There are numerous publications about pairwise velocity dispersion ( PVD ) of galaxies in real redshift surveys. It is customary to use an exponential form for the distribution of pairwise velocities and then model the redshift space distortions in the 2PCF to retrieve the PVD.(adsbygoogle = window.adsbygoogle || []).push({});

Now if i have a cosmological simulation i know exactly the position and the velocity of every particle (x,y,z) (u_x,u_y,u_z). I want to compute the PVD from cosmological simulations.

If i take u_{12}(r)=u_1(x)-u_2(x+r) and then σ_{12}=<u_{12}^2-<u_{12}>^2> i can have the σ_{12}(r).

My question is how can i retrieve σ_{12}(r_p), (i.e. in terms of the perpendicular distance)????

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# Pairwise velocity dispersion in Cosmological simulations

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