The Sunyaev-Zeldovich effect in galaxy clusters

Transcription

1 The Sunyaev-Zeldovich effect in galaxy clusters Cathy Horellou, Onsala The background I. The SZ effect II. Its use in astrophysics and cosmology Galaxy clusters - physics of the hot intracluster medium Cosmology: H 0, cosmological parameters, T CMB (z) III. SZ observations Past and current SZ experiments ALMA

2 I. The SZ effects Inverse Compton scattering of CMB photons by hot electrons

3 An especially interesting episode of the TV series The Big Bang Theory The Compton parameter y The Kompaneets equation Change in the photon occupation number x = hν/ktcmb

4 I. The SZ effects Charateristic distortions of the CMB spectrum: 1. Thermal SZ effect Decrement in the radio/mm, increment in the submm ΔT SZ,th /T CMB (ν) cluster n e T e dl = gas pressure 2. Kinetic SZ effect: 10 times weaker ΔT 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 > M sun. Important: independent of redshift!

5 The brightness of the SZ signal is redshift-independent Maps of the 30 GHz SZ decrement in clusters at different redshifts Insets: X-ray surface brightness from XMM-Newton John Carlstrom, OVRO/BIMA observations

6 BIMA (Berkeley Illinois Maryland Association) (9 x 6.1 m) OVRO (Owens Valley Radio Observatory) (6 x 10.4 m) CARMA (Combined Array for Research in Millimeter-wave Astronomy): OVRO + BIMA + SZA (8 x 3.5 m; Sunyaev-Zeldovich Array)

7 La Roque et al. 2003, ApJ 30 GHz, OVRO, BIMA 8 clusters at z > 0.5 (X-ray selected)

8 The first distant clusters detected in SZ: z = 1.03, 0.92, GHz SZA observations (Muchovej et al ApJ) Angular resolution = 2 The SZA is sensitive to angular scales up to 5 SZA= 8 x 3.5 m

9 SZ highlights 1969,1972: Sunyaev & Zeldovich's papers. Many attempts, no detection. 1980's: First detections of the decrement (Birkinshaw et al.) 1990's: Follow-up; First interferometric SZ image (Abell 2218 with the Ryle telescope, 8x13m, Jones et al. 1993, Nature); Observations in the mm, first detection of the increment. Interferometric observations (OVRO, BIMA at 30 GHz...) 2000 s: Images with bolometer arrays (APEX-SZ, SPT, ACT, ASTE...) 2010 s: Continuation of the above Herschel, Planck all-sky survey, ALMA

10 ``A hole in the relic radiation (Zel dovich & Sunyaev 1972) Birkinshaw 1999 Abell 2218, HST image

11 Abell 2163: 30, 140, 218, 270 GHz. V pec = km/s.

12 II. SZ for astrophysics and cosmology cluster physics: - a measure of the cluster's integrated pressure cluster n e T e dl - a measure of the mass of the intracluster gas (baryons) ( => Ω m ). cosmology: - combined with X-ray observations ( cluster n e2 T e 0.5 dl), possibility to determine H 0 ; - possibility to probe peculiar velocities; - cluster SZ surveys: exploit the redshift independence and constrain the cosmological parameters: Ω m, Ω Λ, σ 8, w, w(z); constrain T CMB (z) (= T 0 (1+z)?); constrain the dark matter properties.

13 H 0 X-ray: cluster n e2 T e dl SZ: cluster n e T e dl assuming homogeneity L= cluster dl assuming sphericity linear size + angular size Angular-diameter DISTANCE to the cluster D A (z) with optical redshift H 0

14 Reese et al ΛCDM, H 0 = km/s/mpc

15 H 0 (continued) H 0,SZ 1/ΔT 2 SZdec In the past, H 0,SZ << H 0, Cepheids : H 0,Cepheids = km/s/mpc (Freedmann et al. 2001) H 0,WMAP = km/s/mpc (Spergel et al. 2003). - over-removal of radio point sources due to lensing effect (Loeb & Refregier 1997); H 0 - under-removal of radio point sources: there are more radio point sources in the vicinity of clusters (Cooray et al. '98); H 0 - CMB anistropies on arcmin scale (Cen '97); - clusters are not spherical? (ex: Sulkanen'99, Cooray'00). Latest: H 0,SZ = km/s/mpc (Reese et al. 2002, 30 GHz, OVRO/BIMA, 18 clusters at higher z) H 0,SZ = km/s/mpc (Udomprasert et al. 2004, CBI, 7 low-z clusters).

16 Cosmological parameters Expected constraints for a SZ survey covering 12 square degrees with a mass detection limit M lim =10 14 h -1 M sun From Carlstrom, Holder, Reese 2002, ARAA

17 Cluster number counts from a 4000 square degree surveys (G. Holder, SPT site)

18 Hydrodynamic simulations of the SZ effects (Springel, White, Hernquist 2001) Image of the SZ decrement at 150 GHz, 1 square degree. Possible to distinguish SZE from CMB anisotropies if sufficient angular resolution. SZ dominates the power spectrum on arcmin scales.

