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15 June 2012

Birth of a Galaxy II: The Role of Radiation Pressure

Authors: Wise, J. et al (2012)
Paper: here

Summary: Using the AMR code ENZO, coupled with a ray-tracing radiative transfer solver, they study how radiation pressure affects the star formation history and growth of an early low-mass galaxy. They run three models, one with only primordial cooling (base model), one which also includes metal cooling (MC model), and one which includes metal cooling, momentum transfer from ionizing radiation, and an H2 dissociating radiation background (RP model). They then study how the metal cooling and radiation pressure affect the internal gas dynamics, the chemo-thermal state of the ISM, the ejecta and outflows, and the star formation history in the three models.

They find that the MC model overcools the gas, which traps the metals in a small region and creates an extremely metal rich dwarf galaxy, which is at odds with observed local dwarfs. When including the RP, however, the SFR is reduced, and the RP adds turbulence, and mixes the SNe ejecta throughout the ISM, preventing over-cooling. This model creates a galaxy which matches the local dwarf mass-metallicity relation.

1 comment:

  1. 1. Why is the J21 (LW) dropping after z=12 in Figure 2 ? Agreed that the Pop III stars, owing to their higher temperature could contribute more per stellar mass to the LW flux, Pop II stars form in clusters, thereby leading to a considerable contribution to the LW flux.

    2. It is hard to compare the three models as you have included the LW feedback in the RP case. LW feedback can prohibit star formation in the minihaloes, hence leading to gas rich mergers, hence leading to a burst in star formation at later times as you correctly mention in the text. So the question is, is the green histogram a sole result of RP or RP+LW?