Observing the Sunyaev-Zel

Transcription

1 Observing the Sunyaev-Zel Zel dovich Effect Matt Dobbs McGill University

2 The Sunyaev-Zel Zel dovich Effect CMB photons are used to backlight structure in the universe. (slide adapted from NASA publicity figure) December 5,

3 Galaxy Clusters Abell 1689 Largest gravitationally collapsed structures largest clusters derived from scales that are almost linear their history traces out interplay between dark energy and matter through cosmic time. ICM: Hot diffuse plasma is bulk of cluster mass Easily seen in SZ and x-ray T e 10 kev K Cluster abundance and evolution are critically dependent on cosmology. Growth based dark energy test (complement to distance based SN tests) Chandra x-ray image of cluster Matt.Dobbs@McGill.ca,, December 5,

4 The Sunyaev-Zel Zel dovich Effect BIMA Diabolo SuZIE FREQUENCY FREQUENCY 1-2% of CMB photons traversing galaxy clusters are inverse Compton scattered to higher energy. December 5,

5 Galaxy cluster searches Carlstrom et al., (BIMA) SZ observations do not fade away over large distances. Unbiased tool for selecting clusters. December 5,

6 Sunyaev-Zel Zel dovich Effect Single Clusters Measure of integrated pressure (total thermal energy) Peculiar velocities at high z Distances, H o, H(z) Cluster gas mass fractions, structure, etc. ΔT T SZ CMB n T dl e e 1 2 S X = ne Λ 4 4π ( 1+ z) ee (compare to x-ray surface brightness) dl Cluster Surveys Exploit SZ redshift independence Measure growth of structure constrain Dark Energy S D ΔT A SZE 1 ( z) 2 dω n e T e dv Matt.Dobbs@McGill.ca,, December 5,

7 SZ Cosmology Example Number count vs. redshift is very sensitive to dark energy and total matter distribution. Simulation by M. White 10 sq. degree Projections for 4000 sq deg SPT by Gil Holder Assuming (optimistic!) σ 8 =0.9 Matt.Dobbs@McGill.ca,, December 5,

8 SZ/CMB Power Spectrum Readhead et al. ApJ. 609 (2004) C l (SZ) σ 8 7 e.g., Komatsu & Seljak astro-ph/ Matt.Dobbs@McGill.ca,, December 5,

9 SZ for Cartography Circa experiments use dozens of detectors Capable of pointed observations at known clusters SZ Forte is (relatively) unbiased selection function- Blind cluster surveys require an order of magnitude increase in sensitivity, or factor 100 in detectors. December 5,

10 (ground based) SZ Instruments (ground based) Existing/Past: Interferometers: Ryle, OVRO/BIMA, CBI (I,II), VSA, Amiba Single dish radio: OVRO 40m, OVRO 5m, Nobeyama 45m, OCRA Single dish bolometers: SuZIE (I,II,II) and Bolocam on CSO 10m, Diabolo on IRAM 30m, SEST 15m, SCUBA on JCMT 15m, MITO 2.6 m, ACBAR, ASTE 10m, MUSTANG on NRAO GBT 100 m New Dedicated SZ Instruments Arcminute Microkelvin Imager (15 GHz, ten 3.6m interferometer) The Sunyaev Zel dovich Array (30,90 GHz, eight 3.5m interferometer) APEX-SZ (12m, 320 pixel) The South Pole Telescope (10m, 1000 pixel) Atacama Cosmology Telescope (6m, 3000 pixel) Matt.Dobbs@McGill.ca,, December 5,

11 BIMA / OVRO Owen s Valley Radio Observatory Imaging of known clusters > 60 SZ clusters observed correlation with Chandra x-x ray for 38 clusters Color: Chandra x-ray Contours: SZ S/N from BIMA Radial profile of x-ray surface brightness Line: best double-β model fit. Radial profile of x-ray plasma temperatures Line: best fit hydrostatic equil. model FWHM of the SZE synthesized beam Bonamente (BIMA +Chandra), ApJ 647 (2006) 25. Matt.Dobbs@McGill.ca,, December 5,

12 Hubble Diagram from SZ + X-rayX ΔT SZ from 38 OVRO/BIMA Clusters, 0.14<z<0.89 S X, T e from Chandra X-ray X data H 0 =76.9 ±4 ±9 km s -1 Mpc -1 (assumes Λ CDM ) Relatively insensitive to cluster radial profile model (+- 3) Weakly sensitive of Ω M, Ω Λ. Agrees well with nearby universe measurements from Hubble Key Project. Bonamente et. al., ApJ 647 (2006) 25. D A ΔT S 2 CMB X T 2 e Λ ee Udompraset et al. (CBI), 2004 (not used in fit) Matt.Dobbs@McGill.ca,, December 5,

