A Primer on SZ Surveys

Gil Holder

Institute for Advanced Study

Outline

• Sunyaev-Zel’dovich effect

• Upcoming surveys

• What’s next?

Optical Image of Cl 0016+16(Clowe et al. 2000)

~ 7’ ~ 2 h-1 Mpc

kT ~ 7.5 keV

Hot Gas in Cl 0016+16

(Reese)

Sunyaev-Zel’dovich Effect

CMB Hot electrons

CMB+

I

Optical depth: τ ~ 0.01

Fractional energy gain per scatter: 2cm

kT

e

~ 0.01

SZ Observables I

Tee

lncm

kTdlg

T

T )()(2

Along a line of sight:

DEPENDS ONLY ON CLUSTER PROPERTIES !!!!

Independent of redshift

Temperature weighted electron column density

Unique spectral signature

Non-Thermal Spectrum

Abell 2163

Data from 3 experiments

SZ Observables II

dVkTnzd

dTS eA

2)(

1

Integrated effect from cluster:

proportional to total thermal energy of electrons

Temperature weighted electron inventory

angular diameter distance, not luminosity distance

SZ Observables III

3/52)(

Mzd

hfS

A

g

In reasonable units ( i.e., 1/h):

Assume a virial relation:3/2MT

TMzd

hfS

A

g

2)(

uncertainties come in mass limit as ^(0.6)

Central decrement vs Mass – 40% scatter

Average SZ flux vs Mass – 10% scatter

Metzler ; astro-ph/9812295SZE Regularity

dTo <dT>

Searching for Galaxy Clusters

Small area; very deep

- AMI, AMIBA, BOLOCAM, SZA

Large area; relatively shallow

- ACBAR, PLANCK

Large area; very deep

- ACT, SPT

Mass Limits

Fluxes at 30 GHz

PLANCK

SZA

Foregrounds

• CMB – need good angular resolution and/or good spectral resolution; problem at all SZ frequencies

• Radio point sources – need good angular resolution for frequencies <90 GHz

• Dusty point sources – need good angular resolution and/or spectral resolution at frequencies >200 GHz

• Radio halos and ghosts – could be a problem at frequencies < 15 GHz

SZA

• Survey 10 square degrees to a few uK at resolution of 2-3 arcminutes at 30 GHz

• Expected mass limit ~

• Follow up catalog at 90 GHz for high resolution (<20”)

• 100 – 500 clusters expected

Mh 11410

Example: RXJ1347-1145

X-ray (colours)SZ (contours)

SZ only

Reese

CMB contamination??

• clusters are clearly at a different spatial scale

• close amplitudes means beam dilution catches up fast !!!

Roughly 1 deg x 1deg – labels are uK

Cosmology With the SZA

Holder, Haiman & Mohr 2001

Dark Energy With the SZA

• 12 square degrees

• assume NO systematic errors

• assume redshifts measured to z=2

PLANCK

• Survey the full sky to a few uK at resolution of 5-10 arcminutes at many frequencies

• Expected mass limit ~

• Cluster detections will be unresolved – point sources with SZE-like spectra

• 1000 – 50000 clusters expected

Mh 114108

Cosmology With Planck

Black: all z

Red: z<0.5 only

Holder, Haiman & Mohr 2001

SPT/ACT/???

• Survey ~1000 square degrees to a few uK at resolution of 1-2 arcminutes at several frequencies

• Expected mass limit ~

• Most powerful for cosmology

• 5000 – 200000 clusters expected

Mh 114105.2

Cosmology with the SPTHolder, Haiman & Mohr 2001

dN/dz for SPT

Dark Energy With the SPT

Also sensitive to time dependent equation of state

(Weller, Battye & Kneissl 2001)

Possible Plan of Action

1) Use AMI/AMIBA/BOLOCAM/SZA to define a significant SZE-selected sample

2) Follow up at many wavelengths: optical, X-ray, radio, cm, mm (including SZA!)

3) Do a very large, deep survey for precise measurements of cosmological parameters

On the Horizon

uK imaging between 30-400 GHz with arcminute resolution

-- SPT, ACT, dedicated interferometers, ALMA, etc.

New science opportunities & challenges

-- peculiar velocities,

-- spectral SZ

-- CMB lensing

Peculiar Velocities (Kinetic SZ)

• Pure redshift, blueshift => thermal spectrum

cT

T v

Arcminutes scales => CMB ~ 1 uK

-- CMB noise contribution = 10 km/s (0.01/τ)

Other contamination: 50 km/s ?

(Fischer & Lange 1993)

Relativistic Corrections

Lensing of the CMB

Typical CMB gradient

-- 15 uK/arcmin

Typical deflection angle

-- ~ 0.1-1 arcmin

(Seljak and Zaldarriaga )

Summary

• New cluster surveys coming soon

• Detailed follow-up will be required of some sample of SZE-selected clusters

• Ambitious survey machines in proposal stages could be extremely powerful

Gallery of SZ ImagesZ=0.83

Z=0.14

sunMhM 114lim 10x5

Holder & Carlstrom 2001

Green: shift in matter density by 10%

Counting Galaxy Clusters

dzd

dVdM

dM

dn

dzd

dN

M lim

Mass function

Volume element

(Jenkins, Press-Schechter)

Mass limit

Self-Similar Evolution

Holder & Carlstrom 2001

Effects of Gas Evolution

Holder & Carlstrom 2001

Angular Power Spectrum of SZ Sources

Holder & Carlstrom 2001