The supermassive black hole Sgr A* at the center of our Galaxy is a source of bright X-ray flares. In certain cases, the bright flares are followed up by weaker ones, also referred to as X-ray hiccups. A recent X-ray Visionary Project (XVP) using the High Energy Transmission Grating Spectrometer (HETGS) of the Chandra X-ray Observatory is expected to observe about three dozen X-ray flares within 2012, thereby providing a unique opportunity to understand the mechanism behind X-ray flares in accretion disks around supermassive black holes and their follow-ups. Such follow-ups may also appear due to caustic echoes. A bright flare near the event horizon of a black hole leads to the formation of a caustic on the other side of the horizon. The echoes generated by these caustics may, in principle, be detected as X-ray follow-ups with sufficiently accurate instruments. Their detection would allow us to measure the mass and the angular momentum of the supermassive black hole. We discuss astrophysical properties of caustic echoes and investigate their detectability as X-ray follow-ups with Chandra--HETGS.
American Astronomical Society Meeting Abstracts #221
- Pub Date:
- January 2013