Recent SZ observations and prospects for cluster surveys

Rüdiger Kneissl

UC Berkeley (Astronomy & Physics)

Distant cluster workshop, Schloss Ringberg, 27 October 2005

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• Examples of recent SZ cluster observations

– Baryon fraction and M-T relation from the VSA sample

– High sensitivity SZ observations (first AMI targets)

• Cluster searches

– Interferometer technique: AMI

– Multi-bolometer arrays: APEX-SZ

– Satellite by-product: Planck

• Outlook

2

The VSA cluster sample: Coma, A1795, A399+A401, A478, A2142, A2244CONT: COMA C IPOL 33841.019 MHZ COMA-S test.ICL001.2PLot file version 1 created 28-MAY-2004 13:45:03

Cont peak flux = -2.4479E-01 JY/BEAM Levs = 3.021E-02 * (-10, -9, -8, -7, -6, -5, -4,-3, -2, -1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

DECLINATION (B1950)

RIGHT ASCENSION (B1950)13 02 01 00 12 59 58 57 56 55 54 53

29 00

28 30

00

27 30

CONT: A1795 IPOL 34096.665 MHZ A1795-6 T.08.ICL001.2PLot file version 3 created 20-MAY-2004 13:33:23

Cont peak flux = -2.0493E-01 JY/BEAM Levs = 3.500E-02 * (-10, -9, -8, -7, -6, -5, -4,-3, -2, -1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

DECLINATION (B1950)

RIGHT ASCENSION (B1950)13 51 50 49 48 47 46 45 44 43 42

27 30

00

26 30

00

CONT: A401 IPOL 33837.746 MHZ A401-6 T.075.ICL001.4PLot file version 3 created 20-MAY-2004 13:40:47

Cont peak flux = 1.5093E-01 JY/BEAM Levs = 4.000E-02 * (-10, -9, -8, -7, -6, -5, -4,-3, -2, -1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

DECLINATION (B1950)

RIGHT ASCENSION (B1950)03 00 02 59 58 57 56 55 54 53 52

14 00

13 30

00

12 30

A399

A401

CONT: A478 IPOL 32999.999 MHZ A478-4 T.16.ICL001.1PLot file version 3 created 20-MAY-2004 13:47:11

Cont peak flux = -1.3904E-01 JY/BEAM Levs = 3.200E-02 * (-10, -9, -8, -7, -6, -5, -4,-3, -2, -1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

DECLINATION (B1950)

RIGHT ASCENSION (B1950)04 15 14 13 12 11 10 09 08 07

11 00

10 30

00

09 30

CONT: A2142 IPOL 34068.122 MHZ A2142-7 T.1.ICL001.2PLot file version 4 created 20-MAY-2004 13:49:41

Cont peak flux = -1.7375E-01 JY/BEAM Levs = 3.800E-02 * (-10, -9, -8, -7, -6, -5, -4,-3, -2, -1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

DECLINATION (B1950)

RIGHT ASCENSION (B1950)16 01 00 15 59 58 57 56 55 54 53 52

28 00

27 30

00

26 30

CONT: A2244 IPOL 33834.418 MHZ A2244-5 T.19.ICL001.1PLot file version 4 created 20-MAY-2004 13:59:34

Cont peak flux = 6.6234E-02 JY/BEAM Levs = 2.600E-02 * (-10, -9, -8, -7, -6, -5, -4,-3, -2, -1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

DECLINATION (B1950)

RIGHT ASCENSION (B1950)17 06 04 02 00 16 58 56

35 00

34 30

00

33 30

Gas fraction measurement

Combined constraint:fg = 0.08

+0.06−0.04h

−1 (Lancaster et al.,astro-ph/0405582)

A mass - temperature relation

Agrees with X-ray determinations

Understanding LSZ - M relation, ie. M-T and fg, will be essential for the SZ surveys.

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Analysis

Cluster model: assume gas density King-profile with HSE giving total mass, eg. M200,

Mr =3βr3

r2c + r2

kT

µG

and gas mass Mg = 4πρg(0)r3c∫ r/rc0 (1 + x

2)−3β/2xdx, x = r/rc. Therefore

fg =Mg

Mrand also A = MrT

−3/2 =3βr3

r2c + r2

kT−1/2

µG

Radio sources: 41 radio source (400 > Sν > 20mJy; ∼ 3σ) simultaneously observedand subtracted from the data; preselecting all NVSS and GB6 sources with predictedfluxes > 50mJy within 2◦ radius and raster-scanning one square-degree with the Ryletelescope to S15GHz > 20mJy.

Bayesian Inference: P (Θ|data, H) = P (data|Θ, H)P (Θ|H)/P (data|H);characterisation of posterior PDF with Monte-Carlo approach; typically 10 Markovchains running in parallel using BAYESYS, evaluation in visibility (Fourier) space; weakpriors on rc, β, Mg, strong prior on Te.

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The Arcminute Micro-Kelvin Imager

10 3.7m (200 λ ∼ 3’) & 8 13m antennae, 12-18 GHz, Tsys = 25K

AMI Collaboration: R. Barker, P. Biddulph, D. Bly, R. Boysen, A. Brown, C. Clementson, M. Crofts, T.

Culverhouse, J. Czeres, R. Dace, R. D’Alessandro, P. Doherty, P. Duffett-Smith, K. Duggan, J. Ely, M.

Felvus, W. Flynn, J. Geisbuesch, K. Grainge, W. Grainger, D. Hammet, R. Hills, M. Hobson, C. Holler, R.

Jilley, M. Jones, T. Kaneko, R. Kneissl, K. Lancaster, A. Lasenby, P. Marshall, F. Newton, O. Norris, I.

