# Has frame dragging been accounted for in galactic rotation curves?

This article explicitly takes frame dragging into account in calculating expected galactic rotation curves in the absence of dark matter, and appears to obtain very close matches to observed curves. Is it true that frame dragging is typically ignored in analysis of galactic rotation curves? If so, it seems like a huge oversight.

• Frame dragging is a small effect, suppressed by order $v^2/c^2$ relative to the gravitational attraction. For objects in the galaxy, $v/c \sim 10^{-3}$, so the effect is order $10^{-6}$ which is far too small. Mar 6, 2021 at 3:29
• The paper has probably just screwed up some step of the analytic argument, resulting in a massive overestimation of the effect. That's what happens when you hyper-focus on solving differential equations exactly, getting a forest of special functions, without ever doing a back of the envelope check. Mar 6, 2021 at 3:30
• Furthermore, there have been lots of papers on adding general relativistic corrections to $N$-body simulations... the only reason you haven't heard much about them is because everybody already knows it's a technical point that will provide small corrections. It's not like everybody forgot general relativity is a thing! Mar 6, 2021 at 3:40
• ^^^ that. should be the answer (preceded by a "yes") rather than just a comment ;)
– rfl
Mar 6, 2021 at 16:15
• That article seems to assume that bulk rotation of the stars (“mass currents”) is key, as though all galaxies are spiral galaxies, but this ignores all the evidence for dark matter in non-rotating galaxies. Jun 10, 2021 at 12:45

Frame dragging is a small effect, suppressed by order $$v^2 / c^2$$ relative to the gravitational attraction. For objects in the galaxy, $$v/c \sim 10^{-3}$$, so the effect is of order $$10^{-6}$$, which is far too small to make a noticeable difference. The other uncertainties are far greater than that.