Stacy McGaugh On Thin Galaxies

Astrophysicist Stacy McGaugh, at his Triton Station blog, observes that there are far more thin spiral galaxies than expected from cold dark matter halo explanations of galactic rotation curves. MOND does much better in this respect.

This is notable because MOND wasn't designed to produce this data point, and because once again, MOND is predictive while the LambdaCDM model of cosmology is not.

He is mostly highlighting results from a December 2025 paper by Benavides et al., that had escaped my notice in the daily flood of new astronomy papers. Some key illustrations from that paper:

q is a mathematical measurement of how thin a galaxy is relative to its diameter (roughly speaking, thickness divided by diameter). The chart above demonstrates how measurement effects driven by the angle of inclination at which we see galaxies make a world with many thin galaxies look more evenly spread.

This chart illustrates that LambdaCDM simulations dramatically underestimate the proportion of thin galaxies at all but the highest masses (and that many models don't even manage that match to reality at any point).

A final illustration is from one of McGaugh's own papers in 1998 and shows that MOND tends to produce flatter galaxies than Newtonian physics does (even though, unlike Deur's model, MOND is spherically symmetric, rather than relying, in part, on  the shape of a galaxy to demonstrate the dark matter replacing gravitational effect).