Suppression of the TeV Pair-beam–Plasma Instability by a Tangled Weak Intergalactic Magnetic Field

Abstract We study the effect of a tangled sub-fG level intergalactic magnetic field (IGMF) on electrostatic instability blazar-induced pair beam. Sufficiently strong IGMF may significantly deflect TeV beams, which would reduce flux secondary cascade emission below observational limits. A similar reduction result from beam–plasma instability, operates best in absence IGMF. Considering with correlation lengths smaller than kiloparsec, we find that weak fields increase transverse momentum pair-beam particles, dramatically reduces linear growth rate and hence energy-loss show is eliminated as an effective agent at strength three orders magnitude needed to suppress by deflection. For intermediate-strength IGMF, do not know viable process explain observed GeV-scale emission.