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PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-4672
DTSTART:20171026T203000Z
DTEND:20171026T220000Z
DTSTAMP:20260419T003538Z
LAST-MODIFIED:20171019T125005Z
LOCATION:4421 Sterling Hall\, Coffee and Cookies at 3:30 PM. Talk begi
ns at 3:45 PM
SUMMARY:The Plasma Physics of TeV Blazars\, Astronomy Colloquium\, Phi
l Chang\, UW - Milwaukee
DESCRIPTION:Constraints on the primordial intergalactic magnetic field
from the non-observation of inverse Compton cascades around extragala
ctic very high energy sources\, i.e.\, the TeV blazars\, assume that i
nverse 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 t
hese 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 pai
r beams leading to an order of magnitude or more suppression in the in
verse Compton cascade. We review the relevant physics of these
\n
plasma instabilities and discuss the linear instability of these pair
beams. We also discuss recent work on the various nonlinear aspects o
f this instability and the effect of density gradients on the instabil
ity. We highlight the effect of this instability on the constraints o
f the intergalactic magnetic field\, arguing that these constraints ar
e precluded in the presences of these instabilities. We also discuss t
he 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 cosmologi
cal structure formation\, in particular\, the
\ntemperature-ov
erdensity profile and the Lyman-alpha forest.
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URL:https://www.physics.wisc.edu/events/?id=4672
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