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The microwave background radiation and the Sunyaev-Zel’dovich effect. Mark Birkinshaw. Outline. The microwave background The origin of the SZ effect SZ observations today Cluster structures and SZ effects Cosmology and SZ effects AMiBA and OCRA Summary. 1. The microwave background. - PowerPoint PPT Presentation
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SZ review
The microwave background radiation and the Sunyaev-
Zel’dovich effect
Mark Birkinshaw
31-October-2002 Mark Birkinshaw, U. Bristol 2
SZ review
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
31-October-2002 Mark Birkinshaw, U. Bristol 3
SZ review
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
31-October-2002 Mark Birkinshaw, U. Bristol 4
SZ review
COBE/FIRAS spectrum
FIRAS results: T = 2.728 ± 0.002 K, |y| < 15 10-6, || < 9 10-5 (Fixsen et al. 1996)
31-October-2002 Mark Birkinshaw, U. Bristol 5
SZ review
COBE/FIRAS+DMR dipole
FIRAS and DMR measured the dipole:amplitude = 3.372 ± 0.007 mKdirection (l,b) = (264.14° ± 0.15°, 48.26° ± 0.15°)
(FIRAS values, consistent with DMR, but more precise)
Can ignore deviation from monopole temperature.
31-October-2002 Mark Birkinshaw, U. Bristol 6
SZ review
BOOMERanG power spectrumPredicted power spectra (MAP errors)
Hu & White (1997)
Temperature power spectrum
BOOMERanGNetterfield et al. (2002)
31-October-2002 Mark Birkinshaw, U. Bristol 7
SZ review
Power spectrum interpretation
• Peak locations show Universe is flatk = –0.02 ± 0.06
• Fluctuations close to Harrison-Zel’dovich–ns = 0.96 ± 0.10
• Peak heights give matter contentsb = (0.022 ± 0.004) h2
CDM = (0.13 ± 0.05) h2
• Cosmological concordance still goodNetterfield et al. (2002)
31-October-2002 Mark Birkinshaw, U. Bristol 8
SZ review
Polarization
E-mode polarization detection
DASI
31-October-2002 Mark Birkinshaw, U. Bristol 9
SZ review
2. The origin of the SZ effect
Clusters of galaxies contain extensive hot atmospheres
Te 6 keV
np 103 protons m-3
L 1 Mpc
2 Mpc
31-October-2002 Mark Birkinshaw, U. Bristol 10
SZ review
Inverse-Compton scatterings
• Cluster atmospheres scatter photons passing through them. Central iC optical depth
enpT L
• Each scattering changes the photon frequency by a fraction
31-October-2002 Mark Birkinshaw, U. Bristol 11
SZ review
Single-scattering frequency shift
5 keV 15 keV
s = log()
P1(s)
31-October-2002 Mark Birkinshaw, U. Bristol 12
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Thermal SZ effect• The fractional intensity change in the background
radiation
I/I = -2 (/ e 10-4
• Effect in brightness temperature terms is
TRJ = -2 Tr (/ e -300 K
• Brightness temperature effect, TRJ, is
independent of redshift
31-October-2002 Mark Birkinshaw, U. Bristol 13
SZ review
Microwave background spectrum
I
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Spectrum of thermal effect
• effect caused by small frequency shifts, so spectrum related to gradient of CMB spectrum
• zero at peak of CMB spectrum
31-October-2002 Mark Birkinshaw, U. Bristol 15
SZ review
Temperature sensitivity• Te < 5 keV: e– non-
relativistic, effect independent of Te
• Te > 5 keV: enough e– relativistic that spectrum is function of Te
• Te > 1 GeV: spectrum independent of Te, negative of CMB (non-thermal SZ effect)
5 keV15 keV
31-October-2002 Mark Birkinshaw, U. Bristol 16
SZ review
Spectrum of kinematic effect
• effect caused by reference frame change, related to CMB spectrum
• maximum at peak of CMB spectrum
• negative of CMB spectrum
31-October-2002 Mark Birkinshaw, U. Bristol 17
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Attributes of SZ effect
TRJ is a redshift-independent function of cluster properties only. If the gas temperature is known, it is a leptometer
TRJ contains a weak redshift-independent kinematic effect, it is a radial speedometer
TRJ has a strong association with rich clusters of galaxies, it is a mass finder
TRJ has polarization with potentially more uses, but signal is tiny
31-October-2002 Mark Birkinshaw, U. Bristol 18
SZ review
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
31-October-2002 Mark Birkinshaw, U. Bristol 19
SZ review
Interferometers
• restricted angular dynamic range set by baseline and antenna size
• good rejection of confusing radio sources
Abell 665 model, VLA observation
31-October-2002 Mark Birkinshaw, U. Bristol 20
SZ review
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)
31-October-2002 Mark Birkinshaw, U. Bristol 21
SZ review
Ryle telescope
• first interferometric map• Abell 2218• brightness agrees with
single-dish data• limited angular dynamic
range
Figure from Jones et al. 1993
31-October-2002 Mark Birkinshaw, U. Bristol 22
SZ review
BIMA/OVRO
• limited angular dynamic range
• high signal/noise (with enough tint)
• clusters easily detectable to z 1
Figure from Carlstrom et al. 1999
31-October-2002 Mark Birkinshaw, U. Bristol 23
SZ review
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
31-October-2002 Mark Birkinshaw, U. Bristol 24
SZ review
OVRO 40-m
• Crude mapping possible• Difficulties with
variable sources• Relatively fast for
detections of SZ effects
Figure from Birkinshaw 1999
31-October-2002 Mark Birkinshaw, U. Bristol 25
SZ review
Viper telescope at the South Pole
• 1998-2000: 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
31-October-2002 Mark Birkinshaw, U. Bristol 26
SZ review
1999 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
• H0=64 km s-1 Mpc-1
Cantalupo, Romer, et al.
