Gabrielle Taylor (UK)

gtaylor @ lsw.uni-heidelberg.de

Multifrequency time series analysis in massive astronomical datasets

Blazars are a subclass of active galactic nuclei which have their highly-collimated relativistic jets directed towards the observer’s line of sight, typically ≲10 degrees. They are the most violent, non-self-destructing objects in the Universe, and show a large variety of spectral appearance and variability, from radio to very-high-energy gamma rays. The variability is especially puzzling as it is strongly frequency dependent, and exhibits, for example, orphan flares: a flare in only one energy band.

Since the 1950s, astronomers have observed and studied these objects, but thus far no theory or model explains the overall properties of blazars. Papers have carried out statistical analyses of the periodicity of the light curves from blazars, often with the aim of trying to predict flares, but some more recent studies have conversely argued that these bodies are stochastic, that is, they cannot be predicted.

During my PhD project, I will work as part of the H.E.S.S. collaboration, which operates the (currently) largest very-high-energy gamma-ray telescope in the world, located in Namibia. Part of my project will involve deriving a census of the various types of variability exhibited by blazars in as many energy bands as possible, certainly including optical, UV, x-ray, and gamma-ray. Another part will involve periodicity and flare analysis. I also aim to incorporate machine learning techniques throughout my research, with the
purpose of hopefully accelerating and improving analyses.

Supervisor:    Stefan Wagner  (LSW)