The Optical Appearance of a Star Orbiting an Extreme Kerr Black Hole

A star in circular orbit in the equatorial plane of an extreme Kerr black hole (a = m) emits radiation iso tropically in its own rest frame. However, due to Doppler effects and the focusing of light in the gravitational field of the black hole, the star's apparent luminosity, seen by a distant observer, will vary periodically. This luminosity may become large compared to its Newtonian value during time intervals short compared to the orbital period of the star, especially if the direction to the observer from the star lies near the equatorial plane. Observation of such a variable source would provide considerable information about the companion black hole.

Перевод пока недоступен