2. The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy Observatory Socorro, NM

3. The Cosmic Background Imager – ATCA, 19 Oct 2004 3 The Cosmic Background Imager A collaboration between –Caltech (A.C.S. Readhead PI, S. Padin PS.) –NRAO –CITA –Universidad de Chile –University of Chicago With participants also from –U.C. Berkeley, U. Alberta, ESO, IAP-Paris, NASA-MSFC, Universidad de Concepción Funded by –National Science Foundation, the California Institute of Technology, Maxine and Ronald Linde, Cecil and Sally Drinkward, Barbara and Stanley Rawn Jr., the Kavli Institute, and the Canadian Institute for Advanced Research

4. The Cosmic Background Imager – ATCA, 19 Oct 2004 4 The CMB Landscape

5. The Cosmic Background Imager – ATCA, 19 Oct 2004 5 The Cosmic Microwave Background Discovered 1965 ( Penzias & Wilson ) –2.7 K blackbody –Isotropic –Relic of hot “big bang” –3 mK dipole (Doppler) COBE 1992 –Blackbody 2.725 K –Anisotropies ≤10 -5

6. The Cosmic Background Imager – ATCA, 19 Oct 2004 6 The Expanding Universe space is expanding with time –measured by scale factor a –or “redshift” z ~ inverse scale factor –a = 1 now; a = 0 at “Big Bang” –all linear scales (like wavelengths) expand as a all else follows from this expansion! –radiation temperature T scales with 1/a –matter density 1/a 3 ; radiation density 1/a 4 rate of expansion = H “Hubble constant” –controlled by matter and radiation density of Universe –H -1 “expansion time”, currently ~13 Gyr –expansion should be decelerating with time accelerating !?  “dark energy” with negative pressure! –speed of light c limits “horizon” of causality isotropy of Universe suggests early phase of “inflation”

7. The Cosmic Background Imager – ATCA, 19 Oct 2004 7 Thermal History of the Universe Courtesy Wayne Hu – http://background.uchicago.edu “First 3 minutes”: very hot (10 million °K) like interior of Sun nucleosynthesis! After “recombination”: cooler, transparent, neutral hydrogen gas Before “recombination”: hot (3000°K) like surface of Sun opaque, ionized plasma “Surface of last scattering” T≈3000°K z≈1000 THIS IS WHAT WE SEE AS THE CMB!

8. The Cosmic Background Imager – ATCA, 19 Oct 2004 8 Matter History of the Universe we see “structure” in Universe now –density fluctuations ~1 on 10 Mpc scales –clusters of galaxies! must have been smaller in past (fluctuations grow) –in expanding Universe growth is approximately linear –CMB @ a = 0.001  density fluctuations ~ 0.001 NOTE: density higher in past, but density fluctuations smaller! Courtesy Wayne Hu – http://background.uchicago.edu

9. The Cosmic Background Imager – ATCA, 19 Oct 2004 9 Angular Power Spectrum brightness fluctuations on surface of last scattering –due to the small (~0.1%) density variations –gravity causes flows (velocities) –radiation pressure resists compression  bounces –acoustic waves! Fourier analysis –break angular ripple pattern into sine & cosine –look for power on particular angular frequencies –like a cosmic Spectrum Analyzer! –acoustic waves + expansion  fundamental + overtones fundamental = scale of first compression since horizon crossing scale set by sound crossing time at last scattering

10. The Cosmic Background Imager – ATCA, 19 Oct 2004 10 CMB Acoustic Peaks Compression driven by gravity, resisted by radiation ≈ “j ladder” series of harmonics + projection corrections peaks: ~  l s j troughs: ~  l s (j ± ½)

11. The Cosmic Background Imager – ATCA, 19 Oct 2004 11 CMB Primary Anisotropies Low l (<100) –primordial power spectrum (+ S-W, tensors, etc.) Intermediate l (100-2000) –dominated by acoustic peak structure –position of peak related to sound crossing angular scale  angular diameter distance to last scattering –peak heights controlled by baryons & dark matter, etc. –damping tail roll-off with  Large l (2000-5000+) –realm of the secondaries (e.g. SZE) Courtesy Wayne Hu – http://background.uchicago.edu

