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Using Symmetry to Detect Velocities with kinetic SZ. “The combination of CMB and LSS is more than the sum of it’s partsâ€. Albert Stebbins Fermilab. External Correlations of the CMBR & Cosmology Fermilab, Batavia 25-26 May 2006. Why Velocities?.
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Using Symmetry to Detect Velocities with kinetic SZ “The combination of CMB and LSS is more than the sum of it’s parts” Albert Stebbins Fermilab External Correlations of the CMBR & Cosmology Fermilab, Batavia 25-26 May 2006
Why Velocities? • Because they are there? If you can measure them why not? It’s mostly free. • Self consistency: Much of cosmology involves determining positions of things: e.g. clustering. Velocity is how they got there and provides and should be consistent with the clustering. • We can learn about forces, forces cause velocities e.g. gravitation forces from dark energy/matter. • Other Goals • To show how, by coherently combining CMBR and large scale structure (LSS) data, one may learn new and interesting things that one cannot from either along. kSZ and Symmetry
12.5o x 12.5o Aghanim et al. 1998 cluster merger Aghanim et al. 1998 CMB+kSZ+ISWslingshot ISWslingshot CMB kSZ slingshot 2 h-1Mpc kSZ Wavelet Wavelet[CMB+ISWslingshot] Nagai et al. 2002 kSZ Pattern Detection kSZ and Symmetry
kinetic Sunyaev Zel’dovich (kSZ) kSZ and Symmetry
How to use kinetic SZ? Conceptualization: continuum field no good spectral signature primary CMB main background statistical detection Conceptualization: ~ Point Sources / clusters 134h-1Mpc 1o x 1o 2o x 2o thermal SZ kinetic SZ Springel, White, & Hernquist 2001 Schafer et al.2004 kSZ and Symmetry
Present & Future Wide Area Surveys kSZ and Symmetry
Dark Secrets of the Universe from LSS • We know where the (dark) matter which causes the velocities are. • We know where the free electrons, which gives the kSZ signal, are. • They’re where the galaxies are! • Ergo: The CMB need not go it alone! • Witness: the utility of LSS in helping correct for CMB lensing. kSZ and Symmetry
CMB CMB CMB CMB CMB Parlor Tricks w/ kSZ e- free electrons m - dark matter - clusters/galaxies Modulating T w/ galaxy overdensity “removes” nasty CMB background Tc=dc Tsky but not from the noise Cov[Tc Tc]=dc d’c Tcmb T’cmb Modulating DT w/ Dz removes primary CMB from correlation function CG-(G,kSZ)=(Ta -Tb) (za -zb) > 0 (do not square it!) Removes most systematics! Noise still ~100 larger. Need ~104 Independent samples! CMBCMB CMB CMBCMB kSZ and Symmetry
What to Measure? Harmonic statistic dg dmdgdT Then weighted sum over lt:( synthetic beam) • Optimize : • synthetic CMBR beam • redshift weight function for z accuracy • Wl[z,z’]=-Wl[z’,z] kSZ and Symmetry
Workinprogress… kSZ and Symmetry
ParameterEstimation? FundamentalPhysics? But is it science? • Precision results require detailed knowledge of gas physics. • These velocity measurements do add some additional knowledge of cosmological parameters, but more importantly, they can provide a totally different check of the overall consistency of the model. • They may reveal something interesting and unknown about the forces of the “dark side”? kSZ and Symmetry