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<jats:title>Abstract</jats:title> <jats:p>Water-rich exoplanets are a type of terrestrial planet that is water-rich and whose ocean depth can reach tens to hundreds of kilometers with no exposed continents. Due to the lack of exposed continents, neither western boundary current nor coastal upwelling exists, and ocean overturning circulation becomes the most important way to return the nutrients deposited in the deep ocean back to the thermocline and to the surface ocean. Here we investigate the depth of the thermocline in both wind-dominated and mixing-dominated systems on water-rich exoplanets using the global ocean model MITgcm. We find that the wind-driven circulation is dominated by overturning cells through Ekman pumping and subduction and by zonal (west–east) circum-longitudinal currents, similar to the Antarctic Circumpolar Current on Earth. The wind-influenced thermocline depth shows little dependence on the ocean depth, and under a large range of parameters, the thermocline is restricted within the upper layers of the ocean. The mixing-influenced thermocline is limited within the upper 10 km of the ocean and cannot reach the bottom of the ocean even under extremely strong vertical mixing. The scaling theories for the thermocline depth on Earth are applicable for the thermocline depth on water-rich exoplanets. However, due to the lack of exposed continents, the zonal and meridional flow speeds are not in the same magnitude as that in the oceans of Earth, which results in scaling relationships for water-rich exoplanets being a little different from that used on Earth.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The outer atmosphere of the Sun is composed of plasma heated to temperatures well in excess of the visible surface. We investigate short cool and warm (&lt;1 MK) loops seen in the core of an active region to address the role of field-line braiding in energizing these structures. We report observations from the High-resolution Coronal imager (Hi-C) that have been acquired in a coordinated campaign with the Interface Region Imaging Spectrograph (IRIS). In the core of the active region, the 172 Å band of Hi-C and the 1400 Å channel of IRIS show plasma loops at different temperatures that run in parallel. There is a small but detectable spatial offset of less than 1″ between the loops seen in the two bands. Most importantly, we do not see observational signatures that these loops might be twisted around each other. Considering the scenario of magnetic braiding, our observations of parallel loops imply that the stresses put into the magnetic field have to relax while the braiding is applied: the magnetic field never reaches a highly braided state on these length scales comparable to the separation of the loops. This supports recent numerical 3D models of loop braiding in which the effective dissipation is sufficiently large that it keeps the magnetic field from getting highly twisted within a loop.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>An extensive exploration of the model parameter space of axisymmetric early type galaxies (ETGs) hosting a central supermassive black hole (SMBH) is conducted by means of high-resolution hydrodynamical simulations performed with our code MACER. Global properties such as (1) total SMBH accreted mass, (2) final X-ray luminosity and temperature of the X-ray emitting halos, (3) total amount of new stars formed from the cooling gas, and (4) total ejected mass in the form of supernovae and active galactic nuclei (AGN) feedback induced galactic winds, are obtained as a function of galaxy structure and internal dynamics. In addition to the galactic dark matter halo, the model galaxies are also embedded in a group/cluster dark matter halo; finally, cosmological accretion is also included, with the amount and time dependence derived from cosmological simulations. Angular momentum conservation leads to the formation of cold H <jats:sc>i</jats:sc> disks; these disks further evolve under the action of star formation induced by disk instabilities, of the associated mass discharge onto the central SMBH, and of the consequent AGN feedback. At the end of the simulations, the hot (metal-enriched) gas mass is roughly 10% the mass in the old stars, with twice as much having been ejected into the intergalactic medium. The cold gas disks are approximately kiloparsec in size, and the metal-rich new stars are in 0.1 kpc disks. The masses of cold gas and new stars are roughly 0.1% of the mass of the old stars. Overall, the final systems appear to reproduce quite successfully the main global properties of real ETGs.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Photometric pipelines struggle to estimate both the flux and flux uncertainty for stars in the presence of structured backgrounds such as filaments or clouds. However, it is exactly stars in these complex regions that are critical to understanding star formation and the structure of the interstellar medium. We develop a method, similar to Gaussian process regression, which we term local pixel-wise infilling (LPI). Using a local covariance estimate, we predict the background behind each star and the uncertainty of that prediction in order to improve estimates of flux and flux uncertainty. We show the validity of our model on synthetic data and real dust fields. We further demonstrate that the method is stable even in the crowded field limit. While we focus on optical-IR photometry, this method is not restricted to those wavelengths. We apply this technique to the 34 billion detections in the second data release of the Dark Energy Camera Plane Survey. In addition to removing many &gt;3<jats:italic>σ</jats:italic> outliers and improving uncertainty estimates by a factor of ∼2–3 on nebulous fields, we also show that our method is well behaved on uncrowded fields. The entirely post-processing nature of our implementation of LPI photometry allows it to easily improve the flux and flux uncertainty estimates of past as well as future surveys.