AAS 204th Meeting, June 2004
Session 34 Detecting the First Stars and AGN
Topical Session, Tuesday, June 1, 2004, 8:30-10:00am, 10:45am-12:30pm, 2:30-4:00pm, 4:15-6:00pm, 707/709

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[34.08] The Ionizing Efficiency and Mass Function of the First Stars

A. Venkatesan (University of Colorado, Boulder)

We present constraints on the masses and ionizing efficiencies of the first stars by considering current data on reionization, the microwave background, and the metal enrichment of the high-redshift intergalactic medium (IGM) and of quasar broad emission line regions. We find, in contrast to some recent studies, that these observations indicate that the initial mass function (IMF) of the first stars need not necessarily have been biased towards high masses, and that very massive stars cannot have existed exclusively at early epochs. Stars of mass about 1-40 solar masses must have existed at redshifts about 10-20, possibly coeval with any hypothesized stars of masses exceeding about 100 solar masses at these epochs. This is in agreement with the nucleosynthetic abundance pattern detected in extremely metal-poor stars in the Galactic halo. Finally, a top-heavy IMF is not preferred as a more efficient high-redshift source of ionizing radiation, based on nucleosynthetic arguments in association with a given level of IGM enrichment. We discuss the implications from these results for the planning of future observations that will target the detection of the first stellar clusters.

The author(s) of this abstract have provided an email address for comments about the abstract: aparna@casa.colorado.edu

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Bulletin of the American Astronomical Society, 36 #2
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