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<jats:title>Abstract</jats:title> <jats:p>We present a simple but general argument that strongly limits the abundance of primordial black holes (PBHs) (or other unknown population of compact objects) with masses similar to those determined by LIGO/Virgo from BH binary mergers. We show that quasar microlensing can be very sensitive to the mass of the lenses, and that it is able to distinguish between stars and BHs of high mass, when the finite size of the source is taken into account. A significant presence of massive BHs would produce frequent high-flux magnifications (except for unrealistically large sources), which have been very rarely observed. On the contrary, a typical stellar population would induce flux magnifications consistent with the observations. This result excludes PBHs (or any type of compact object) in the mass range determined by LIGO/Virgo as the main dark matter constituents in the lens galaxies.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The observed star formation rate of the Milky Way can be explained by applying a metallicity-dependent factor to convert CO luminosity to molecular gas mass and a star formation efficiency per freefall time that depends on the virial parameter of a molecular cloud. These procedures also predict the trend of star formation rate surface density with Galactocentric radius. The efficiency per freefall time variation with virial parameter plays a major role in bringing theory into agreement with observations for the total star formation rate, while the metallicity dependence of the CO luminosity-to-mass conversion is most notable in the variation with Galactocentric radius. Application of these changes resolves a factor of over 100 discrepancy between observed and theoretical star formation rates that has been known for nearly 50 yr.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The tidal interactions between a planet and moon can provide insight into the properties of the host planet. The recent exomoon candidates Kepler-1708 b-i and Kepler-1625 b-i are Neptune-sized satellites orbiting Jupiter-like planets and provide an opportunity to apply such methods. We show that if the tidal migration time is roughly equal to the age of these systems, then the tidal dissipation factor <jats:italic>Q</jats:italic> for the planets Kepler-1708 b and Kepler-1625 b have values of ∼3 × 10<jats:sup>5</jats:sup>–3 × 10<jats:sup>6</jats:sup> and ∼1.5 × 10<jats:sup>5</jats:sup>–4 × 10<jats:sup>5</jats:sup>, respectively. In each case, these are consistent with estimates for gas-giant planets. Even though some work suggests an especially large semimajor axis for Kepler-1625 b-i, we find that this would imply a surprisingly low <jats:italic>Q</jats:italic> ∼ 2000 for a gas giant unless the moon formed at essentially its current position. More detailed predictions for the moons’ initial semimajor axis could provide even better constraints on <jats:italic>Q</jats:italic>, and we discuss the formation scenarios for a moon in this context. Similar arguments can be used as more exomoons are discovered in the future to constrain exoplanet interior properties. This could be especially useful for exoplanets near the sub-Neptune/super-Earth radius gap where the planet structure is uncertain.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The SPT 0311–58 system at <jats:italic>z</jats:italic> = 6.900 is an extremely massive structure within the reionization epoch and offers a chance to understand the formation of galaxies at an extreme peak in the primordial density field. We present 70 mas Atacama Large Millimeter/submillimeter Array observations of the dust continuum and [C <jats:sc>ii</jats:sc>] 158 <jats:italic>μ</jats:italic>m emission in the central pair of galaxies and reach physical resolutions of ∼100–350 pc, among the most detailed views of any reionization-era system to date. The observations resolve the source into at least a dozen kiloparsec-size clumps. The global kinematics and high turbulent velocity dispersion within the galaxies present a striking contrast to recent claims of dynamically cold thin-disk kinematics in some dusty galaxies just 800 Myr later at <jats:italic>z</jats:italic> ∼ 4. We speculate that both gravitational interactions and fragmentation from massive parent disks have likely played a role in the overall dynamics and formation of clumps in the system. Each clump individually is comparable in mass to other 6 &lt; <jats:italic>z</jats:italic> &lt; 8 galaxies identified in rest-UV/optical deep field surveys, but with star formation rates elevated by a factor of ~3-5. Internally, the clumps themselves bear close resemblance to greatly scaled-up versions of virialized cloud-scale structures identified in low-redshift galaxies. Our observations are qualitatively similar to the chaotic and clumpy assembly within massive halos seen in simulations of high-redshift galaxies.