SUNYAEV-ZELDOVICH EFFECT

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SUNYAEV-ZELDOVICH EFFECT
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OUTLINE

• What is SZE
• What Can we learn from SZE
• SZE Cluster Surveys
• Experimental Issues
• SZ Surveys are coming What do we do?

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INTRODUCTION

• Inverse Compton Scattering of CMB photons.
• Decrement in intensity below SZ null (218 GHz),
  increment above
• Small spectral distortion of CMB of order 1 mk.
• Independent of redshift.

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kSZ Effect The Doppler effect of line of sight
cluster velocity -gt observed shift of the CMB
spectrum.
In the nonrelativistic limit, the spectral
signature of the kinetic SZE is a pure thermal
distortion of magnitude of the CMB signal
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SZE FOR ASTROPHYSICS
Cluster physics measure integrated
pressure Peculiar velocities at high z Cluster
gas mass fraction, OM clean measure of baryon
gas mass Hubble constant, H(z) combined with
x-ray ?? DA(z) Cluster surveys exploit
redshift independence constrain OM , O? s8, w,
w(t)
S
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Cluster gas mass fraction, OM
Since clusters collapse from large volumes of
order 1000 Mpc3, the ratio of baryons to dark
matter should be a reasonable approximation to
the mix in the universe as a whole.
Isothermal b model
Constrain b and rc with SZE, integrate-gttotal gas
mass. Total mass of the cluster can be estimated
from X-ray or lensing measurements.
Grego et. al.,2001
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Hubble constant, H(z)
33 SZ distances vs. redshift Ho 63 ? 3
km/s/Mpc for ?M 0.3 and ?? 0.7, fitting all
SZE distances
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Constraining Dark Energy
The observed cluster red-shift distribution in a
survey is the co-moving volume per unit red-shift
and solid angle dV/dzdW times the co-moving
density of clusters ncl with masses above the
survey detection limit Mlim.
1/H(z) mass function
Majumdar,2004
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CLUSTER SURVEYS WITH SZE

• Create cluster catalogs independent (almost) of
  cosmology and redshift.
• Trace structure formation from z2 or 3 to
  present day.
• Sample to study individual clusters to study
  cluster physics.

Cluster Abundance
Number density of clusters as a function of mass
and redshift
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Comoving volume element (left) and comoving
number density (center) for two cosmologies, (OM,
O?)(0.3, 0.7) (solid ) and (0.5, 0.5) (dashed).
(Middle) The normalization of the matter power
spectrum was taken to be s80.9 and the
Press-Schechter mass function was assumed. The
lower set of lines in the middle panel correspond
to clusters with mass greater than 1015 h-1 Msun
while the upper lines correspond to clusters with
mass greater than 1014 h-1 Msun.
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Mass Limits of Observability
(1z)4 enhancement compared to usual flux limit.
zgt 1, DA is slowly varying, Te is
higher gtlimiting mass of an SZ survey gently
declines
S
Deep Surveys10 clusters per square degree Less
Deep Surveys (all sky Plank Survey) 1 cluster
every few square degree.
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Experimental Challenge
Small signal Must make differential
measurements Synchronous offsets
Contaminations Radio Point Sources
(synchrotron) Point sources in mm/submm
(Galactic and Extragalactic dust) Primary
anisotropies of the CMB .
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SZE and PRIMARY CMB ANISOTROPY
Arc minute anisotropy dominated by diffuse SZE
except at ?s near SZE null SZE requires small
beam and/or multi-frequency observations
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Point Source Removal
Point source removed low resolution
Point source removed high resolution
Point source
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SZE Foregrounds -- point sources
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Some SZ-Experiments
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SZ Surveys are coming What should we do
Simulations to study survey selection function
and observable uncertainties
Plot of the matched filter noise Y as a function
of filter scale qc (core radius of a cluster
matched to the filter) for different surveys, as
labeled. The filter noise is generated by primary
CMB anisotropy and instrumental noise. Clusters
lying above the curve of a particular experiment
have S/N gt 1.
Bartlett,2006
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SZ Surveys are coming What should we do
Integrated source counts at S/N gt 5 for each
survey are shown , along with the simulation
input counts (curve labeled mass function).
Catalog completeness percentage (ratio of the
experimental curve to the input mass function
counts) is given in the inset. The important
point is that the surveys are not flux limited,
and are significantly incomplete even at 5 times
their point source sensitivities.
Bartlett,2006
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SZ Surveys are coming What should we do
Photometric recovery in terms of integrated
Compton Y parameter for SPT (left) and AMI
(right). Compton Y values (in arcmin2) recovered
by the matched filter are plotted against the
input Y values taken from the simulation catalog.
Each point represents a single cluster detected
at S/N gt 5. The red dashed curve gives the
equality line. For SPT the characteristic scatter
at fixed Ytrue is 40. Confusion with primary
CMB anisotropy seriously compromises photometric
recovery of the single frequency survey (chosen
here as AMI).
Multiple frequency observation or a follow up in
X-ray is necessary
Bartlett,2006
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SUMMARY
CLUSTERS ARE GREAT!!! SZE is COOL. However.