Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>We present a recent Atacama Large Millimeter/submillimeter Array observation of the CO(1−0) line emission in the central galaxy of the Zw 3146 galaxy cluster (<jats:italic>z</jats:italic> = 0.2906). We also present updated X-ray cavity measurements from archival Chandra observations. The 5 × 10<jats:sup>10</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> supply of molecular gas, which is confined to the central 4 kpc, is marginally resolved into three extensions that are reminiscent of the filaments observed in similar systems. No velocity structure that would be indicative of ordered motion is observed. The three molecular extensions all trail X-ray cavities, and are potentially formed from the condensation of intracluster gas lifted in the wakes of the rising bubbles. Many cycles of feedback would be required to account for the entire molecular gas reservoir. The molecular gas and continuum source are mutually offset by 2.6 kpc, with no detected line emission coincident with the continuum source. It is the molecular gas, not the continuum source, that lies at the gravitational center of the brightest cluster galaxy. As the brightest cluster galaxy contains possible tidal features, the displaced continuum source may correspond to the nucleus of a merging galaxy. We also discuss the possibility that a gravitational wave recoil following a black hole merger may account for the displacement.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The estimation of spectroscopic and photometric redshifts (spec-<jats:italic>z</jats:italic> and photo-<jats:italic>z</jats:italic>) is crucial for future cosmological surveys. It can directly affect several powerful measurements of the universe, such as weak lensing and galaxy clustering. In this work, we explore the accuracies of spec-<jats:italic>z</jats:italic> and photo-<jats:italic>z</jats:italic> that can be obtained by the China Space Station Optical Surveys, which is a next-generation space survey, using a neural network. The one-dimensional Convolutional Neural Networks and Multi-Layer Perceptron (MLP, the simplest form of an artificial neural network) are employed to derive spec-<jats:italic>z</jats:italic> and photo-<jats:italic>z</jats:italic>, respectively. The mock spectral and photometric data used for training and testing the networks are generated based on the COSMOS catalog. The networks have been trained with noisy data by creating Gaussian random realizations to reduce the statistical effects, resulting in a similar redshift accuracy for data with both high and low signal-to-noise ratios. The probability distribution functions of the predicted redshifts are also derived via Gaussian random realizations of the testing data, and then the best-fit redshifts and 1<jats:italic>σ</jats:italic> errors also can be obtained. We find that our networks can provide excellent redshift estimates with accuracies of ∼0.001 and 0.01 on spec-<jats:italic>z</jats:italic> and photo-<jats:italic>z</jats:italic>, respectively. Compared to existing photo-<jats:italic>z</jats:italic> codes, our MLP has a similar accuracy but is more efficient in the training process. The fractions of catastrophic redshifts or outliers can be dramatically suppressed compared to the ordinary template-fitting method. This indicates that the neural network method is feasible and powerful for spec-<jats:italic>z</jats:italic> and photo-<jats:italic>z</jats:italic> estimations in future cosmological surveys.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Some observations of warm carbon-chain chemistry (WCCC) cores indicate that they are often located near the edges of molecular clouds. This finding may suggest that WCCC is promoted in star-forming cores exposed to radiation from the interstellar medium. We aim to investigate the chemistry of carbon chains in such a core. A chemical simulation of a gas parcel in a low-mass star-forming core with a full level of irradiation by interstellar photons and cosmic rays was compared to a simulation of a core receiving only 1/10 of such irradiation. In the full irradiation model, the abundances of carbon chains were found to be higher by a factor of a few to a few hundred, compared to the model with low irradiation. Higher carbon-chain abundances in the prestellar stage and, presumably, in the extended circumstellar envelope arise because of irradiation of gas and dust by interstellar photons and cosmic rays. A full standard rate of cosmic-ray-induced ionization is essential for a high carbon-chain abundance peak to occur in the circumstellar envelope, which is heated by the protostar (the “true” WCCC phenomenon). The full irradiation model has lower abundances of complex organic molecules than the low-irradiation model. We conclude that WCCC can be caused by exposure of a star-forming core to interstellar radiation, or even just to cosmic rays. The Appendix describes an updated accurate approach for calculating the rate of cosmic-ray-induced desorption.