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Solar extreme ultraviolet (EUV) waves are spectacular propagating disturbances with EUV enhancements in annular shapes in the solar corona. These EUV waves carry critical information about the coronal magnetized plasma that can shed light on the elusive physical parameters (e.g., the magnetic field strength) by global solar coronal magnetoseismology. EUV waves are closely associated with a wide range of solar atmospheric eruptions, from violent flares and coronal mass ejections to less energetic plasma jets or mini-filament eruptions. However, the physical nature and driving mechanism of EUV waves are still controversial. Here, we report the unique discovery of twin EUV waves (TEWs) that were formed in a single eruption with observations from two different perspectives. In all earlier studies, a single eruption was associated at most with a single EUV wave. The newly found TEWs urge us to revisit our theoretical understanding of the underlying formation mechanism(s) of coronal EUV waves. Two distinct scenarios of TEWs were found. In the first scenario, the two waves were separately associated with a filament eruption and a precursor jet, while in another scenario, the two waves were successively associated with a filament eruption. Hence, we label these distinguished scenarios as “fraternal TEWs” and “identical TEWs,” respectively. Further, we also suggest that impulsive lateral expansions of two distinct groups of coronal loops are critical to the formation of TEWs in a single eruption.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>A particle orbiting a misaligned eccentric orbit binary undergoes nodal precession either around the binary angular momentum vector (a circulating orbit) or around a stationary inclination (a librating orbit). In the absence of general relativity (GR), the stationary inclination is inclined by 90° to the binary angular momentum vector (aligned with the binary eccentricity vector) and does not depend on the particle semimajor axis. GR causes apsidal precession of the binary orbit. Close to the binary, the behavior of the particle is not significantly affected, and a librating particle precesses with the binary. However, we find that the stationary inclination and the minimum inclination required for libration both increase with the particle semimajor axis. There is a critical radius beyond which there are no librating orbits, only circulating orbits, and therefore there is a maximum orbital radius for a stationary polar-orbiting body. The critical radius is within planet-forming regions around binaries with a semimajor axis ≲1 au. This has implications for the search for misaligned circumbinary planets and the radial extent of polar circumbinary disks.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Using the Parker Solar Probe data taken in the inner heliosphere, we investigate the power and spatial anisotropy of magnetic field spectra at kinetic scales (i.e., around sub-ion scales) in solar wind turbulence in the inner heliosphere. We find that strong anisotropy of the magnetic spectra occurs at kinetic scales with the strongest power in the perpendicular direction with respect to the local magnetic field (forming an angle <jats:italic>θ</jats:italic> <jats:sub>B</jats:sub> with the mean flow velocity). The spectral index of the magnetic spectra varies from −3.2 to −5.8 when the angle <jats:italic>θ</jats:italic> <jats:sub>B</jats:sub> changes from 90° to 180° (or 0°), indicating that strong anisotropy of the spectral indices occurs at kinetic scales in the solar wind turbulence. Using a diagnosis based on the magnetic helicity, we show that the anisotropy of the spectral indices can be explained by the nature of the plasma modes that carry the cascade at kinetic scales. We discuss our findings in light of existing theories and current development in the field.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report the discovery of the BL Lacertae object FIRST J233153.20+112952.11 at redshift &gt;6 using near-infrared spectroscopy and broadband observations in the infrared, submillimeter, and radio wavelengths. The detection of the continuum break at ∼0.92 <jats:italic>μ</jats:italic>m in the near-infrared spectrum of FIRST J233153.20+112952.11 provides an approximate redshift of 6.57, corresponding to an age of the universe of ∼800 Myr. The rest-frame UV/optical spectrum of FIRST J233153.20+112952.11 shows no emission lines detected with equivalent width &gt;1.5 Å. The nondetection of the C <jats:sc>iv</jats:sc> <jats:italic>λ</jats:italic>1549 broad emission line constrains the luminosity of the accretion disk to be ≲10<jats:sup>45</jats:sup> erg s<jats:sup>−1</jats:sup>, which corresponds to the radiatively inefficient accretion regime of BL Lacertae objects. The spectral index of the rest-frame UV/optical continuum, <jats:italic>α</jats:italic> <jats:sub> <jats:italic>ν</jats:italic>,opt</jats:sub> = 1.43 ± 0.23, is consistent with the expected spectral index of the synchrotron emission spectrum of the relativistic jet. The flat radio continuum (<jats:italic>α</jats:italic> <jats:sub> <jats:italic>ν</jats:italic>,<jats:italic>r</jats:italic> </jats:sub> ≈ 0) in a rest-frame frequency interval of 7–23 GHz is similar to that of the typical BL Lacertae objects and also consistent with originating from the synchrotron jet emission. The rest-frame UV/optical and radio fluxes of FIRST J233153.20+112952.11 show significant (15%–40%) variations. The shortest recorded rest-frame timescale of these variations is ∼8 days. Assuming the local scaling relation between the radio luminosity and black hole mass, the 5 GHz radio luminosity of FIRST J233153.20+112952.11, 1.6 × 10<jats:sup>33</jats:sup> erg s<jats:sup>−1</jats:sup> Hz<jats:sup>−1</jats:sup>, suggests a billion solar mass central supermassive black hole.