My review assignment has a question that asks us to use the Navarro–Frenk–White (NFW) profile to find total mass in the galaxy using
$$\rho(R)=\frac{\rho_0}{1+\frac{R}{R_c}}$$ then taking a triple integral of it in spherical coordinates.
I do not have a problem taking the integral or converting it, but I am struggling with what $R_c$ (the critical radius) should be. I must have missed it in class and cannot quite understand it by looking through other online resources. I feel like it would be a constant but I cannot find it online and am wondering if I need to calculate it somehow. Any help with explaining $R_c$ would be greatly appreciated.