Seminars at FGG

The connection between the optical and the extragalactic gamma-ray sky

Speaker: Josefa Becerra Gonzalez (Univ. del Maryland - EEUU)

Date and time: 2015-10-08 11:30

The exploration of the very high energy (VHE, E>100 GeV) gamma-ray sky started only recently thanks to the construction of the ground-based Cherenkov telescopes (e.g. MAGIC). Only ~60 sources populate the extragalactic VHE sky, largely dominated by blazars. Besides the study of their intrinsic emission, gamma-ray blazars can be used to probe the extragalactic background light (EBL) and the intergalactic magnetic field (IGMF), which allow us to test the cosmological evolution. The launch of the gamma-ray satellite Fermi in 2008 helps us to understand better the gamma-ray sky at lower energies (100 MeV-100 GeV) and provides potential VHE candidates. However, the full exploitation of the gamma-ray data sample requires strong support from the multi-wavelength community. Specially, the optical spectroscopic observations allow us to classify the sources and measure their redshifts which are essential in the study of both, their intrinsic characteristics as well as the cosmological studies. We will discuss the state-of-the-art of the extragalactic gamma-ray sky with special focus in the coordination with optical observations