UC Irvine-led research reveals two young galaxies that collided 11 billion years ago are rapidly forming a massive galaxy about 10 times the size of the Milky Way.
The revelation, published Wednesday in the journal Nature, is being likened to discovering a missing link between winged dinosaurs and early birds.
Julie Wardlow, a UC Irvine postdoctoral scholar, initially spotted the galaxy, noticing "an amazing, bright blob" in the "cold cosmos," or areas where gas and dust join together to form stars, reports Phys.org. She saw these in images recorded by the European Space Agency's Herschel telescope, with important contributions from the Jet Propulsion Laboratory in Pasadena, then followed up with views from more than a dozen ground-based observatories, particularly the W.M. Keck Observatory in Hawaii.
The new mega-galaxy, dubbed HXMM01, "is the brightest, most luminous and most gas-rich submillimeter-bright galaxy merger known," the authors write in the catchily titled "The Rapid Assembly of an Elliptical Galaxy of 400 Billion Solar Masses at a Redshift of 2.3."
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The discovery is changing the way astronomers view the development of galaxies. Giant elliptical galaxies were born quickly in the early universe, but stopped producing stars soon after. Some had theorized giant black holes in the heart of galaxies blew strong winds that expelled the gas. But cosmologist Asantha Cooray, the UCI team's leader, says definitive proof has now been found and confirmed by colleagues around the world that the quick burnouts were caused by galaxies merging and quickly and efficiently consuming gas for stars.
"These galaxies entered a feeding frenzy that would quickly exhaust the food supply in the following hundreds of million years and lead to the new galaxy's slow starvation for the rest of its life," lead author Hai Fu, a UCI postdoctoral scholar, tells Phys.org.
"Finding this type of galaxy is as important as the discovery of the archaeopteryx was in understanding dinosaurs' evolution into birds because they were both caught at a critical transitional phase."