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Strong Gravity around Black Holes

Because of Suzaku's ability to precisely determine the energy of incident X-rays, it will be able to study the motion of blobs of gas around a black hole. The motion of this gas is subject to the strong gravity around the black hole. Suzaku will be able to see these effects.

The gas around a black hole consists of atoms whose electrons are continually undergoing energy transitions. As such, the gas emits light at particular energies. As the gas moves around the black hole, the energy of this light is shifted. It is shifted due to:

  • Dopper Effect - The light is redshifted and blueshifted as it is moves away from us and then toward us as the gas orbits the black hole.

  • Special Relativity - Because the gas orbits around the black hole at speeds close to the speed of light, it also undergoes effects due to special relativity. We observe a time dilation effect, which causes both a redshift and a dimming of the observed intensity of the light.

  • Gravitational Red Shift - As light moves away from the strong gravity near the black hole, it loses energy, causing a redshift. In addition, when the blob of gas is on the far side of the black hole, its light must pass around the black hole. This causes further redshifting of the light and changes in its intensity.

Suzaku will be able to accurately measure the resulting profile from this emission. Studying this profile, scientists will be able to determine characteristics of the gas and of the black hole.

Emission from a blob of gas orbiting a black hole.
Emission from a blob of gas orbiting around a black hole. Click on the image for an animation.

Profile of an emission line from gas orbiting near a black hole.
The profile of an emission line from gas orbiting near a black hole

Publication Date: June 2005

Imagine the Universe is a service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA's Goddard Space Flight Center.

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