UMN-TH-2018/01

TPI-MINN-01/34

astro-ph/0107389

July 2001

Recent observations suggest the existence of a white dwarf population in the Galactic halo , while others suggest that deuterium has been astrated in systems at high redshift and low metallicity .
We propose that these observations could be signatures of an early population of intermediate-mass stars .
Such a population requires a Population III initial mass function different from that of the solar neighborhood , as perhaps also suggested by the observed cosmic infrared background .
Also , to avoid overproduction of C and N , it is required that the Z = 0 yields of these stars have low ( \sim 10 ^ { -3 } solar ) abundances as suggested by some recent calculations .
Under these assumptions , we present a model which reproduces the observed D vs Si trend , and predicts a high cosmic Type Ia supernova rate , while producing a white dwarf population that accounts for only \sim 1.5 \% of the dark halo .
This scenario can be tested by observations of the cosmic supernova rate , and by confirmation and further studies of the putative white dwarf halo population .