Find out the latest thinking about our universe.
-
MargaritaMc
- Look to the Evenstar
- Posts: 1836
- Joined: Wed Jan 09, 2013 10:14 pm
- Location: 28°16'7"N 16°36'20"W
Post
by MargaritaMc » Tue Feb 03, 2015 12:51 pm
International Centre for Radio Astronomy Research
1 February 2015
Live fast die young galaxies lose the gas that keeps them alive
Galaxies can die early because the gas they need to make new stars is suddenly ejected, research published today suggests.
Most galaxies age slowly as they run out of raw materials needed for growth over billions of years. But a pilot study looking at galaxies that die young has found some might shoot out this gas early on, causing them to redden and kick the bucket prematurely.
Astrophysicist Ivy Wong, from the University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR), said there are two main types of galaxies; ‘blue’ galaxies that are still actively making new stars and ‘red’ galaxies that have stopped growing.
Most galaxies transition from blue to ‘red and dead’ slowly after two billion years or more, but some transition suddenly after less than a billion years—young in cosmic terms.
Dr Wong and her colleagues looked for the first time at four galaxies on the cusp of their star formation shutting down, each at a different stage in the transition.
The researchers found that the galaxies approaching the end of their star formation phase had expelled most of their gas. ...
An image showing galaxy J0836, the approximate location of the black hole residing at the galaxy’s core, and the expelled gas reservoir. Credit: ICRAR.
... The study appeared in the journal Monthly Notices of the Royal Astronomical Society*
* Not behind a paywall. Also available at arXiv:
http://arxiv.org/abs/1501.07653
Monthly Notices of the Royal Astronomical Society
Misalignment between cold gas and stellar components in early-type galaxies
O. Ivy Wong, K. Schawinski, et al
Abstract
Recent work suggests blue ellipticals form in mergers and migrate quickly from the blue cloud of star-forming galaxies to the red sequence of passively evolving galaxies, perhaps as a result of black hole feedback. Such rapid reddening of stellar populations implies that large gas reservoirs in the pre-merger star-forming pair must be depleted on short time-scales. Here we present pilot observations of atomic hydrogen gas in four blue early-type galaxies that reveal increasing spatial offsets between the gas reservoirs and the stellar components of the galaxies, with advancing post-starburst age. Emission line spectra show associated nuclear activity in two of the merged galaxies, and in one case radio lobes aligned with the displaced gas reservoir. These early results suggest that a kinetic process (possibly feedback from black hole activity) is driving the quick truncation of star formation in these systems, rather than a simple exhaustion of gas supply.
MNRAS (March 11, 2015) 447 (4): 3311-3321. doi: 10.1093/mnras/stu2724
First published online February 1, 2015
M
"In those rare moments of total quiet with a dark sky, I again feel the awe that struck me as a child. The feeling is utterly overwhelming as my mind races out across the stars. I feel peaceful and serene."
— Dr Debra M. Elmegreen, Fellow of the AAAS