31-October-2002 Mark Birkinshaw, U. Bristol 27
SZ review
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.
31-October-2002 Mark Birkinshaw, U. Bristol 28
SZ review
SCUBA
850 µm images: SZ effect measured in one; field too small
31-October-2002 Mark Birkinshaw, U. Bristol 29
SZ review
MITO
• MITO experiment at Testagrigia
• 4-channel photometer: separate components
• 17 arcmin FWHM• Coma cluster detection
Figure from De Petris et al. 2002
31-October-2002 Mark Birkinshaw, U. Bristol 30
SZ review
ACBAR cluster observations
• ACBAR 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, 0658-556, A3667, A3266, A3827,
A3112, A3158 already imaged
Romer, Gomez, Peterson, Holzapfel, Ruhl et al.
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SZ review
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
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Integrated SZ effects• Total SZ flux density
thermaleeRJ UdzTndS Thermal energy content immediately measured in redshift-independent wayVirial theorem then suggests SZ flux density is direct measure of gravitational potential energy
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Integrated SZ effects• Total SZ flux density
eeeeRJ TNdzTndS If have X-ray temperature, then SZ flux density measures electron count, Ne (and hence baryon count)Combine with X-ray derived mass to get fb
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SZ review
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
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Cluster velocitiesNeed• good SZ spectrum• X-ray temperature
Confused by CMB structure
Sample vz2
Three clusters so far, vz 1000 km s
A 2163; figure from LaRoque et al. 2002.
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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 ne rather than ne
2 dependence, so good SZ structure should extend out further and show more about halo
31-October-2002 Mark Birkinshaw, U. Bristol 37
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Cluster distances and massesDA = 1.36 0.15 Gpc
H0 = 68 8 18 km s-1 Mpc-1
Mtot(250 kpc) = (2.0 0.1) 1014 M XMM+SZ
Mtot(250 kpc) = (2.7 0.9) 1014 M lensing
Mgas(250 kpc) = (2.6 0.2) 1013 M XMM+SZCL 0016+16 with XMM; Worrall & Birkinshaw 2002
31-October-2002 Mark Birkinshaw, U. Bristol 38
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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
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Cluster Hubble diagram
X-ray surface brightness
X ne2 Te
½ L SZ effect intensity change
I ne Te L
Eliminate unknown ne
L I2 X1 Te
3/2
H0 X I2 Te
3/2
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Hubble diagram
• poor leverage for other parameters
• need many clusters at z > 0.5
• need reduced random errors
• ad hoc sample • systematic errors
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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
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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
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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
31-October-2002 Mark Birkinshaw, U. Bristol 44
SZ review
Cluster counts and cosmologyCluster counts and redshift distribution provide strong constraints on 8, m, and cluster heating.
z
dN/dzm=1.0
m=0.3
m=0.3
Figure from Fan & Chiueh 2000
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Baryon mass fraction
SRJ Ne Te
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. 1999.
b/m
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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. 2002.
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SZ review
Microwave background temperature• Ratio of SZ effects at two different frequencies
is a function of CMB temperature (with slight dependence on Te 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)
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Microwave background temperature• Test T (1 + z)
• SZ results for two clusters plus results from molecular excitation
Battistelli et al. (2002)
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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
31-October-2002 Mark Birkinshaw, U. Bristol 50
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New SZ facilities• AMiBA• OCRA (-p, -F, -)• AMI• MAP• Planck• SuZIE-n• BOLOCAM• CARMA• ALMA
• SZA• ACBAR• MITO/MAD• APEX
etc., etc., etc.
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SZ review
Survey speeds
• OCRA will be fastest survey radiometer
• AMiBA will be fastest survey interferometer
• Frequencies complementary
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AMiBA
• ASIAA/NTU-led project• Operational in 2004, prototype
2002• 19 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
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Visibility curves• AMIBA 90 GHz• SZA 30 GHz• AMI 15 GHz
Complementary frequencies
Solid: nearby, high-MDashed: distant, low-M
AMiBASZAAMI
31-October-2002 Mark Birkinshaw, U. Bristol 54
SZ review
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.
31-October-2002 Mark Birkinshaw, U. Bristol 55
SZ review
AMiBA imaging
Simulated AMiBA field from deep survey: two SZ effects detected
Based on da Silva et al. simulations
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SZ review
AMiBA survey sensitivity
• 5 mass limits in survey modes
• Shallow: 175 deg2 in 6 mon, 100 clusters
• Medium: 70 deg2 in 1 year, 350 clusters
• Deep: 3 deg2 in 6 mon, 100 clusters
shallow
medium
deepM = 214 M
z = 1
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SZ review
OCRA
Torun Observatory, Jodrell Bank, Bristol, …
OCRA-p
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SZ review
OCRA
• 30 GHz
• Tsys = 40 K
• 1 arcmin FWHM beam
• 5 mJy sensitivity in 10 sec
31-October-2002 Mark Birkinshaw, U. Bristol 59
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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 H0 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
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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
LX(5)
z
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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
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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
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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