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There are a lot of questions and answers on this site that deal with galaxies receding from us faster then the speed of light like this one:

In summary, Hubble Law: v=H(t)D, where v is recession velocity, D is distance, and H(t) is the Hubble "constant" at a given time, requires that beyond a certain distance velocity is greater than the speed of light.

How Are Galaxies Receding Faster Than Light Visible To Observers?

And this one:

But remote objects may indeed be becoming more remote faster than light.

Some areas of the universe are moving away from us FTL but surely as we get closer to that area, the speed of expansion would gradually slow?

Now these answers commonly only talk about galaxies receding from us, and as seen from us, they might be receding faster then light. None of them talk about whether it is possible, for us, to view two other (other then ours) distant galaxies to recede from each other faster then light.

Question:

  1. Can we observe two galaxies (other then ours) to be receding from each other faster then the speed of light?
Árpád Szendrei
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1 Answers1

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Yes. Any galaxy with a redshift $z\gtrsim 2$ has a recessional speed relative to us that is larger than $c$ now and at all past and future times. So you could take, e.g., two galaxies with equal redshifts larger than 2 that are separated by 60° in the sky. They form an equilateral triangle with us and all pairwise recessional speeds are about the same. Any angle larger than 60°, or a smaller angle and larger redshift, would also work.

benrg
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