GRS 1915 is an x-ray binary star system consisting of a star and a black-hole, and it’s got a heartbeat.
Well, a pulsating x-ray light that is, one pulse every 50 seconds.
And you’re like, “bro, what’s CAUSING this pulse?, that’s strange and I’m interested in science so I need to know..”
Turns out the black hole (spinning at 1,150 times per sec) is sucking in the matter from it’s companion star at 50% the speed of light though letting some of that energy escape. “The jet of materials being ejected is occasionally choked off by a hot wind blowing off the accretion disk. The wind deprives the jet of materials needed to sustain it. When the wind dies down, the jet returns (wiki)”, giving us the “pulse.”
From: Heartbeat of a Black Hole