2003/01/04 by Jian Feng Ji, Shuang Nan Zhang, Jin Lu Qu +1 · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/368269
published as Astrophys.J. 584 (2003) L23-L26 · latex, 10 pages with 3 figures
arxiv created 2003/01/04 · openalex publication_date 2003/02/10 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We present results from the analysis of X-ray power density spectra and coherence when GRS 1915+105 is in soft states. We use three data sets that belong to μ, φ and δ classes in Belloni et al (2000). We find that the power density spectra appear to be complex, with several features between 0.01 and 10 Hz. The coherence deviates from unity above a characteristic frequency. We discuss our results in different models. The corona size in the sphere-disk model implied by this break frequency is on the order of 104 GM/c2, which is unphysical. Our results are more consistent with the prediction of the model of a planar corona sustained by magnetic flares, in which the characteristic frequency is associated with the longest time-scale of an individual flare, which is about eight seconds.