Primordial black hole formation in supergravity - art. no. 043512.

We study a double inflation model (a preinflation + a new inflation) in sup ergravity and discuss the formation of primordial black holes which may be identified with massive compact halo objects (MACHOs) observed in the halo of our galaxy. The preinflation drives an inflaton for the new inflation cl ose to the origin through supergravity effects and the new inflation natura lly occurs. If the total e-fold number of the new inflation is smaller than similar to 60, both inflations produce cosmologically relevant density flu ctuations. If the coherent inflaton oscillation after the preinflation cont inues until the beginning of the new inflation, density fluctuations on sma ll cosmological scales can be set suitably large to produce black holes MAC HOs of masses similar to 1M(.) in a wide region of parameter space in the d ouble inflation model. [S0556-2821(99)03402-5].