WISE Discovers Galactic Hot DOGs
When NASA launched a wide-field, infrared telescope named WISE to survey the cosmos, scientists figured it would unearth some new objects. They didn’t, however, expect to find a whole new type of galaxy.
WISE scientists are calling their find “hot DOG,” for hot, Dust-Obscured Galaxy, which is an apt description, considering the galaxies are twice as hot as similar objects and difficult to find since most of their radiation is blocked by shrouds of dust.
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But WISE ferreted out about 1,000 hot DOGS, each of which can put out more than 1,000 times the energy of the Milky Way, thus earning themselves top billing on the list of most luminous objects in the universe.
In astronomical numbers, 1,000 is tiny, accounting for about 1-in-100,000 light sources, scientists said during a conference call with reporters on Wednesday.
About 70 percent of the hot DOGS are 10 billion light-years away, meaning they formed when the universe was quite young. (The most precise measurement for the age of the universe is 13.75 billion years.)
Scientists aren’t sure if conditions were more suited for forming hot DOGS then, or if they are just a relatively quick phase in a galaxy’s life and could exist in the modern universe as well.
The objects, however, are raising new questions about the relationship between black holes and their host galaxies. Hot DOGs seem to be far brighter than what their stars can account for, leading some astronomers to suspect that a super-active, supermassive black hole may have preceded the galaxy’s formation.
Black holes are regions of space so dense with matter than not even photons of light can escape the grip of gravity. They can be detected as they consume nearby matter. The majority of galaxies are believed to contain a black hole, though some, like the one at the center of our Milky Way galaxy, are relatively quiet.
The findings, released Wednesday, are being published in the Astrophysical Journal.
WISE researchers also reported they’ve found millions of supermassive black holes.
Images: Top: NASA’s WISE telescope has found about 1,000 hot, extremely shrouded galaxies, called hot DOGs, shown in magenta. Right: A portion of WISE’s all-sky survey shows which hot DOGS, in the magenta circle, were discovered first. The information was collected in 2010 and released this week. Credit: NASA/JPL-Caltech/UCLA