Star Formation In Galaxies Is Suppressed By Extremely Red Quasars, New Study Reveals

Star formation in a galaxy occurs when clouds of gas and dust cool down enough to condense. If, for some reason, gas clouds in parts of the galaxy are heated up, they become so turbulent that it inhibits the formation of stars.

Previous observations have shown that energetic plasma jets created by black holes at the centre of a galaxy can prevent accretion of gas and dust. Now, a study published Tuesday in the Monthly Notices of the Royal Astronomical Society has highlighted something else that may play a role — extremely reddened quasars.

Quasars — quasi-stellar radio sources — have been objects of intrigue for astronomers ever since they were first detected in the 1960s. A quasar is a compact region surrounding a galaxy’s supermassive black hole, heated to such an extent that it emits massive amounts of energy and can even outshine the galaxy in which it resides.

The study details the discovery of the new population of extremely red quasars detected as part of the Baryon Oscillation Sky Survey (BOSS) of the Sloan Digital Sky Survey (SDSS). The red color of the light being emitted from these quasars can be attributed to clouds of dust that obscure these objects.

According to the researchers, extremely red quasars — more than any other class of quasars — may be playing a key role in regulating star formation in their host galaxies by occasionally ejecting material at high speeds. This outflow of gas and dust, when it occurs, increases turbulence in vast swathes of region around the galactic centre, thereby extinguishing star formation.

“Overall, the gaseous environments around the black holes appear to be more extended and more energetic than the environments of normal quasars, which might occur at specific times when young gas-rich host galaxies are dumping prodigious amounts of matter into the central black holes, creating an exotic extreme variety of quasars,” the University of California, Riverside, whose researchers led the study, said in a statement. “More work is needed now to examine the extremely red quasars population further and understand its relationship to the general phenomenon of quasars and, perhaps, to a particularly violent young phase of quasar-galaxy evolution.”