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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
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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: • Sλ(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 TBC= 0.03Gyr
L-Galaxies: evolution of star-formation history time-bins Picture credit: Rob Yates
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.