A holistic view of a black hole binary: bringing together spectral, timing, and polarization analysis of Cygnus X-1
Abstract
The microquasar Cygnus X-1 is a persistent high mass X-ray binary, consisting of an O-type supergiant and a stellar mass black hole, and therefore one of those systems which are often considered downscaled versions of AGN, an analogy supported in Cyg X-1 by observations of radio jets. The size and proximity of such systems allow us to observe phenomena on time-scales which are not accessible in their supermassive siblings. Cyg X-1 shows distinct X-ray states, characterized by X-ray spectral and timing properties. Radio behavior is strongly correlated with the X-ray states and a jet-break exists in the mid-IR range in the hard state. The source state is therefore essential for the interpretation of data at all wavelengths. For most observations lacking broadband X-ray coverage, however, the exact state determination proves challenging. In this work, I will present a recently developed novel approach that uses data from all sky monitors such as RXTE-ASM, MAXI, Swift-BAT, and Fermi-GBM to define states and state transitions on a timescales of a few hours over a period of more than 17 years. This approach can be used to investigate the context of high resolution observations of Cyg X-1 with Chandra and XMM, and to conduct state-resolved polarization analysis with INTEGRAL. I then combine spectral and model-independent X-ray timing analysis of over 1900 RXTE orbits over 14 years and investigate the evolution of Fourier-dependent timing parameters such as power spectra, coherence, and time lag at different photon energies over all spectral states. Results include a correlation between the shape of the power and time lag spectra in all hard and intermediate states, a photon-energy dependent increase of the fractional rms in the soft state, and a strong energy-dependency of the power spectra shapes during state transitions. The findings are crucial for constraining physical models for accretion and ejection in compact objects and for comparisons with other accreting objects, especially AGN, since timescales and energies in accreting black holes scale with mass so that observations at the same energies may probe different physical processes therefore show different spectral and timing behavior.
- Publication:
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American Astronomical Society Meeting Abstracts #223
- Pub Date:
- January 2014
- Bibcode:
- 2014AAS...22332301G