  In this work we show that modifying the thermal history of the Universe by
including an early period of matter domination can lead to the formation of
astronomical objects. However, the survival of these objects can only be
possible if the dominating matter decays to a daughter particle which is not
only almost degenerate with the parent particle but also has an open
coannihilation channel. This requirement translates in an upper bound for the
coupling of such a channel and makes the early structure formation viable.

High Energy Physics - Phenomenology;Cosmology and Nongalactic Astrophysics