Current status of SZ measurementsoberon.roma1.infn.it/memorial/Docs/Talks/Birkinshaw.pdf14 April 2006 Mark Birkinshaw, U. Bristol 21 Francesco Melchiorri Memorial Conference New instruments

Francesco Melchiorri Memorial Conference

Current status of SZ measurements

Mark BirkinshawUniversity of Bristol

14 April 2006 Mark Birkinshaw, U. Bristol 2


Phases of progress• First phase: proof of concept

– Complete since mid 1980s



Proof of concept• Radiometer measurements• Small groups of X-ray

luminous clusters• Issues with radio source

confusion• First indications of structure• Clusters over wide z range

equally detectable

Birkinshaw 1999



Proof of concept

Interferometric detection: Ryle telescope, Abell 2218Jones et al. (1993)




– Complete since mid 1980s• Second phase: use of thermal effect for many

clusters– H0 programme sufficiently complete– Astrophysics of cluster gas barely started



Use of thermal effect for many clustersInterferometer mapping

(BIMA + OVRO)

• restricted angular dynamic range

• high signal/noise (long integrations possible)

• clusters detectable to z ≈ 1

Carlstrom et al. 1999



Use of thermal effect for many clustersVSA: low-z clusters

About 100 hours/mapHigh signal/noise detectionApparent noise is confusion from CMB primordial fluctuations –limitation of all single-frequency work

AMI: high-resolution version now functioning – much faster, survey instrument and mapper.

Lancaster et al. (2004; astro-ph/0405582)



Use of thermal effect for many clusters

Measurement of Hubble constant, using different ways SZE and X-ray brightness scale with cluster density and size

CL 0016+16; DA = 1.36 ± 0.15 GpcH0 = 68 ± 8 ± 18 km s-1 Mpc-1; Worrall & Birkinshaw 2003




Cluster Hubble diagram

• Adequate for H0 –accuracy about 10%

• poor leverage for other parameters

• need reduced errors• ad hoc sample • systematic errors

Carlstrom, Holder & Reese 2002




SRJ ∝ Ne Te

Total SZ flux density ⇒ total electron count ⇒ total baryon count

Compare with total mass (from X-ray or gravitational lensing) ⇒ baryon mass fraction

Figure from Carlstrom et al. 1999.

Ωb/Ωm



Use of thermal effect for many clusters1E 0657-56

X-ray image complex.

Shocks/cold fronts.

SZE data not yet good enough to make pressure map that would help astrophysical interpretation: need better angular resolution and sensitivity



Astrophysics: structure and spectrum

MITO: multi-pixel, multi-band; spectrum and structure for nearby clusters – check astrophysics.




– Complete since mid 1980s

• Second phase: use of thermal effect for many clusters– H0 programme sufficiently complete– Astrophysics of cluster gas barely started

• Third phase: use of effect to find clusters, do astrophysics

– About to start – new instruments



New instruments

OCRA: Torun Observatory, Jodrell Bank, Bristol, Bologna

OCRA-p



New instruments

• 30 GHz• Tsys = 40 K• 1 arcmin FWHM

beam• 5 mJy sensitivity in

10 sec• now on telescope• OCRA-F in progress



New instrumentsPhase 1: 2005-6 SZ observations with OCRA-p: about 2 hr/cluster

Cluster On/mJy Trail/mJy On-trail/mJy

0016+16 -1.4 ± 0.4 +0.1 ± 0.4 -1.5 ± 0.50451-03 -1.9 ± 0.3 +0.8 ± 0.4 -2.7 ± 0.51054-03 -2.0 ± 0.5 +0.1 ± 0.5 -2.2 ± 0.7Abell 2218 -1.4 ± 0.3 +0.1 ± 0.3 -1.5 ± 0.4Abell 2390 +0.5 ± 0.3 -0.3 ± 0.3 +0.7 ± 0.4J2129+03 -0.2 ± 0.5 -0.7 ± 0.4 +0.5 ± 0.6



New instruments

Phase 2: cover sample

OCRA-p, 2006

Similar X-ray luminosities over z = 0.2 – 0.45



New instruments

Phase 3: OCRA-F, 16 elements, later this year

OCRA-F



SZ sky predicted using structure formation code (few deg2, y = 0 – 10-4)

Primordial fluctuations ignored

Cluster counts strong function of cosmological parameters and cluster formation physics.

Need new technology to perform surveys.

Cluster finding



New instrumentsAMiBA• ASIAA/NTU project• Operational later in 2006• 19(?) dishes, 1.2/0.3 m

diameters, 1.2 – 6 m baselines• ν = 95 GHz, Δν = 20 GHz• Dual polarization• 1.3 mJy/beam in 1 hr



New instrumentsAMiBA• Discrete radio sources

– expect 0.3 sources above 1 mJy per fields: not a problem • CMB primary anisotropy

– declines at AMiBA angular scales– much can be filtered out in mosaic mode , σ < 0.3 mJy

• Faint SZ clusters– expect ~ 1 source above 1 mJy per survey field– clusters cluster, gives extra noise < 0.3 mJy



New instruments

AMiBA platform, November 2005; pointing tests



New instruments

XMM LSS field: AMiBA deep survey for clusters, 200 to z > 1



New instruments

AMiBA survey • expect > 200 clusters• X-ray/SZ comparison will give Hubble diagram

to z = 1 • Combining X-ray, SZ, shear mapping at z < 0.5

will give baryon fractions and total masses• possible SZ detection of IGM filaments?



New instrumentsAzTEC144-element Si3N4

bolometer array

JCMT commissioning run (June 2005)

LMT after 2007



New instruments

J0717.5+3745z = 0.548Clearly disturbed,

shock-like substructure, filament

AzTEC SZE image will have few arcsec resolution.



New instruments

SZA (autumn 2005; photo Erik Leitch)



New instrumentsALMA: composite array



New instruments

APEXSZ effect receiver, multi-element

bolometer, fast SZ survey. 330 element array, 2 mm or 1.4 mm, planned 200 square deg survey to 10 microK

(See also SPT and other projects, no time to talk about more)



Advanced phases

• Fourth phase: spectral studies – detection of the kinematic effect, spectral deviations

– Single-cluster attempts at cluster velocities– Need new instruments; samples

• Fifth phase: detection of polarization– Further instrumental developments

• Final phase: use of all effects for cosmology and astrophysics

– Possible in 2015+

Documents

Current status of SZ measurementsoberon.roma1.infn.it/memorial/Docs/Talks/Birkinshaw.pdf14 April 2006 Mark Birkinshaw, U. Bristol 21 Francesco Melchiorri Memorial Conference New instruments