hmf.alternatives.wdm.Viel05.lam_eff_fs

property Viel05.lam_eff_fs

Effective free-streaming scale \(\alpha\), in comoving \(h^{-1}{\rm Mpc}\).

Viel et al. (2005), eq. 7 (thermal relics), also Schneider et al. (2012), eq. 5:

\[\alpha = 0.049 \left(\frac{m_x}{\rm keV}\right)^{-1.11} \left(\frac{\Omega_x}{0.25}\right)^{0.11} \left(\frac{h}{0.7}\right)^{1.22} h^{-1}{\rm Mpc}.\]

The extra factor \((1.5/g_x)^{0.29}\) is not in Viel et al. (2005); hmf borrows it from Bode et al. (2001), eq. A9. It is unity for the default \(g_x = 1.5\).