Our sun may be bright enough to burn our skin from nearly 100 million miles away — but compared with the most luminous galaxy in the universe, it might as well be a candle.
Far off in the universe is an unimaginably bright galaxy that gives off more light than 300 trillion suns, according to NASA. The galaxy was discovered using NASA's Wide-field Infrared Survey Explorer (WISE) — and is even brighter than previously thought possible.
"Very luminous galaxies are at a key rapid growing phase of galaxy evolution," said lead author Chao-Wei Tsai in an interview with Tech Times.
The amount of light a galaxy emits is linked to the growth of the black hole at its center. Hungry for matter, growing black holes draw materials toward it. This can lead to a chaotic black hole feeding frenzy.
"When materials approach black holes they bump into each other, causing them to heat up and generate light," Tsai said.
The extremely luminous galaxy doesn't however give off as much light as it could, because it's encapsulated in dust. The dust blocks the light that the black hole chow produces — causing the dust to heat up and give off infrared light. Human eyes can't see infrared light, but WISE is specially designed to detect it.
Data from WISE reveals that the black hole at the center of this newly discovered galaxy is enormous in spite of its relatively young age — leaving scientists to question previously conceived limits on black hole growth.
"One limit to how fast the black hole can consume those falling materials is that the light that the material generates will actually push the material out of the black hole," Tsai explained.
Breaking this limit imposed by light is one way the black hole could have grown so large. Another possibility is that it was simply born larger than previously thought possible. A slower spin presents another potential loophole in these limits, as black holes that spin more slowly don't repel material as strongly.
Tsai and his colleagues reported a total of 20 new extremely luminous infrared galaxies in their study. These galaxies had escaped earlier detection because they give off infrared rather than visible light. WISE has made these discoveries possible, but further research on the galaxies is needed to determine the secret to their supreme shine.
This report was published in The Astrophysical Journal.
