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SUMMARY:GR interpretation of Newtonian simulations for structure formation
  - David Wands (ICG Portsmouth)
DTSTART:20180430T120000Z
DTEND:20180430T130000Z
UID:TALK103342@talks.cam.ac.uk
CONTACT:Tobias Baldauf
DESCRIPTION:Cosmologists routinely use Newtonian N-body simulations to sim
 ulate the complex nonlinear processes of structure formation\, which we be
 lieve approximates the "true" relativistic behaviour in general relativity
 . I will show first how we can make a consistent GR interpretation of the 
 Newtonian solutions in the simplest case of linear perturbations with zero
  pressure\, and then how this can be extended to include (a) non-zero pres
 sure and (b) non-linear perturbations\, in a weak-field limit. I will advo
 cate an computationally efficient approach that uses unmodified Newtonian 
 simulations to simulate non-linear structures and embeds them in a perturb
 ative relativistic spacetime\, including radiation perturbations\, calcula
 ted using standard Einstein-Boltzmann codes. I will discuss existing appro
 aches to incorporating radiation in Newtonian simulations and how they can
  be interpreted in a relativistic framework. An outstanding challenge rema
 ins how to incorporate nonlinear metric perturbations and initial conditio
 ns.
LOCATION:CMS\, Pav. B\, CTC Common Room (B1.19) [Potter Room]
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