Of the approximately 100 Million galaxies in the visible universe, we see incredible variation. We always try to classify them based on their shape, size, and peak radiation, but even then we still find others that stray from the usual patterns. In recent years, a new class of galaxies named Extremely Luminous Infrared Galaxies (ELIRGs) has been found with data from the Wide Field Infrared Survey (WISE). Now the king of the ELIRGs has been found, the most luminous galaxy in the universe.
The galaxy, designated WISE J224607.57-052635.0, has a luminosity equal to 300 Trillion suns, and may owe its brightness to a supermassive black hole in its core swallowing up gas at an incredible rate, giving it a ‘growth spurt.’ Generally, a central black hole heats up gas to millions of degrees in its accretion disk, releasing high energy visible, ultraviolet, and x-ray light. But when the galaxy enshrouds that accretion disk in a dusty veil, the dust absorbs the radiation, heating up and re-emitting it as infrared light. Astronomers believe that this is what is happening in ELIRGs. This particular galaxy lives in the early universe, its light having travelled 12.5 Billion years to reach us, it is like looking back in time.
WISE had been finding several hundred other strange galaxies in its 2010 infrared survey of the entire sky. Its unprecedented detail gives a view of objects that have been overlooked by other surveys. With further study of the central black holes, astronomers will slowly peel away the layers to reveal the intense history of these incredible objects, piecing together the state of the universe where these galaxies are found, in the distant past.