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Title: "Blazars in the very-high energies"

Dr. Dimitrios Emmanoulopoulos
School of Physics & Astronomy
University of Southampton
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When:  Wednesday, February 16 2011 at 2 p.m.
Where: 2nd Floor Seminar Room

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Abstract:

Blazars are thought to be active galactic nuclei (AGN) that have their
jet axis oriented close to the observer's line of sight. Over the past
15 years, very high energy (VHE:>100GeV) emission from these objects
have been observed from the ground based Atmospheric Cherenkov
Telescopes (ACTs) giving us a great opportunity to probe into the
properties of the acceleration processes working in their jet. Moreover,
since VHE gamma-rays are attenuated by photons from the extragalactic
background light (EBL), observations of distant blazars can be used as a
tool in order to determine the EBL spectrum, assuming that the intrinsic
spectral shape of the former is known. Finally, VHE observations of
distant blazars can hide possible indications of energy dependence of
the speed of light in the form of time-lags as it is predicted by the
quantum gravity models. I am going to present the current status and
results for all the aforementioned subjects in the framework of
variability and spectral studies.