I am (as many here it seems) on the side of wishing that all the phenomena currently ascribed to dark matter will be all explained away by some more elegant and less "tunable" theory. However, imo the chances of the specific idea from the article being the case are very low, and it's more likely that there is a problem with the new way of calculating the gravitomagnetic contribution, either in theory or with the code/computation.

I've had the same idea a few years ago. It's nice because the effect is that the moving matter in a certain orbit causes an increase in the centripetal acceleration (i.e. higher velocity) for orbits further out, and a reduction for orbits further in, which is in the right direction to flatten the rotation curves.

Being a procrastinating amateur and not knowing/being able to invent sophisticated techniques such as the one in the article, I didn't fully go though with the calculations, because after some unsuccessful attempts I convinced myself that the effects involved are way too small to matter.

Consider two equal electric charges a certain distance from each other. If they move perpendicularly to the line between them at constant velocity, there will be an attractive force due to the magnetic field that opposes the electric repulsion. However, the ratio of the magnetic to electric force is the familiar (v/c)^2, at least for non-relativistic speeds, and in any case the magnetic force can never exceed the electric force, because perpendicular distances are preserved in the Lorentz transformation. Hence the most the magnetic force can do is slow down the repulsion between the charges, exactly in the amount consistent with time dilation in the moving frame (where the charges are stationary so there is no magnetic field).

Transposing that to gravitomagnetism, I think that within that approximation the situation is the same. At the very best the gravtomagnetic force can equal the gravitoelectric force when masses move close to the speed of light, making it mathematically impossible to account for the DM mass being greater than the baryonic mass. On top of that, at typical velocities in galaxies the magnetic effect is ~1M times smaller.

Together with the facts that 1. there are other unexplained phenomena that won't be explained by this, and 2. it's trivial in retrospect so probably some truly smart person thought of it already and discarded it a minute later without even thinking it's worth publication, I just abandoned it, always wanting to get back to it eventually just for fun when I have the time (sadly this seems to always mean never).

Fast forward a few years, and I see this article on HN, and really regretted having been lazy with my dismissal, maybe I missed something along with everyone else, and should have really done the calculations. So I found a few hours this weekend, learned julia for the Nth time, and finally did what I should have done years ago... and as expected the gravitomagnetic effects have zero material impact on the rotation curves.

Now, admittedly my calculations are not fully correct, but I think my approximations are reasonable enough that they wouldn't be many orders of magnitude off, validating the intuition about relative strength of electric vs magnetic force. So I'd be very surprised if the results in the article turn out to be right.

I don't think it's fair to attack scientists for not having simulated galaxies with full GR. They realized with much less work than me that it does not matter. At the sizes, masses, and velocities of galaxies, the effects are minuscole, and using Newtonian gravity is sufficient, especially if the phenomenon to explain is so large. It's like in the solar system: GR can explain Mercury's precession, but it wouldn't help if we had orbital anomalies equivalent to effect of 5 solar masses scattered throughout the orbital plane.

Anyway, another thing I've put off forever is making an HN account after a long time reading. So since I saw this story here and it made me finally get that idea out of my system, what better occasion to also create an account and get that out of my system too :)