the sunyaev-zel’dovich effect the sunyaev-zel’dovich effect ami day, 2011 september 30 mark...
Post on 20-Dec-2015
221 views
TRANSCRIPT
The Sunyaev-Zel’dovich effect
The Sunyaev-Zel’dovich effectAMI day, 2011 September 30
Mark Birkinshaw
University of Bristol
2011 September 30 Mark Birkinshaw, U. Bristol 2
The Sunyaev-Zel’dovich effect
The thermal SZ effect
The effect comes from the inverse-Compton scattering of the CMB by the hotter electrons in the ICM.
Thermal SZ effect strength Comptonization parameter, ye, the dimensionless electron temperature weighted by the scattering optical depth.
2011 September 30 Mark Birkinshaw, U. Bristol 3
The Sunyaev-Zel’dovich effect
The thermal SZ effect
Total SZ flux density
thermaleeRJ UdzTndS • z-independent measure of ICM thermal energy content• Virial theorem – measures gravitational potential energy unless cluster in dynamically-active state
• With X-ray data for electron temperature, get gas mass and lepton count, hence baryonic mass fraction
2011 September 30 Mark Birkinshaw, U. Bristol 4
The Sunyaev-Zel’dovich effect
Now easy to detect for known clusters such as those from X-ray surveys
e.g., Lancaster et al. (2011) complete sample of 18 high-LX ROSAT BCS clusters (Ebeling et al. 1998) at z > 0.2
• OCRA-p on Toruń 32-m (OCRA-F now being debugged; OCRA-C possible)
• noise ~ 0.4 mJy [less than 1 hour/cluster]AMI highly effective at this (e.g.,
Rodríguez-Gonzálvez et al. 2011, Shimwell et al. 2011)
The thermal SZ effect
2011 September 30 Mark Birkinshaw, U. Bristol 5
The Sunyaev-Zel’dovich effect
Harder work in blank fields, but rewarding because of expected linear scaling with Uthermal; e.g.,
• Planck survey (Planck collaboration 2011), 189 clusters to z = over 3 104 deg2 (ERSC)
• ACT survey (Marriage et al. 2010), 23 clusters to z = 1.07 over 455 deg2 (2008 dataset)
• SPT survey (Vanderlinde et al. 2010; Williamson et al. 2011), 21 clusters to z =1.16 over 178 deg2 (2008 dataset), 26 high-significance clusters to z = 1.13 over 2500 deg2 (2010 dataset)
The thermal SZ effect
2011 September 30 Mark Birkinshaw, U. Bristol 6
The Sunyaev-Zel’dovich effect
Cluster numbers appearing in surveys are lower than original estimates 8 assumptions– optimistic assumptions about survey performance– confusion levels on primordial CMB and source
populations
• Value of survey high – want to get to lower cluster masses (currently see only mass function above 3 1014 M)
The thermal SZ effect
2011 September 30 Mark Birkinshaw, U. Bristol 7
The Sunyaev-Zel’dovich effect
Source contaminationSZ effects usually evident before source correction – compare cluster and trail statistics.
Uncorrected: lose 20% of clusters.Corrected: lose 10% of clusters (5% of trails).Lancaster et al. (2011)
2011 September 30 Mark Birkinshaw, U. Bristol 9
The Sunyaev-Zel’dovich effect
Source contaminationContamination also important in sub-mm: e.g., Bullet cluster (Johansson et al. 2011) – lensed sub-mm galaxies dominate image
Need multi-resolution (AMI-type interferometer) and/or multi-frequency data.
2011 September 30 Mark Birkinshaw, U. Bristol 10
The Sunyaev-Zel’dovich effect
Scaling relation: flux density/X-ray kT
Low-z scaling relations consistent with expected self-similar model, but errors large – LX and TX ranges too small (Lancaster et al. 2011)
2011 September 30 Mark Birkinshaw, U. Bristol 11
The Sunyaev-Zel’dovich effect
Next step: blind survey
Potential field: XMM-LSS. Survey blind in SZ, provides parallel X-ray, lensing, IR data.
Too far south for Toruń: accessible to AMiBA.
2011 September 30 Mark Birkinshaw, U. Bristol 12
The Sunyaev-Zel’dovich effect
Train-wreck astronomy
RXJ 1347-1145 (z = 0.45) GBT/MUSTANG, 90 GHz, 10 arcsec resolution (Mason et al. 2010)Left: colour = SZ; green = HST/ACS; contours = surface mass density (Bradac et al. 2008). Right: contours= SZ; colour = X-ray (Chandra)
2011 September 30 Mark Birkinshaw, U. Bristol 13
The Sunyaev-Zel’dovich effect
Train-wreck astronomy
MACS 0744+3927 (z = 0.69): shock discovered with high resolution SZ observations: GBT/MUSTANG, X-ray; Korngut et al. (2010)
2011 September 30 Mark Birkinshaw, U. Bristol 14
The Sunyaev-Zel’dovich effect
Train-wreck astronomy
MACS J0717.5+3745
z = 0.548
Clearly disturbed, shock-like substructure, filament
What will the SZ image look like?
2011 September 30 Mark Birkinshaw, U. Bristol 15
The Sunyaev-Zel’dovich effect
Train-wreck astronomy
MACS J0717.5+3745, z = 0.548, AMI image
2011 September 30 Mark Birkinshaw, U. Bristol 16
The Sunyaev-Zel’dovich effect
Science to come• Cluster physics
– Now getting fast SZ follow-up of known clusters to very high redshift (AMI, OCRA, etc., etc.)
– SZ gives linear measures of energy and mass – excellent probes of structure formation from appropriate samples, and testing scaling relations
– Resolving train-wreck structures – measures of thermalization of kinetic energy and cluster formation
• Cosmology– Structure formation and cosmological parameters from cluster counts:
need to go factor 5 – 10 below current mass limits– Baryonic mass fraction measurements with redshift and radius (lensing)
• Other SZ observables (kinematic effect, spectral distortions, polarization)