Accounting for Cosmological Expansion in Distance Measurements

[Brantoc]

Some objects, Quasars for example have extremely high redshifts, and come from a time long past, and place far away. When determining distance on such large scales, how do you also factor in the cosmological expansion of the universe, meaning 10 billion years ago the universe was much smaller than today, the light would be stretched over time as the universe expands.

In some respects, if we see an object that is very old, were we really this far away when the light was emitted, and how far are we away today? do you assume consistent expansion, or did it once expand faster and today is it slowing?

Does someone have an example equation/result from a distant object?

 

[bartek2009]

Things you could read about:

co-moving coordinates
co-moving distance
luminosity distance
diameter distance
proper distance

The expansion is different in each cosmological model
and it can also vary with time within the model itself.
For example you can distinguish between radiation
dominated era and matter dominated era and then
obtain different functions for the expansion.

The book that I would suggest would be
"Introduction to Cosmology" by A. Liddle.

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