A recent paper attempts to say that maybe the distance of NGC 1052-DF4 is actually 17 Mpc, not 20 Mpc after all ! GASP !

Why is this in any way interesting ? Well, DF4 was one of those galaxies claimed to lack dark matter. The distance in this case matters a lot : if it was at 20 Mpc, it'd be weird, but if it was only 13 Mpc, it'd be normal. Independent measurements have confirmed it's actually 20 Mpc, so it is indeed a strange object after all. But then, simulations found a way to produce such an object just by rare but physically-normal conditions : in the right circumstances, it is possible to strip the dark matter from a dwarf galaxy but leave its stars intact.

The authors of this paper say there should still be some signatures of tidal interactions left over though, so they go looking for them with incredibly deep imaging. They confirm that this is the case for the similarly-famous galaxy NGC 1052-DF2 (thought I'm skeptical of this), but very clearly show that DF4 is undisturbed. Absolutely nothing is going on in its outskirts at all. This is the reason they propose that the distance controversy might need to be re-ignited, noting that other galaxies in the region have been found to be at 17 Mpc rather than 20 Mpc.

To me this feels like a weak and circumstantial argument, and 17 Mpc wouldn't be enough to explain the lack of dark matter anyway. Not only that, but this ignores the now-sizeable population of other galaxies with similar claims for serious dark matter deficiencies.

#Space
#Science
#Astronomy
#Astrophysics

https://llittlephysicists.blogspot.com/2024/02/back-from-grave.html