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report the first spatially resolved measurements of gas-phase metallicity radial gradients in star-forming galaxies in overdense environments at <jats:italic>z</jats:italic> ≳ 2. The spectroscopic data are acquired by the MAMMOTH-Grism survey, a Hubble Space Telescope (HST) cycle 28 medium program. This program is obtaining 45 orbits of WFC3/IR grism spectroscopy in the density peak regions of three massive galaxy protoclusters (BOSS 1244, BOSS 1542, and BOSS 1441) at <jats:italic>z</jats:italic> = 2–3. Our sample in the BOSS 1244 field consists of 20 galaxies with stellar mass ranging from 10<jats:sup>9.0</jats:sup> to 10<jats:sup>10.3</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, star formation rate (SFR) from 10 to 240 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> yr<jats:sup>−1</jats:sup>, and global gas-phase metallicity (<jats:inline-formula> <jats:tex-math> <?CDATA $12+\mathrm{log}({\rm{O}}/{\rm{H}})$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>12</mml:mn> <mml:mo>+</mml:mo> <mml:mi>log</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:mi mathvariant="normal">O</mml:mi> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:mi mathvariant="normal">H</mml:mi> <mml:mo stretchy="false">)</mml:mo> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjlac626fieqn1.gif" xlink:type="simple" /> </jats:inline-formula>) from 8.2 to 8.6. At 1<jats:italic>σ</jats:italic> confidence level, 2/20 galaxies in our sample show positive (inverted) gradients—the relative abundance of oxygen increasing with galactocentric radius, opposite the usual trend. Furthermore, 1/20 shows negative gradients, and 17/20 are consistent with flat gradients. This high fraction of flat/inverted gradients is uncommon in simulations and previous observations conducted in blank fields at similar redshifts. To understand this, we investigate the correlations among various observed properties of our sample galaxies. We find an anticorrelation between metallicity gradient and global metallicity of our galaxies residing in extreme overdensities, and a marked deficiency of metallicity in our massive galaxies as compared to their coeval field counterparts. We conclude that the cold-mode gas accretion plays an active role in shaping the chemical evolution of galaxies in the protocluster environments, diluting their central chemical abundance, and flattening/inverting their metallicity gradients.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report the archival discovery of Ly<jats:italic>α</jats:italic> emission from the bright ultraviolet galaxy Y002 at <jats:italic>z</jats:italic> = 7.677, spectroscopically confirmed by its ionized carbon [C <jats:sc>ii</jats:sc>] 158 <jats:italic>μ</jats:italic>m emission line. The Ly<jats:italic>α</jats:italic> line is spatially associated with the rest-frame UV stellar emission (<jats:italic>M</jats:italic> <jats:sub>UV</jats:sub> ∼ −22, 2× brighter than <jats:inline-formula> <jats:tex-math> <?CDATA ${M}_{\mathrm{UV}}^{\star }$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>UV</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⋆</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjlac62ccieqn1.gif" xlink:type="simple" /> </jats:inline-formula>), and it appears offset from the peak of the extended [C <jats:sc>ii</jats:sc>] emission at the current ∼1″ spatial resolution. We derive an estimate of the unobscured SFR<jats:sub>UV</jats:sub> = (22 ± 1) <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> yr<jats:sup>−1</jats:sup> and set an upper limit of SFR<jats:sub>IR</jats:sub> &lt; 15 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> yr<jats:sup>−1</jats:sup> from the far-infrared (FIR) wavelength range, which globally places Y002 on the SFR(UV+IR)–<jats:italic>L</jats:italic> <jats:sub>[C <jats:sc>II</jats:sc>]</jats:sub> correlation observed at lower redshifts. In terms of velocity, the peak of the Ly<jats:italic>α</jats:italic> emission is redshifted by Δ<jats:italic>v</jats:italic> <jats:sub>Ly<jats:italic>α</jats:italic> </jats:sub> ∼ 500 km s<jats:sup>−1</jats:sup> from the systemic redshift set by [C <jats:sc>ii</jats:sc>] and a high-velocity tail extends up to ∼1000 km s<jats:sup>−1</jats:sup>. The velocity offset is up to ∼3.5× higher than the average estimate for similarly UV-bright emitters at <jats:italic>z</jats:italic> ∼ 6–7, which might suggest that we are witnessing the merging of two clumps. A combination of strong outflows and the possible presence of an extended ionized bubble surrounding Y002 would likely facilitate the escape of copious Ly<jats:italic>α</jats:italic> light, as indicated by the large equivalent width EW<jats:sub>0</jats:sub>(Ly<jats:italic>α</jats:italic>)<jats:inline-formula> <jats:tex-math> <?CDATA $\,=\,{24}_{-6}^{+5}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mspace width="0.50em" /> <mml:mo>=</mml:mo> <mml:mspace width="0.50em" /> <mml:msubsup> <mml:mrow> <mml:mn>24</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>6</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>5</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjlac62ccieqn2.gif" xlink:type="simple" /> </jats:inline-formula> Å. Assuming that [C <jats:sc>ii</jats:sc>] traces the neutral hydrogen, we estimate a H <jats:sc>i</jats:sc> gas fraction of <jats:italic>M</jats:italic> <jats:sub>H I</jats:sub>/<jats:italic>M</jats:italic> <jats:sub>⋆</jats:sub> ≳ 8 for Y002 as a system and speculate that patches of high H <jats:sc>i</jats:sc> column densities could contribute to explaining the observed spatial offsets between Ly<jats:italic>α-</jats:italic> and [C <jats:sc>ii</jats:sc>]-emitting regions. The low dust content, implied by the nondetection of the FIR continuum emission at rest frame ∼160 <jats:italic>μ</jats:italic>m, would be sufficient to absorb any potential Ly<jats:italic>α</jats:italic> photons produced within the [C <jats:sc>ii</jats:sc>] clump as a result of large H <jats:sc>i</jats:sc> column densities.</jats:p>