Scientists Detect White Dwarf Orbiting Close to Supermassive Black Hole
WASHINGTON—Researchers have observed flashes of X-rays increasing in frequency emanating from the nucleus of a galaxy near the Milky Way, believed to be coming from a white dwarf—a dense stellar ember—on an orbit around the galaxy’s supermassive black hole.
Using the European Space Agency’s XMM-Newton X-ray telescope, the observations suggest that the white dwarf is nearing the event horizon of the black hole, marking an extremely close encounter, according to Megan Masterson, a Massachusetts Institute of Technology doctoral student and lead author of the study presented at the American Astronomical Society meeting.
Black holes, known for their intense gravitational pull, typically consume objects that come too close. However, in this case, the white dwarf seems to have stabilized its orbit around the black hole instead of being pulled in.
The galaxy where this phenomenon is occurring is located about 270 million light-years from Earth, with the supermassive black hole in question being a million times more massive than the sun. The white dwarf, about 10% the mass of the sun, is orbiting at nearly half the speed of light, producing X-ray flashes as it moves around the black hole.
As the white dwarf’s orbit shrinks, the X-ray flashes become shorter and more frequent, indicating its proximity to the black hole. Despite the close encounter, researchers believe that the white dwarf may survive due to the kick-back action caused by its outer layers being sucked into the black hole.
Future observatories like NASA’s LISA may help confirm the identity of the white dwarf and provide more insights into objects orbiting supermassive black holes.
“This result suggests that objects can orbit very close to supermassive black holes, and I’m hopeful for joint detections with both X-ray light and gravitational wave emission,” said Erin Kara, MIT astrophysicist and study co-author.
