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.
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Emission from a blob of gas orbiting
around a black hole. Click on the
image for an animation.
(Description)
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The profile of an emission line from gas
orbiting near a black hole
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Publication Date: June 2005
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