The role of resonant plasma instabilities in the evolution of blazar induced pair beams

Understand

The fate of relativistic pair beams produced in the intergalactic medium by very high energy emission from blazars remains controversial in the literature.

• The possible role of resonance beam plasma instability has been studied both analytically and numerically but no consensus has been reached.
• In this paper, we thoroughly analyze the development of this type of instability.
• This analysis takes into account that a highly relativistic beam loses energy only due to interactions with the plasma waves propagating within the opening angle of the beam (we call them parallel waves), whereas excitation of oblique waves results merely in an angular spreading of the beam, which reduces the instability growth rate.