WISE discovers brightest galaxy in the universe
A fresh study examining data from NASA's Wide-field Infrared Survey Explorer (WISE) spacecraft has led to to the discovery of the brightest galaxy in the universe. The galaxy, dubbed WISE J224607.57-052635.0, is believed to contain in excess of 300 trillion stars, and has given rise to a new group of astronomical objects – Extremely Luminous Infrared Galaxies, or ELIRGs.
The ELIRGs were imaged by WISE in infrared light, as this medium has the ability to shine through the dense bands of gas that enshroud the massive galaxies, and cut off other light emissions in the visible, ultraviolet, and X-ray spectra.
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Prior to being detected by WISE, light from the dazzling galaxy had traveled for an impressive 12.5 billion years. This means that when we observe WISE J224607.57-052635.0 today, we are essentially observing a galactic relic from the ancient past.
In order to contain such a mind-boggling amount of stars, astronomers believe that a supermassive black hole must reside at the center of the super-sized galaxy. At the time of emitting the light, astronomers estimate that the leviathan black hole at the heart of WISE J224607.57-052635.0 already had a mass the equivalent to billions of times that of our own Sun.
"We are looking at a very intense phase of galaxy evolution," states Chao-Wei Tsai of NASA's Jet Propulsion Laboratory (JPL), and lead author of the paper on the findings. "This dazzling light may be from the main growth spurt of the galaxy’s black hole."
The aspect of the discovery that is baffling astronomers is just how ELIRGs such as WISE J224607.57-052635.0 grow to become so large. The study acknowledges the presence of 20 of the titanic galaxies, and puts forward 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 on the primordial seeds of the galaxies, stating that their unusual size may stem from the initial galaxy forming black hole being much larger than that which would ordinarily be expected under the standard model for galactic evolution.
Another possibility is that the black holes at the center of the ELIRGs are simply not spinning as fast as a normal black hole. Spinning at a slower speed would repel less matter, allowing them to consume fuel at a faster rate than their more ordinary cousins, who are constrained by what is known as the Eddington limit.
The next step for Tsai and his team will be to determine the mass of the black holes at the center of the ELIRGs, which will be instrumental in informing any future theories on the curious giants.
A paper outlining the study is available in the Astrophysical Journal.