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Dust emission at 8 <jats:italic>μ</jats:italic>m has been extensively calibrated as an indicator of current star formation rate for galaxies and ∼kpc-size regions within galaxies. Yet, the exact link between the 8 <jats:italic>μ</jats:italic>m emission and the young stellar populations in galaxies is still under question, as dust grains can be stochastically heated also by older field stars. In order to investigate this link, we have combined midinfrared images from the Spitzer Space Telescope with a published star cluster candidates catalog for the Local Group galaxy M33. M33 is sufficiently close that the Spitzer's 8 <jats:italic>μ</jats:italic>m images resolve individual regions of star formation. Star clusters represent almost-single-age stellar populations, which are significantly easier to model than more complex mixtures of stars. We find a decrease in the 8 <jats:italic>μ</jats:italic>m luminosity per unit stellar mass as a function of age of the star clusters, with a large scatter that is consistent with varying fractions of stellar light absorbed by dust. The decrease and scatter both confirm findings based on more distant galaxies and are well described by simple models for the dust emission of a young stellar population. We conclude that the dust emission at 8 <jats:italic>μ</jats:italic>m depends sensitively on the age of the stellar population, out to at least the oldest age analyzed here: ∼400 Myr. This dependence complicates the use of the 8 <jats:italic>μ</jats:italic>m emission as a star formation rate indicator, at least for small galactic regions and individual star-forming regions. By leveraging the Spitzer legacy, this investigation paves the way for future explorations with the James Webb Space Telescope.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report new H <jats:sc>i</jats:sc> observations of the Type Ia supernova remnant (SNR) SN 1006 using the Australia Telescope Compact Array with an angular resolution of <jats:inline-formula> <jats:tex-math> <?CDATA $4\buildrel{\,\prime}\over{.} 5\times 1\buildrel{\,\prime}\over{.} 4$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>4</mml:mn> <mml:mo>.′</mml:mo> <mml:mn>5</mml:mn> <mml:mo>×</mml:mo> <mml:mn>1</mml:mn> <mml:mo>.′</mml:mo> <mml:mn>4</mml:mn> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac7465ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> (∼2 pc at the assumed SNR distance of 2.2 kpc). We find an expanding gas motion in position–velocity diagrams of H <jats:sc>i</jats:sc> with an expansion velocity of ∼4 km s<jats:sup>−1</jats:sup> and a mass of ∼1000 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>. The spatial extent of the expanding shell is roughly the same as that of SN 1006. We here propose a hypothesis that SN 1006 exploded inside the wind-blown bubble formed by accretion winds from the progenitor system consisting of a white dwarf and a companion star, and then the forward shock has already reached the wind wall. This scenario is consistent with the single-degenerate model. We also derived the total energy of cosmic-ray protons <jats:italic>W</jats:italic> <jats:sub>p</jats:sub> to be only ∼1.2–2.0 × 10<jats:sup>47</jats:sup> erg by adopting the averaged interstellar proton density of ∼25 cm<jats:sup>−3</jats:sup>. The small value is compatible with the relation between the age and <jats:italic>W</jats:italic> <jats:sub>p</jats:sub> of other gamma-ray SNRs with ages below ∼6 kyr. The <jats:italic>W</jats:italic> <jats:sub>p</jats:sub> value in SN 1006 will possibly increase up to several 10<jats:sup>49</jats:sup> erg in the next ∼5 kyr via the cosmic-ray diffusion into the H <jats:sc>i</jats:sc> wind shell.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We analyze the <jats:inline-formula> <jats:tex-math> <?CDATA ${}_{55}^{134}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow /> <mml:mrow> <mml:mn>55</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>134</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac74b3ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>Cs<jats:inline-formula> <jats:tex-math> <?CDATA $\,{\to \,}_{56}^{134}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mspace width="0.10em" /> <mml:msubsup> <mml:mrow> <mml:mo>→</mml:mo> <mml:mspace width="0.10em" /> </mml:mrow> <mml:mrow> <mml:mn>56</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>134</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac74b3ieqn2.gif" xlink:type="simple" /> </jats:inline-formula>Ba and <jats:inline-formula> <jats:tex-math> <?CDATA ${}_{55}^{135}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow /> <mml:mrow> <mml:mn>55</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>135</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac74b3ieqn3.gif" xlink:type="simple" /> </jats:inline-formula>Cs <jats:inline-formula> <jats:tex-math> <?CDATA ${\to }_{\,56}^{\,135}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mo>→</mml:mo> </mml:mrow> <mml:mrow> <mml:mspace width="0.25em" /> <mml:mn>56</mml:mn> </mml:mrow> <mml:mrow> <mml:mspace width="0.15em" /> <mml:mn>135</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjac74b3ieqn4.gif" xlink:type="simple" /> </jats:inline-formula>Ba <jats:italic>β</jats:italic> <jats:sup>−</jats:sup> decays, which are crucial production channels for Ba isotopes in asymptotic giant branch (AGB) stars. We calculate, starting from relativistic quantum mechanics, the effects of multichannel scattering onto weak decays, including nuclear and electronic excited states (ESs) populated above ≃10 keV, for both parent and daughter nuclei. We find increases in the half-lives for <jats:italic>T</jats:italic> &gt; 10<jats:sup>8</jats:sup> K (by more than a factor of 3 for <jats:sup>134</jats:sup>Cs) as