Some galaxies have active outflows of material (mostly gas) that would eventually stop at some distance and then fall again into the galaxy due to gravitational attraction.

However, can dark energy influence this mechanism so that in the outflow the material would fall again towards the galaxy but a greater distance than it would without dark energy?

  • 1
    $\begingroup$ The inward acceleration is slightly reduced. The escape velocity is reduced so more of the outward moving material is lost and infall takes longer. Where the material turns around depends on its kinetic energy. For specifics one needs to do numerical integrations. $\endgroup$
    – eshaya
    Commented Sep 24, 2023 at 14:29
  • $\begingroup$ @eshaya and could dark energy make the ejected material be further away from the galaxy (but at a relatively close distance so all the material would return to the galaxy) than it would without it, thus making the return trip longer and adding potential energy to the ejected material? $\endgroup$
    – vengaq
    Commented Sep 26, 2023 at 10:02
  • $\begingroup$ If we are ignoring the other galaxies, then without dark energy, some material could go out arbitrarily far and then fall back. With dark energy, the maximum turnaround radius is where the two opposing forces are equal. $\endgroup$
    – eshaya
    Commented Sep 26, 2023 at 14:37


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