Fountain of the galaxy seen in full glory

Astronomers have long thought that such fountains continually recycled the fuel that formed the stars of a galaxy. The new observations of ABell 2597 in Atacama's Abell 2597 reveal the first clear and convincing evidence of the simultaneous collapse and exit of gas powered by a supermassive black hole. The researchers report their observations in the last issue of the Astrophysical Journal.

"The supermassive black hole in the center of this giant galaxy acts as a mechanical" pump "in a fountain," said Grant Tremblay, an astrophysicist at the Harvard-Smithsonian Astrophysics Center in Cambridge, Massachusetts, and lead author of the newspaper. . "This is one of the first systems in which we find clear evidence of an influx of cold molecular gas to the black hole and a flow out of or out of the jets thrown by the black hole."

According to the researchers, the entire system operates via a self-regulated feedback loop. The infallible material feeds the fountain when it "drains" to the central black hole, as water enters the pump of a fountain. This infiltrant gas then causes intense activity of the black hole, which launches high velocity jets of superheated materials that spurt out of the galaxy. As it moves, this material expels gas flushes and gas streaks into the galaxy's large halo, where it eventually falls back onto the black hole, triggering the process again.

In total, about three billion solar masses of molecular gases are part of this fountain, forming a filamentous nebula that extends over the deepest 100,000 light-years of the galaxy.

In an earlier study by the same authors published in the journal Nature, researchers were able to verify the interconnection between the black hole and the galactic fountain by observing the region over a range of wavelengths or portions of the spectrum. By studying the location and movement of carbon monoxide (CO) molecules with ALMA, which gleam under millimetric light, the researchers were able to measure the movement of gas that was heading towards the black hole.

Previous data from the multi-unit spectroscopic explorer (MUSE) on ESO's very large telescope (VLT) revealed that hot ionized gases were being expelled from the galaxy – essentially the plume of the fountain. The new ALMA observations revealed clusters of cold molecular gases in the same places as the hot gas observed in previous observations.

"The unique look here is a very detailed coupled analysis of the source with the help of ALMA data and the MUSE instrument. Both facilities constitute an incredibly powerful combination," he said. said Mr. Tremblay. "ALMA has revealed the distribution and motions of cold molecular gas clouds, and MUSE has done the same for hot ionized gas."

The ALMA and MUSE data were combined with a new ultra-deep observation of the cluster by NASA's Chandra X-ray Observatory, revealing the hot phase of this fountain in exquisite detail, the researchers noted.

The observations also support the hypothesis that hot ionized and cold molecular nebulae are only one and the same, the hot ionized gas is only the "shell" around the cold molecular nuclei that disintegrate in this fountain at the scale of the galaxy.

This multi-wavelength approach offers an unusual picture of this system. "It's like watching both the rain cloud, the rain and the puddle of water," noted Tremblay. Although it is only an observation of a galaxy, astronomers speculate that they may be observing a process common to these galaxies and fundamental to their evolution.

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More information:
G. R. Tremblay et al, A fountain of cold molecular gas pumped by a black hole on the scale of a galaxy, The astrophysical journal (2018). DOI: 10.3847 / 1538-4357 / aad6dd