Presentation on theme: "Star-formation histories Sorour Shamshiri with Peter Thomas and thanks to Bruno Henriques Rita Tojiero."— Presentation transcript:
Star-formation histories Sorour Shamshiri with Peter Thomas and thanks to Bruno Henriques Rita Tojiero
Star- Formation Histories Outline: VESPA What is VESPA What is the result? Evolution of star-formation history time-bins Comparison SFH between SAMs and VESPA For different redshits Conclusions
What is VESPA An analysis to the Sloan Digital Sky Survey final spectroscopic data release of MGS and LRG sample. The result is a catalogue of star formation and metallicity histories, dust content and stellar masses of nearly 800,000 galaxies. VESPA is intrinsically model dependent, including the SSP modeling, IMF or dust modeling.
Method VESPA solves the following problem: S λ (t,Z) is the luminosity per unit wavelength of a single stellar population of age t and metallicity Z, per unit mass.
VESPA’s bins In HR bin, it is assumed a constant star formation rate For low-resolution, a decaying star formation history is used.
Model Initial mass function – BC03 models: a Chabrier initial mass function – Maraston (M05): with a Kroupa initial mass function Dust model: – One_parameter – Two_parameter T BC = 0.03Gyr
Conclusions We presented Star-Formation Histories for two different versions of the L-Galaxies SA model and compared them with observations from VESPA. The Guo11 and HWT12 models bracket the VESPA results: HWT12 forms fewer stars at early times (ie high redshift) but a higher star- formation rate at all subsequent times.