The radial dependence of the Lyα photon recoil heating efficiency for a point continuum source at z = 10 in intergalactic gas with temperature T = 10 K. The points show the results solving the full integro-differential radiative transfer equation. The efficiency approaches a constant value distant from the source, corresponding to the efficiency expected for a homogeneous distribution of such sources. The dashed line shows the estimate using the diffusion approximation to the radiative transfer equation for homogeneously distributed sources.