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The Subaru Seminar is usually held in Room 104 of the Hilo Base Facility, adjacent to the main lobby. Everyone is welcome to attend. If you are interested in giving a seminar, please contact Subaru seminar organizers (Tae-Soo Pyo, Sherry Yeh, Nagayoshi Ohashi) by email : (please change"_at" to @).

May 23, Friday, at 11:00 am

" How to detect directly the black hole parameters "

Hiromi Saida

(Daido University)

I explain a principle (proposal) to measure directly the black hole parameters (mass and spin angular momentum), which makes use of the time series data obtained by one telescope. There are two points in our proposal: (1) Consider the case that an emission of light with short duration (burst-like emission) occurs near a black hole. Then, due to the strong gravity of black hole (strong gravitational lensing effect), some light rays wind (or coil) around the black hole before coming to observer. (And some light rays are absorbed by the black hole.) This means that, before coming to the observer, one light ray propagates along the shortest path which does not wind around the black hole ("0th ray" or "direct ray"), and another light ray propagates along the secondary short path which winds once around the black hole ("1st ray" or "secondary ray"). (2) When the observer detects the 0th and 1st rays by one telescope, he/she can (in principle) readout two informations from the time series data obtained by the telescope: the delay between detection time of 0th and 1st rays, and the ratio of intensity (or amplitude) of 0th and 1st rays. By the general theory of relativity, these two quantities (time delay and intensity ratio) are determined by the black hole's mass and spin angular momentum. In this talk, I propose a method how to readout those two quantities from the time series data, and explain (without stepping in mathematics of general relativity) how to readout the black hole parameters from those two quantities.

Seminars are also held at JAC, CFHT, and IfA.

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