Open AccessGaussianity of cosmic velocity fields and linearity of the velocity–gravity relation
Author(s) -
Cieciela̧g Paweł,
Chodorowski Michał J.,
Kiraga Marcin,
Strauss Michael A.,
Kudlicki Andrzej,
Bouchet François R.
Publication year - 2003
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2003.06202.x
Subject(s) - physics , peculiar velocity , divergence (linguistics) , estimator , gaussian , acceleration , gravitational field , cosmic cancer database , smoothing , thermal velocity , classical mechanics , astrophysics , flow velocity , mechanics , statistics , redshift , quantum mechanics , mathematics , linguistics , philosophy , flow (mathematics) , galaxy
We present a numerical study of the relation between the cosmic peculiar velocity field and the gravitational acceleration field. We show that on mildly non‐linear scales ( 4–10 h −1 Mpc Gaussian smoothing), the distribution of the Cartesian coordinates of each of these fields is well approximated by a Gaussian. In particular, their kurtoses and negentropies are small compared to those of the velocity divergence and density fields. We find that at these scales the relation between the velocity and gravity field follows linear theory to good accuracy. Specifically, the systematic errors in velocity–velocity comparisons due to assuming the linear model do not exceed 6 per cent in β. To correct for them, we test various non‐linear estimators of velocity from density. We show that a slight modification of the α‐formula proposed by Kudlicki et al. yields an estimator which is essentially unbiased and has a small variance.