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Dec 13 – 18, 2015
International Conference Centre Geneva
Europe/Zurich timezone

How the observational quantities of strong gravitational lens effect depend on BH's mass and spin

Dec 17, 2015, 2:00 PM
Level -1, Room 16 (International Conference Centre Geneva)

Level -1, Room 16

International Conference Centre Geneva

17 Rue de Varembé, 1211 Geneva


Hiromi Saida (Daido University)


According to the general relativity (GR), the black hole (BH) is characterized by three parameters: mass $M$, spin angular momentum $J$ and electric charge $Q$. In real cases, the charge is expected to be zero, $Q=0$. Then, the "BH observation" may be understood as the measurement of $M$ and $J$ through a direct observation of GR phenomena, for example the strong gravitational lens effect. I am studying how the two parameters $(M,J)$ appear in a time series data (light curve) seen by single telescope observing the strong gravitational lens effect by Kerr BH. The situation treated in my study consists of three parts as follows: (1) If an emission of light with short duration (burst-like emission) occurs near a BH, we focus on two light rays: One light ray propagates from the source to observer along the shortest path which does not wind around the BH ("direct ray" or "zero-winding ray"). Another ray propagates along the secondary short path which winds once around the BH ("secondary ray" or "1-winding ray"). (2) When the observer detects the 0-winding and 1-winding rays by single telescope, he/she can (in principle) readout following two informations from the light curve seen by the telescope: the time delay $\Delta t_{obs}$ between detection time of 0-winding and 1-winding rays, and the ratio of brightness $R_{obs}$ of 0-winding and 1-winding rays. (3) These two parameters $(\Delta t_{obs} , R_{obs})$ are determined by BH parameters $(M,J)$ and also the position and velocity $(\vec{x},\vec{v})$ of source at the emission. I will report how these quantities $(M,J,\vec{x},\vec{v})$ determine the two observational quantities $(\Delta t_{obs},R_{obs})$. Also, it will be found that the estimated values of $\Delta t_{obs}$ and $R_{obs}$ seem to be detectable by the present telescope capability.

Primary author

Hiromi Saida (Daido University)

Presentation materials