Fast variability as a probe of the smallest regions around accreting black holes
2013 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 431, no 2, 1987-1994 p.Article in journal (Refereed) Published
We extract the spectra of the fastest variability (above 10 Hz) from the black hole XTE J1550-564 during a transition from hard to soft state on the rise to outburst. We confirm previous results that the rapid variability contains no significant disc component despite this being strongly present in the total spectrum of the softer observations. We model ionized reflection significantly better than previous work, and show that this is also suppressed in the rapid variability spectrum compared to the total emission. This is consistent with the fast variability having its origin in a hot inner flow close to the black hole rather than in the accretion disc or in a corona above it. However, the rapid variability spectrum is not simply the same as the total Comptonized emission. It is always significantly harder, by an amount which increases as the spectrum softens during the outburst. This adds to evidence from time lags that the Comptonization region is inhomogeneous, with harder spectra produced closest to the black hole, the same region which produces the fastest variability.
Place, publisher, year, edition, pages
2013. Vol. 431, no 2, 1987-1994 p.
accretion, accretion discs, X-rays: binaries, X-rays: individual: XTE J1550-564
Astronomy, Astrophysics and Cosmology
IdentifiersURN: urn:nbn:se:su:diva-90777DOI: 10.1093/mnras/stt315ISI: 000318345200076OAI: oai:DiVA.org:su-90777DiVA: diva2:628690
FunderSwedish Research Council, 623-2009-691The Wenner-Gren Foundation