SZ review The microwave background radiation and the Sunyaev- Zel’dovich effect Mark Birkinshaw

SZ review 31-October-2002Mark Birkinshaw, U. Bristol2 Outline 1.The microwave background 2.The origin of the SZ effect 3.SZ observations today 4.Cluster structures and SZ effects 5.Cosmology and SZ effects 6.AMiBA and OCRA 7.Summary

SZ review 31-October-2002Mark Birkinshaw, U. Bristol3 1. The microwave background Provides an intense background thermal radiation –illuminates foreground structures Has significant structure itself –limits “shadowology” Has polarization structure –limits foreground polarization studies

SZ review 31-October-2002Mark Birkinshaw, U. Bristol4 COBE/FIRAS spectrum FIRAS results: T = ± K, |y| < 15  10 -6, |  | < 9  (Fixsen et al. 1996)

SZ review 31-October-2002Mark Birkinshaw, U. Bristol5 COBE/FIRAS+DMR dipole FIRAS and DMR measured the dipole: amplitude = ± mK direction (l,b)= (264.14° ± 0.15°, 48.26° ± 0.15°) (FIRAS values, consistent with DMR, but more precise) Can ignore deviation from monopole temperature.

SZ review 31-October-2002Mark Birkinshaw, U. Bristol6 BOOMERanG power spectrum Predicted power spectra (MAP errors) Hu & White (1997) Temperature power spectrum BOOMERanG Netterfield et al. (2002)

SZ review 31-October-2002Mark Birkinshaw, U. Bristol7 Power spectrum interpretation Peak locations show Universe is flat –  k = –0.02 ± 0.06 Fluctuations close to Harrison-Zel’dovich –n s = 0.96 ± 0.10 Peak heights give matter contents –  b = (0.022 ± 0.004) h 2 –  CDM = (0.13 ± 0.05) h 2 Cosmological concordance still good Netterfield et al. (2002)

SZ review 31-October-2002Mark Birkinshaw, U. Bristol8 Polarization E-mode polarization detection DASI

SZ review 31-October-2002Mark Birkinshaw, U. Bristol9 2. The origin of the SZ effect Clusters of galaxies contain extensive hot atmospheres T e  6 keV n p  10 3 protons m -3 L  1 Mpc 2 Mpc

SZ review 31-October-2002Mark Birkinshaw, U. Bristol10 Inverse-Compton scatterings Cluster atmospheres scatter photons passing through them. Central iC optical depth  e  n p  T L    Each scattering changes the photon frequency by a fraction    

SZ review 31-October-2002Mark Birkinshaw, U. Bristol11 Single-scattering frequency shift 5 keV15 keV s = log(  ) P 1 (s)

SZ review 31-October-2002Mark Birkinshaw, U. Bristol12 Thermal SZ effect The fractional intensity change in the background radiation  I/I = -2 (  /   e  Effect in brightness temperature terms is  T RJ = -2 T r (  /   e  -300  K Brightness temperature effect,  T RJ, is independent of redshift

SZ review 31-October-2002Mark Birkinshaw, U. Bristol13 Microwave background spectrum  II

SZ review 31-October-2002Mark Birkinshaw, U. Bristol14 Spectrum of thermal effect effect caused by small frequency shifts, so spectrum related to gradient of CMB spectrum zero at peak of CMB spectrum

SZ review 31-October-2002Mark Birkinshaw, U. Bristol15 Temperature sensitivity T e < 5 keV: e – non- relativistic, effect independent of T e T e > 5 keV: enough e – relativistic that spectrum is function of T e T e > 1 GeV: spectrum independent of T e, negative of CMB (non- thermal SZ effect) 5 keV 15 keV

SZ review 31-October-2002Mark Birkinshaw, U. Bristol16 Spectrum of kinematic effect effect caused by reference frame change, related to CMB spectrum maximum at peak of CMB spectrum negative of CMB spectrum

SZ review 31-October-2002Mark Birkinshaw, U. Bristol17 Attributes of SZ effect  T RJ is a redshift-independent function of cluster properties only. If the gas temperature is known, it is a leptometer  T RJ contains a weak redshift-independent kinematic effect, it is a radial speedometer  T RJ has a strong association with rich clusters of galaxies, it is a mass finder  T RJ has polarization with potentially more uses, but signal is tiny

