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The First Stars and Galaxies: Challenges for the Next Decade Participants
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Talk
Title: Radiative Feedback and the Formation of High Redshift Dwarf Galaxies Author(s): John Wise Abstract: It has been argued that low-luminosity dwarf galaxies are the dominant source of ionizing radiation during cosmological reionization. The fraction of ionizing radiation that escapes into the intergalactic medium from dwarf galaxies with masses less than ~10^11 solar masses plays a critical role during this epoch. Using an extensive suite of adaptive mesh refinement, radiation hydrodynamical simulations of idealized and cosmological dwarf galaxies, we characterize the behavior of the escape fraction in galaxies between 3 x 10^6 and 4 x 10^9 solar masses with different spin parameters, amounts of turbulence, and baryon mass fractions. For a given halo mass, escape fractions can vary up to a factor of two, depending on the initial setup of the idealized halo. In a cosmological setting, we find that the time-averaged photon escape fraction always exceeds 25% and reaches up to 80% in halos with masses of 10^8 solar masses and a top-heavy IMF. The instantaneous escape fraction can vary up to an order of magnitude in a few million years. These high escape fractions suggest that low-luminosity galaxies below 10^10 solar masses were very efficient in contributing to cosmological reionization.
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