CLUSTERS of GALAXIES & COSMOLOGY Cathy Horellou, Onsala Space Observatory, Chalmers University of Technology, Sweden Introduction My own interests – Clusters as cosmological tools Sunyaev-Zel ʼ dovich observations – Probes, processes, Radio synchrotron from clusters (LOFAR...) & the importance of systematics XXL: The Ultimate XMM Extragalactic Survey Tuesday, February 5, 2013
Vikhlinin et al. 2009 Tuesday, February 5, 2013
Numerical simulations of structure formation (dark matter only) 200 Mpc Ω m = 0.3 Ω Λ = 0.7 Ω m = 1 Credit: The Virgo consortium, 1996 170 Mpc Observations of clusters make it possible to – measure the growth of structure in the expanding Universe – constrain the cosmological parameters Ex: The observation of 1 single massive cluster at z = 0.8 (MS1054-0321) made it possible to exclude Ω m > 1 (Jetlema et al. 2001) Tuesday, February 5, 2013
Cluster number counts in different dark energy models w = p/ ρ : equation-of-state parameter of dark energy w = – 1 ( Λ CDM) w = – 0.8 w = – 0.6 A constant limiting mass was assumed. To relate observations to models, it is important to know the selection function of the survey, and the Mass-Observable relation Figure: Horellou & Berge 2005, MNRAS Tuesday, February 5, 2013
Cluster masses 5% 10% Galaxies Hot gas Dark matter 85% • Velocity dispersion of cluster galaxies + virial theorem • Hot gas in equilibrium with the gravitational � � R eff � − 1 � GMm p � � M k B T e � � 7 keV 3 × 10 14 M � 2 R eff 1Mpc • Gravitational lensing (strong + weak lensing) ⇒ Total mass: a few times 10 13 to 10 15 M sun • Scaling relations M - Observable Tuesday, February 5, 2013
Scaling relations: Mass – Observable L X X-ray N 200 T X Mass Y SZ mm- σ V radio Optical/ Lensing NIR mass Tuesday, February 5, 2013
Scaling relations: Mass – Observable L X X-ray N 200 T X Mass Y SZ mm- σ V radio Optical/ Lensing NIR mass Tuesday, February 5, 2013
Constrain cosmologically-relevant quantities & the cosmological model with clusters: - Clusters are natural TE LES CO PES (Gravitational lenses to probe the high- z Universe) - Number counts n(M,z) + 2-point correlation function ξ (M,z) ➜ CosmoParams, neutrino mass, non-Gaussianity, ... - Baryon mass fraction in virialized clusters (Allen et al. 2011) ➜ CosmoParams... - SZ: – Thermal SZ + X-rays of virialized clusters: D A (z) ➜ H 0 – Kinetic SZ: Peculiar velocities ➜ CosmoParams... – T CMB (z ≠ 0) . ➜ Standard law T CMB = T 0 (1+z) , or more exotic model? - Dark matter : – Merging clusters ➜ Constraints on the properties of DM (self-interaction cross- section) – DM annihilation ➜ secondary electrons ➜ SZ signature ➜ gamma rays - Cosmic magnetic fields (LOFAR/SKA) via observations of polarized emission and of Faraday Rotation Measures ( ∝ ∫ n e B // dl ) of background sources (tomography) Tuesday, February 5, 2013
Tuesday, February 5, 2013
X-ray (Bremsstrahlung) p γ CMB X/Gamma Th. e- Relat. e- γ CMB (Inv. Compton) γ CMB Dark matter SZ Th. e- (Inverse π 0 Compton γ CMB γ + γ Gamma scattering) rays π 0 γ CMB Relat. e- γ CMB Th. e- γ CMB B B Radio Faraday rotation Radio synchrotron ( ∝ ∫ n e B // dl ) Thermal e- (keV), suprathermal e- (>10 keV), relativistic e- (power-law, MeV-GeV) Tuesday, February 5, 2013
THE SUNYAEV-ZEL ʼ DOVICH EFFECT & SZE OBSERVATIONS of CLUSTERS x = h ν /kT The Compton parameter y y ∝ ∫ n e T e dl ∝ ∫ P e dl y is dimensionless We measure Y = ∫ y d Ω in units of solid angle (sr, arcmin 2 ) Y is tightly related to the Mass! Picture: Sheldon ʼ s and Lennart ʼ s white board The Kompaneets equation in the TV series The Big Bang Theory Change in the photon occupation number ∆ n Tuesday, February 5, 2013
The SZ effect: Inverse Compton scattering of CMB APEX-SZ LABOCA Zel ʼ dovich & Sunyaev 1969; Reviews by Birkinshaw 1999; Carstrom et al. 2002 Tuesday, February 5, 2013
APEX-SZ LABOCA Characteristic distortions of the CMB spectrum: 1. Thermal SZ effect Decrement in the radio/mm, increment in the submm Δ T SZ,th /T CMB ( ν ) ∝ ∫ cluster n e T e dl = gas pressure 2. Kinetic SZ effect: ~ 10 times weaker Δ T SZ,kin /T CMB ( ν ) ∝ - v pec /c Depends on the mass of the intracluster gas. Current observations are sensitive to clusters with masses M > a few 10 14 M sun . Important: independent of redshift ! 3. Relativistic SZ effect (High T e , high frequencies) Tuesday, February 5, 2013
The Planck Early Science SZ catalog: 189 clusters (incl. 20 new) (the Planck Collaboration 2011, A&A) Angular resolution: 24 ʼ to 5 ʼ 2 degrees Planck observation of Abell 2319 at z = 0.056 ( D L = 236 Mpc) Image Credit: ESA / HFI & LFI Consortia Tuesday, February 5, 2013
