Model Chemical Evolution: Starburst Environment

Once upon a time… Somewhat big bang started it all. Radiation domination Matter domination Matter gets clumpy: stars and galaxies started forming 75% Hydrogen 25% Helium

It continues… Nitrogen, Oxygen, Carbon formed. More and more stars formed from the enriched gas present. It all gives more and more elements to the universe. Modelling starburst chemical evolution: Calculates thrown-out elements called yields Calculates thrown-out elements called yields Estimates how much of different elements exist. Estimates how much of different elements exist. Has many parameters Has many parameters

Our general model The model is simple Instantaneous burst only Some parameters: Starforming efficiency, SNIa/SNII-rate, IMF, Infall parameters, burst-length, number of bursts.

Recent Data and Yields Portinari et.al – Stellar winds + Type II supernovae. Portinari et.al – Stellar winds + Type II supernovae. Van der Hoek et. al – Intemerdiate mass star. Van der Hoek et. al – Intemerdiate mass star. Nomoto et. al. – Supernovae Type Ia. Nomoto et. al. – Supernovae Type Ia. Various different masses Different metallicities Interpolation necessary

Example Burst Parameters SNIa/SNII = 0.15 N No infall Initial Metal = Eff = 0.15 Salpeter IMF Six bursts, 2Gyr each.

Standard vs General No Infall No SNIa Initial Metal = Eff = 0.15 Salpeter IMF One burst, 2Gyr Comparison: Olofsson’s standard model vs our general model. Parameters Blue = General Blue = General Red = Standard Red = Standard

Blue Compact Galaxies Dwarf-galaxies, dominated by a younger stellar population. Dwarf-galaxies, dominated by a younger stellar population. Blue colors. Blue colors. High gas content and low metallicity (Z~ ). High gas content and low metallicity (Z~ ). Massive starbursts during usually no loger than 100Myr Massive starbursts during usually no loger than 100Myr Starburst environment, chemical evolution plays an important role. Starburst environment, chemical evolution plays an important role. (Example of where our model applies)

Observations - I No Infall SNIa/SNII = 0.15 Initial Metal = Eff = 0.15 Salpeter IMF Six bursts, 2Gyr each. Parameters

Observations - II No Infall SNIa/SNII = 0.10 Initial Metal = Eff = 0.15 Salpeter IMF Six bursts, 2Gyr each. Parameters

Why? Many possible parameters Many possible parameters Matteucci et.al: Matteucci et.al: "Other parameters such as the number and duration of bursts, the effeiciency of the SF and the galactic wind, the slope of the IMF and the production of N, regarding it's primary or secondary origin in massive stars, were varied in order to understand the observed distribution of N/O, C/O, Si/O and [O/Fe] versus O/H in BCGs.” "Other parameters such as the number and duration of bursts, the effeiciency of the SF and the galactic wind, the slope of the IMF and the production of N, regarding it's primary or secondary origin in massive stars, were varied in order to understand the observed distribution of N/O, C/O, Si/O and [O/Fe] versus O/H in BCGs.” (O/H) is pretty ok, N/O and C/O to high! (O/H) is pretty ok, N/O and C/O to high!

Variable IMF No Infall SNIa/SNII = 0.15 Initial Metal = Eff = 0.15 Six bursts, 2Gyr each. Variable IMF Parameters x = 1.35 (Salpeter) Red: x = 1.35 (Salpeter) x = 0.35 Blue: x = 0.35 x = 0 Green: x = 0

Infall - Example Non-zero Infall parameters SNIa/SNII = 0.15 Eff = 0.15 Two bursts, 2Gyr each. Salpeter IMF Parameters

Supernovae Type Ia No Infall SNIa/SNII variable Eff = 0.15 One burst, 2Gyr. Salpeter IMF Parameters : Rate = 0.15 Red : Rate = 0.15 : Rate = 0 Blue : Rate = 0

Conclusions The result of the general model is surprisingly similar to the standard model, since only instantaneous bursts considered. The result of the general model is surprisingly similar to the standard model, since only instantaneous bursts considered. Supernovae Type Ia and Infall seems reasonable. Supernovae Type Ia and Infall seems reasonable. The abundance of O/H seems reasonable. The abundance of O/H seems reasonable. The standard setup seems incomplete to reach the observed abundance-ratios in N/O and C/O. The standard setup seems incomplete to reach the observed abundance-ratios in N/O and C/O. Possible alternations of parameters like IMF and SNIa/SNII- rate needs justification to fit observational data. Possible alternations of parameters like IMF and SNIa/SNII- rate needs justification to fit observational data. Future work include fitting parameters and further applications and comparison with other type models. Future work include fitting parameters and further applications and comparison with other type models.