Measuring Sgr A*'s Intra-Day Variability at 3mm Using Galactic Centre SiO Masers
Abstract
Mauerhan et al. (2005) have recently claimed that Sgr A* exhibits 20% intra-day variations at 3 mm, adding to the recent detections of X-ray and IR variability in this source. However, the reality of the mm-wavelength variations is questionable: the observations were made at low elevation from Owens valley, and a poor calibration strategy likely contributed to the apparent variability. We wish to make reliable measurements of Sgr A*'s variability using a robust calibration scheme. We will calibrate its variability against the several Galactic Centre SiO masers that are visible in the ATCA primary beam centred on Sgr A*, thus using a set of continuously-visible calibration sources which will be subject to atmospheric fluctuations identical to those experienced by Sgr A* itself. Variations on the timescales claimed by Mauerhan et al. probe the accretion environment within 100 Schwarschild radii of the black hole.
- Publication:
-
ATNF Proposal
- Pub Date:
- April 2006
- Bibcode:
- 2006atnf.prop..105M
- Keywords:
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- Galactic;
- ATCA