Research interests

Continuum and emission-line variability studies are an extrememly powerful tool for investigating the geometry, kinematics and physical conditions of the broad emission-line region in Active Galactic Nuclei (AGN), allowing us to probe size scales (~a few microarcseconds) currently inaccessible with more conventional (e.g. direct imaging) techniques. Using both short- and long-timescale spectrophotometric continuum and emission-line variability data in combination with detailed photoionisation calculations we can determine the physical properties (spatial distribution, kinematics, density and ionisation state) of the emission-line gas, the temperature structure of the purported accretion disc, and ultimately the mass accretion rate of the supermassive black hole thought to lie at the heart of all AGN. By extending these studies to in-house variability data obtained on the Liverpool Telescope and other major observatories, we can investigate black hole demographics over a range of redshift (cosmological epoch), and ultimately reveal the processes responsible for galaxy formation and evolution.

13-year continuum (5100A) and H-beta emission-line light curves of the Seyfert~1 galaxy NGC5548 - courtesy AGNWatch

Line equivalent width line contours as a function of ionizing photon flux and gas density nh for high- and low-ionization lines. Greyscale contours indicate the local response of the line to small variations in continuum level, with the darkest contours indicating the largest positive response.

Road trip 2004

Mike Goad, Leicester, last updated July 2010.