beecee Posted November 30, 2018 Posted November 30, 2018 https://phys.org/news/2018-11-black-hole-donuts-fountains.html Black hole 'donuts' are actually 'fountains' November 30, 2018, National Astronomical Observatory of Japan Based on computer simulations and new observations from the Atacama Large Millimeter/submillimeter Array (ALMA), researchers have found that the rings of gas surrounding active supermassive black holes are not simple donut shapes. Instead, gas expelled from the center interacts with infalling gas to create a dynamic circulation pattern, similar to a water fountain in a city park. Most galaxies host a supermassive black hole, millions or billions of times as heavy as the Sun, in their centers. Some of these black holes swallow material quite actively. But astronomers have believed that rather than falling directly into the black hole, matter instead builds up around the active black hole forming a donut structure.Artist’s impression of the gas motion around the supermassive black hole in the center of the Circinus Galaxy. The three gaseous components form the long-theorized “donut” structure: (1) a disk of infalling dense cold molecular gas, (2) outflowing hot atomic gas, and (3) gas returning to the disk. Credit: NAOJ Read more at: https://phys.org/news/2018-11-black-hole-donuts-fountains.html#jCp :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: the paper: http://iopscience.iop.org/article/10.3847/1538-4357/aae20b/meta Circumnuclear Multiphase Gas in the Circinus Galaxy. II. The Molecular and Atomic Obscuring Structures Revealed with ALMA: Abstract: We used the Atacama Large Millimeter/Submillimeter Array (ALMA) to map the CO(3–2) and [C i](1–0) lines, as well as their underlying continuum emission, from the central ~200 pc region of the Circinus galaxy that hosts the nearest type 2 Seyfert-class active galactic nucleus (AGN), with a spatial resolution of ~6–15 pc. The lines and continuum-emitting regions consist of a circumnuclear disk (CND; 74 pc × 34 pc) and spiral arms. The distribution of the continuum emission revealed a temperature-dependent dust geometry and possibly polar dust elongation in the torus region. The molecular mass of the CND is , with a beam-averaged H2 column density of ~5 × 1023 cm−2toward the AGN position, which contributes significantly to the nuclear obscuration. The [C i](1–0)/CO(3–2) ratio at the AGN position is unusually high, suggesting an X-ray-dominated region-type chemistry. We decomposed the observed velocity fields into rotational and dispersion components, and revealed a multiphase dynamic nature in the r 10 pc torus region, i.e., the diffuse atomic gas is more spatially extended along the vertical direction of the disk than the dense molecular gas. Through comparisons with our model predictions based on the radiation-driven fountain scheme, we indicate that atomic outflows are the driver of the geometrical thickness of the atomic disk. This supports the validity of the radiation-driven fountain scheme in the vicinity of this AGN, which would explain the longstanding mystery of the physical origin of the AGN torus.
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