13 Gas Mass Fractions from BIMA/OVRO Derived from 38 clusters, 0.14 < z < 0.89 Significant scatter, but no evidence for redshift trend. Triangles=cool-core clusters, squares=noncool-core clusters (assumes ΛCDM) LaRoque et al. (BIMA/OVRO), Astro J. 652 (2006) 917. f gas f gas Matt.Dobbs@McGill.ca,, December 5,

14 Eight 3.5m telescopes 30 & 90 GHz SZA at Owens Valley U.Chicago/KICP, Caltech, Columbia, NASA/MSFC X-ray selected cluster obs 6 sq degree blind survey 2008 CARMA 23- element array: Merge BIMA + OVRO + SZA Detailed SZ imaging First SZA images Muchovej et. al., ApJ 663 (2007) 708 (astro-ph: ). z = 0.17 z = 0.17 z = 0.69 z = 0.89 z = 1.03 Matt.Dobbs@McGill.ca,, December 5,

15 Test of SZA survey on Cl pointing SZA mosaic 4.8 arcminute separation Median rms 0.31mJy/beam Bright radio source at > 60 sigma Two Clusters Detected Cl M ~ 1.3 x 10^15 M_solar (Hughes et al., 1995, ApJ448:L93) RXJ M ~ 5 x 10^14 M_solar (Hughes & Birkinshaw, 1998, ApJ 497:645) Loh et. al, in prep Matt.Dobbs@McGill.ca,, December 5,

16 SZA High-z z Clusters Above: x-ray x in color, SZ contours Right: same cluster fields, before removing point sources ν I31 GHz 31GHz α Spectral index from SZA bands alone Muchovej et. al. (SZA), Astro J., 663 (2007) 708. Matt.Dobbs@McGill.ca,, December 5,

17 SZA blind SZ-survey ~ 6 square degrees complete (Muchovej in prep, Ph.D. Thesis) radio source contamination is big issue at 30 GHz both point like and extended sources present SZA has 90 GHz follow-up, 5 & 8 GHz from VLA. Matt.Dobbs@McGill.ca,, December 5,

18 Enabling Technology for SZ Surveys big bolometer arrays readout multiplexing cooling without expendable cryogens

19 Coherent Amplification vs. Bolometers Projected Sensitivity 2010 Bolometers HEMT 250 S ensitivity [ μ K s ] Quantum Noise Limit Frequency [ GHz ] Source: Weiss DOE/NSF/NASA CMB Taskforce, Table 7.2 Matt.Dobbs@McGill.ca,, December 5,

20 Transition Edge Sensor Bolometer Incident Radiation Absorber C Thermometer T bolo =T bath + P/G Thermal Bath T bath G Thermal Conductivity Voltage biased in electro- thermal feedback Al These detectors fabricated at UC Berkeley by Erik Shirokoff, Sherry Cho, Jared Mehl Ti 4 mm Matt.Dobbs@McGill.ca,, December 5,

21 Example: SPT Bolometer Array 180 mm; ~1 degree on sky Built at UC Berkeley 150 GHz 90 GHz 150 GHz 150 GHz 5 Apex-SZ proto 220 GHz 90 GHz 160 possible channels on each wedge, 8x multiplex Transition Edge Sensor bolometers with Tc ~500mK Spiderweb Bolometers Al/Ti TES

22 ACT MBAC Array 32 x 32 array of Goddard pop- up bolometers Close packed Niemack et al., to appear in J. Low Temp. Phys. Matt.Dobbs@McGill.ca,, December 5,

23 Readout Multiplexing Time-domain multiplexer NIST / UBC for ACT, (Clover, Spider, SCUBA-II, etc.) SQUID Output SQUID Output Frequency-domain multiplexer LBNL / Berkeley / McGill for APEX, SPT, (EBEX, ) Pulse Height time

24 Readout Multiplexing Time-domain multiplexer NIST / UBC for ACT, (Clover, Spider, SCUBA-II, etc.) Frequency-domain multiplexer LBNL/Berkeley/McGill for APEX, SPT, (EBEX, )

25 Cooling without Expendable Cryogens Mechanical cooling for bolometer experiments is challenging microphonic pickup (vibrations) moving parts at 4K New generation of experiments using Pulse Tube Coolers Piston in cold head is a shock-wave of helium gas Eliminates need for cryogens, allowing experiments to run long term at remote locations. (APEX, SPT, ACT all use PTCs) APEX-SZ Camera is shown mounted in cabin with pulse tube lines & ballasts visible. Matt.Dobbs@McGill.ca,, December 5,

26 December 5,

27 APEX-SZ U.C. Berkeley/LBNL, Max Planck IfR, Bonn, Boulder, Cardiff, McGill 12m ALMA prototype 1 resolution 320 bolometer array 150 GHz TES Frequency multiplexed readout pulse tube cooler w/ 3He sorption fridge First light, Dec 2005

