Astronomy
The invisible halo around a galaxy
Build a Navarro–Frenk–White halo. Probe its enclosed mass, circular speed and light deflection at different galactic radii.
The model and its limits
Spherical untruncated NFW halo with H₀ = 70 km/s/Mpc plus an exponential baryonic disk (scale length 3 kpc) whose enclosed mass is taken as if spherical. Coloured halo tracers represent inferred density, not luminous dark matter. Deflection is the halo’s thin-lens bending angle. Halo and probe radii use the same logarithmic distance mapping; the visible disk marks a 25 kpc radius.
Equations used in the module
Equations ρ = ρ_s/[x(1+x)²]; M = 4πρ_s r_s³[ln(1+x)−x/(1+x)]; v² = GM/r.
