Dark energy workshop. Copenhagen Aug. 2007. Why the SNLS ?. One of the biggest high-z supernova survey ~500+ supernovae at the end of the survey. + a huge catalogue of galaxies in the lines of sight. Questions to be addressed:
Copenhagen Aug. 2007
One of the biggest high-z supernova survey ~500+ supernovae at the end of the survey. + a huge catalogue of galaxies in the lines of sight
Questions to be addressed:
-Can the intrinsic scatter in the Hubble diagram be further reduced?
-Is it possible to detect a correlation between residuals and magnification?
-Is it possible to say something about the dark matter distribution of the galaxies?
700 simulated type Ia Sne using SNLS Sne observations (Astier et al 2006)
Magnification of each supernova is estimated using SNOC The SuperNova Observation Calculator Goobar et al (astro-ph/0206409)
Most Sne are demagnified and some are significantly magnified
and due to lensing ~ 2-3 %
Uncertainties due to lensing ~ 1-2%
Lensing accounts for 7.5% of the dark energy task force figure of merit
Expected standard candle
(calculated from a cosmological model)
Plots of residuals vs magnification
For estimations of the magnification
errors, a work on the GOODs fields
has been used
(Jonsson et al astro-ph/0612324)
Expected linear correlation
2 different samples:
-with lensing effects
-without lensing effects
Confidence level of >99%
Galaxy catalogue including magnitudes in the g r i (u) and z -bands + photometric redshift
Using the Faber-Jackson relation for ellipticals and the Tully-Fisher relation for spirals we can relate luminosity with mass (for a given model).
Estimation of the mass of the galaxy using galaxy models like SIS or NFW
Estimation of the eta-parameter
Using PEGASE : a UV to NIR spectral evolution model of galaxies
all sorts of
Estimation of the magnifi-cation of each SNe
Using Q-LET, a multiple lens plane algorithm which calculates the magnification with respect to a homogeneous universe
-Photometric redshift code
-Fits redshifted spectral templates
Absolute B-band magnitudes
The Faber-Jackson or Tully-Fisher relations relates the velocity dispersion and the Luminosity of the galaxy.
F-J relation (ellipticals)
Mitchell et al. (2005)
T-F relation (spirals)
Bohm et al. (2004)
Using a specific model (SIS or NFW) then relates the luminosity to the mass which is finite providing you choose a cut-off radius.
The radius inside which the mean mass density is 200 times the present critical density
The smoothness parameter
All “unobserved” matter is put into a smoothly distributed component.
Good test whether the galaxy model is OK
Masse of elliptical galaxies
Jonsson et al.
Hoekstra et al.
Using the F-J/T-F relations for the second field