Feedback regulated star formation, from star clusters to galaxies

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• Sami Dib (Imperial College London)
• Wednesday 11 January 2012, 14:00-15:00
• Physics Library, Physics West Building.

If you have a question about this talk, please contact Alastair Sanderson.

I will summarise results from a model which describes star formation in protocluster clumps of different metallicities. In this model, gravitationally bound cores form uniformly in the clump following a prescribed core formation efficiency per unit time. After a contraction timescale which is equal to a few times their free-fall times, the cores collapse into stars and populate the IMF . Winds from the newly formed OB stars remove gas from the clump until core and star formation are quenched. The power of the radiation driven winds has a strong dependence on metallicity and increases with increasing metallicity. Thus, winds from stars in the high metallicity models lead to a rapid evacuation of the gas from the protocluster clump and to a reduced star formation efficiency, SFE _exp, as compared to their low metallicity counterparts. By combining the SFE _exp with the timescales on which gas expulsion occurs, we derive the metallicity dependent star formation rate per unit time in this model as a function of the gas surface density Sigma_g. This is combined with the molecular gas fraction in order to derive the dependence of the surface density of star formation Sigma_SFR on Sigma_g in galactic disks. This feedback regulated model of star formation reproduces very well the observed star formation laws extending from low gas surface densities up to the starburst regime. Furthermore, the results show a dependence of Sigma_SFR on metallicity over the entire range of gas surface densities.

This talk is part of the Astrophysics Seminars series.

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