A near-IR variability study of the Galactic black hole: a red noise source with no detected periodicity

Understand

We present the results of near-infrared (2 and 3 microns) monitoring of Sgr A*-IR with 1 min time sampling using the natural and laser guide star adaptive optics (LGS AO) system at the Keck II telescope.

• Sgr A*-IR was observed continuously for up to three hours on each of seven nights, between 2005 July and 2007 August.
• Sgr A*-IR is detected at all times and is continuously variable, with a median observed 2 micron flux density of 0.192 mJy, corresponding to 16.3 magnitude at K'.
• These observations allow us to investigate Nyquist sampled periods ranging from about 2 minutes to an hour.