Publication Date:
2016-01-01
Description:
Active galactic nuclei (AGN) vary in their brightness across all wavelengths. Moreover, longer wavelength ultraviolet–optical continuum light curves appear to be delayed with respect to shorter wavelength light curves. A simple way to model these delays is by assuming thermal reprocessing of a variable point source (a lamp post) by a blackbody accretion disc. We introduce a new method, cream (Continuum REprocessed AGN Markov Chain Monte Carlo), that models continuum variations using this lamp post model. The disc light curves lag the lamp post emission with a time delay distribution sensitive to the disc temperature-radius profile and inclination. We test cream 's ability to recover both inclination and product of black hole mass and accretion rate ${M\dot{M}}$ , and show that the code is also able to infer the shape of the driving light curve. cream is applied to synthetic light curves expected from 1000 s exposures of a 17th magnitude AGN with a 2-m telescope in Sloan g and i bands with Signal-to-Noise Ratio (SNR) of 500–900 depending on the filter and lunar phase. We also test cream on poorer quality g and i light curves with SNR = 100. We find in the high-SNR case that cream can recover the accretion disc inclination to within an uncertainty of 5° and an ${M\dot{M}}$ to within 0.04 dex.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
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