Cygnus X-1 is entering its X-ray hard state
Abstract
In the last few days, MAXI/GSC's monitoring data shows a decrease of the X-ray intensity of Cygnus X-1 from 0.678+/-0.011 Crab on MJD 56732 to 0.512+/-0.009 Crab on MJD 56736 in 2-10 keV. On the other hand, Swift/BAT data indicates an increase from 0.385+/-0.009 Crab on MJD56732 to 0.584+/-0.012 Crab on MJD 56736 in 15-50 keV. The hardness ratio between the Swift/BAT intensity (15-50 keV) and the MAXI/GSC intensity (2-10 keV) has increased from 0.57+/-0.02 on MJD 56732 to 1.14+/-0.03 on MJD 56736.
- Publication:
-
The Astronomer's Telegram
- Pub Date:
- March 2014
- Bibcode:
- 2014ATel.5995....1Z
- Keywords:
-
- X-ray;
- Binary;
- Black Hole