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Grupe and colleagues observe black hole flare

Dr. Dirk GrupeDr. Dirk Grupe, associate professor of astrophysics and space science and Morehead State, recently used NASA’s NuSTAR telescope to detect a flare from one of the most massive black holes known.   

Grupe made the observation along with his colleague, Stephanie Komossa at the Max Plank Institute of Radio Astronomy in Bonn, Germany. Grupe’s students at MSU assisted with the project by analyzing the data collected by Grupe and Komossa.   

OJ 287 is a blazar hosting a black hole with a mass 18 billion times that of the Sun at a distance of five billion lightyears. Not only is this one of the most massive black holes in existence, but observation suggests it is a binary black hole system. OJ 287 is orbited by a smaller companion black hole that is 150 million times more massive than the Sun. These black holes are about 1000 times and 40 times more massive than the black hole at the center of our own Milky Way galaxy. OJ 287 is the only plunging binary supermassive black hole system currently known and provides a unique laboratory to study black hole feeding, jet formation, and general relativity.  

Grupe said there is much to be learned from the discovery.  

“The discovery of the April 2020 flare is important because it is an after flare that is predicted by the binary-black hole model,” Grupe said. “What most people are not aware of is that when you are in research a lot of the day-to-day work seems to be kind of boring to most people but getting the data analysis done is necessary to make discoveries. What looks repetitive is actually not because when you open a new data set from an observation, you never know what you get. So, finding an object in an extreme state is always exciting because it allows us to study the physics that is going on in these objects.”  

The passage of the smaller black hole through the disk of material around the larger black hole can also cause after-flares of emission seen in the X-rays. Grupe and Komossa have been monitoring OJ 287 since late 2015 with NASA’s Swift satellite looking for these flares and after-flares. In a recently published paper, Grupe and collaborators reported a flare of ultraviolet and X-ray emission from OJ 287 detected between April and June of this year, nearly a year after the impact flare in July 2019. Once the after-flare was detected with Swift, Grupe and Komossa quickly triggered additional observations with NuSTAR and other X-ray telescopes to study the flare.  

These flashes have been recorded by astronomers since 1891, first on photographic plates, then on electrical devices, and, most recently, from observatories in space. OJ 287 sometimes gets bright enough to be seen with binoculars during these events, making it amongst the most distant objects visible without a telescope.   

To learn more about programs in MSU’s Department of Physics, Earth Science and Space Systems Engineering, visit, email or call 606-783-2381.  

Morehead State is a NASA Space Grant University. The Space Grant national network includes over 850 affiliates from universities, colleges, industry, museums, science centers, and state and local agencies.