Has frame dragging been accounted for in galactic rotation curves?

Question

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.

Answer 1

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.

That 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. Unfortunately, it has received far more attention than it deserves, because of a lot of uncritical news articles.

Answer 2

You can check this recent paper, that (hopefully) add a quite final point to the discussion of GR effects on the rotation curves of disk galaxies:

https://arxiv.org/pdf/2207.09736.pdf

The gravitomagnetic effect on the rotation curve of a disk galaxy model with realistic (i.e. exponentially declining) density profile is rigorously calculated. The corrections over the newtonian predictions are found of the order (v/c)^2 ~ 10^-6 over the whole disk, confirming standard GR expectations: GR and newtonian rotation curves are for all practical purposes identical, and DM is required in GR as in newtonian gravity.

Notice that the newtonian rotation curve of an exponential disk is almost flat up to ~ 3 scale-lenghts of the (visibile) stellar disk (already containing more than 80 per cent of the stars), so DM indications from rotation curves are NOT derived from rotation curves of stars. This is well known in astronomy since the '80: the only robust indications of DM in disk galaxies are obtained from the rotation curve in HI, well beyond the end of the visibile disk.

To predict a flat rotation curve of stars in a stellar disk by using GR is not resolving the problem of DM: quite the opposite, is just a confirmation (as expected) of the newtonian predictions.

Answer 3

Even assuming the theorized frame dragging effect in its most fundamental level thus of frame dragging of curved spacetime itself (i.e without assuming the presence of space dust) described in G.O. Ludwig's paper is valid, this mass current or may I say rather "gravity current" the paper describes as being responsible for the anomalous additional rotation speed observed at the rim of galaxies then this would also imply a quantum vacuum. Which when polarized through rotation of Baryonic mass (i.e. galaxy) exhibits gravitational properties and an effective mass (i.e. probably created by the circular polarization of the ZPE of the vacuum around the galaxy). Therefore, also the presence of a possible stable vacuum quanta or else particle of the fabric of spacetime and vacuum which demonstrates only gravitational interaction with normal matter is inferred thus we go full circle back to the dark matter hypothesis as being valid.

IMHO the analysis and conclusion of this paper although novel and ingenious is not fundamental.