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Francesco Melchiorri Memorial Conference
Current status of SZ measurements
Mark BirkinshawUniversity of Bristol
14 April 2006 Mark Birkinshaw, U. Bristol 2
Francesco Melchiorri Memorial Conference
Phases of progress• First phase: proof of concept
– Complete since mid 1980s
14 April 2006 Mark Birkinshaw, U. Bristol 3
Francesco Melchiorri Memorial Conference
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
14 April 2006 Mark Birkinshaw, U. Bristol 4
Francesco Melchiorri Memorial Conference
Proof of concept
Interferometric detection: Ryle telescope, Abell 2218Jones et al. (1993)
14 April 2006 Mark Birkinshaw, U. Bristol 5
Francesco Melchiorri Memorial Conference
Phases of progress• First phase: proof of concept
– Complete since mid 1980s• Second phase: use of thermal effect for many
clusters– H0 programme sufficiently complete– Astrophysics of cluster gas barely started
14 April 2006 Mark Birkinshaw, U. Bristol 6
Francesco Melchiorri Memorial Conference
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
14 April 2006 Mark Birkinshaw, U. Bristol 7
Francesco Melchiorri Memorial Conference
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)
14 April 2006 Mark Birkinshaw, U. Bristol 8
Francesco Melchiorri Memorial Conference
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
14 April 2006 Mark Birkinshaw, U. Bristol 9
Francesco Melchiorri Memorial Conference
Use of thermal effect for many clusters
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
14 April 2006 Mark Birkinshaw, U. Bristol 10
Francesco Melchiorri Memorial Conference
Use of thermal effect for many clusters
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
14 April 2006 Mark Birkinshaw, U. Bristol 11
Francesco Melchiorri Memorial Conference
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
14 April 2006 Mark Birkinshaw, U. Bristol 12
Francesco Melchiorri Memorial Conference
Astrophysics: structure and spectrum
MITO: multi-pixel, multi-band; spectrum and structure for nearby clusters – check astrophysics.
14 April 2006 Mark Birkinshaw, U. Bristol 13
Francesco Melchiorri Memorial Conference
Phases of progress• First phase: proof of concept
– 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
14 April 2006 Mark Birkinshaw, U. Bristol 14
Francesco Melchiorri Memorial Conference
New instruments
OCRA: Torun Observatory, Jodrell Bank, Bristol, Bologna
OCRA-p
14 April 2006 Mark Birkinshaw, U. Bristol 15
Francesco Melchiorri Memorial Conference
New instruments
• 30 GHz• Tsys = 40 K• 1 arcmin FWHM
beam• 5 mJy sensitivity in
10 sec• now on telescope• OCRA-F in progress
14 April 2006 Mark Birkinshaw, U. Bristol 16
Francesco Melchiorri Memorial Conference
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
14 April 2006 Mark Birkinshaw, U. Bristol 17
Francesco Melchiorri Memorial Conference
New instruments
Phase 2: cover sample
OCRA-p, 2006
Similar X-ray luminosities over z = 0.2 – 0.45
14 April 2006 Mark Birkinshaw, U. Bristol 18
Francesco Melchiorri Memorial Conference
New instruments
Phase 3: OCRA-F, 16 elements, later this year
OCRA-F
14 April 2006 Mark Birkinshaw, U. Bristol 19
Francesco Melchiorri Memorial Conference
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
14 April 2006 Mark Birkinshaw, U. Bristol 20
Francesco Melchiorri Memorial Conference
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
14 April 2006 Mark Birkinshaw, U. Bristol 21
Francesco Melchiorri Memorial Conference
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
14 April 2006 Mark Birkinshaw, U. Bristol 22
Francesco Melchiorri Memorial Conference
New instruments
AMiBA platform, November 2005; pointing tests
14 April 2006 Mark Birkinshaw, U. Bristol 23
Francesco Melchiorri Memorial Conference
New instruments
XMM LSS field: AMiBA deep survey for clusters, 200 to z > 1
14 April 2006 Mark Birkinshaw, U. Bristol 24
Francesco Melchiorri Memorial Conference
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?
14 April 2006 Mark Birkinshaw, U. Bristol 25
Francesco Melchiorri Memorial Conference
New instrumentsAzTEC144-element Si3N4
bolometer array
JCMT commissioning run (June 2005)
LMT after 2007
14 April 2006 Mark Birkinshaw, U. Bristol 26
Francesco Melchiorri Memorial Conference
New instruments
J0717.5+3745z = 0.548Clearly disturbed,
shock-like substructure, filament
AzTEC SZE image will have few arcsec resolution.
14 April 2006 Mark Birkinshaw, U. Bristol 27
Francesco Melchiorri Memorial Conference
New instruments
SZA (autumn 2005; photo Erik Leitch)
14 April 2006 Mark Birkinshaw, U. Bristol 28
Francesco Melchiorri Memorial Conference
New instrumentsALMA: composite array
14 April 2006 Mark Birkinshaw, U. Bristol 29
Francesco Melchiorri Memorial Conference
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)
14 April 2006 Mark Birkinshaw, U. Bristol 30
Francesco Melchiorri Memorial Conference
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+