Oct 26, 2017

Phil Chang, UW- Milwaukee

"The Plasma Physics of TeV Blazars"

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.

Event Details

Date:
Oct 26, 2017

Time:
11:55am

Location:
4421 Sterling Hall

Notes:
Coffee served at 3:30pm; talk starts at 3:45pm

UW-Madison Astronomy Home