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>A highly important aspect of solar activity is the coupling between eruptions and the surrounding coronal magnetic field topology, which determines the trajectory and morphology of the event and can even lead to sympathetic eruptions from multiple sources. In this paper, we report on a numerical simulation of a new type of coupled eruption, in which a coronal jet initiated by a large pseudostreamer filament eruption triggers a streamer-blowout coronal mass ejection (CME) from the neighboring helmet streamer. Our configuration has a large opposite-polarity region positioned between the polar coronal hole and a small equatorial coronal hole, forming a pseudostreamer flanked by the coronal holes and the helmet streamer. Further out, the pseudostreamer stalk takes the shape of an extended arc in the heliosphere. We energize the system by applying photospheric shear along a section of the polarity inversion line within the pseudostreamer. The resulting sheared-arcade filament channel develops a flux rope that eventually erupts as a classic coronal-hole-type jet. However, the enhanced breakout reconnection above the channel as the jet is launched progresses into the neighboring helmet streamer, partially launching the jet along closed helmet streamer field lines and blowing out the streamer top to produce a classic bubble-like CME. This CME is strongly deflected from the jet’s initial trajectory and contains a mixture of open and closed magnetic field lines. We present the detailed dynamics of this new type of coupled eruption, its underlying mechanisms, and the implications of this work for the interpretation of in situ and remote-sensing observations.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The detection of phosphorous-bearing molecules in interstellar environments constitutes a fundamental task for understanding the formation of prebiotic molecules, but it is also a challenge. In cold interstellar environments, where rich chemistry is expected to happen, only PN and PO have been detected. Phosphine (PH<jats:sub>3</jats:sub>) must also play an essential role in these regions, since P is expected to deplete onto dust grains significantly, and hydrogenation reactions are dominant in such environments. Surface chemistry on dust grains shows a particular idiosyncrasy where an equilibrium between competitive reactions, photoconversion processes, and desorption are in continuous interplay, modifying both the dust composition and the gas composition. In this study, we theoretically study in detail the interconversion of P to PH<jats:sub>3</jats:sub> via subsequent additions of H on cold dust grain analogs. For all reactions, we provide the binding energy of the adsorbates, reaction energies, and, when present, activation barriers and tunneling-corrected rate constants. We also present an estimate of the desorption temperature of these species based on transition state theory. Using recently available experimental results on PH<jats:sub>3</jats:sub> desorption via chemical reactions, we conclude that all of the intermediate products of the hydrogenation sequence to phosphine may be released to the gas phase.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Infrared observations probe the warm gas in the inner regions of planet-forming disks around young Sun-like T Tauri stars. In these systems, H<jats:sub>2</jats:sub>O, OH, CO, CO<jats:sub>2</jats:sub>, C<jats:sub>2</jats:sub>H<jats:sub>2</jats:sub>, and HCN have been widely observed. However, the potentially abundant carbon carrier CH<jats:sub>4</jats:sub> remains largely unconstrained. The James Webb Space Telescope (JWST) will be able to characterize mid-infrared fluxes of CH<jats:sub>4</jats:sub> along with several other carriers of carbon and oxygen. In anticipation of the JWST mission, we model the physical and chemical structure of a T Tauri disk to predict the abundances and mid-infrared fluxes of observable molecules. A range of compositional scenarios are explored involving