Degenerate electron gas ($k_{B}T\ll E_F$)

An electron Fermi gas whose occupation is governed mainly by the Pauli exclusion principle, with thermal energy small compared with its kinetic Fermi energy. At zero temperature its momentum states are filled up to $p_F$. In the ultrarelativistic limit $E/V=3nc{p}_F/4\propto n^{4/3}$, with $n=4\pi g_s{p}_F^3/(3h^3)$. This supplies the pressure supporting a white dwarf until the relativistic mass limit is approached.