How much does peculiar velocity affect distance measurement?

[TomServo]

I'm a PhD student who's taken GR, so I have studied gravity and cosmology, and we have the underlying assumption of homogeneity and isotropy, but since this assumption comes from how we've calculated the distribution of galaxies in the visible universe I want to make sure I really understand it.

I have read about the cosmic distance ladder, but what I'm wondering is when astronomers make their measurements of where distance galaxies "are" in relation to the Sun's frame, after calculating this distance from us, do they then perform any sort of final correction (or give a range) for where that galaxy would be *now* given some measured transverse component of velocity against the celestial globe? And if so, are these "corrected" positions the information from which our cosmic galaxy distributions are generated, or do we simply use the "raw" distances?

I gather that the recessional velocity can be orders of magnitude greater than peculiar velocity, but I'm wondering if for very distant objects with a larger-than-normal peculiar velocity, some correction ought to be made? Are there any good papers that review how this is carried out in a way a non-specialist could understand? Thanks.

 

[phyzguy]

These effects are called "redshift space distortions", and they need to be corrected for. This website might be a good place to start.

 

[kimbyd]

Also, a quick rule of thumb: peculiar velocities tend to be of the order of 1000 km/s. In dense clusters, they can go faster, but usually within an order of magnitude. That can be used to provide a rough idea.