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
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.
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