Astronomy and Astrophysics – Astrophysics
Scientific paper
2000-10-13
Astronomy and Astrophysics
Astrophysics
Accepted for publication in ApJ
Scientific paper
10.1086/319028
This paper employs direct spectral fitting of individual orbital data in order to measure rapid X-ray iron K_alpha line and continuum spectral slope variations in Seyfert 1 galaxies with unprecedented temporal resolution. Application of this technique to a long RXTE observation of MCG--6-30-15 indicates that the line flux does vary on short (~1d) timescales, but that these variations are not correlated with changes in the continuum flux or slope. These rapid variations indicate that the line does indeed originate close to the black hole, confirming predictions based on its very broad profile. However, the lack of a correlation with the continuum presents problems for models in which the line variations are driven by those in the continuum, modified only by light-travel time effects. Instead, it may be that the line responds according to a physical process with a different time scale, such as ionization instabilities in the disk, or perhaps that the geometry and physical picture is more complex than implied by the simplest disk-corona models. These data also indicate that the slope of the underlying power-law continuum (Gamma) shows strong variability and is tightly correlated with the continuum flux in the sense that the spectrum steepens as the source brightens. All of these results have been checked with extensive simulations, which also indicated that a spurious correlation between Gamma and Compton reflection fraction (R) will result if these quantities are measured from the same spectra. This casts serious doubts on previous claims of such a Gamma-R correlation.
Edelson Rick
Vaughan Stewart
No associations
LandOfFree
Evidence for Rapid Iron K_alpha Line Flux Variability in MCG--6-30-15 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Evidence for Rapid Iron K_alpha Line Flux Variability in MCG--6-30-15, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Evidence for Rapid Iron K_alpha Line Flux Variability in MCG--6-30-15 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-725503