Long term variability of Cygnus X-1. V. State definitions with all sky monitors
- Grinberg, V.
- Hell, N.
- Pottschmidt, K.
- Böck, M.
- Nowak, M.A.
- Rodriguez, J.
- Bodaghee, A.
- Cadolle Bel, M.
- Case, G.L.
- Hanke, M.
- Kühnel, M.
- Markoff, S.
- Pooley, G.G.
- Rothschild, R.E.
- Tomsick, J.A.
- Wilson-Hodge, C.A.
- Wilms, J.
DOIAbstract
We present a scheme for determining the spectral state of the canonical black hole Cyg X-1 using data from previous and current X-ray all sky monitors (RXTE-ASM, Swift-BAT, MAXI, and Fermi-GBM). Determinations of the hard/intermediate and soft state agree to better than 10% between different monitors, facilitating the determination of the state and its context for any observation of the source, potentially over the lifetimes of different individual monitors. A separation of the hard and the intermediate states, which strongly differ in their spectral shape and short-term timing behavior, is only possible when data in the soft X-rays (<5 keV) are available. A statistical analysis of the states confirms the different activity patterns of the ...
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