'Heartbeats' From a Black Hole System

The above animation shows how radio jets may be suppressed in the micro-quasar GRS 1915. Material is being pulled from a red companion star into a black hole via a blue, rapidly rotating disk. The animation begins with a jet blowing material away from the black hole. Later, when the disk is heated by powerful radiation from close to the black hole, a wind is driven off the disk. As the wind strengthens, the jet apparently is shut down because the wind deprives the jet of material that would otherwise have fueled it.

GRS 1915+105 contains a black hole about 14 times the mass of the Sun that is feeding off material from a nearby companion star. As the material swirls toward the black hole, a disk forms. The black hole in GRS 1915+105 has been estimated to rotate at the maximum possible rate, allowing material in the inner disk to orbit very close to the black hole -- at a radius only 20% larger than the event horizon -- where the material travels at 50% the speed of light.

Researchers monitored this black hole system with the Chandra X-ray Observatory and the Rossi X-ray Timing Explorer (RXTE) over a period of eight hours. As they watched, GRS 1915+105 gave off a short, bright pulse of X-ray light approximately every 50 seconds. This type of rhythmic cycle closely resembles an electrocardiogram of a human heart -- though at a slower pace. It was previously known that GRS 1915+105 can develop such heartbeats, but researchers gained new understanding into what drives the beats, and used the pulses to figure out what controls how much material the black hole consumes from the RXTE data.

The heartbeat variation of GRS 1915+105 is shown here in a repeated cycle to emphasize the similarity between the X-ray light curve and an electrocardiogram. The period has been sped up by a factor of 40. Details from NASA.

Beginning with a wide-field optical image from the Digitized Sky Survey, the view then zooms into a Chandra X-ray Observatory image of GRS 1915+105. With its spectrograph, Chandra observed this black hole eleven times over the past ten years. This accumulation of data allowed scientists to track the black hole's behavior and determine how it uses different mechanisms - involving a jet and wind - to regulate its growth. credit: X-ray (NASA/CXC/Harvard/J.Neilsen); Optical (Palomar DSS2).