Northrop, G. Pooley, V. Quy, R. Saunders, A. Scaife, J. Schofield, P. Scott, C. Shaw, A. Taylor, D.

Titterington, M. Velic, E. Waldram, S. West, B. Wood, G. Yassin, J. Zwart

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IF system: downconverters, amplifiers, filters, path compensator, gain control units for6–12 GHz.

Correlator:

• 16-lag analogue correlator → 8 complex frequency channels

• detect phase-switched power with Schottky diodes

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First AMI cluster detections - high sensitivity SZ observations

13.0 14.0 15.0 16.0 17.0 18.0Channel Centre Frequency (GHz)

2.0

3.0

4.0

5.0

6.0

Inte

grat

ed S

Z flu

x (−

mJy

)

Spectrum of SZ effect in A1914

A1914 (astro-ph/0509215; Accepted A773 (6h observation)for publication in MNRAS Letters)S = -8.6 mJy, noise = 0.2 mJy/beam

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Cluster survey in the presence of primordial CMB

Grayscale image: Virgo cluster positions with scaled β model clusters, plus CMBContour overlay: 6 months survey, 2 arcmin resolution. Sources subtracted!

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Sensitivity and CMB Confusion

Thermal flux sensitivity (6 × 8-hours; within a 21 arcmin aperture) of the compact array3.7-m and large array 13-m dishes compared to primordial CMB and 4 clusters withmasses of M = 2 / 5 ×1014M� and at redshifts z = 0.15/0.8.

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SZ selection function

Melin, Bartlett, Delabrouille2005, A&A 429, 417

Culverhouse(Moriond 2004)

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Cluster masses and redshifts

RK et al. 2001

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Imaging cluster substructureConstruction phase 3: Compactifying the Ryle telescope

current wideEast-Westalignment

Hydrosimulation:5× 1014 M� mergingcluster at z = 0.155.

morecompact

array withimproved

North-South

resolution

high declination (45 deg)

low declination (-5 deg)

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Pointed high redshift cluster observations

Cluster merger at redshift 1.5 of totalmass 2 × 1014 M� from a hydrody-namical simulation (G. Tormen); iny-units of 10−6.

Simulated 14 × 8−h observation withcompact array and Ryle mosaic; in µJybeam−1.

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The SZ receiver for the APEX telescopeMPIfR Bonn & UC Berkeley

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People:

Max Planck Institute for Radioastronomy:

K. Basu, F. Bertoldi (U Bonn), R. Güsten, E. Kreysa, K. Menten, D. Muders, P. Schilke

MPE: H. Böhringer

University of California, Berkeley

Physics Department: H.-M. Cho, N. W. Halverson (U Colorado), W. L. Holzapfel, R.Kneissl, T. M. Lanting, A. T. Lee, M. Lueker, J. Mehl, T. Plagge, P. L. Richards, D.Schwan, M. White

LBNL: M. Dobbs (U McGill), H. Spieler

• 12 m Atacama Pathfinder Experiment telescope, on-axis Cassegrain

• 0.75 m secondary, tertiary optics, 0.4 degree field-of-view

• Spiderweb Transition-Edge Sensor bolometer array with 330 elements

• SQUID readout, frequency multiplexing for SPT

• dry (τ = 0.061 at 225 GHz), high elevation (5000 m) site, 23◦S latitude

• observing frequencies (90) 150 (217) GHz

• 100-200 deg2, several months integration, 10 µK, 60” FWHM ( 150 GHz) resolution

Observing strategy

Optimise scanning speed, cross-linking, field size, geometry, etc.

Science goals / cluster yield with APEX-SZ

• Evolution of cluster mass function• Cluster correlation function• Evolution of gas fraction and M-T re-

lation• Dark matter density and distribution• Dark energy equation of state• Population of inverted spectrum radio

sources• High redshift star forming galaxies• Density-velocity field correlations• Lensing of the cosmic microwave

background

SZ / X-ray cluster selection

Planck all-sky CMB (and cluster) component separation(Stolyarov et al. 2002)

Input component maps Recovered power spectra

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Towards a complete and pure Planck cluster sample

Geisbüsch, RK, Hobson, 2005, MNRAS 360, 41

• Virgo HVLC catalogues (Sphere, Octants, ’Evrard mass function’)

• ΛCDM and τCDM cosmologies

• rescaling of cluster catalogue with σ8

• M − T relation with different normalisation (virial + ’X-ray’)

• analytic isothermal gas profile truncated at rv (90 % unresolved clusters)

• assume constant gas fraction fg

• assume NFW profile to rescale dark matter mass definitions

• fix total cluster flux, ’adjust’ central density and rc/rv

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Recovered cluster fluxes

ΛCDM: σ8 = 1 (virial) ΛCDM: σ8 = 0.7 (virial) ΛCDM: σ8 = 0.7 (xnorm)

Scatter, completeness and purity for a variety of cosmological SZ realisations.

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Mass function and completeness in redshift bins

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Outlook

• First generation (testing) SZ survey instruments (interferometers) beginning to takedata: SZA, AMI (known clusters until spring 2006, surveys from summer), limitedby radio source confusion until large telescopes, e.g. Ryle array, become available.

• Second generation (fast surveying), large bolometer arrays on single telescope,starting soon, e.g. APEX-SZ engineering run this year, full commissioning spring2006.

• High sensitivity SZ cluster data are very interesting to explore gas physics

• SZ will provide high-z clusters to study evolution and large samples to constraincosmology, hopefully with advantageous selection

• Multi-wavelength (optical,IR,X-ray,radio,sub-mm) (pre-)follow-up important

• Third generation (digesting) SZ instruments (high resolution imaging, SZspectroscopy)

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