Using the same photometric catalogues used for photometric redshifts   we have modified 
HyperZ code (Bolzonella, Miralles & Pello' 2000) to estimate photometric stellar Mass content:

N.B.: when used in Hyperz instrumental CFHT filters are convolved with the CCD transmission function of the "EPI" CCD. We use AB magnitude system.

Assuming a Star formation history :  SFR=Mgal/tau * exp(-age/tau)

Best fit to model parameters (age, SF, dust,....etc)

==> Mass processed = int [ sfr(t) * dt ]
       
==> Stellar Mass = int [ sfr(t) * (1- R(t)) * dt ]    where R(t) is the gas return fraction

TEST AND SIMULATIONS

1- Bruzual & Charlot 2003 spectral energy modeling code :  
     Salpeter IMF,
     SF history: tau=0.1,0.3,1,2,3,5,10,15,30,infinity  Gyrs
     age=0.01 to age of universe(z)
     dust content: Av=0 to 1.8 mag.
     dust extinction law = Calzetti 2000

2- SED simulated at the same depth as in VVDS images

RESULTS:

1- Stellar Masses are whithin a factor 2 using different codes (HyperZMass & Lucia-ZMass)

2- Using UBVRIJK bands:
     Stellar Masses recovered are within a factor 2 (sigma=0.29 see below),
     but problems in models with age<0.1 Gyrs, which
     underestimate the stellar mass (black points in the plot below)

age vs. age: excess of age<0.1 models  :

3- Using age>0.1 Gyrs the fit improve :  the total dispersion become sigma=0.21 (see below histogram)

4- Using only BVRI photometric bands: the total dispersion increase to sigma=0.58 (see below histogram)

5- Using  UBVRIJK + IRAC (3.6, 4.5, 5.8, 8 micron) photometric bands:   the total dispersion decrease  to sigma=0.18 (see below histogram)

Now you can take a look at the results web page.
 

last update: February 24, 2005