NASA | RXTE Detects ’Heartbeat’ Of Smallest Black Hole Candidate

This animation compares the X-ray ’heartbeats’ of GRS 1915 and IGR J17091, two black holes that ingest gas from companion stars. GRS 1915 has nearly five times the mass of IGR J17091, which at three solar masses may be the smallest black hole known. A fly-through relates the heartbeats to hypothesized changes in the black hole’s jet and disk. Data from NASA’s Rossi X-ray Timing Explorer (RXTE) satellite has identified a candidate for the smallest-known black hole. The evidence comes from a specific type of X-ray pattern -- nicknamed a “heartbeat“ because of its resemblance to an electrocardiogram -- that until now has been recorded in only one other black hole system. Named IGR J17091-3624 after the astronomical coordinates of its sky position, the binary system pairs a normal star with a black hole that may weigh less than three times the sun’s mass, near the theoretical boundary where black-hole status is first becomes possible. Flare-ups occur when gas from the normal