the destruction of refractory carbon materials and alterations to the total elemental (volatile and refractory) C/O ratio. Photon-driven chemistry in the inner disk surface layers largely destroys the initial carbon and oxygen carriers. This causes models with the same physical structure and C/O ratio to have similar steady-state surface compositions, regardless of the initial chemical abundances. Initial disk compositions are better preserved in the shielded inner disk midplane. The degree of similarity between the surface and midplane compositions in the inner disk will depend on the characteristics of vertical mixing at these radii. Our modeled fluxes of observable molecules respond sensitively to changes in the disk gas temperature, inner radius, and total elemental C/O ratio. As a result, mid-infrared observations of disks will be useful probes of these fundamental disk parameters, including the C/O ratio, which can be compared to values determined for planetary atmospheres.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We investigate the mass–velocity dispersion relation (MVDR) in 29 galaxy clusters in the HIghest X-ray FLUx Galaxy Cluster Sample (HIFLUGCS). We measure the spatially resolved, line-of-sight velocity dispersion profiles of these clusters, which we find to be mostly flat at large radii, reminiscent of the rotation curves of galaxies. We discover a tight empirical relation between the baryonic mass <jats:italic>M</jats:italic> <jats:sub>bar</jats:sub> and the flat velocity dispersion <jats:italic>σ</jats:italic> of the member galaxies, i.e., MVDR, <jats:inline-formula> <jats:tex-math> <?CDATA $\mathrm{log}({M}_{\mathrm{bar}}/{M}_{\odot })={4.1}_{-0.4}^{+0.4}\,\mathrm{log}(\sigma /\mathrm{km}\,{{\rm{s}}}^{-1})+{1.6}_{-1.3}^{+1.0}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>bar</mml:mi> </mml:mrow> </mml:msub> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> <mml:mo stretchy="false">)</mml:mo> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>4.1</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.4</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.4</mml:mn> </mml:mrow> </mml:msubsup> <mml:mspace width="0.25em" /> <mml:mi>log</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:mi>σ</mml:mi> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:mi>km</mml:mi> <mml:mspace width="0.25em" /> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">s</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> <mml:mo stretchy="false">)</mml:mo> <mml:mo>+</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>1.6</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1.3</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>1.0</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabe45cieqn1.gif" xlink:type="simple" /> </jats:inline-formula>, with the lognormal intrinsic scatter of <jats:inline-formula> <jats:tex-math> <?CDATA ${12}_{-3}^{+3} \% $?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>12</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>3</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>3</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo>%</mml:mo> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabe45cieqn2.gif" xlink:type="simple" /> </jats:inline-formula>. The residuals of the MVDR are uncorrelated with other cluster properties like temperature, cluster radius, baryonic mass surface density, and redshift. These characteristics are reminiscent of the MVDR for individual galaxies, albeit at about a ten times larger characteristic acceleration scale. The cluster baryon fraction falls short of the cosmic value, exposing a problem: the discrepancy increases systematically for clusters of lower mass and lower baryonic acceleration.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We study the carbon monoxide (CO) excitation, mean molecular gas density, and interstellar radiation field (ISRF) intensity in a comprehensive sample of 76 galaxies from local to high redshift (<jats:italic>z</jats:italic> ∼ 0–6), selected based on detections of their CO transitions <jats:italic>J</jats:italic> = 2 → 1 and 5 → 4 and their optical/infrared/(sub)millimeter spectral energy distributions (SEDs). We confirm the existence of a tight correlation between CO excitation as traced by the CO (5–4)<jats:italic>/</jats:italic>(2–1) line ratio <jats:italic>R</jats:italic> <jats:sub>52</jats:sub> and the mean ISRF intensity <jats:inline-formula> <jats:tex-math> <?CDATA $\left\langle U\right\rangle $?