SZ review 31-October-2002Mark Birkinshaw, U. Bristol18 3. SZ observations today Interferometers: Ryle, BIMA, OVRO, … –Structural information –Baseline range Single-dish radiometers: 40-m, Corona, … –Speed –Systematic effects Bolometers: SuZIE, MAD, ACBAR, … –Frequency coverage –Weather

SZ review 31-October-2002Mark Birkinshaw, U. Bristol19 Interferometers restricted angular dynamic range set by baseline and antenna size good rejection of confusing radio sources Abell 665 model, VLA observation

SZ review 31-October-2002Mark Birkinshaw, U. Bristol20 Interferometers good sky and ground noise rejection because of phase data long integrations and high signal/noise possible 10 years of data, tens of cluster maps SZ detected for cluster redshifts from 0.02 (VSA) to 1.0 (BIMA)

SZ review 31-October-2002Mark Birkinshaw, U. Bristol21 Ryle telescope first interferometric map Abell 2218 brightness agrees with single-dish data limited angular dynamic range Figure from Jones et al. 1993

SZ review 31-October-2002Mark Birkinshaw, U. Bristol22 BIMA/OVRO limited angular dynamic range high signal/noise (with enough t int ) clusters easily detectable to z  1 Figure from Carlstrom et al. 1999

SZ review 31-October-2002Mark Birkinshaw, U. Bristol23 Single-dish radiometers Potentially fast way to measure SZ effects of particular clusters Multi-beams better than single beams at subtracting atmosphere, limit cluster choice Less fashionable now than formerly: other techniques have improved faster New opportunities: e.g., GBT

SZ review 31-October-2002Mark Birkinshaw, U. Bristol24 OVRO 40-m Crude mapping possible Difficulties with variable sources Relatively fast for detections of SZ effects Figure from Birkinshaw 1999

SZ review 31-October-2002Mark Birkinshaw, U. Bristol25 Viper telescope at the South Pole : 1-pixel receiver (Corona); 40 GHz Since 2001: 16-pixel bolometer (ACBAR); 150, 220, 275 GHz Dry air, 3º chopping tertiary, large ground shield Excellent for SZ work

SZ review 31-October-2002Mark Birkinshaw, U. Bristol Corona observation of A3667 A 3667: brightest z < 0.1 REFLEX cluster far enough South for Viper 3.6 º  2.0º raster scan shows cold spot at the X-ray centroid and hot regions at the radio halo H 0 =64 km s -1 Mpc -1 Cantalupo, Romer, et al.

SZ review 31-October-2002Mark Birkinshaw, U. Bristol27 Bolometers Should be fast way to survey for SZ effects Wide frequency range possible on single telescope, allowing subtraction of primary CMB structures Atmosphere a problem at every ground site Several experiments continuing, SuZIE, MITO, ACBAR, BOLOCAM, etc.

SZ review 31-October-2002Mark Birkinshaw, U. Bristol28 SCUBA 850 µm images: SZ effect measured in one; field too small

SZ review 31-October-2002Mark Birkinshaw, U. Bristol29 MITO MITO experiment at Testagrigia 4-channel photometer: separate components 17 arcmin FWHM Coma cluster detection Figure from De Petris et al. 2002

SZ review 31-October-2002Mark Birkinshaw, U. Bristol30 A CBAR cluster observations A CBAR produces simultaneous 3-frequency images, subtracts primary CMB fluctuations Observing complete luminosity-limited sample (~10 REFLEX clusters) with Viper XMM/Chandra and weak lensing data AS1063, , A3667, A3266, A3827, A3112, A3158 already imaged Romer, Gomez, Peterson, Holzapfel, Ruhl et al.

SZ review 31-October-2002Mark Birkinshaw, U. Bristol31 4. Cluster structures and SZ effects Integrated SZ effects –total thermal energy content –total hot electron content SZ structures –not as sensitive as X-ray data –need for gas temperature Radial velocity of clusters via kinematic effect Mass structures and relationship to lensing

SZ review 31-October-2002Mark Birkinshaw, U. Bristol32 Integrated SZ effects Total SZ flux density Thermal energy content immediately measured in redshift-independent way Virial theorem then suggests SZ flux density is direct measure of gravitational potential energy

SZ review 31-October-2002Mark Birkinshaw, U. Bristol33 Integrated SZ effects Total SZ flux density If have X-ray temperature, then SZ flux density measures electron count, N e (and hence baryon count) Combine with X-ray derived mass to get f b

