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APEX S-Z observations of the XMM-LSS field Marguerite PIERRE (CEA Saclay) Rüdiger KNEISSL (Berkeley) Clusters of galaxies Center of Abell 2218 viewed by HST z = 0.176 Dark matter: Zwicky 1933 X-ray emission from clusters • MASS fractions: • Dark matter : 80% • Hot gas : 15% • Galaxies : 5% • Theory’s pov A cluster of galaxies = an object with a MASS of ~1014-16 Mo Cosmology with clusters 0<z<2 Clusters are the most massive entities of the universe Trace the node of the cosmic structure = potential wells (much better than galaxies!) Constraints on cosmology from clusters are complementary to those provided from the CMB and the SN : they do not rely on the same physical phenomena An example Priors: Wbh2 = 0.0214 +/- 0.002 h = 0.72 +/- 0.08 Rappeti et al 2005 Plan of the talk: close to the first joint X-ray/S-Z survey on large scales 1. Reminder on the S-Z effect and its cosmological applications 2. The Apex S-Z instrument 3. Observations of the XMM-LSS field What will we get? What will we be able to say about cosmology? The S-Z thermal effect APEX frequencies (from Carlstrom + Bertoldi) S-Z versus X-ray SZ : DTCMB ≈ ∫ neTe dl (independent of z – integrated pressure) Integrated SZ (over solid angle) ≈ N<T> /DA2 ≈ M<T> /DA2 X-ray emissivity : e ≈ n2T1/2 dV Flux (over cluster volume) ≈ ∫edV /DL2 ≈ L/DL2 Cosmological applications of the S-Z effect Evolution of the number density of clusters + space distribution • Underlying cosmology • Equation of state of the dark energy S-Z + X-ray • Hubble constant • Angular diameter distance relation out to z~2 • Cluster gas mass fraction => Wm, distance indicator Caveat ! In order to constrain cosmology, we must understand how clusters evolve • The detected N(M,z) is not only a result of gravitational physics. • M->T-> Lx (z) , ngaz(z) The evolution of the physics of the ICM is a key issue: accretion, shocks, feedback, cooling... for the S-Z and X-ray domains, we must have – or determine – mass-observable relations at any z The S-Z reciever (Berkeley) 330 elements (TES Bolometers) Commissioning of the full array in spring 2006 Operating l : 2mm (150 GHz), 90 and 220 planned A few numbers (1) Apex +tertiary optics built in Berkeley: • FWHM = 1arcmin XMM • FWHM = 6” (on-axis) Cluster core radius of 250 kpc • • • • 2.3’ at z =0.1 41” at z = 0.5 31” at z= 1 28” at z= 2 A few numbers (2) Apex S-Z sensitivity : • 10 mk XMM point source sensitivity in 10 ks exposure : • 5E-15 erg/s/cm2 in [0.5-2] keV The XMM-LSS field Current multi-l coverage XMDS & VVDS deep VVDS wide XMM Subaru Deep Survey SPITZER Legacy : SWIRE NOAO Deep Survey X-ray data status: Galex - Received - received - received - Planned and covered by W1 CFHTLS, VLA and Integral The XMM-LSS/CFHTLS/SWIRE field : an XMM Large Programme XMM pointings : . Done . To be redone . Subaru DS (done) . To be done in 2006-2007 Square = SWIRE 10deg2 field Scuba 2 Legacy A piece of the XMM-LSS mosaic ~ 1x2 deg2 RASS sources Image by A. Read 10 ks exp. red [0.3-1] keV green [1-2.5] keV blue [2.5-10]keV Constructing a COMPLETE cluster sample with XMM Suitable for cosmological studies Selection effects controlled a priori : NOT flux limited sample • Clusters span a range of sizes and profiles • Measured flux Emitted flux • groups at 0.3< z < 1 Detection rates Core radius (arsec) Pacaud et al 2006 Countrate The cluster selection function Is monitored via extensive simulations In the following, we a assume a simple flux limit. CFHTLS Images of D1 clusters C1 z=0.05 CFHTLS Images of D1 clusters C1 z=0.31 CFHTLS Images of D1 clusters C1 z =1.05 Physics of the XMM For the first time, • the XMM-LSS detects the group (T<2 keV) population out to z=0.5 • We measure the L-T relations of these objects • light on the ICM physics! The L-T relation 1 4 keV T ______ L-T at z=0 -------- L-T at z=0.5 (self-similar evolution) A few numbers (3) Coverage of the 10 deg2 • XMM : ~ 1Ms ~ 12 days • Apex : ~ 2 weeks Cluster number density • XMM: ~ 15 clusters/deg2 • Apex: 4 clusters/deg2 (> 2-3 E14 Mo) How do the n(z) compare ? 10 mk y=0.5 E-4 arcmin2 Influence of the low-end of the mass function (X-ray clusters) Pacaud et al, in prep Influence of the X-ray flux limit Pacaud et al, in prep Influence of the cosmological parameters on n(z) Example for X-ray clusters Similar behaviour for S-Z clusters Influence of the cluster evolution Pacaud et al, in prep Influence of the equation of state of the Dark Energy Pacaud et al, in prep Combining XMM and Apex Ho / Da comparison vs cosmology Use the joint data sets to get insights into the evolution of the ICM physics • S-Z integrated pressure along the line of sight • X L-T (z) relation Add mass information from the weak lensing survey on the CFHTLS data (Refregier et al, in prep) Calibrate mass-observables relations Hints on the cosmology Apex S-Z survey to start by Spring 2006