LA CAÑADA FLINTRIDGE >> A distant galaxy sizzling with light from more than 300 trillion stars has been named the most luminous galaxy, NASA’s Jet Propulsion Laboratory announced Thursday.
NASA’s Wide-field Infrared Survey Explorer (WISE) spacecraft, managed and operated by JPL, discovered the bright galaxy, which belongs to a new class of objects called extremely luminous infrared galaxies (ELIRGs). The light may originate from a major growth spurt of the galaxy’s black hole, said Chao-Wei Tsai of JPL and lead author of a report published Friday.
“Astronomy is always trying to find the most extreme objects,” Tsai said. “There are millions of galaxies out there. We are always trying to find the most extreme ones to inspire us — how we understand the galaxy or how we understand the universe.”
WISE captured images of the entire sky in 2010, helping astronomers discover eccentric galaxies that would otherwise have been missed. The new study identified 20 new ELIRGs altogether. The last time a whole-sky infrared was taken was in 1983, Tsai said. The new queen dethroned the most luminous infrared galaxy, which was crowned in the 1990s, Tsai added.
The brilliant galaxy may have a supersized black hole pigging out on surrounding gas and matter. This feasting attracts a disk that is heated to millions of degrees and shoots high-energy, visible, ultraviolet and X-ray light. Dust shells block the light, which can be observed as infrared light.
Light from the hosting galaxy traveled 12.5 billion years to reach Earth, so what astronomers observed happened eons ago. The black hole was billions of times the mass of Earth’s sun when the universe was only a tenth of its current age, 13.8 billion years.
“We already know that our galaxy is not a very dramatic one,” Tsai said. “We are not the biggest. We are not the oldest. Our black hole is not the most massive, the most active one. Maybe that is the reason why we have such a lovely environment for species to grow. But in the early history of the universe, the situation could be very harsh.”
The study gives three reasons for why black holes in ELIRGs have become so massive. The first possibility is that the “seeds” for black holes are bigger than previously imagined.
“How do you get an elephant?” asked Peter Eisenhardt, project scientist for WISE at JPL, in a statement. “One way is start with a baby elephant.”
Another explanation breaks or bends the theoretical limit of black hole feeding or the Eddington limit. When a black hole is feasting, gas is sucked in and blasts out light. Pressure from light beams repel the gas, thus limiting how fast a black hole can continue to swallow matter. If a black hole broke this limit, it could fatten up in no time.
Scientists have observed black holes that broke the limit before, but for this black hole to achieve its size, the imaginary elastic belt would have had to be repeatedly torn asunder.
“Another way for a black hole to grow this big is for it to have gone on a sustained binge, consuming food faster than typically thought possible,” Tsai said in a statement. “This can happen if the black hole isn’t spinning that fast.”
In a slow spin, the black hole won’t push away as much of its chow, thus it could scarf down more matter than a fast spinner.
“It’s like winning a hot-dog-eating contest lasting hundreds of millions of years,” co-author Andrew Blain from the University of Leicester said in a statement.
