  The asteroid belt is an open window on the history of the Solar System, as it
preserves records of both its formation process and its secular evolution. The
progenitors of the present-day asteroids formed in the Solar Nebula almost
contemporary to the giant planets. The actual process producing the first
generation of asteroids is uncertain, strongly depending on the physical
characteristics of the Solar Nebula, and the different scenarios produce very
diverse initial size-frequency distributions. In this work we investigate the
implications of the formation of Jupiter, plausibly the first giant planet to
form, on the evolution of the primordial asteroid belt. The formation of
Jupiter triggered a short but intense period of primordial bombardment,
previously unaccounted for, which caused an early phase of enhanced collisional
evolution in the asteroid belt. Our results indicate that this Jovian Early
Bombardment caused the erosion or the disruption of bodies smaller than a
threshold size, which strongly depends on the size-frequency distribution of
the primordial planetesimals. If the asteroid belt was dominated by
planetesimals less than 100 km in diameter, the primordial bombardment would
have caused the erosion of bodies smaller than 200 km in diameter. If the
asteroid belt was instead dominated by larger planetesimals, the bombardment
would have resulted in the destruction of bodies as big as 500 km.
