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Chemical evolution of the sculptor dwarf spheroidal and its implications on the epoch of reionization

Breddels, M.A. (2009) Chemical evolution of the sculptor dwarf spheroidal and its implications on the epoch of reionization. Master's Thesis / Essay, Astronomy.

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Abstract

We develop a galactic chemical evolution for Sculptor which is able to reproduce the metallicity distribution functions (MDFs) of Mg, Ca and Fe. The relative star formation history from the literature is converted to an absolute star formation history by calculating the average star formation rate from CMD analysis. Because of the spatial sampling and the metallicity gradient present in Sculptor we have to correct its observed MDFs. The star formation history and the corrected MDF combined with a galactic chemical evolution model allows us to derive the inflow rate of primordial gas onto Sculptor and the amount of metals ejected into the intergalactic medium. The rate of inflow is constrained by the corrected Ca MDF. Since dwarf galaxies were probably dominant during the end of the Universe’s Dark Ages, we use Sculptor as a template to study their influence on the ionization of the intergalactic medium. We assume these dwarf galaxies are populated by PopII stars. Using the STARBUST99 software packet, we calculate the production rate of ionising photons based on the star formation rate of Sculptor. Using the Press-Schechter formalism and a scaling relation for the star formation rate relative to that of Sculptor we create a model for the reionization history of the Universe. We find that ancient stellar populations in dwarf galaxies such as Sculptor are sufficient to ionize the Universe at the assumed epoch of reionization of z = 6.5

Item Type: Thesis (Master's Thesis / Essay)
Degree programme: Astronomy
Thesis type: Master's Thesis / Essay
Language: English
Date Deposited: 15 Feb 2018 07:30
Last Modified: 15 Feb 2018 07:30
URI: http://fse.studenttheses.ub.rug.nl/id/eprint/8922

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