19 New SZ catalogs Planck: Beam dilution South Pole Telescope GHz, 1ʼ 224 cluster candidates in 720 deg 2 (out of 2500 deg 2 ), 158 confirmed in opt/nir. Median z = 0.55 Mlim = /h Msun at z > 0.6 ROSAT: Cosmological dimming Reichardt et al. 2012, arxiv: v1 South Pole Telescope, photo from Mc Mahon

20 The Planck Early Science SZ catalog: 189 clusters (the Planck Collaboration 2011, A&A) 2 degrees Planck observation of Abell 2319 at z = (DL = 236 Mpc) Image Credit: ESA / HFI & LFI Consortia Angular resolution of Planck data: 24ʼ to 5ʼ

21 APEX-SZ observations of galaxy clusters Mapping the SZ decrement at 2 mm (150 GHz) Angular resolution of 1ʼ; FOV = 24ʼ Observations between 2005 and clusters + 2 deep fields.

22 APEX-SZ (150 GHz), LABOCA (345 GHz) APEX-SZ: Collaboration North America (UC Berkeley, Colorado, Mc Gill), Germany (MPI Bonn & Munich, U. Bonn), Sweden (Onsala). 324-element spider web TES (transition edge sensors) array built at Berkeley. Needs to be cooled to 0.3 K for optimum operation! APEX-SZ: lambda= 2 mm, FOV = 30, FWHM = 1 Large Programme: about 2 weeks per year since LABOCA: lambda = 870 micron, FOV = 12, FWHM = 20.

23 Example of APEX-SZ 150 GHz maps (M. Nord, PhD thesis)

24 The Bullet Cluster at z = 0.3 Credit: X-ray: NASA/CXC/CfA/M.Markevitch et al.; Optical: NASA/STScI; Magellan/U.Arizona/

25 The Bullet Cluster at z=0.3 SZ increment: SZ decrement: Halverson et al Sigurdarson, Horellou, Johansson et al., in p Star: Bright submm galaxy (50 mjy at 870 micron) at z=2.7 near a critical line of the Bullet Cluster and magnified 100 times (Johansson et al. 2010); its flux at 2 mm is negligible compared to the SZ Elliptical beta-model X-ray-derived prior on beta= , Contours: X-ray Colors: SZ, resolution 27 Substructure in the SZ, offset from the X-ray Central SZ decrement: 771 ± 71 μkcmb; rc = 142 ± 18 ; axial ratio=0.889 ± 0.072, Using ne from Chandra, Tmass weighted = 10.8 ± 0.9 kev

26 Another merging cluster at z= 0.3, Abell 2163 Nord et al. 2009, A&A (PhD thesis in Bonn) APEXSZ + X-ray (white contours) Profile of SZ temperature decrement

27 Abell 2163 at z=0.3, Nord et al The SZ increment at 350 GHz + submm point sources The SZ increment (color) + the APEX-SZ decrement (contours)

28 Abell 2163 at z=0.3, Nord et al The SZE spectrum Fixing temperature gives constraint on peculiar velocity-central Compton parameter

29 Abell 2163 at z=0.3, Nord et al De-projected density & temperature Joint X-ray/SZ analysis: n e SZ: los n e T e dl X-ray: los n e2 Lambda(T e ) dl Assuming spherical symmetry, one can use the Abel transformation T e

30 A relaxed cluster at z=0.15: Abell 2204, Basu et al APEX-SZ + X-ray (white contours) Profile of SZ temperature decrement Blue: raw profile; Red: deconvolved from the transfer function Dashed lines: 5 randomly selected deconvolved profiles

31 Abell 2204 at z=0.15, Basu et al De-projected density & temperature Profile of the enclosed gas mass and the total mass (assuming hydrostatic equilibrium) n e M tot (<R) M gas (<R) T e f gas (<R)

32 Best angular resolution so far: ~10 Green Bank Telescope 90 GHz map of RXJ (the Lighthouse cluster) at z = MUSTANG: 64-pixel bolometer array on 100-m telescope Mason et al ApJ, 8 hours of observing time Left: Red/blue=SZ; Green=HST; contours=projected mass Right: Colors=X-ray; contours= SZ

33 ALMA 1) 50 (32*) x 12 m (the 12m array), baselines from ~200 m to 16 km 2) 12 (9*) x 7 m (the 7m array), fixed compact configuration 2) 4 (2*) x 12 m (total power antennas) * as of June 2012 (Cycle 1). 2) and 3) form the Atacama Compact Array (Iguchi et al PASJ). Prepared for 10 frequency bands from 30 to 860 GHz.

34

35 0.6 Thermal SZ effect, y = 3 x 10 4 and kt e = 6 kev S! [MJy sr 1 ] ! [GHz] Transmission in Chajnantor, PWV = 0.5 mm (blue) and 3 mm (red) ! [GHz]

36 From What is suited for SZ?

37 Band 1 (31-45 GHz): Originally planned. Workshop Science at Q Band held in Manchester in Sep 2009 (mostly to assess the interest in the UK) The Science Case for Building a Band 1 Receiver for ALMA (Johnstone et al arxiv: v2)

38 Slide fromsteve Myers

39 ALMA Band 1 simulation of the SZ from bubbles in Perseus (Scaife & Grainge 2010 arxiv ) Model Antennas + uv plane

40 Left: noise-free map. Right: after 32 hours of integration with ALMA AMI (Arcminute MicroKelvin Imager) uv plane and 15 GHz map

41 Summary SZ observations require - sensitivity to extended emission (a 0.5 to a few arcmin) - an angular resolution of a few arcsec. Only the lower frequency bands of the 12-m array (in its most compact configuration) and of the ACA are suitable. Sensitivity of the ACA (?) The higher frequency bands are useful to study point-source contamination. Complementary: Bolometer arrays on single-dish. Observe substructure in clusters.