Annu. Rev. Astron. Astrophys. 1994. 32: 531-590 Copyright © 1994 by Annual Reviews. All rights reserved

5. CONSTRAINTS ON POPULATION III

In this section we review the constraints that can be placed on Population III stars and their remnants by considering their generation of background light and nucleosynthetic products. The discussion is only brief because these limits are essentially the same as they were a decade ago. The constraints on _*(M), the density of stars of mass M in units of the critical density, are summarized in Figure 2, which is an updated version of Figure 6 from Carr et al (1984). The remnant constraints, which are also shown in Figure 2, are discussed in detail in Section 6.

Figure 2. Summary of the various constraints on the density of Population III stars of mass M (an updated version of Figure 6 in Carr et al 1984). All the limits except the "light" one assume that the objects are inside galactic halos. The light limit is only interesting for stars that burn at z < 30 unless the light is reprocessed by dust. The nucleosynthesis limits for M > 102 M assume that the fraction of mass lost during the hydrogen and helium burning phase is not too large.