I have a question about measuring the distances and recession speeds of galaxies

Question

I have a question about measuring the distances and recession speeds of galaxies, which is also linked to dark matter/energy.

My understanding is that measurements indicate that space is expanding, and it is this that is responsible for the redshift observed by inter alia Hubble.

My question is, are all galaxies moving away from each other only because of the expansion of space, or if one was to remove this expansion effect could they be moving towards each other and or away from each other? It is perhaps difficult to word - I am imagining a rubber band with two points representing two galaxies of static distance controlling for the expansion of space. Stretch the rubber band and the distance increases between the points. If you replace the points with two ants, and stretch the band, the distance between them may increase although the ants themselves may be walking towards each other or it may increase faster than anticipated if they are walking away from each other. Is the universe like the points or the ants?

It occurs to me that if, controlling for the expansion of space, the galaxies are moving together in some regions of space, or away from each other in others, this could indicate the influence of dark matter or energy, or some other interesting effect.

I imagine there is a problem - measuring the actual distances to the galaxies to then control for the expansion of space. I understand that standard candles were used to measure distances to galaxies and from this the distance/red shift relationship observed. Do we have reliable candles for a good proportion of galaxies I wonder, or when we hear of galaxies being at such and such a distance, are we more typically measuring the red shift from them and using that to obtain the distance. If the latter then presumably one would not be able to tell if, controlling for the expansion of space, they are going away from or towards us. Or are there other ways of measuring distance?

Explanation / Answer

So, it

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