Modelling X-ray RMS spectra I: intrinsically variable AGN

Abstract

We present simple XSPEC models for fitting excess variance spectra of AGN. Using a simple Monte-Carlo approach, we simulate a range of spectra corresponding to physical parameters varying, then calculate the resulting variance spectra. Starting from a variable power-law, we build up a set of models corresponding to the different physical processes that can affect the final excess variance spectrum. We show that the complex excess variance spectrum of IRAS 13224-3809 can be well described by such an intrinsic variability model, where the power-law variability is damped by relativistic reflection and enhanced by an ultra fast outflow. The reflection flux is correlated with that of the power-law, but not perfectly. We argue that this correlation is stronger at high frequencies, where reverberation lags are detected, while excess variance spectra are typically dominated by low frequency variability.

8 pages, 4 figures, accepted for publication in MNRAS. Updated to accepted version

References in corpus (6)

• XMM-Newton study of the complex and variable spectrum of NGC 4051
• The response of relativistic outflowing gas to the inner accretion disk of a black hole
• The Broad-band X-ray Spectrum of IC 4329A from a Joint NuSTAR/Suzaku Observation
• Modelling the Extreme X-ray Spectrum of IRAS 13224-3809
• Using principal component analysis to understand the variability of PDS 456
• Origin of the Characteristic X-ray Spectral Variations of IRAS 13224$-$3809

Cited by in corpus (3)

• Searching for Ultra-fast Outflows in AGN using Variability Spectra
• Incoherent fast variability of X-ray obscurers. The case of NGC 3783
• Blueshifted absorption lines from X-ray reflection in IRAS 13224-3809