This paper https://arxiv.org/abs/2405.04933 claims - not yet peer reviewed though - that assuming cylindrical symmetry the vacuum solution yields flat galactic rotation curves without dark matter.
Two questions:
Are the flat rotation curves predetermined by choosing the correct symmetry?
Imagine a solar system or a protoplanetary disk which apart from the size has similar matter distribution like a flat galaxy. If correct then obviously the assumption of cylinder symmetry would according to this paper falsely yield flat rotation curves too. Or am I wrong here? Is perhaps this comparison galaxy vs. solar system not applicable?
