UCL’s interests: photo-z, mass-obs calibration, systematics Granada, Sep 2010 Ofer Lahav, University College London Ofer Lahav, Stephanie Jouvel, Ole Host University College London

Problems for LCDM on the ‘small scales’ The MW satellites – too many in simulations? Cluster mass profiles – concentration too low in simulations? Hierachical clustering – the wrong order? Galaxies in voids- too many in simulations? Superclusters – too few in simulatons? Are we near a centre of a void?

Photometric and Spectroscopic surveys

The Dark Energy Survey (DES) Proposal: –Perform a 5000 sq. deg. survey of the southern galactic cap; –300 million galaxies –Measure dark energy with LSS, clusters, WL, SN New Instrument: –2.2 FOV, 520 Mega pixel optical CCD camera + corrector Time scale: –Instrument Construction Survey: –525 nights during Oct.–Feb –Area overlap with SPT SZ survey and VISTA VHS Use the Blanco 4m Telescope at the Cerro Tololo Inter-American Observatory (CTIO)

From Tom Broadhurst’s talk Sample selection in Color-Color Red – background Blue – background Green – cluster +~background Pink – foreground +background A370

The zoo of photo-z codes

1.5M LRGs (“MegaZ”) photo-z code comparison SDSS HpZ+BC Le PHARE Zebra ANNz HpZ+WWC Abdalla, Banerji, Lahav & Rashkov Cf. PHAT (Hildebrandt et al. 2010)

Sensitivity of Cosmology to photo-z methods Baryon Fraction Omega_matter Thomas, Abdalla & Lahav 2010

Photo-z challenges for CLASH Cluster, fg, bg membership with probabilities Try hybrid template + training methods Biases in input photometry due to blending and lensing Optimal filters for WL (4-5) and for SL (16) Spectroscopic training sets “Self calibration”, “colour tomography”, “SB prior”

The End

Neutrino mass from MegaZ-LRG 700,000 galaxies within 3.3 (Gpc/h)^3 Thomas, Abdalla & Lahav, PRL (2010) Total mass < 0.28 eV (95% CL)