Starship Asterisk*

ESO’s MUSE instrument on the VLT discovers new way to fuel black holes

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Observations of “Jellyfish galaxies” with ESO’s Very Large Telescope have revealed a previously unknown way to fuel supermassive black holes. It seems the mechanism that produces the tentacles of gas and newborn stars that give these galaxies their nickname also makes it possible for the gas to reach the central regions of the galaxies, feeding the black hole that lurks in each of them and causing it to shine brilliantly. The results appeared today in the journal Nature.

An Italian-led team of astronomers used the MUSE (Multi-Unit Spectroscopic Explorer) instrument on the Very Large Telescope (VLT) at ESO’s Paranal Observatory in Chile to study how gas can be stripped from galaxies. They focused on extreme examples of jellyfish galaxies in nearby galaxy clusters, named after the remarkable long “tentacles” of material that extend for tens of thousands of light-years beyond their galactic discs [1][2].

The tentacles of jellyfish galaxies are produced in galaxy clusters by a process called ram pressure stripping. Their mutual gravitational attraction causes galaxies to fall at high speed into galaxy clusters, where they encounter a hot, dense gas which acts like a powerful wind, forcing tails of gas out of the galaxy’s disc and triggering starbursts within it.

Six out of the seven jellyfish galaxies in the study were found to host a supermassive black hole at the centre, feeding on the surrounding gas [3]. This fraction is unexpectedly high — among galaxies in general the fraction is less than one in ten. ...

Examples of Jellyfish Galaxies: JW206 (above), JO204 (top right), and JW100 (bottom right) ~ Credit: ESO / GASP Collaboration

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GASP (GAs Stripping Phenomena in galaxies with MUSE)

geckzilla wrote:
I have to say I find this particular galaxy type to be quite interesting and attractive.

Six out of the seven jellyfish galaxies in the study were found to host a supermassive black hole at the centre, feeding on the surrounding gas [3]. This fraction is unexpectedly high — among galaxies in general the fraction is less than one in ten. ...

https://www.eso.org/public/unitedkingdom/news/eso1725/
Six out of the seven jellyfish galaxies in the study were found to host a supermassive black hole at the centre, feeding on the surrounding gas [3]. This fraction is unexpectedly high — among galaxies in general the fraction is less than one in ten.

“This strong link between ram pressure stripping and active black holes was not predicted and has never been reported before,” said team leader Bianca Poggianti from the INAF-Astronomical Observatory of Padova in Italy. “It seems that the central black hole is being fed because some of the gas, rather than being removed, reaches the galaxy centre.” [4]

A long-standing question is why only a small fraction of supermassive black holes at the centres of galaxies are active. Supermassive black holes are present in almost all galaxies, so why are only a few accreting matter and shining brightly? These results reveal a previously unknown mechanism by which the black holes can be fed.

geckzilla wrote:I have to say I find this particular galaxy type to be quite interesting and attractive.

MargaritaMc wrote:
This puzzled me

Six out of the seven jellyfish galaxies in the study were found to host a supermassive black hole at the centre, feeding on the surrounding gas. This fraction is unexpectedly high — among galaxies in general the fraction is less than one in ten. ...

Obviously, what is meant is an Active Galactic Nucleus not simply a Supermassive BH, which, it seems, the majority of galaxies possess.

neufer wrote: Feeding means active (and vs-a-versa)

https://en.wikipedia.org/wiki/Sagittarius_A*
The comparatively small mass of this black hole, along with the low luminosity of the radio and infrared emission lines, imply that the Milky Way is not a Seyfert galaxy.‡

‡ https://www.britannica.com/topic/Seyfert-galaxy
Seyfert galaxy, any of a class of galaxies known to have active nuclei.

http://www.skyandtelescope.com/astronom ... 924201567/
Is the Milky Way’s Black Hole Feeding?
By: Monica Young | September 24, 2015
The answer is a tantalizing maybe. Astronomers are investigating whether an increase in the number of flares from Sgr A* is due to the recent close passage of a dusty object known as G2.

MargaritaMc wrote:

neufer wrote:
Feeding means active (and vs-a-versa)

I don't agree that they are exact equivalents in this context.

For example, the SMBH in the centre of the Milky Way is not considered to be an AGN

But it has been observed - possibly - feeding

• I haven't been feeding it
  Have you been feeding it

neufer wrote:

MargaritaMc wrote:

neufer wrote:
Feeding means active (and vs-a-versa)

I don't agree that they are exact equivalents in this context.

For example, the SMBH in the centre of the Milky Way is not considered to be an AGN

But it has been observed - possibly - feeding

• I haven't been feeding it
  Have you been feeding it