Speaker
Philip Chang
Description
Constraints on the primordial intergalactic magnetic field from the
non-observation of inverse Compton cascades around extragalactic very
high energy sources, i.e., the TeV blazars, assume that inverse
Compton scattering is the dominant physical mechanism by which dilute
ultrarelativistic pair beams lose their energy. Over the last few
years, we have considered the effect of plasma instabilities on these
ultrarelativistic beams. We argue that the linear growth rate of
these instabilities, and in particular the oblique instability, are so
fast that these instabilites may dominate the cooling of these pair
beams leading to an order of magnitude or more suppression in the
inverse Compton cascade. We review the relevant physics of these
plasma instabilities and discuss the linear instability of these pair
beams. We also discuss recent work on the various nonlinear aspects
of this instability and the effect of density gradients on the
instability. We highlight the effect of this instability on the
constraints of the intergalactic magnetic field, arguing that these
constraints are precluded in the presences of these instabilities. We
also discuss the implication of these instabilities on the population
of TeV blazars, and the intergalactic gamma ray background. Finally,
we close with a discussion on the effect of these extra blazar heating
on cosmological structure formation, in particular, the
temperature-overdensity profile and the Lyman-alpha forest.
Primary authors
Dr
Astrid Lamberts
(California Institute of Technology)
Prof.
Avery Broderick
(Perimeter Institute and University of Waterloo)
Dr
Christoph Pfrommer
(HITS)
Dr
Ewald Puchwein
(University of Cambridge)
Mr
Mohamad Shalaby
(University of Waterloo)
Philip Chang
