A Primer on SZ Surveys Gil Holder Institute for Advanced Study.
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Transcript of A Primer on SZ Surveys Gil Holder Institute for Advanced Study.
A Primer on SZ Surveys
Gil Holder
Institute for Advanced Study
Outline
• Sunyaev-Zel’dovich effect
• Upcoming surveys
• What’s next?
Optical Image of Cl 0016+16(Clowe et al. 2000)
~ 7’ ~ 2 h-1 Mpc
kT ~ 7.5 keV
Hot Gas in Cl 0016+16
(Reese)
Sunyaev-Zel’dovich Effect
CMB Hot electrons
CMB+
I
Optical depth: τ ~ 0.01
Fractional energy gain per scatter: 2cm
kT
e
~ 0.01
SZ Observables I
Tee
lncm
kTdlg
T
T )()(2
Along a line of sight:
DEPENDS ONLY ON CLUSTER PROPERTIES !!!!
Independent of redshift
Temperature weighted electron column density
Unique spectral signature
Non-Thermal Spectrum
Abell 2163
Data from 3 experiments
SZ Observables II
dVkTnzd
dTS eA
2)(
1
Integrated effect from cluster:
proportional to total thermal energy of electrons
Temperature weighted electron inventory
angular diameter distance, not luminosity distance
SZ Observables III
3/52)(
Mzd
hfS
A
g
In reasonable units ( i.e., 1/h):
Assume a virial relation:3/2MT
TMzd
hfS
A
g
2)(
uncertainties come in mass limit as ^(0.6)
Central decrement vs Mass – 40% scatter
Average SZ flux vs Mass – 10% scatter
Metzler ; astro-ph/9812295SZE Regularity
dTo <dT>
Searching for Galaxy Clusters
Small area; very deep
- AMI, AMIBA, BOLOCAM, SZA
Large area; relatively shallow
- ACBAR, PLANCK
Large area; very deep
- ACT, SPT
Mass Limits
Fluxes at 30 GHz
PLANCK
SZA
Foregrounds
• CMB – need good angular resolution and/or good spectral resolution; problem at all SZ frequencies
• Radio point sources – need good angular resolution for frequencies <90 GHz
• Dusty point sources – need good angular resolution and/or spectral resolution at frequencies >200 GHz
• Radio halos and ghosts – could be a problem at frequencies < 15 GHz
SZA
• Survey 10 square degrees to a few uK at resolution of 2-3 arcminutes at 30 GHz
• Expected mass limit ~
• Follow up catalog at 90 GHz for high resolution (<20”)
• 100 – 500 clusters expected
Mh 11410
Example: RXJ1347-1145
X-ray (colours)SZ (contours)
SZ only
Reese
CMB contamination??
• clusters are clearly at a different spatial scale
• close amplitudes means beam dilution catches up fast !!!
Roughly 1 deg x 1deg – labels are uK
Cosmology With the SZA
Holder, Haiman & Mohr 2001
Dark Energy With the SZA
• 12 square degrees
• assume NO systematic errors
• assume redshifts measured to z=2
PLANCK
• Survey the full sky to a few uK at resolution of 5-10 arcminutes at many frequencies
• Expected mass limit ~
• Cluster detections will be unresolved – point sources with SZE-like spectra
• 1000 – 50000 clusters expected
Mh 114108
Cosmology With Planck
Black: all z
Red: z<0.5 only
Holder, Haiman & Mohr 2001
SPT/ACT/???
• Survey ~1000 square degrees to a few uK at resolution of 1-2 arcminutes at several frequencies
• Expected mass limit ~
• Most powerful for cosmology
• 5000 – 200000 clusters expected
Mh 114105.2
Cosmology with the SPTHolder, Haiman & Mohr 2001
dN/dz for SPT
Dark Energy With the SPT
Also sensitive to time dependent equation of state
(Weller, Battye & Kneissl 2001)
Possible Plan of Action
1) Use AMI/AMIBA/BOLOCAM/SZA to define a significant SZE-selected sample
2) Follow up at many wavelengths: optical, X-ray, radio, cm, mm (including SZA!)
3) Do a very large, deep survey for precise measurements of cosmological parameters
On the Horizon
uK imaging between 30-400 GHz with arcminute resolution
-- SPT, ACT, dedicated interferometers, ALMA, etc.
New science opportunities & challenges
-- peculiar velocities,
-- spectral SZ
-- CMB lensing
Peculiar Velocities (Kinetic SZ)
• Pure redshift, blueshift => thermal spectrum
cT
T v
Arcminutes scales => CMB ~ 1 uK
-- CMB noise contribution = 10 km/s (0.01/τ)
Other contamination: 50 km/s ?
(Fischer & Lange 1993)
Relativistic Corrections
Lensing of the CMB
Typical CMB gradient
-- 15 uK/arcmin
Typical deflection angle
-- ~ 0.1-1 arcmin
(Seljak and Zaldarriaga )
Summary
• New cluster surveys coming soon
• Detailed follow-up will be required of some sample of SZE-selected clusters
• Ambitious survey machines in proposal stages could be extremely powerful
Gallery of SZ ImagesZ=0.83
Z=0.14
sunMhM 114lim 10x5
Holder & Carlstrom 2001
Green: shift in matter density by 10%
Counting Galaxy Clusters
dzd
dVdM
dM
dn
dzd
dN
M lim
Mass function
Volume element
(Jenkins, Press-Schechter)
Mass limit
Self-Similar Evolution
Holder & Carlstrom 2001
Effects of Gas Evolution
Holder & Carlstrom 2001
Angular Power Spectrum of SZ Sources
Holder & Carlstrom 2001