CfA Oct 8 2003

Determining the Cosmic Distance Scale with Galaxy

Clusters

Erik Reese

University of California, Berkeley

CfA Oct 8 2003

The Sunyaev-Zel’dovich Effect

CfA Oct 8 2003

BIMA & OVRO

CfA Oct 8 2003

CfA Oct 8 2003

Distance Calculation

With geometry of the cluster

CfA Oct 8 2003

Hubble Constant

With z and geometry of the universe

Independent of the extra-galactic distance ladder!

For a sample of clusters, fit to the theoretical DA relation, where H0 is the normalization

CfA Oct 8 2003

Angular Diameter Distances: Present

CfA Oct 8 2003

H0 Current Results• Ryle → 5 clusters (Jones et al. 2003)

• OVRO 5m → 7 clusters (Mason et al. 2000)

• OVRO/BIMA → 18 clusters (Reese et al. 2002)

CfA Oct 8 2003

H0 Current Results

• Combined → 41 distances

Reminder: All ROSAT data

CfA Oct 8 2003

SystematicsSZE calibration [H0~(∆T0)-2] ± 8%

X-ray calibration ±10%

NH ± 5%

Asphericity● ± 5%

Isothermality ±10%

Clumping −20%

Undetected radio sources ±12%

Kinetic SZE● ± 2%

Primary CMB● ± 1%

Radio Halos ± 4%

Primary Beam ± 3%

Total +22% −30%

CfA Oct 8 2003

Chandra

CfA Oct 8 2003

Angular Diameter Distances: Chandra

CfA Oct 8 2003

DA Future

CfA Oct 8 2003

Supernovae Type Ia

CfA Oct 8 2003

Challenges

• Systematics• Modeling• Sample selection

– Sample sizes – Unbiassed selection criteria– Wonky clusters

• Convince X-ray TACs• High redshift→cosmology

CfA Oct 8 2003

SZE Surveys

• Large samples of clusters• High redshift clusters• Clean selection function

Holder et al. 2000

CfA Oct 8 2003

Simulations

Courtesy of Martin White

CfA Oct 8 2003

Summary• H0 independent of extragalactic distance ladder

• Systematics are approachable• SZE Surveys

– Large numbers of clusters– High redshift – Sample selection

• Symbiotic with cluster number counts