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SUMMARY:Robert Pego (Carnegie Mellon University)
DTSTART:20220914T160000Z
DTEND:20220914T170000Z
DTSTAMP:20260423T041032Z
UID:nwcs2020/33
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/nwcs2020/33/
 ">Nonlinear waves and photon loss in the Kompaneets model of Compton scatt
 ering</a>\nby Robert Pego (Carnegie Mellon University) as part of Nonlinea
 r Waves and Coherent Structures Webinar Series\n\n\nAbstract\nThe Kompanee
 ts equation is fundamental for explaining the  Sunyaev-Zeldovich effect\, 
 which involves deformation of the cosmic  microwave background energy spec
 trum due to Compton scattering of photons  by electrons.  We establish L1 
 convergence to Bose-Einstein equilibria in  large time and prove several r
 esults on the existence and behavior of a  `condensate' of photons at the 
 zero-energy boundary.  The Kompaneets  equation is a scalar conservation l
 aw with a degenerate parabolic nature  that permits a loss of photons in f
 inite time due to shock formation at  zero energy.  Solutions satisfy entr
 opy decay\, an Oleinik one-sided slope  bound\, and L1 contraction and com
 parison principles.\n
LOCATION:https://researchseminars.org/talk/nwcs2020/33/
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