Beyond boundaries of redshift surveys: assessing mass fluctuations on "super-survey" scales

Understand

The observed density field in redshift space is directly affected by the radial motions generated from mass fluctuations outside the volume occupied by a given galaxy redshift survey.

• These motions introduce redshift space anisotropies which are more pronounced at larger distances from the survey's center, thus offering clues to the nature of mass fluctuations on super-survey scales.
• Furthermore, we note that all estimates of the growth factor derived from redshift space distortions are based on relations which explicitly assume that the velocity field is generated by mass fluctuations inside the survey volume.
• This may cause uncertainties in these estimates which are on the order of a few percent.