Figure 37

Figure 37: The surface brightness (a) and velocity dispersion (b) profiles of the elliptical galaxy NGC 7507 [375] fitted by MOND (lines [399]). Elliptical galaxies can be approximated in MOND as high-order polytropes with some radial orbit anisotropy [388]. This particular case has a polytropic index of 14 with anisotropy of the Osipkov–Merritt form with an anisotropy radius of 5 kpc and maximum anisotropy β = 0.75 at large radii [399]. The stellar mass-to-light ratio is ϒB = 3.03M ⊙∕L ⊙ ∗. This simple model captures the gross properties of both the surface brightness and velocity dispersion profiles. The galaxy is well-fitted by MOND, contrary to the claim of [375].