Speaker
Description
Blazars are a special type of AGN, with jets that happen to
point very close to the direction towards Earth. The powerful
gamma-ray beam from distant blazars represents a unique tool to
explore the environment along its path, and allows us to probe opacity
both inside the source and in the intergalactic medium. Internally,
gamma-rays experience attenuation due to photon-photon absorption, a
result of interactions with AGN-generated photon fields. This
interaction introduces distinct features in gamma-ray spectra. Upon
exiting the source, gamma-rays encounter attenuation due to the
Extragalactic Background Light (EBL). Understanding and characterizing
these absorption processes reveals the complex structure of
blazars, including the spatial distribution of the photon fields, and
the poorly known location of the gamma-ray emitting zone. In this
work, we perform analysis and detailed physical modeling of Fermi-LAT
data of nine high-redshift (z > 3) blazars, and search for
characteristic features in the gamma-ray spectra induced by
the internal absorption. Our results yield important constraints on
the precise location of the gamma-ray production site along the blazar
jet in these sources.
