Super-massive black holes are known to dwell at the center of galaxies. When accreting matter they are observed from Earth as active galactic nuclei (AGNs). In a minority of AGNs the accretion of matter onto the black-hole is associated with the ejection of a relativistic jet of plasma along the polar axis. 
When the black-hole's jet points right in the direction of the Earth, relativistic effects boost the emission and make these objects among the brightest in the Universe. This peculiar AGNs are called blazars. 

Blazars are detected at all wavelengths, from radio up to gamma-rays, and there is some evidence that they are also bright neutrino emitters. In particular they dominate the extra-galactic gamma-ray sky. In addition to their luminosity they are characterized by rapid flux variability, detected down to the minutes time-scale. 

The TeV energy band is accessed from the ground with Cherenkov telescopes. These instruments image the Cherenkov light produced by the electromagnetic cascade triggered by the interaction of the gamma-ray with the Earth's atmosphere. The internship will make use of data from the H.E.S.S. array of Cherenkov telescopes. The candidate will analyze H.E.S.S. data on flaring blazars, and perform spectral and temporal studies. In addition, he/she will perform multi-wavelength studies using archival online databases to identify potential low-energy correlations.