Astronomy Professors in Tribeca Observe Black Hole Flare Brighter Than Ten Trillion Suns
Two astronomy professors at the Borough of Manhattan Community College (BMCC) in Tribeca, Kathleen E. Saavik Ford and Barry McKernan, have led a research team of 20 international astrophysicists who recently documented the brightest and most distant black hole flare ever recorded.
Their paper, “An Extremely Luminous Flare Recorded from a Supermassive Black Hole,” was published this month in the peer-reviewed journal Nature Astronomy. Using data from the Zwicky Transient Facility at Caltech’s Palomar Observatory (which is designed to detect stellar objects that rapidly and temporarily change in brightness – hence “transient”), the team observed a black hole at the heart of galaxy J2245+3743, located about ten billion light years from Earth. In 2018, this black hole (or “singularity”) suddenly flared up to 40 times its usual brightness, making it 30 times more powerful than any previous black hole flash on record, eventually reaching a luminosity equivalent to ten trillion of our suns. (For context, the black hole at the heart of J2245+3743 is estimated to be 500 million times more massive than the star that warms our planet.) In the years since, it receded to its normal radiance.
So what happened? The black hole at the center of J2245+3743 is what astronomers call an accreting (or feeding) black hole – with a gravitational tug so strong that it devours anything that strays too close, including stars and planets. The best theory is that a gargantuan star (at least 30 times more massive than our sun) was pulled into the black hole, and spouted an effulgence of light as it was torn to pieces.
“This is probably the most massive star ever seen shredded by a super-massive black hole,” professor Ford says. “That’s exciting because it tells us that massive stars must live in the gas disks around super-massive black holes.”
An indication of the energy level involved in this event, she adds, is, “if you convert our entire sun to energy, using Albert Einstein’s famous formula, E = mc2, that’s how much energy has been pouring out from this flare since we began observing it.”
“In my class,” says professor McKernan, “we’re thinking at the moment about how you know things in science in general and how you test ideas. The cool thing about this work is it took a lot of detective work to figure out what we can rule in and rule out. We end up in a really cool place, the most energetic flare ever seen, as a super-massive black hole tears apart a massive star.”
Because the events observed by the team that professors Ford and McKernan led are so distant, they are also very old. The flash detected by the researchers has taken some ten billion years (more than twice the age of the Earth itself) to reach human observers. In a further twist, while the drama of a massive star being swallowed by a black hole has played out over seven years as time is measured on Earth, it happened at almost quadruple speed in galaxy J2245+3743. The difference arises from “cosmological time dilation,” which stretches out the fabrics of both space and time as signals make their way across the universe.