SZ review 31-October-2002Mark Birkinshaw, U. Bristol34 Radial velocity Kinematic effect separable from thermal SZ effect because of different spectrum Confusion with primary CMB fluctuations limits velocity accuracy to about 150 km s -1 If velocity substructure in atmospheres, even less accuracy will be possible Statistical measure of velocity distribution of clusters as a function of redshift in samples

SZ review 31-October-2002Mark Birkinshaw, U. Bristol35 Cluster velocities Need good SZ spectrum X-ray temperature Confused by CMB structure Sample   v z 2  Three clusters so far,  v z  1000 km s  A 2163; figure from LaRoque et al

SZ review 31-October-2002Mark Birkinshaw, U. Bristol36 SZ effect structures Currently only crudely measured by any method (restricted angular dynamic range) X-ray based structures superior Structure should be more extended in SZ than in X-ray because of n e rather than n e 2 dependence, so good SZ structure should extend out further and show more about halo

SZ review 31-October-2002Mark Birkinshaw, U. Bristol37 Cluster distances and masses D A = 1.36  0.15 Gpc H 0 = 68  8  18 km s -1 Mpc -1 M tot (250 kpc) = (2.0  0.1)  M  XMM+SZ M tot (250 kpc) = (2.7  0.9)  M  lensing M gas (250 kpc) = (2.6  0.2)  M  XMM+SZ CL with XMM; Worrall & Birkinshaw 2002

SZ review 31-October-2002Mark Birkinshaw, U. Bristol38 5. Cosmology and SZ effects Cosmological parameters –cluster-based Hubble diagram –cluster counts as function of redshift Cluster evolution physics –evolution of cluster atmospheres via cluster counts –evolution of radial velocity distribution –evolution of baryon fraction Microwave background temperature elsewhere in Universe

SZ review 31-October-2002Mark Birkinshaw, U. Bristol39 Cluster Hubble diagram X-ray surface brightness  X  n e 2 T e ½ L SZ effect intensity change  I  n e T e L Eliminate unknown n e  L   I 2  X  1 T e  3/2  H 0   X  I  2 T e 3/2 

SZ review 31-October-2002Mark Birkinshaw, U. Bristol40 Hubble diagram poor leverage for other parameters need many clusters at z > 0.5 need reduced random errors ad hoc sample systematic errors

SZ review 31-October-2002Mark Birkinshaw, U. Bristol41 Critical assumptions spherical cluster (or randomly-oriented sample) knowledge of density and temperature structure to get form factors clumping negligible selection effects understood need orientation-independent sample

SZ review 31-October-2002Mark Birkinshaw, U. Bristol42 SZ effect surveys SZ-selected samples needed for reliable cosmology –almost mass limited –flat redshift response X-ray samples –SZ follow-ups for ROSAT-derived samples –selects more stratified clusters Optical samples –much used in past, line-of-sight confusion problem

SZ review 31-October-2002Mark Birkinshaw, U. Bristol43 Distribution of central SZ effects Mixed sample of 37 clusters OVRO 40-m data, 18.5 GHz No radio source corrections 40% of clusters have observable  T < –100  K

SZ review 31-October-2002Mark Birkinshaw, U. Bristol44 Cluster counts and cosmology Cluster counts and redshift distribution provide strong constraints on  8,  m, and cluster heating. z dN/dz  m =1.0       m =0.3       m =0.3      Figure from Fan & Chiueh 2000

SZ review 31-October-2002Mark Birkinshaw, U. Bristol45 Baryon mass fraction S RJ  N e T e Total SZ flux  total electron count  total baryon content. Compare with total mass (from X-ray or gravitational lensing)  baryon fraction Figure from Carlstrom et al b/mb/m

SZ review 31-October-2002Mark Birkinshaw, U. Bristol46 Cluster velocities Confused by CMB structure, cluster velocity errors of 150 km s -1 at best (currently worse) Sample could give  z 2 (z): dynamics A 2163; figure from LaRoque et al

SZ review 31-October-2002Mark Birkinshaw, U. Bristol47 Microwave background temperature Ratio of SZ effects at two different frequencies is a function of CMB temperature (with slight dependence on T e and cluster velocity) So can use SZ effect spectrum to measure CMB temperature at distant locations and over range of redshifts Test T  (1 + z)

SZ review 31-October-2002Mark Birkinshaw, U. Bristol48 Microwave background temperature Test T  (1 + z) SZ results for two clusters plus results from molecular excitation Battistelli et al. (2002)

SZ review 31-October-2002Mark Birkinshaw, U. Bristol49 6. AMiBA and OCRA Many new SZ facilities under development –bolometers and interferometers most popular –south pole, Chile, Mauna Kea, Tenerife AMiBA –ASIAA/NTU development –operational in 2003 OCRA –-p operational in 2003, -F in 2005

SZ review 31-October-2002Mark Birkinshaw, U. Bristol50 New SZ facilities AMiBA OCRA (-p, -F, -  ) AMI MAP Planck SuZIE-n BOLOCAM CARMA ALMA SZA ACBAR MITO/MAD APEX etc., etc., etc.

