Shakura-Sunyaev accretion disc temperature profile

What you are seeing: the temperature profile of a steady, optically thick, geometrically thin accretion disc around a compact object. The Shakura-Sunyaev (1973) closed form is

The bracket factor vanishes at the inner edge (so $T(R_\text{in}) = 0$ even though the bare $r^{-3/4}$ scaling would diverge from below); the maximum of $T(r)$ occurs at $r = (49/36) R_\text{in}$.

The top panel shows $T(r)$ in cyan and the bare $r^{-3/4}$ scaling in dashed orange. The bottom panel is a face-on rendering of the disc with annulus colors set by local temperature. The hot inner ring shows the temperature peak and the gradual cooling toward larger radii.