Model Chemical Evolution:

Starburst EnvironmentStarburst Environment

Once upon a time…Once upon a time… Somewhat big bang Somewhat big bang

started it all.started it all. Radiation dominationRadiation domination Matter dominationMatter domination Matter gets clumpy: Matter gets clumpy:

stars and galaxies stars and galaxies started formingstarted forming

75% Hydrogen75% Hydrogen

25% Helium 25% Helium

It continues…It continues… Nitrogen, Oxygen, Carbon Nitrogen, Oxygen, Carbon

formed.formed. More and more stars formed More and more stars formed

from the enriched gas present.from the enriched gas present. It all gives more and more It all gives more and more

elements to the universe.elements to the universe.

Modelling starburst chemical evolution:Modelling starburst chemical evolution:

Calculates thrown-out Calculates thrown-out elements called yields elements called yields

Estimates how much of Estimates how much of different elements exist.different elements exist.

Has many parametersHas many parameters

Our general modelOur general model The model is simpleThe model is simple Instantaneous burst onlyInstantaneous burst only Some parameters: Starforming Some parameters: Starforming

efficiency, SNIa/SNII-rate, IMF, efficiency, SNIa/SNII-rate, IMF, Infall parameters, burst-length, Infall parameters, burst-length, number of bursts.number of bursts.

Recent Data and YieldsRecent Data and Yields Portinari et.al – Stellar winds + Portinari et.al – Stellar winds +

Type II supernovae.Type II supernovae. Van der Hoek et. al – Van der Hoek et. al –

Intemerdiate mass star.Intemerdiate mass star. Nomoto et. al. – Supernovae Nomoto et. al. – Supernovae

Type Ia.Type Ia.

Various different massesVarious different masses

Different metallicitiesDifferent metallicities

Interpolation necessaryInterpolation necessary

Example BurstExample BurstParametersParameters

SNIa/SNII = 0.15SNIa/SNII = 0.15 No infallNo infall Initial Metal = Initial Metal =

0.0040.004 Eff = 0.15Eff = 0.15 Salpeter IMFSalpeter IMF Six bursts, 2Gyr Six bursts, 2Gyr

each.each.

Standard vs GeneralStandard vs General

No InfallNo Infall No SNIaNo SNIa Initial Metal = 0.004Initial Metal = 0.004 Eff = 0.15Eff = 0.15 Salpeter IMFSalpeter IMF One burst, 2GyrOne burst, 2Gyr

Comparison: Olofsson’s standard model vs our general model.Comparison: Olofsson’s standard model vs our general model.

ParametersParameters

BlueBlue = General = General

Red Red = Standard= Standard

Blue Compact GalaxiesBlue Compact Galaxies

Dwarf-galaxies, dominated by Dwarf-galaxies, dominated by a younger stellar population.a younger stellar population.

Blue colors.Blue colors. High gas content and low High gas content and low

metallicity (Z~0.01-0.0004).metallicity (Z~0.01-0.0004). Massive starbursts during Massive starbursts during

usually no loger than 100Myrusually no loger than 100Myr Starburst environment, Starburst environment,

chemical evolution plays an chemical evolution plays an important role.important role.

(Example of where our model applies)(Example of where our model applies)

Observations - IObservations - I

No InfallNo Infall SNIa/SNII = 0.15SNIa/SNII = 0.15 Initial Metal = 0.004Initial Metal = 0.004 Eff = 0.15Eff = 0.15 Salpeter IMFSalpeter IMF Six bursts, 2Gyr each.Six bursts, 2Gyr each.

ParametersParameters

Observations - IIObservations - II

No InfallNo Infall SNIa/SNII = 0.10SNIa/SNII = 0.10 Initial Metal = 0.004Initial Metal = 0.004 Eff = 0.15Eff = 0.15 Salpeter IMFSalpeter IMF Six bursts, 2Gyr each.Six bursts, 2Gyr each.

ParametersParameters

Why?Why?

Many possible parametersMany possible parameters

Matteucci et.al: Matteucci et.al:

"Other parameters such as the number and duration of "Other parameters such as the number and duration of bursts, the effeiciency of the SF and the galactic wind, the bursts, the effeiciency of the SF and the galactic wind, the slope of the IMF and the production of N, regarding it's slope of the IMF and the production of N, regarding it's primary or secondary origin in massive stars, were varied primary or secondary origin in massive stars, were varied in order to understand the observed distribution of N/O, in order to understand the observed distribution of N/O, C/O, Si/O and [O/Fe] versus O/H in BCGs.”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 IMFVariable IMF

No InfallNo Infall SNIa/SNII = 0.15SNIa/SNII = 0.15 Initial Metal = 0.004Initial Metal = 0.004 Eff = 0.15Eff = 0.15 Six bursts, 2Gyr each.Six bursts, 2Gyr each. Variable IMFVariable IMF

ParametersParameters

Red: x = 1.35 (Salpeter) x = 1.35 (Salpeter)

Blue: x = 0.35 x = 0.35

Green: x = 0 x = 0

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

ParametersParameters

Supernovae Type IaSupernovae Type Ia

No InfallNo Infall SNIa/SNII variableSNIa/SNII variable Eff = 0.15Eff = 0.15 One burst, 2Gyr.One burst, 2Gyr. Salpeter IMFSalpeter IMF

ParametersParameters

Red : Rate = 0.15 : Rate = 0.15

Blue : Rate = 0 : Rate = 0

ConclusionsConclusions

The result of the general model is surprisingly similar to the The result of the general model is surprisingly similar to the standard model, since only instantaneous bursts considered.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 The standard setup seems incomplete to reach the observed abundance-ratios in N/O and C/O.abundance-ratios in N/O and C/O.

Possible alternations of parameters like IMF and SNIa/SNII-Possible alternations of parameters like IMF and SNIa/SNII-rate needs justification to fit observational data.rate needs justification to fit observational data.

Future work include fitting parameters and further applications Future work include fitting parameters and further applications and comparison with other type models.and comparison with other type models.