Quasar’s belch solves longstanding mystery.

Artist’s concept of the environment around the supermassive

black hole at the center of Mrk 231. The broad outflow seen

in the Gemini data is shown as the fan-shaped wedge at the

top of the accretion disk around the black hole.

Picture:Gemini Observatory/AURA, artwork by Lynette Cook

When two galaxies merge to form a giant, the central supermassive black hole in the new galaxy develops an insatiable appetite. However, this ferocious appetite is unsustainable. Now, for the first time, observations with the Gemini Observatory clearly reveal an extreme, large-scale galactic outflow that brings the cosmic dinner to a halt.

The outflow is effectively blowing the galaxy apart in a negative feedback loop, depriving the galaxy’s monstrous black hole of the gas and dust it needs to sustain its frenetic growth. It also limits the material available for the galaxy to make new generations of stars. The groundbreaking work is a collaboration between David Rupke of Rhodes College in Tennessee and the University of Maryland’s Sylvain Veilleux. The results are to be published in the March 10 issue of The Astrophysical Journal Letters and were completed with support from the US National Science Foundation.

According to Veilleux, Markarian 231 (Mrk 231), the galaxy observed with Gemini, is an ideal laboratory for studying outflows caused by feedback from supermassive black holes. “This object is arguably the closest and best example that we know of a big galaxy in the final stages of a violent merger and in the process of shedding its cocoon and revealing a very energetic central quasar. This is really a last gasp of this galaxy; the black hole is belching its next meals into oblivion!”

As extreme as Mrk 231’s eating habits appear, Veilleux adds that they are probably not unique: “When we look deep into space and back in time, quasars like this one are seen in large numbers and all of them may have gone through shedding events like the one we are witnessing in Mrk 231.”

The environment around such a black hole is commonly known as an active galactic nucleus (AGN), and the extreme influx of material into these black holes is the power source for quasi-stellar objects or quasars. Merging galaxies help to feed the central black hole and also shroud it in gas. Mrk 231 is in transition, now clearing its surroundings.

Eventually, running out of fuel, the AGN will become extinct. Without gas to form new stars, the host galaxy also starves to death, turning into a collection of old aging stars with few young stars to regenerate the stellar population. Ultimately, these old stars will make the galaxy appear redder giving these galaxies the moniker “red and dead”.

Source: Gemini Observatory