Does that galaxy really lack dark matter ?

Stacy McGaugh's thoughts on that galaxy without any dark matter. Pretty reasonable I'd say.

What I found most interesting was the comment on the distance of the galaxy. There are two giant galaxies in this region, but distance estimates of the two disagree. If the lower value is correct, then (as noted by the original authors) the conclusions would have to be changed quite strongly. This, though, would conflict with the distance predicted from Hubble expansion (based on redshift measurements), giving an extreme value of its peculiar velocity.

What the author's fail to mention is that the spiral galaxy is already known to have an extreme peculiar velocity, of about 850 km/s. That's not as high as the 1,200 km/s peculiar velocity of DF2 if it's at the lower distance, but if the two are associated then this suddenly becomes very much more plausible.

Except, if you look in NED for the distance measurements of the spiral galaxy (NGC 1042), you see they're all derived from the Tully Fisher relation. That requires an estimate of the galaxy's rotation speed, which is affected by its inclination towards the observer. And this galaxy is nearly face-on, meaning we can't get a very accurate rotation width. I'd bet you anything you like this galaxy actually has a higher line width than estimated, putting it at a larger distance and explaining away its otherwise very high peculiar motion.

I'm loathe to admit it, but this would then mean that the dark matter free DF2 galaxy would be in a stronger gravitational field from its neighbours. That's going to affect the MOND estimate of its velocity width, probably making it predict a lower dispersion and bringing it into closer agreement with observations. Which is a shame, because the external field effect is the MONDers answer to literally everything.

https://tritonstation.wordpress.com/2018/04/02/the-dwarf-galaxy-ngc1052-df2/amp/