Tremaine-Gunn bound
= Tremaine-Gunn bound
{c}
The maximum primordial occupation of a collisionless <fermion> distribution limits the coarse-grained phase-space density attainable in a halo. Combining that bound with an observed <velocity dispersion> and <mass density> gives a lower candidate <mass>. This tests light-fermion halo models independently of whether the candidate is optically visible.<Dynamical Role of Light Neutral Leptons in Cosmology by Scott Tremaine and James Edward Gunn>[Physical Review Letters 42, pp. 407–410]{ref}