Prague Synergy 2013: Abstract

Shinya YamadaKazuo Makishima; Chris Done; Shunsuke Torii; Hirofumi Noda; Hitoshi Negoro; Shin Mineshige20 min

Suzaku Wide-band and Temporal Analysis of Cygnus X-1 : inhomogeneous coronae and cool disk

Wide-band X-ray studies of Cygnus X-1 using Suzaku in the low/hard revealed inhomogeneous coronae and cool disk, and their temporal evolution. Variations on short (1--2 sec) and long (days to months) time scales require a constant component localized below 2~keV, a broad soft one dominating in the 2--10 keV range, and a hard one mostly seen in 10--300 keV range. In view of the truncated disk/hot inner flow picture, these are respectively interpreted as emission from the truncated cool disk, a soft Compton component, and a hard Compton component. Long-term spectral evolution can be produced by the constant disk increasing in temperature and luminosity as the truncation radius decreases. On much shorter time scale (< 1 sec), we found that the spectral change is more prominent in energies above ~100 keV, resulting in the instant temperature changes by ~20% within 0.1 sec. It implies the existence of some instant mechanism for direct entropy production. I'll present future prospects on black hole binary of ASTRO-H.