We study the consequences of supersymmetry for primordial black hole (PBH)
abundance constraints. PBHs will emit supersymmetric particles during their
evaporation when their mass is less than about 10(11) g. In most models of
supersymmetry the lightest of these particles, the lightest supersymmetric
particle (LSP), is stable and will hence survive to the present day. We ca
lculate the limit on the initial abundance of PBHs from the requirement tha
t the present day LSP density be less than the critical density. We apply t
his limit, along with those previously obtained from the effects of PBH eva
poration on nucleosynthesis and the present day density of PBHs, to PBHs fo
rmed from the collapse of inflationary density perturbations in the context
of supersymmetric inflation models. If the reheat temperature after inflat
ion is low, so as to avoid the overproduction of gravitinos and moduli, the
n the lightest PBHs which are produced in significant numbers will be evapo
rating around the present day and there are therefore no constraints from t
he effects of the evaporation products on nucleosynthesis or from the produ
ction of LSPs. We then examine models with a high reheat temperature and a
subsequent period of thermal inflation. In these models avoiding the overpr
oduction of LSPs limits the abundance of low mass PBHs which were previousl
y unconstrained. Throughout we incorporate the production, at fixed time, o
f PBHs with a range of masses, which occurs when critical collapse is taken
into account. [S0556-2821(99)01318-1].