出版社:SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要:We present highlights from a series of four simultaneous Suzaku/Rossi X-ray Timing Explorer
(RXTE) observations of the black hole candidate Cyg X-1. We first briefly summarize several
key results from our decade long RXTE monitoring campaign (which to date contains over 250
observations). We then comment on challenges of analyzing the Suzaku data, i.e., improving the
aspect correction beyond that of the existing tools, and quantitatively assessing pileup. All of our
Suzaku observations (one, by design) occurred at or very near orbital phase 0 (superior conjunction),
and hence show evolution in color-color diagrams due to X-ray absorption by material from
the wind of the secondary. We present simple partial absorption models for this evolution. We
then compare the Suzaku and RXTE data, and explicitly divide the Fe line region into narrow
and broad components. Both are required for the Suzaku data, and are seen to be consistent with
the RXTE data. These Suzaku observations occurred near historically hard, low flux states. We
present fits of the broad band spectra with a simple phenomenological broken powerlaw model, as
well as a more physically motivated Comptonization model. Whereas the former class of models
described nearly all of the RXTE campaign better than any physical model, here the latter model
is slightly more successful. The Comptonization model, however, exhibits little evidence for a
soft disk component, which formally corresponds to a small, inner disk radius. Whether this is
physical, due to unmodeled absorption, or is a calibration issue, remains an open question.