Institut für Astronomie und Astrophysik
Abteilung AstronomieSand 1, D-72076 Tübingen, Germany
Hinweis: Einige Seiten auf astro.uni-tuebingen.de können veraltet sein und werden nicht mehr aktualisiert.
Note: Some webpages at astro.uni-tuebingen.de may be outdated and will no longer be updated.
K. Pottschmidt (1), J. Wilms (1), M.A. Nowak (2), W.A. Heindl (3), D.M. Smith (4), and R. Staubert (1)
(1) Institut für Astronomie und Astrophysik, Astronomie, Universität
Tübingen, Waldhäuser Str. 64, D-72076 Tübingen, Germany
(2) JILA, University of Colorado, Boulder, CO 80309440, U.S.A.
(3) Center for Astronomy and Space Sciences, Code 0424, University of California at San Diego, La Jolla, CA 92093, U.S.A.
(4) Space Sciences Laboratory, University of California at Berkeley, Berkeley, CA 94720, U.S.A.
To appear in: Astronomy & Astrophysics Letters
Abstract. We present the long term evolution of the frequencydependent Xray time lags of the black hole candidate Cygnus X1 as measured in 1996 and 1998 with the Rossi Xray Timing Explorer (RXTE). Lag spectra measured during the 1996 June soft state are very similar to those seen during 1996 December and most of 1998 while Cyg X1 was in its hard state. During state transitions, however, the shape and magnitude of the Xray lag is highly variable and tends to be much larger than outside of the state transitions. This behavior is most obvious in the 1-10 Hz band. The increase of the Xray lag during the state transitions might be related to the formation and destruction of the synchrotron radiation emitting outflows present during the hard state.
Key words: stars: individual (Cyg X1) - binaries: close - Xrays: stars
Paper (56k gzip'ed Postscript including figures)
[Home Page] [Preprints 2000] [Quick Reference] [Feedback]
Last modified 14 Nov 2002