Newborn galaxies most often form very massive stars. These behemoths are short-lived, however, and quickly die in violent explosions.
In addition to energy from the central black hole, repeated supernova explosions inside growing galaxies would also release energy that would heat surrounding gases and create the cosmic blobs, as seen above in an artist's conception.
Eventually the heat builds up to a point where stars can no longer form, researchers said in June 2009.
"[The blobs] could be a fairly short-lived stage in galaxy evolution," study leader James Geach, also of Durham University in the U.K., said today during a briefing. "The fraction of time they're observable for is quite short."
Image courtesy NASA/CXC/M.Weiss