Secondary Anisotropies in Cosmic Microwave Background

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Secondary Anisotropiesin Cosmic Microwave
Background

• Niayesh Afshordi
• Institute for Theory and Computation
• Harvard-Smithsonian Center for Astrophysics

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Outline

• CMB and WMAP
• General Framework
• (Integrated) Sachs-Wolfe (ISW)
• Rees-Sciama
• Sunyaev-Zeldovich (SZ)
• Thermal SZ (tSZ)
• Kinetic SZ (kSZ)
• Ostriker-Vishniac (OV)
• 21 cm radio emission as a probe of Reionization
• Cross-Correlation of CMB and LSS
• CMB lensing (Uros Lectures)

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Cosmic Microwave Background

• Remnant of the hot early universe
• Isotropic up to 1 part in 105
• Fluctuations
• Primary fluctuations (at LSS), above 0.1 deg (l lt
  1000)
• Linear perturbation theory
• Excellent measure of cosmology and initial
  conditions
• Secondary fluctuations, below 0.1 deg (l gt1000)
  
• (Mostly) non-linear structure formation
• Measures of various phenomena in the mature
  universe

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Wilkinson Microwave Anisotropy Probe (WMAP)-First
Year Data Release
2nd yr data release is due out any daaaaaay
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(Integrated) Sachs-Wolfe (ISW) Effect

• Linearly Perturbed FRW metric
• Approaching Radial photons
• But
• Therefore

Gravitational Redshift
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Sachs-Wolfe Effect (cont.)
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Sachs-Wolfe Effect (cont.)

• Integrated Sachs-Wolfe (ISW) effect
• Domination of dark energy/ spatial curvature
• decay of linear gravitational
  potential
• Important at large angles, as it traces the
  potential
• Not observed in the CMB auto-power (at the 3s
  level)!

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Rees-Sciama Effect

• Potential Wells deepen upon non-linear collapse
  . Cancels ISW on small scales (Rees Sciama
  1968)
• Moving Halo Effect (Birkinshaw Gull 1983)

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Thermal Sunyaev-Zeldovich (SZ) Effectand
Intra-Cluster Medium (ICM)

• Probes the thermal energy distribution of
  electrons in the Intra-Cluster Medium
• Dominates CMB at angles lt 0.1o
• Frequency dependent Signature Generates an
  anti-correlation between WMAP and galaxy/cluster
  distribution

WMAP sees here
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Thermal Sunyaev-Zeldovich (SZ) Effectand the CMB
Readhead et al. 2004
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Can SZ surveys sustain the CMB dominance?

• SZ clusters can be
• Detected up to high redshifts
• Their number counts probe Dark Energy/Cosmology
• Many SZ surveys are underway APEX, SZA, ACT,
  SPT, Planck,
• Can they deliver?
• Calibration of SZ-Mass relation, Gastrophysics,

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SZ Clusters from SUZiE II
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Kinetic SZ Effect

• Due to scattering by electrons with a bulk motion
• Probes Peculiar Velocity of IGM or ICM (?
  Veolcity Surveys)
• Ostriker-Vishniac (OV) ?T/ ?.v

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kSZ from Reionization

• ?? / xHI vL (1z)2 due to reionization bubbles
  can be significant if reionization happens early

Santos et al., 2003
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21cm Hydrogen Emission Tomography of
Reionization

• Hyperfine Transition
• The emission is enhanced significantly through
  spontaneous emission induced by CMB
  TbTCMBexp(-?)TS1-exp(-?), where
• Thus

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21cm Hydrogen Emission Tomography of
Reionization

• Despite the dominance of foregrounds, 21cm
  emission is much more structured in frequency,
  which can be used to extract its signature

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Cross-Correlation with Large Scale Structure

• Unlike the primary anisotropies, the secondary
  anisotropies are correlated with tracers of the
  large scale structure (galaxies, clusters, etc.)
  in the low-redshift universe.
• This provides us with a means to extract small
  secondaries out of the sea of primary anisotropies

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The Projected Cross-Power Spectrum
Projected galaxy number density
Projected Cross-Power Spectrum
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The Cross-Power Spectrum Signal
A random field, e.g. density, potential

• For a generic secondary effect like
• Limber equation gives

The observable temperature shift due to the
secondary anisotropy
The redshift dependent kernel, depends on the
secondary anisotropy
At most 2-3 for lowest ls
Galaxy comoving density, depends on the sample
3D cross-power spectrum, May depend on redshift
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The Cross-Power Spectrum Error

• For a small cross-correlation signal, the error
  is
• One can use the observed auto-powers to estimate
  the error
• Includes the unknown systematics in CMB/galaxy
  survey.

CMB auto-power
Auto-power of projected galaxy distribution
The sky coverage fraction
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ISW and SZ in WMAPx2MASS

• data best fit model
• ISW SZ
  Point Sources

l
l
l
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ISW in WMAPx(HEAO-A1 and NVSS)

• HEAO-A1 x WMAP, 2.5 s
• Boughn Crittenden 2004
• Z0.5-1
• NVSS x WMAP, 2 s
• Boughn Crittenden 2004
• Nolta, et. al 2003
• Z0.5-1

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ISW in WMAPx(APM and SDSS LRGs)

• SDSS x WMAP, z 0.5
• Scranton, et al. 2003
• Fosalba, Gaztanaga, Castander 2003
• 2-3s (jack-knife errors)

• APM x WMAP, z 0.15
• Fosalba Gaztanaga 2003
• 2s (jack-knife errors)

X
Monte-Carlo
Jack-knife
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Prospects of ISW in Cross-Correlation ISW effect
and Dark Energy
Spergel et al. 2003

• ISW effect
• Not the best probe of Dark Energy
• A good probe of Large Scale Physics

SDSS 2dF
Perfect ISW, zlt 3
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Probing of the modified gravity models ISW vs.
Growth Factor
The ratio of growth factors for Dark Energy and
Modified Gravity
ISWxSDSS cross-correlation signal
Dark Energy
Modified Gravity
Lue, Scoccimarro, Starkman 2003
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Looking for SZ in WMAP

• Using known clusters can help us make SZ
  templates to isolate the SZ signal

Abell 2319 3.5? signal
Coma 2.5? signal
3 deg
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Implied Gas Fraction (/ SZ flux)Based on WMAP SZ
signal of 116 X-ray Clusters (assumed NFW
haloes template making)

• The mean gas fraction of ICM is 20-40 less
  than cosmic budget
• ltfgas hgt 0.08 0.01
• X-ray gas mass estimates consistent with SZ
  estimates
• Both X-ray and SZ gas mass estimates show an
  increasing trend with Tx

• SZ observation
• X-ray Observation

fgas Mgas/Mtot , H0 100 h km/s/Mpc
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Final Words

• Secondary Anisotropies provide us with unique
  ways to probe
• Large Scale Gravity (ISW)
• Hot Gas inside clusters (tSZ)
• Cluster abundance and its evolution (SZ surveys)
• Bulk motion in the IGM (kSZ)
• Reionization History (21cm)