compared to previous works based on systematics. We also discuss our method in view of these previous calculations. An important impact on half-lives comes from nuclear ES decays, while including electronic temperatures yields further increases of about 20% at energies of 10–30 keV, typical of AGB stars of moderate mass (<jats:italic>M</jats:italic> ≲ 8 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>). Despite properly considering these effects, the new rates remain sensitively lower than the Takahashi &amp; Yokoi values, implying longer half-lives at least above 8–9 keV. Our rate predictions are in substantial accord with recent results based on the shell model, and strongly modify branching ratios along the <jats:italic>s</jats:italic>-process path previously adopted. With our new rate, nucleosynthesis models well account for the isotopic admixtures of Ba in presolar SiC grains and in the Sun.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We report the discovery of three millisecond pulsars (MSPs): PSRs J1120−3618, J1646−2142, and J1828+0625 with the Giant Metrewave Radio Telescope (GMRT) at a frequency of 322 MHz using a 32 MHz observing bandwidth. These sources were discovered serendipitously while conducting the deep observations to search for millisecond radio pulsations in the directions of unidentified Fermi Large Area Telescope (LAT) <jats:italic>γ</jats:italic>-ray sources. We also present phase coherent timing models for these MSPs using ∼5 yr of observations with the GMRT. PSR J1120−3618 has a 5.5 ms spin period and is in a binary system with an orbital period of 5.6 days and minimum companion mass of 0.18 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>, PSR J1646−2142 is an isolated object with a spin period of 5.8 ms, and PSR J1828+0625 has a spin period of 3.6 ms and is in a binary system with an orbital period of 77.9 days and minimum companion mass of 0.27 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>. The two binaries have very low orbital eccentricities, in agreement with expectations for MSP-helium white dwarf systems. Using the GMRT 607 MHz receivers having a 32 MHz bandwidth, we have also detected PSR J1646−2142 and PSR J1828+0625, but not PSR J1120−3618. PSR J1646−2142 has a wide profile, with significant evolution between 322 and 607 MHz, whereas PSR J1120−3618 exhibits a single peaked profile at 322 MHz and PSR J1828+0625 exhibits a single peaked profile at both the observing frequencies. These MSPs do not have <jats:italic>γ</jats:italic>-ray counterparts, indicating that these are not associated with the target Fermi LAT pointing emphasizing the significance of deep blind searches for MSPs.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Thirteen dwarf galaxies have recently been found to host radio-selected accreting massive black hole (MBH) candidates, some of which are “wandering” in the outskirts of their hosts. We present 9 GHz Very Long Baseline Array (VLBA) observations of these sources at milliarcsecond resolution. Our observations have beam solid angles ∼10<jats:sup>4</jats:sup> times smaller than the previous Very Large Array (VLA) observations at 9 GHz, with comparable point-source sensitivities. We detect milliarcsecond-scale radio sources at the positions of the four VLA sources most distant from the photocenters of their associated dwarf galaxies. These sources have brightness temperatures of &gt;10<jats:sup>6</jats:sup> K, consistent with active galactic nuclei (AGNs), but the significance of their preferential location at large distances (<jats:italic>p</jats:italic>-value = 0.0014) favors a background AGN interpretation. The VLBA nondetections toward the other nine galaxies indicate that the VLA sources are resolved out on scales of tens of milliarcseconds, requiring extended radio emission and lower brightness temperatures consistent with either star formation or radio lobes associated with AGN activity. We explore the star formation explanation by calculating the expected radio emission for these nine VLBA nondetections, finding that about five have VLA luminosities that are inconsistent with this scenario. Of the remaining four, two are associated with spectroscopically confirmed AGNs that are consistent with being located at their galaxy photocenters. There are therefore between five and seven wandering MBH candidates out of the 13 galaxies we observed, although we cannot rule out background AGNs for five of them with the data in hand.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We investigate the spatial distribution of the satellites of isolated host galaxies in the IllustrisTNG100 simulation. In agreement with a previous, similar analysis of the Illustris-1 simulation, the satellites are typically poor tracers of the mean host mass density. Unlike the Illustris-1 satellites, here the spatial distribution of the complete satellite sample is well fitted by an NFW profile; however, the concentration is a factor of ∼2 lower than that of the mean host mass density. The spatial distributions of the brightest 50% and faintest 50% of the satellites are also well fitted by NFW profiles, but the concentrations differ by a factor of ∼2. When the sample is subdivided by host color and luminosity, the number density profiles for blue satellites generally fall below the mean host mass density profiles, while the number density profiles for red satellites generally rise above the mean host mass density profiles. These opposite, systematic offsets combine to yield a moderately good agreement between the mean mass density profile of the brightest blue hosts and the corresponding number density profile of their satellites. Lastly, we subdivide the satellites according to the redshifts at which they joined their hosts. From this, we find that neither the oldest one-third of the satellites nor the youngest one-third of the satellites faithfully trace the mean host mass density.</jats:p>