28 APEX-SZ Beams Mapping mars, without applying pixel offsets Typically ~260/320 pixels active December 5,

29 APEX-SZ Cluster Image Examples Chandra x-ray x surface brightness superimposed Bullet Cluster Abell 3404 Matt.Dobbs@McGill.ca,, December 5,

30 Atacama Cosmology Telescope December 5,

31 Atacama Cosmology Telescope (ACT) 6m off-axis dish 3000 bolometers: 145, 220, 265 GHz fabbed at Goddard 1.7 arcminute resolution Deploying near ALMA site 1st light achieved June 2007 with 32 detector CCAM prototype receiver. (new!) MBAC 1024 pixel camera operating now at 145 GHz (typically 900 detectors live) Plan to install 3 color (145,220, 265 GHz) in May st Light Jupiter With 32 pixel CCAM Cardiff Columbia CUNY Drexel Haverford NASA/GSFC Penn Princeton Rutgers Univ. de Catolica UMASS Matt.Dobbs@McGill.ca,, December 5,

32 The South Pole Telescope Last flight out - austral Summer 07/08 Photo Credit Steffen Richter Matt.Dobbs@McGill.ca,, December 5,

33 The South Pole Telescope 960 TES Bolometers frequency multiplexed readout pulse tube cooler 90, 150, 220 GHz bands 1 arcmin resolution at 2mm 20 μm RMS surface over 10m cold (10 K) secondary mirror 1 degree FOV, 1 pointing SZE and CMB Anisotropy 4000 sq deg SZE survey deep CMB anisotropy fields deep CMB Polarization fields First light achieved Feb 16, 2007 Matt.Dobbs@McGill.ca,, December 5,

34 Deployment: Nov 06 - Feb 07 Matt.Dobbs@McGill.ca,, December 5,

35 SPT Optics and radiometer 250mK 10K December 5,

36 First Light and Test Observations First light with scans across Jupiter, Feb ! Scanning across Mars, without correcting for pixel offsets ~400 detectors working on first days. December 5,

37 SPT: First Cluster Observation (AS1063) April 7, 2007 (Combined 90 and 150 GHz detectors) December 5,

38 Beginning of SPT Survey BCS Field Co-added 150 GHz Maps, smoothed to 2 SUM DIFFERENCE Matt.Dobbs@McGill.ca,, December 5,

39 Challenges for SZ Cartography (just a two examples )

40 Scaling Relations Key challenge for SZ surveys how to relate observations (Y SZ ) to a quantity that is well predicted by theory (e.g. total cluster mass) If gravitational processes dominate cluster evolution, a self-similar similar scaling gives a simple relation Y SZ D 2 A f gas M 5/3 TOT E(z) 2/3 Bonamente et al. (BIMA), astro-ph/ Numerical sim on large scales, Y SZ should be a good proxy for M TOTAL. Agrees best with simulations that include radiative cooling, star formation, and feedback. Shaw et al., astro-ph reduce scatter by e.g. using Y(R 500 ) to infer M TOT (R 200 ) Figure assumes ΛCDM. Y D 2 A E(z)-2/3 Simple Model All Clusters 0.14<z< <z<0.89 SLOPE ± ± ± E 2 3 ( z) = ΩM (1 + z) + ΩΛ + Ωk (1 + z ) 2 M TOT Matt.Dobbs@McGill.ca,, December 5,

41 Scaling Relations Y SZ D 2 A f gas T 5/ 2 e E( z) 1 Bonamente et al. (BIMA), astro-ph/ Y D 2 A E(z) Simple Model All Clusters 0.14<z< <z<0.89 SLOPE ± ± ±0.30 kt e (kev) Matt.Dobbs@McGill.ca,, December 5,

42 Radio Point Source Contamination Correlated with clusters, obscuring signal. If you just extrapolate the known 30 GHz sources to 150 with the same frequency relation, you re in trouble. But typically there s s a break point. Tools: SZA GHz First 150 GHz maps expected soon from APEX, SPT, ACT Combine with existing radio surveys A piece of the 30 GHz sky from SZA (from Muchovej in prep, Ph.D. Thesis) A (much bigger) piece of the 150 GHz sky from SPT Matt.Dobbs@McGill.ca,, December 5,

43 Summary SZ redshift independent cluster observations Samples of several dozen clusters (e.g. BIMA, SZA) Consistent picture emerging from x-ray x / SZ Cluster surveys exploit the redshift independence to measure the growth of structure through cosmic time. Enabling technology: large bolometer array cameras Next generation experiments (e.g. ACT, SPT) have begun operations s and producing first images. First Light Feb 07 (SPT), May 07 (ACT) Stay tuned Still some challenges to conquer Does radio spectrum break soon enough? Scaling relations and calibration of the Y SZ M TOT relation. SZ imagine machines such as SZA will have a lot to say on this in next year. Matt.Dobbs@McGill.ca,, December 5,