Aug. 15, 2013 — Studying the evolution and anatomy of galaxies using the Hubble Space Telescope, an international team of astronomers led by doctoral candidate BoMee Lee and her advisor Mauro Giavalisco at the University of Massachusetts Amherst have established that mature-looking galaxies existed much earlier than previously known, when the universe was only about 2.5 billion years old, or 11.5 billion years ago.
“Finding them this far back in time is a significant discovery,” says lead author Lee.
Galaxies as massive as the Milky Way are relatively rare in the young Universe. This scarcity prevented previous studies from gathering a large enough sample of mature galaxies to properly describe their characteristics. Galaxies at these early times appear to be mostly irregular systems with no clearly defined morphology. There are blue star-forming galaxies that sometimes show structures such as discs, bulges and messy clumps, as well as red galaxies with little or no star formation. Until now, nobody knew if the red and blue colors were related to galaxy morphology, the UMass Amherst authors note.
“Clearly, the Hubble Sequence formed very quickly in the history of the cosmos, it was not a slow process,” adds Giavalisco. “Now we have to go back to theory and try to figure out how and why.”
Why does everything big in nature seem to point not to a long slow process of evolution but sudden emergence and long periods of stasis?