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SUMMARY:General relativistic corrections in N-body simulations -- The N-bo
dy gauge
DTSTART;VALUE=DATE-TIME:20150909T091000Z
DTEND;VALUE=DATE-TIME:20150909T093000Z
DTSTAMP;VALUE=DATE-TIME:20191017T031647Z
UID:indico-contribution-1090989@indico.cern.ch
DESCRIPTION:Speakers: Christian Fidler (CP3 \, Belgium)\nWe discuss differ
ent gauge choices and their advantages in the context of N-body simulation
s. The initial conditions for N-body simulations are usually generated by
employing the Zel'dovich approximation. We show that the initial displacem
ents generated in this way generally receive a first-order relativistic co
rrection.\nWe identify a novel gauge\, called N-body gauge in the followin
g\, in which this relativistic correction is absent. Therefore the Zel'dov
ich approximation provides accurate initial conditions in the N-body gauge
.\nFurthermore we show that a conventional Newtonian N-body simulation inc
ludes all first-order relativistic contributions in the absence of pressur
e perturbations and anisotropic stresses if we identify the coordinates in
Newtonian simulations with those in the N-body gauge.\nWe therefore concl
ude that the N-body gauge is uniquely suited for N-body simulations. When
setting the initial conditions using the Zel'dovich approximation and runn
ing a conventional Newtonian N-body simulation the results include all lin
ear relativistic effects if the output is understood in terms of the N-bod
y gauge. \nIn addition we analyse the limitations of the N-body gauge due
to pressure perturbations and anisotropic stresses from residual radiation
or a non standart cosmology.\n\nhttps://indico.cern.ch/event/438475/contr
ibutions/1090989/
LOCATION: Rm 207
URL:https://indico.cern.ch/event/438475/contributions/1090989/
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