224 cluster candidates South Pole Telescope in 720 deg 2 (out of 2500 deg 2 ), Angular resolution 1 ʼ 158 confirmed in opt/NIR. 150 + 95 GHz Median z = 0.55 M lim = 5 10 14 /h M sun at z > 0.6 Planck: Beam dilution ROSAT: Cosmological dimming Reichardt et al. 2013 Tuesday, February 5, 2013
APEX-SZ PI: Adrian Lee • Mapping the SZ decrement at 2 mm (150 GHz) • Angular resolution of 1 ʼ ; FOV = 24 ʼ • Observations between 2005 and 2010 • 48 clusters + 2 deep fields. Dec 2009 Tuesday, February 5, 2013
Example of APEX-SZ 150 GHz maps (Schwan et al. 2012, The ESO Messenger) Tuesday, February 5, 2013
The Bullet Cluster at z = 0.3 Hot gas (X-ray) Galaxies Dark matter (lensing) Credit: X-ray: NASA/CXC/CfA/M.Markevitch et al.; Optical: NASA/STScI; Magellan/U.Arizona/ D.Clowe et al.; Lensing Map: NASA/STScI; ESO WFI; Magellan/U.Arizona/D.Clowe et al. Tuesday, February 5, 2013
The Bullet Cluster as a gravitational lens (Johansson, Horellou et al. 2010, A&A) • 17 submm galaxies (APEX-LABOCA 870 micron map) • The brightest one is a z = 2.8 galaxy located near a caustic line and magnified ~ 100 times Red:Total mass distribution Red: X-ray (XMM) (Weak lensing from Clowe et al.) Tuesday, February 5, 2013
The Bullet Cluster at z = 0.3 SZ decrement (APEX-SZ, 2mm): SZ increment (LABOCA, 870 micron): Halverson et al. 2009 Horellou et al., in prep Contours : X-ray Contours + Colors: SZ, resolution 1.4 ʼ Colors: SZ, resolution 27” Substructure in the SZ, Star: Bright submm galaxy (50 mJy at 870 micron, offset from the X-ray Johansson et al. 2010) at z=2.8 near a critical line of the Bullet Cluster and magnified 100 times; its flux at 2 mm is negligible compared to the SZ Tuesday, February 5, 2013
Abell 2163 at z = 0.3, Nord et al. 2009 The SZE spectrum Fixing temperature gives constraint on peculiar velocity-central Compton parameter v pec,los = – 140 ± 460 km s − 1 , Tuesday, February 5, 2013
Abell 2163 at z = 0.3, Nord et al. 2009 De-projected density & temperature Joint X-ray/SZ analysis: n e SZ: ∫ los n e T e dl X-ray: ∫ los n e 2 Lambda(T e ) dl Assuming spherical symmetry, one can use the Abel transformation T e Tuesday, February 5, 2013
Abell 2204, a relaxed cluster at z = 0.15, Basu et al. 2010 Profile of the enclosed gas mass and the total mass De-projected density & temperature (assuming hydrostatic equilibrium) n e M tot (<R) M gas (<R) T e f gas (<R) Tuesday, February 5, 2013
APEX-SZ scaling relations Bender et al., in prep The integrated Compton parameter Y SZ is a good proxy of the cluster ʼ s total mass (e.g. Motl et al. 2006, Arnaud et al. 2010) Y 500 Tuesday, February 5, 2013
Lensing follow-up of the 15 clusters of our sample for which no weak lensing data exist Ongoing PhD work of Matthias Klein, Bonn BVR observations with the wide field imager (WFI) on the ESO/ MPG 2.2 m telescope in La Silla, FOV = 33 ʼ x34 ʼ S/N map of the reconstructed projected mass and shear profile RXC 0532 M 200 = 11.4 (+2.5 -2.2) x 10 14 M sol R 200 = 1.96 +/- 0.13 Mpc Photo: www.eso.org Tuesday, February 5, 2013
RADIO SYNCHROTRON OBSERVATIONS of CLUSTERS, LOFAR The Onsala LOFAR station Credit: Onsala Space Observatory/Leif Helldner Tuesday, February 5, 2013
Giant radio halos in (some) galaxy clusters • Synchrotron emission on Mpc scale • Low surface brightness: ~3 mJy/arcmin 2 at 1.4 GHz • Steep spectrum ( α < –1, S ν ~ ν α ) ⇒ brighter at lower frequencies • Unpolarized Detected in ~30% of X-ray clusters (Ferretti et al. 2012) Origin of the relativistic electrons? Accelerated in turbulence generated in mergers (e.g. Brunetti 2001)? Figure: Radio halo of the Bullet Cluster (grey) + X-ray surface brightness contours (Liang et al. 2000) after subtraction of the radio point sources Tuesday, February 5, 2013
Feretti et al. 2012 Tuesday, February 5, 2013
2 Mpc long radio relic in the z = 0.19 Sausage Cluster (van Weeren et al. 2010, Science) Tuesday, February 5, 2013
The radio–X-ray correlation Bi-modality ON! OFF! ? Figure: Brown et al. 2011, ApJ Red points: Detection of radio signal at 843 MHz by stacking ~100 clusters Tuesday, February 5, 2013
The radio–X-ray correlation Bi-modality ON! ? OFF! ? Figure: Brown et al. 2011, ApJ Red points: Detection of radio signal at 843 MHz by stacking ~100 clusters What about lower X-ray luminosity clusters/groups? ➜ XXL Tuesday, February 5, 2013
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