WISE discovers brightest galaxy in the universe
A fresh study examiningdata from NASA's Wide-field Infrared Survey Explorer (WISE) spacecraft has ledto to the discovery of the brightest galaxy in the universe. Thegalaxy, dubbed WISE J224607.57-052635.0, is believed to contain inexcess of 300 trillion stars, and has given rise to a new group ofastronomical objects – Extremely Luminous Infrared Galaxies, orELIRGs.
The ELIRGs were imagedby WISE in infrared light, as this medium has the ability to shinethrough the dense bands of gas that enshroud the massive galaxies,and cut off other light emissions in the visible, ultraviolet, andX-ray spectra.
Prior to being detectedby WISE, light from the dazzling galaxy had traveled for an impressive12.5 billion years. This means that when we observe WISEJ224607.57-052635.0 today, we are essentially observing a galacticrelic from the ancient past.
In order to containsuch a mind-boggling amount of stars, astronomers believe that asupermassive black hole must reside at the center of the super-sizedgalaxy. At the time of emitting the light, astronomers estimate thatthe leviathan black hole at the heart of WISE J224607.57-052635.0already had a mass the equivalent to billions of times that of ourown Sun.
"We are looking ata very intense phase of galaxy evolution," states Chao-Wei Tsaiof NASA's Jet Propulsion Laboratory (JPL), and lead author of thepaper on the findings. "This dazzling light maybe from the main growth spurt of the galaxy’s black hole."
The aspect of thediscovery that is baffling astronomers is just how ELIRGs such asWISE J224607.57-052635.0 grow to become so large. The studyacknowledges the presence of 20 of the titanic galaxies, and putsforward a number of explanations as to how the celestial structures,and more specifically the central black holes, came to be so immense.
One theory focuses onthe primordial seeds of the galaxies, stating that their unusual sizemay stem from the initial galaxy forming black hole being much largerthan that which would ordinarily be expected under the standard modelfor galactic evolution.
Another possibility isthat the black holes at the center of the ELIRGs are simply notspinning as fast as a normal black hole. Spinning at a slower speedwould repel less matter, allowing them to consume fuel at a fasterrate than their more ordinary cousins, who are constrained by what isknown as the Eddington limit.
The next step for Tsaiand his team will be to determine the mass of the black holes at the center of the ELIRGs, which will be instrumental in informing anyfuture theories on the curious giants.
A paper outlining thestudy is available in the Astrophysical Journal.
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