Meta-cold dark matter, also known as mCDM, is a form of cold dark matter proposed to solve the cuspy halo problem. It consists of particles "that emerge relatively late in cosmic time (z ≲ 1000) and are born non-relativistic from the decays
of cold particles".[{{cite journal|title=Dark Matter Halos with Cores from Hierarchical Structure Formation|doi=10.1103/PhysRevD.75.061303|year=2007|journal=Physical Review D|volume=75|issue=6|pages=061303|arxiv=astro-ph/0606281|last1=Strigari|first1=Louis|last2=Kaplinghat|first2=Manoj|last3=Bullock|first3=James|bibcode = 2007PhRvD..75f1303S |s2cid=119436792}}]