Biggest galaxies formed when universe was young
Some of the most massive galaxies may have formed billions of years earlier than believed.
Washington: A new research led by Tufts University has found that some of the universe`s most massive galaxies may have formed billions of years earlier than current scientific models predict.
"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."
Collaborating with Marchesini were researchers from Yale University, Carnegie Observatories, Leiden University, Princeton University, the University of Kansas and the University of California-Santa Cruz.
The newly identified galaxies were five to ten times more massive than our own Milky Way. They were among a sample studied at redshift, when the universe was between 1.5 and 2 billion years old.
Redshift refers to the phenomenon of a light wave stretching and moving toward longer wavelengths (the red end of the spectrum) as the emitting object travels away from an observer (Doppler Effect).
This is similar to the pitch of a siren getting lower as the siren moves away. The redshift of distant galaxies is due to the expansion of the universe.
The larger the redshift, the more distant the galaxy is, or the farther back in time we are observing. The larger the redshift, the younger the universe in which the galaxy is observed.
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.
The findings appear in the Astrophysical Journal published online November 24 in advance of print publication on December 10, 2010.