We calculate the time delay between different relativistic images formed by black hole gravitational lensing in the strong field limit. For spherically symmetric black holes, it turns out that the time delay between the first two images is proportional to the minimum impact angle. Their ratio gives a very interesting and precise measure of the distance of the black hole. Moreover, using also the separation between the images and their luminosity ratio, it is possible to extract the mass of the black hole. The time delay for the black hole at the center of our Galaxy is just few minutes, but for supermassive black holes with M=10<SUP>8</SUP> ÷10<SUP>9</SUP><SUB>solar</SUB> in the neighbourhood of the Local Group the time delay amounts to few days, thus being measurable with a good accuracy.
Bozza, V., Mancini, L. (2004). Time delay in black hole gravitational lensing as a distance estimator. GENERAL RELATIVITY AND GRAVITATION, 36(2), 435-450 [10.1023/B:GERG.0000010486.58026.4f].
Time delay in black hole gravitational lensing as a distance estimator
Mancini L.
2004-01-01
Abstract
We calculate the time delay between different relativistic images formed by black hole gravitational lensing in the strong field limit. For spherically symmetric black holes, it turns out that the time delay between the first two images is proportional to the minimum impact angle. Their ratio gives a very interesting and precise measure of the distance of the black hole. Moreover, using also the separation between the images and their luminosity ratio, it is possible to extract the mass of the black hole. The time delay for the black hole at the center of our Galaxy is just few minutes, but for supermassive black holes with M=108 ÷109solar in the neighbourhood of the Local Group the time delay amounts to few days, thus being measurable with a good accuracy.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
