Peculiar velocities in large-scale structure - The problem of incomplete sampling

Abstract

view Abstract Citations (8) References (45) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Peculiar Velocities in Large-Scale Structure: The Problem of Incomplete Sampling Bothun, Gregory D. ; West, Michael J. ; Mould, Jeremy R. ; Schommer, R. A. Abstract Using N-body simulations of gravitational clustering scenarios with various amounts of power on large scales, we investigate the nature of the observed peculiar velocity field that arises when incompletely sampling a distant but very large structure. We examine the effect of placing the centroid of a large mass distribution at a distance of 45h^-1^ Mpc from the observer and imposing a distance cutoff such that only the near side of thiS mass distribution is actually sampled. These constraints are consistent with the Aaronson et al. data set in combination with the nominal distance of the putative great attractor. We find that, under these circumstances, simulations with significant large-scale power (i.e., those with power that scales as k^-2^) produce clusters which can have mean peculiar velocities of as high as 600 km s^-1^, but this is rare. A more typical value is 300-400 km s^-1^. Using the simulations, we evaluate the effects of projection, distance errors, and cluster internal velocity dispersion on the observed peculiar velocity field. We conclude that much of the cluster peculiar velocities are due to infall at or near the turnaround radius of the largest structure at the simulation center. Hence nonlinear effects are important and, in combination with incomplete sampling, could easily conspire to produce the pattern of peculiar velocities which is observed. Although these peculiar velocities are real, their interpretation is highly ambiguous and does not necessarily require streaming toward any distant point mass. Publication: The Astrophysical Journal Pub Date: April 1990 DOI: 10.1086/168621 Bibcode: 1990ApJ...353..344B Keywords: Galactic Clusters; Galactic Structure; Many Body Problem; Mass Distribution; Velocity Distribution; Group Velocity; Red Shift; Astrophysics; GALAXIES: CLUSTERING; GALAXIES: REDSHIFTS; NUMERICAL METHODS full text sources ADS | data products SIMBAD (1)