Tufts University | 24 Nov 2010
The Most Massive Galaxies at 3.0 ≤ z < 4.0 in the Newfirm Medium-band Survey: Properties and Improved Constraints on the Stellar Mass FunctionSome of the universe's most massive galaxies may have formed billions of years earlier than current scientific models predict, according to surprising new research led by Tufts University. The findings appear in the Astrophysical Journal online Nov. 24 and in print Dec. 10, 2010.New Findings Disagree with Current Models
"We have found a relatively large number of very massive, highly luminous galaxies that existed almost 12 billion years ago when the universe was still very young, about 1.5 billion years old. These results appear to disagree with the latest predictions from models of galaxy formation and evolution," said Tufts astrophysicist Danilo Marchesini, lead author on the paper and assistant professor of physics and astronomy at the Tufts School of Arts and Sciences. "Current understanding of the physical processes responsible in forming such massive galaxies has difficulty reproducing these observations."
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The newly identified galaxies were five to ten times more massive than our own Milky Way. They were among a sample studied at redshift 3≤z<4, when the universe was between 1.5 and 2 billion years old.
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By complementing existing data with deep images obtained through a new system of five customized near-infrared filters, the researchers were able to get a more complete view of the galaxy population at this early stage and more accurately characterize the sampled galaxies.
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The researchers made another surprising discovery: More than 80 percent of these massive galaxies show very high infrared luminosities, which indicate that these galaxies are extremely active and most likely in a phase of intense growth. Massive galaxies in the local universe are instead quiescent and do not form stars at all.
- Astrophysical Journal 725(1) 1277 (10 Dec 2010) DOI: 10.1088/0004-637X/725/1/1277 D Marchesini et al