With the help of HXMM01, it appears the latter may be true.
"We're looking at a younger phase in the life of these galaxies - an adolescent burst of activity that won't last very long," said Hai Fu of the University of California, Irvine, lead author of the study published in the May 22 online issue of Nature.
"These merging galaxies are bursting with new stars and completely hidden by dust," said co-author Asantha Cooray. "Without Herschel's far-infrared detectors, we wouldn't have been able to see through the dust to the action taking place behind."
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Indeed, mergers were common in the early history of the cosmos, but what sets HXMM01 apart is the huge quantity of dust contained within the colliding galaxies, the rapid star formation and the sheer size of the two galaxies colliding. Comparing HXMM01′s star formation rate with our galaxy's star formation rate of only 2-3 newborn stars per year, 2,000 stars per year makes this merger a veritable stellar breeding ground!