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mfenced close="〉" open="〈"> <mml:mrow> <mml:mi>U</mml:mi> </mml:mrow> </mml:mfenced> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabd801ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> as derived from infrared SED fitting using dust SED templates. By modeling the molecular gas density probability distribution function (PDF) in galaxies and predicting CO line ratios with large velocity gradient radiative transfer calculations, we present a framework linking global CO line ratios to the mean molecular hydrogen gas density <jats:inline-formula> <jats:tex-math> <?CDATA $\left\langle {n}_{{{\rm{H}}}_{2}}\right\rangle $?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mfenced close="〉" open="〈"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>n</mml:mi> </mml:mrow> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">H</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> </mml:msub> </mml:mrow> </mml:mfenced> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabd801ieqn2.gif" xlink:type="simple" /> </jats:inline-formula> and kinetic temperature <jats:italic>T</jats:italic> <jats:sub>kin</jats:sub>. Mapping in this way observed <jats:italic>R</jats:italic> <jats:sub>52</jats:sub> ratios to <jats:inline-formula> <jats:tex-math> <?CDATA $\left\langle {n}_{{{\rm{H}}}_{2}}\right\rangle $?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mfenced close="〉" open="〈"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>n</mml:mi> </mml:mrow> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">H</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> </mml:msub> </mml:mrow> </mml:mfenced> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabd801ieqn3.gif" xlink:type="simple" /> </jats:inline-formula> and <jats:italic>T</jats:italic> <jats:sub>kin</jats:sub> probability distributions, we obtain positive <jats:inline-formula> <jats:tex-math> <?CDATA $\left\langle U\right\rangle $?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mfenced close="〉" open="〈"> <mml:mrow> <mml:mi>U</mml:mi> </mml:mrow> </mml:mfenced> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabd801ieqn4.gif" xlink:type="simple" /> </jats:inline-formula>–<jats:inline-formula> <jats:tex-math> <?CDATA $\left\langle {n}_{{{\rm{H}}}_{2}}\right\rangle $?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mfenced close="〉" open="〈"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>n</mml:mi> </mml:mrow> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">H</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> </mml:msub> </mml:mrow> </mml:mfenced> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabd801ieqn5.gif" xlink:type="simple" /> </jats:inline-formula> and <jats:inline-formula> <jats:tex-math> <?CDATA $\left\langle U\right\rangle $?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mfenced close="〉" open="〈"> <mml:mrow> <mml:mi>U</mml:mi> </mml:mrow> </mml:mfenced> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabd801ieqn6.gif" xlink:type="simple" /> </jats:inline-formula>–<jats:italic>T</jats:italic> <jats:sub>kin</jats:sub> correlations, which imply a scenario in which the ISRF in galaxies is mainly regulated by <jats:italic>T</jats:italic> <jats:sub>kin</jats:sub> and (nonlinearly) by <jats:inline-formula> <jats:tex-math> <?CDATA $\left\langle {n}_{{{\rm{H}}}_{2}}\right\rangle $?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mfenced close="〉" open="〈"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>n</mml:mi> </mml:mrow> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">H</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> </mml:msub> </mml:mrow> </mml:mfenced> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabd801ieqn7.gif" xlink:type="simple" /> </jats:inline-formula>. A small fraction of starburst galaxies showing enhanced <jats:inline-formula> <jats:tex-math> <?CDATA $\left\langle {n}_{{{\rm{H}}}_{2}}\right\rangle $?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mfenced close="〉" open="〈"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>n</mml:mi> </mml:mrow> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">H</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> </mml:msub> </mml:mrow> </mml:mfenced> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabd801ieqn8.gif" xlink:type="simple" /> </jats:inline-formula> could be due to merger-driven compaction. Our work demonstrates that ISRF and CO excitation are tightly coupled and that density–PDF modeling is a promising tool for probing detailed ISM properties inside galaxies.