Astronomy and Astrophysics – Astrophysics – High Energy Astrophysical Phenomena
Scientific paper
2010-09-29
Astronomy and Astrophysics
Astrophysics
High Energy Astrophysical Phenomena
22 pages, 10 figures, resubmitted to match accepted version, in press at ApJ
Scientific paper
In this work we have developed a new stochastic model for the fluctuations in lightcurves of accreting black holes. The model is based on a linear combination of stochastic processes and is also the solution to the linear diffusion equation perturbed by a spatially correlated noise field. This allows flexible modeling of the power spectral density (PSD), and we derive the likelihood function for the process, enabling one to estimate the parameters of the process, including break frequencies in the PSD. Our statistical technique is computationally efficient, unbiased by aliasing and red noise leak, and fully accounts for irregular sampling and measurement errors. We show that our stochastic model provides a good approximation to the X-ray lightcurves of galactic black holes, and the optical and X-ray lightcurves of AGN. We use the estimated time scales of our stochastic model to recover the correlation between characteristic time scale of the high frequency X-ray fluctuations and black hole mass for AGN, including two new `detections' of the time scale for Fairall 9 and NGC 5548. We find a tight anti-correlation between the black hole mass and the amplitude of the driving noise field, which is proportional to the amplitude of the high frequency X-ray PSD, and we estimate that this parameter gives black hole mass estimates to within ~ 0.2 dex precision, potentially the most accurate method for AGN yet. We also find evidence that ~ 13% of AGN optical PSDs fall off flatter than 1 / f^2, and, similar to previous work, find that the optical fluctuations are more suppressed on short time scales compared to the X-rays, but are larger on long time scales, suggesting the optical fluctuations are not solely due to reprocessing of X-rays.
Kelly Brandon C.
Siemiginowska Aneta
Sobolewska Malgorzata
No associations
LandOfFree
A Stochastic Model for the Luminosity Fluctuations of Accreting Black Holes 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 A Stochastic Model for the Luminosity Fluctuations of Accreting Black Holes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A Stochastic Model for the Luminosity Fluctuations of Accreting Black Holes will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-242049