Supermassive black holes in dust-obscured galaxies show no influence on them

Emissions from WISE1029 (Image ALMA (ESO/NAOJ/NRAO), Toba et al.)
Emissions from WISE1029 (Image ALMA (ESO/NAOJ/NRAO), Toba et al.)

An article published in “The Astrophysical Journal” describes a research on gas outflows from the center of an active galaxy. A team of astronomers used the ALMA radio telescope to observe highly ionized gas outflows caused by the supermassive black hole at the center of a dust-obscured galaxy (DOG) known as WISE1029+0501 or simply WISE1029 achieving surprising results. In fact, they detected the “signature” of carbon monoxide associated with the galactic disk but also discovered that the carbon monoxide gas in the galaxy isn’t influenced by the outflow of the strongly ionized gas launched from the galactic center, contradicting the models that seemed more plausible.

Supermassive black holes normally form at the center of galaxies so the research on the influence they have on them has become an important part of the research on galaxy evolution. Various researches of the last few years provided results that seem contradictory on the possibility that those black holes favor or inhibit star formation. Recently, a research provided surprising results on the correlation between the growth of those black holes and star formation.

The various researches suggests that there are feedback mechanisms that determine a certain influence of a supermassive black hole on their host galaxy. A crucial element of those mechanisms could be in the gas outflow caused by the black hole’s activity when it ionizes the gas influencing the molecular gas which is the main ingredient of the new stars. What is not clear is when the strong radiations emitted favor star formation and when they inhibit it.

This new research focused on the galaxy WISE1029, of the dust-obscured type. This means that many electromagnetic frequencies are blocked by the presence of dust but others can be detected by suitable instruments. The ALMA (Atacama Large Millimeter/submillimeter Array) radio telescope, inaugurated in March 2013, can detect a part of them and it’s for this reason that it was used for these observations.

The top image above shows some emissions detected by the ALMA radio telescope in the galaxy WISE1029: carbon monoxide in green on the left and cold dust in red on the right. The jets of ionized gas are shown in green in the artist’s representation of a supermassive black hole in the center of a galaxy in the bottom image.

The remarkable activity of the supermassive black hole at the center of WISE1029 suggested an influence on the galaxy, but the researchers found no traces of it. The outflow of ionized gas doesn’t seem to favor the formation of new stars nor inhibit it. Basically, in the past cases those influences were found, now in some dust-obscured galaxies neutral cases have been found.

Dr. Yoshiki Toba of the Academy of Sinica Institute of Astronomy and Astrophysics (ASIAA, Taiwan), first author of this research, stressed the fact that this result adds perplexity to astronomers who are studying the influence of supermassive black holes on the galaxies that host them. He added that the next step is to examine more data on this type of galaxy to fully understand their formation and evolution.

Artist's impression of WISE1029 (Image ALMA (ESO/NAOJ/NRAO))
Artist’s impression of WISE1029 (Image ALMA (ESO/NAOJ/NRAO))

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