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Constraints on the IMF of the first stars

R. Schneider·R. Salvaterra·A. Ferrara·B. Ciardi
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Abstract

Motivated by theoretical predictions that first stars were predominantly very massive, we investigate the physics of the transition from an early epoch dominated by massive Pop III stars to a later epoch dominated by familiar low-mass Pop II/I stars by means of a numerically-generated catalogue of dark matter halos coupled with a self-consistent treatment of chemical and radiative feedback. Depending on the strength of the chemical feedback, Pop III stars can contribute a substantial fraction (several percent) of the cosmic star formation activity even at moderate redshifts, z = 5. We find that the three z = 10 sources tentatively detected in NICMOS UDFs should be powered by Pop III stars, if these are massive; however, this scenario fails to reproduce the derived WMAP electron scattering optical depth. Instead, both the UDFs and WMAP constraints can be fulfilled if stars at any time form with a more standard, slightly top-heavy, Larson IMF in the range 1 Msun < M < 100 Msun.

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R. Schneider, R. Salvaterra, A. Ferrara, B. Ciardi. 2005-10-24. Constraints on the IMF of the first stars. https://doi.org/10.1111/j.1365-2966.2006.10331.x

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