2004/05/19 by Ludwik Liszka, Liszka, Ludwik, A. G. Pacholczyk +3
Mathematics · Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics (astro-ph) #FOS: Physical sciences #Statistical and numerical algorithms #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0405366
pdf document with 26 pages, 17 figures to be published in Astrophysical Journal Suplement
arxiv created 2004/05/19 · openalex publication_date 2004/05/19 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
In discussing the short-time variability of extragalactic X-ray sources, we focus on explaining how wavelet transform in conjunction with non-linear filtering methods are used to remove Poisson statistics and wobble-related variability from the data. This enables the resolution of their intrinsic stochastic, quasi-periodic and deterministic variable components, as well the determination of their persistence. As detailed examples we review and extend the application of these techniques to ROSAT data for the Seyfert I galaxy NGC 5548 and for the QSO 3C273. Besides illustrating the discriminating power of these methods, these treatments confirm the intrinsic character of the transient quasi-periodic and deterministic events in NGC 5548 and 3C273 and enable us to compare both the elementary events and the short-time variability in the two types of sources. These methods can be applied in the investigation of intrinsic source variability in other spectral regions.