Two hungry young galaxies that collided 11 billion years ago are rapidly forming a massive galaxy about 10 times the size of the Milky Way, according to UC Irvine-led research conducted on the W. M. Keck Observatory and other research facilities around the world. The results will be published today in the journal Nature.
Capturing the creation of this type of large, short-lived star body is extremely rare – the equivalent of discovering a missing link between winged dinosaurs and early birds, said the scientists, who relied primarily on data from Keck Observatory’s NIRC2 fitted with the laser guide star adaptive optics (LGSAO) system. The new mega-galaxy, dubbed HXMM01, is the brightest, most luminous and most gas-rich submillimeter-bright galaxy merger known.
HXMM01 is fading away as fast as it forms, a victim of its own cataclysmic birth. As the two parent galaxies smashed together, they gobbled up huge amounts of hydrogen, emptying that corner of the universe of the star-making gas.
“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,” said lead author Hai Fu, a UC Irvine postdoctoral scholar.
The discovery solves a riddle in understanding how giant elliptical galaxies developed quickly in the early universe and why they stopped producing stars soon after. Other astronomers have theorized that giant black holes in the heart of the galaxies blew strong winds that expelled the gas. But cosmologist Asantha Cooray, the UC Irvine team’s leader, said that they and colleagues across the globe found definitive proof that cosmic mergers and the resulting highly efficient consumption of gas for stars are causing the quick burnout.