A model for AGN variability on multiple time-scales

Lia F Sartori, Kevin Schawinski, Benny Trakhtenbrot, Neven Caplar, Ezequiel Treister, Michael J Koss, C Megan Urry, Ce Zhang
2018 Monthly Notices of the Royal Astronomical Society: Letters  
We present a framework to link and describe AGN variability on a wide range of timescales, from days to billions of years. In particular, we concentrate on the AGN variability features related to changes in black hole fuelling and accretion rate. In our framework, the variability features observed in different AGN at different timescales may be explained as realisations of the same underlying statistical properties. In this context, we propose a model to simulate the evolution of AGN light
more » ... s with time based on the probability density function (PDF) and power spectral density (PSD) of the Eddington ratio (L/L_ Edd) distribution. Motivated by general galaxy population properties, we propose that the PDF may be inspired by the L/L_ Edd distribution function (ERDF), and that a single (or limited number of) ERDF+PSD set may explain all observed variability features. After outlining the framework and the model, we compile a set of variability measurements in terms of structure function (SF) and magnitude difference. We then combine the variability measurements on a SF plot ranging from days to Gyr. The proposed framework enables constraints on the underlying PSD and the ability to link AGN variability on different timescales, therefore providing new insights into AGN variability and black hole growth phenomena.
doi:10.1093/mnrasl/sly025 fatcat:2cyfcrptbra75dnmj2qcehj6h4