SZ review 31-October-2002Mark Birkinshaw, U. Bristol51 Survey speeds OCRA will be fastest survey radiometer AMiBA will be fastest survey interferometer Frequencies complementary

SZ review 31-October-2002Mark Birkinshaw, U. Bristol52 AMiBA ASIAA/NTU-led project Operational in 2004, prototype dishes, 1.2/0.3 m diameters, 1.2 – 6 m baselines = 95 GHz,  = 20 GHz Dual polarization 1.3 mJy/beam in 1 hr

SZ review 31-October-2002Mark Birkinshaw, U. Bristol53 Visibility curves AMIBA 90 GHz SZA 30 GHz AMI 15 GHz Complementary frequencies Solid: nearby, high-M Dashed: distant, low-M AMiBA SZA AMI

SZ review 31-October-2002Mark Birkinshaw, U. Bristol54 AMiBA confusion Discrete radio sources –scaled from 8.4 GHz and 30 GHz counts –expect 1 source >1 mJy per 3 fields: not a problem CMB primary anisotropy –most can be filtered out in mosaic mode,  < 0.3 mJy Faint SZ clusters –cluster counts expect ~ 1 source >1 mJy per field –cluster counts don’t tell the full story since clusters are clustered. Simulations suggest  < 0.3 mJy.

SZ review 31-October-2002Mark Birkinshaw, U. Bristol55 AMiBA imaging Simulated AMiBA field from deep survey: two SZ effects detected Based on da Silva et al. simulations

SZ review 31-October-2002Mark Birkinshaw, U. Bristol56 AMiBA survey sensitivity 5  mass limits in survey modes Shallow: 175 deg 2 in 6 mon, 100 clusters Medium: 70 deg 2 in 1 year, 350 clusters Deep: 3 deg 2 in 6 mon, 100 clusters shallow medium deep M = 2  14 M  z = 1

SZ review 31-October-2002Mark Birkinshaw, U. Bristol57 OCRA Torun Observatory, Jodrell Bank, Bristol, … OCRA-p

SZ review 31-October-2002Mark Birkinshaw, U. Bristol58 OCRA 30 GHz T sys = 40 K 1 arcmin FWHM beam 5 mJy sensitivity in 10 sec

SZ review 31-October-2002Mark Birkinshaw, U. Bristol59 XMM + AMiBA survey aims Map large-scale structure of Universe to z = 1 using cluster and quasar populations. Cluster formation and evolution will be traced. Cluster Hubble diagram: –Compare H 0 with value from local Universe standard candles –Compare with CMB results to check SN Ia results on   Use cluster z distrubution to get   and  m Cluster physics and baryon fraction at z = 0 – 1

SZ review 31-October-2002Mark Birkinshaw, U. Bristol60 Cluster finding: XMM and AMiBA AMiBA is better than XMM for finding clusters at z > 0.7 AMiBA surveys will provide an almost mass limited catalogue L X (5  ) z

SZ review 31-October-2002Mark Birkinshaw, U. Bristol61 7. Summary (1) SZ effects are now easily measurable to z = 1 Individual cluster SZ effects give –total thermal energy contents –total electron contents –structural information (especially on large scales) –peculiar radial velocities –cluster masses

SZ review 31-October-2002Mark Birkinshaw, U. Bristol62 7. Summary (2) Sample studies give –Hubble diagram and cosmological parameters –cluster number counts and cosmological parameters –baryon mass fraction –evolution of cluster atmospheres –evolution of radial velocities –microwave background temperature in distant Universe

SZ review 31-October-2002Mark Birkinshaw, U. Bristol63 7. Summary (3) Improved SZ data may give –radio source energetics (non-thermal SZ effect) –transverse velocities of clusters (polarization effect) –detections of gas in in-falling filaments