Using Symmetry to Detect Velocities with kinetic SZ

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Using Symmetry to Detect Velocities with kinetic
SZ

• The combination of CMB and LSS is more than the
  sum of its parts

Albert Stebbins Fermilab
External Correlations of the CMBR
Cosmology Fermilab, Batavia 25-26 May 2006
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Why Velocities?

• Because they are there? If you can measure them
  why not? Its 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.

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kSZ Pattern Detection
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kinetic Sunyaev Zeldovich (kSZ)
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How to use kinetic SZ?
Conceptualization Point Sources / clusters
Conceptualization continuum field no good
spectral signature primary CMB main
background statistical detection
134h-1Mpc 1o x 1o
2o x 2o
thermal SZ
kinetic SZ
Springel, White, Hernquist 2001
Schafer et al.2004
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Present Future Wide Area Surveys
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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.

• Theyre where the galaxies are!

• Ergo The CMB need not go it alone!
• Witness the utility of LSS in helping correct
  for CMB lensing.

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Parlor Tricks w/ kSZ
CMB CMB CMB CMB CMB
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 CovTc Tc?dc dc ? ?Tcmb Tcmb?
Modulating DT w/ Dz removes primary CMB from
correlation function CG-(G,kSZ)?(Ta -Tb) (za
-zb)? gt 0 (do not square it!) Removes most
systematics! Noise still 100 larger. Need 104
Independent samples!
CMB CMB CMB
CMB CMB
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What to Measure?
Harmonic statistic ? dg dm dgdT?
Then weighted sum over lt( synthetic beam)

• Optimize
• synthetic CMBR beam
• redshift weight function for z accuracy
• Wlz,z-Wlz,z

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Workinprogress
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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?