Dark matter halo and the galactic rotation curve

What you are seeing: a 3D galactic disk with its dark-matter halo (transparent purple sphere) on the left, and the rotation curve $v_c(r)$ on the right. The bulge (gold), exponential disk (cyan), and NFW dark halo (purple) contributions to $v_c$ are plotted separately, with the total (white) on top. Toggle the dark halo off to see the flat plateau collapse into a Keplerian fall

Figure 1. Three-component galactic rotation curve (Hernquist bulge, exponential disk, NFW dark halo) with 3D disk + halo inset. Method: closed-form enclosed-mass integrals; v_c(r) = sqrt(G M(<r) / r).

M_DM80

concentration c12

scale radius r_s20

dark halo

presetvisible+dm

WHAT TO TRY

Vary each control and watch the rail readouts respond.
Compare the diagnostic plot against the live scene.