Search for an extended emission around blazars with the MAGIC telescope

TL;DR

This paper investigates the potential for detecting extended gamma-ray emission halos around blazars caused by electromagnetic cascades, using MAGIC telescope observations and simulations.

Contribution

It presents the first dedicated Monte Carlo simulation study of extended gamma-ray emission profiles around blazars with MAGIC.

Findings

No extended emission detected around Mrk 421 and Mrk 501.

Simulations set constraints on the size and brightness of possible halos.

Methodology can be applied to future observations for halo detection.

Abstract

Very high energy gamma rays coming from extra-galactic sources can interact with intergalactic radiation fields. This process may result in electromagnetic cascades with the following cycle: the production of electron-positron pairs and then secondary gamma-rays due to inverse Compton scattering. Since electrons and positrons will be scattered in the intergalactic magnetic field, under certain conditions their radiation may be redirected towards the observer. Thus one can anticipate that the secondary gamma-ray emission may produce an apparent extended halo around the source. MAGIC is an Imaging Atmospheric Cerenkov Telescope located on Canary island of La Palma at Roque de los Muchachos Observatory (2200 m.a.s.l). Various source sizes and extended emission profiles within $1^\circ$ diameter have been studied by using dedicated Monte Carlo simulations for the MAGIC telescope. We present results of the study of a possible extended emission for Mrk 421 and Mrk501 done with the MAGIC telescope.