Copyright by Athena Ranice Stacy 2011 - The University of Texas at ...

leaving behind a neutron star or black hole. Thus, the masses of the first stars
are the main determinant of their cosmological impact, though other factors
such as the typical rotation rate and the overall formation rate also play a
vital role.
Improving our understanding of the formation of the first stars and
their resulting initial mass function (IMF) is thus central to understanding this
turning point in the universe and the environment in which the first galaxies
formed. Such work is especially important now in order to prepare for up-
coming observations of instruments such as the James Webb Space Telescope
(JW ST ), the Square Kilometer Array, and LISA, as well as the future ground-
based Extremely Large Telescopes such as the E-ELT, GMT, and TMT (e.g.
Greif et al. 2009; Johnson et al. 2009). In particular, JWST is expected to
detect z 10 galaxies and give constraints on the IMF of their constituent
stars (Pawlik et al. 2011). It will also be exciting to match predictions from
upcoming numerical work with spectroscopic observations of individual stars
in nearby ultra-faint dwarfs (‘dwarf archaeology’), as these stars may hold the
SN abundance signatures of Pop III stars (Frebel and Bromm 2010).
1.2 Relation to Previous Work
Much numerical work has already been carried out in attempting to
predict the typical mass of the first stars. The earliest simulations found
that Pop III stars were very massive (> ∼ 100 M⊙) due to a lack of metal and
dust cooling, and that these stars formed in isolation (e.g. Abel et al. 2002;
Bromm et al. 2002). Later simulations confirmed this (e.g. Yoshida et al.
2006). However, while these cosmological simulations could study the initial
collapse of primordial gas to very high densities, near the point when a Pop
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