α</jats:italic>, the brightest UV emission line of late-type stars, are critical for understanding stellar chromospheres and transition regions, modeling photochemistry in exoplanet atmospheres, and measuring the abundances of neutral hydrogen and deuterium in the interstellar medium. Yet Ly<jats:italic>α</jats:italic> observations are notoriously challenging owing to severe attenuation from interstellar gas, hindering our understanding of this important emission line’s basic morphology. We present high-resolution far- and near-UV spectroscopy of five G, K, and M dwarfs with radial velocities large enough to Doppler-shift the stellar Ly<jats:italic>α</jats:italic> emission line away from much of the interstellar attenuation, allowing the line core to be directly observed. We detect self-reversal in the Ly<jats:italic>α</jats:italic> emission-line core for all targets, and we show that the self-reversal depth decreases with increasing surface gravity. Mg <jats:sc>ii</jats:sc> self-reversed emission-line profiles provide some useful information to constrain the Ly<jats:italic>α</jats:italic> line core, but the differences are significant enough that Mg <jats:sc>ii</jats:sc> cannot be used directly as an intrinsic Ly<jats:italic>α</jats:italic> template during reconstructions. We show that reconstructions that neglect self-reversal could overestimate intrinsic Ly<jats:italic>α</jats:italic> fluxes by as much as 60%–100% for G and K dwarfs and 40%–170% for M dwarfs. The five stars of our sample have low magnetic activity and subsolar metallicity; a larger sample size is needed to determine how sensitive these results are to these factors.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Observational precursors of large solar flares provide a basis for future operational systems for forecasting. Here, we study the evolution of the normalized emergence (EM), shearing (SH), and total (T) magnetic helicity flux components for 14 flaring (with at least one X-class flare) and 14 nonflaring (&lt;M5-class flares) active regions (ARs) using the Space-weather Helioseismic Magnetic Imager Active Region Patches vector magnetic field data. Each of the selected ARs contain a <jats:italic>δ</jats:italic>-type spot. The three helicity components of these ARs were analyzed using wavelet analysis. Localized peaks of the wavelet power spectrum (WPS) were identified and statistically investigated. We find that (i) the probability density function of the identified WPS peaks for all the EM/SH/T profiles can be fitted with a set of Gaussian functions centered at distinct periods between ∼3 and 20 hr. (ii) There is a noticeable difference in the distribution of periods found in the EM profiles between the flaring and nonflaring ARs, while no significant difference is found in the SH and T profiles. (iii) In flaring ARs, the distributions of the shorter EM/SH/T periods (&lt;10 hr) split up into two groups after flares, while the longer periods (&gt;10 hr) do not change. (iv) When the EM periodicity does not contain harmonics, the ARs do not host a large energetic flare. (v) Finally, significant power at long periods (∼20 hr) in the T and EM components may serve as a precursor for large energetic flares.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In this paper, we report a robust measurement of the morphology, color, and galaxy size dependences of the stellar–halo mass relation (SHMR) at the high-mass end (10<jats:sup>11.3</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> &lt; <jats:italic>M</jats:italic> <jats:sub>⋆</jats:sub> &lt; 10<jats:sup>11.7</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>) at redshift <jats:italic>z</jats:italic> <jats:sub> <jats:italic>s</jats:italic> </jats:sub> ∼ 0.6.<jats:xref ref-type="fn" rid="apjac4707fn1"> <jats:sup>3</jats:sup> </jats:xref> <jats:fn id="apjac4707fn1"> <jats:label> <jats:sup>3</jats:sup> </jats:label> <jats:p>Throughout the paper, we use <jats:italic>z</jats:italic> <jats:sub> <jats:italic>s</jats:italic> </jats:sub> for redshift and <jats:italic>z</jats:italic> for the <jats:italic>z</jats:italic>-band magnitude.</jats:p> </jats:fn> Applying our method, Photometric objects Around Cosmic webs (PAC), developed in a previous work to Baryon Oscillation Spectroscopic Survey and Hyper Suprime-cam Subaru Strategic Program observations, we measure the excess surface density (<jats:inline-formula> <jats:tex-math> <?CDATA ${\bar{n}}_{2}{w}_{p}({r}_{p})$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mover accent="true"> <mml:mrow> <mml:mi>n</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>¯</mml:mo> </mml:mrow> </mml:mover> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> <mml:msub> <mml:mrow> <mml:mi>w</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>p</mml:mi> </mml:mrow> </mml:msub> <mml:mo stretchy="false">(</mml:mo> <mml:msub> <mml:mrow> <mml:mi>r</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>p</mml:mi> </mml:mrow> </mml:msub> <mml:mo stretchy="false">)</mml:mo> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac4707ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>) of satellites around massive central galaxies with different morphologies indicated by the Sérsic index <jats:italic>n</jats:italic>. We find that more compact (larger <jats:italic>n</jats:italic>) central galaxies are surrounded by more satellites. With the abundance matching method, we estimate the halo mass for the central galaxies and find that it increases monotonically with <jats:italic>n</jats:italic>, solid evidence for a morphology dependence of the SHMR. Specifically, our results show that most compact galaxies (<jats:italic>n</jats:italic> &gt; 6) have a halo mass around 5.5 times larger than disk galaxies (<jats:italic>n</jats:italic> &lt; 2). Similarly, using the effective radius <jats:italic>R</jats:italic> <jats:sub> <jats:italic>e</jats:italic> </jats:sub> and the rest-frame <jats:italic>u</jats:italic> − <jats:italic>r</jats:italic> color, we find that red (large) galaxies reside in halos that are in average 2.6 (2.3) times more massive than those hosting blue (small) galaxies.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The pulsar light curves and energy spectra in dissipative pulsar magnetospheres are explored with Aristotelian electrodynamics (AE), where particle acceleration is fully balanced with the radiation reaction. AE magnetospheres with nonzero pair multiplicity are computed using a pseudo-spectral method in the co-moving frame. The dissipative region near the current sheet outside the light cylinder is accurately captured by a high-resolution simulation. The pulsar light curves and spectra are computed using the test particle trajectory method, including the influence of both the consistent accelerating electric field and radiation reaction. Our results can generally reproduce the double-peak light curves and the GeV cutoff energy spectra in agreement with the Fermi observations for the pair multiplicity <jats:italic>κ</jats:italic> ≳ 1.</jats:p>