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We study the mass–metallicity relation for 19 members of a spectroscopically confirmed protocluster in the COSMOS field at <jats:italic>z</jats:italic> = 2.2 (CC2.2), and compare it with that of 24 similarly selected field galaxies at the same redshift. Both samples are H<jats:italic>α</jats:italic> emitting sources, chosen from the HiZELS narrowband survey, with metallicities derived from the <jats:inline-formula> <jats:tex-math> <?CDATA ${\rm{N}}2\ \left(\tfrac{[\mathrm{NII}]\lambda 6584}{{\rm{H}}\alpha }\right)$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="normal">N</mml:mi> <mml:mn>2</mml:mn> <mml:mspace width="0.33em" /> <mml:mfenced close=")" open="("> <mml:mrow> <mml:mstyle displaystyle="false"> <mml:mfrac> <mml:mrow> <mml:mo stretchy="false">[</mml:mo> <mml:mi>NII</mml:mi> <mml:mo stretchy="false">]</mml:mo> <mml:mi>λ</mml:mi> <mml:mn>6584</mml:mn> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">H</mml:mi> <mml:mi>α</mml:mi> </mml:mrow> </mml:mfrac> </mml:mstyle> </mml:mrow> </mml:mfenced> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjabe5a3ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> line ratio. For the mass-matched samples of protocluster and field galaxies, we find that protocluster galaxies with 10<jats:sup>9.9</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> ≤ <jats:italic>M</jats:italic> <jats:sub>*</jats:sub> ≤ 10<jats:sup>10.9</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> are metal deficient by 0.10 ± 0.04 dex (2.5<jats:italic>σ</jats:italic> significance) compared to their coeval field galaxies. This metal deficiency is absent for low-mass galaxies, <jats:italic>M</jats:italic> <jats:sub>*</jats:sub> &lt; 10<jats:sup>9.9</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub>. Moreover, relying on both spectral energy distribution derived and H<jats:italic>α</jats:italic> (corrected for dust extinction based on M<jats:sub>*</jats:sub>) star formation rates (SFRs), we find no strong environmental dependence of the SFR–<jats:italic>M</jats:italic> <jats:sub>*</jats:sub> relation; however, we are not able to rule out the existence of small dependence due to inherent uncertainties in both SFR estimators. The existence of 2.5<jats:italic>σ</jats:italic> significant metal deficiency for massive protocluster galaxies favors a model in which funneling of the primordial cold gas through filaments dilutes the metal content of protoclusters at high redshifts (<jats:italic>z</jats:italic> ≳ 2). At these redshifts, gas reservoirs in filaments are dense enough to cool down rapidly and fall into the potential well of the protocluster to lower the gas-phase metallicity of galaxies. Moreover, part of this metal deficiency could be originated from galaxy interactions that are more prevalent in dense environments.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) images the full solar disk in several extreme-ultraviolet (EUV) bands that are each sensitive to coronal plasma emissions of one or more specific temperatures. We observe that when isolated active regions (ARs) are on the disk, full-disk images in some of the coronal EUV channels show the outskirts of the AR as a dark moat surrounding the AR. Here we present seven specific examples, selected from time periods when there was only a single AR present on the disk. Visually, we observe the moat to be most prominent in the AIA 171 Å band, which has the most sensitivity to emission from plasma at log<jats:sub>10</jats:sub> <jats:italic>T</jats:italic> = 5.8. By examining the 1D line-of-sight emission measure temperature distribution found from six AIA EUV channels, we find the intensity of the moat to be most depressed over the temperature range log<jats:sub>10</jats:sub> <jats:italic>T</jats:italic> ≈ 5.7–6.2 for most of the cases. We argue that the dark moat exists because the pressure from the strong magnetic field that splays out from the AR presses down on underlying magnetic loops, flattening those loops—along with the lowest of the AR’s own loops over the moat—to a low altitude. Those loops, which would normally emit the bulk of the 171 Å emission, are restricted to heights above the surface that are too low to have 171 Å emitting plasmas sustained in them, according to Antiochos &amp; Noci, while hotter EUV-emitting plasmas are sustained in the overlying higher-altitude long AR-rooted coronal loops. This potentially explains the low-coronal-temperature dark moats surrounding the ARs.</jats:p>