12. The Cosmic Background Imager – ATCA, 19 Oct 2004 12 only transverse polarization can be transmitted on scattering! CMB Polarization Due to quadrupolar intensity field at scattering Courtesy Wayne Hu – http://background.uchicago.edu NOTE: polarization maximum when velocity is maximum (out of phase with compression maxima)

13. The Cosmic Background Imager – ATCA, 19 Oct 2004 13 CMB Polarization E & B modes: translation invariance –E (even parity, “gradient”) from scalar density fluctuations  predominant! –B (odd parity, “curl”) from gravity wave tensor modes, or secondaries Courtesy Wayne Hu – http://background.uchicago.edu

14. The Cosmic Background Imager – ATCA, 19 Oct 2004 14 Polarization Power Spectrum Hu & Dodelson ARAA 2002 Planck “error boxes” Note: polarization peaks out of phase w.r.t. intensity peaks

15. The Cosmic Background Imager – ATCA, 19 Oct 2004 15 The Gold Standard: WMAP + “ext” WMAP ACBAR

16. The Cosmic Background Imager – ATCA, 19 Oct 2004 16 The Cosmic Background Imager

17. The Cosmic Background Imager – ATCA, 19 Oct 2004 17 The Instrument 13 90-cm Cassegrain antennas –78 baselines 6-meter platform –Baselines 1m – 5.51m 10 1 GHz channels 26-36 GHz –HEMT amplifiers (NRAO) –Cryogenic 6K, Tsys 20 K Single polarization (R or L) –Polarizers from U. Chicago Analog correlators –780 complex correlators Field-of-view 44 arcmin –Image noise 4 mJy/bm 900s Resolution 4.5 – 10 arcmin

18. The Cosmic Background Imager – ATCA, 19 Oct 2004 18 CMB Interferometers CMB issues: –Extremely low surface brightness fluctuations < 50  K Large monopole signal 3K, dipole 3 mK Polarization less than 10%  signal < 5  K –No compact features, approximately Gaussian random field –Foregrounds both galactic & extragalactic Traditional direct imaging –Differential horns or focal plane arrays Interferometry –Inherent differencing (fringe pattern), filtered images –Works in spatial Fourier domain –Element-based errors vs. baseline-based signals –Limited by need to correlate pairs of elements –Sensitivity requires compact arrays

19. The Cosmic Background Imager – ATCA, 19 Oct 2004 19 Traditional Inteferometer – The VLA The Very Large Array (VLA) –27 elements, 25m antennas, 74 MHz – 50 GHz (in bands) –independent elements  Earth rotation synthesis

20. The Cosmic Background Imager – ATCA, 19 Oct 2004 20 CMB Interferometer – The CBI The Cosmic Background Imager (CBI) –13 elements, 90 cm antennas, 26-36 GHz (10 channels) –fixed to 3-axis platform  telescope rotation synthesis!

21. The Cosmic Background Imager – ATCA, 19 Oct 2004 21 Other CMB Interferometers: DASI, VSA DASI @ South Pole VSA @ Tenerife

22. The Cosmic Background Imager – ATCA, 19 Oct 2004 22 CBI milestones 1980’s –1984 OVRO 40m single-dish work (20 GHz maser Rx!) –1987 genesis of idea for CMB interferometer 1990’s –1992 OVRO systems converted to HEMTs –1994 NSF proposal (funded 1995) –1998 assembled and tested at Caltech –1999 August shipped to Chile –1999 November Chile first “light” 2000+ –2000 January routine observing begins –2001 first paper; 2002 first year results; 2003 2yrs; 2004 pol –2002 continued NSF funding to end of 2004 –exploring funding prospects to operate until end of 2005

23. The Cosmic Background Imager – ATCA, 19 Oct 2004 23 CBI Operations Telescope at high site in Andes –16000 ft (~5000 m) oxygen an issue! –Located on Science Preserve, co-located with ALMA –Now also ATSE (Japan) and APEX (Germany) –Future home of ACT, AT-25m, others? –Controlled on-site, oxygenated quarters in containers Operations base in San Pedro de Atacama –population ~900 (but lots of tourists, and now astronomers!) –“low” elevation 8000 ft. (2500m) –about 1 ½ hours to site, good highway access

24. The Cosmic Background Imager – ATCA, 19 Oct 2004 24 CBI Site – Northern Chilean Andes Elevation 16500 ft.!

25. The Cosmic Background Imager – ATCA, 19 Oct 2004 25 CBI Instrumentation

26. The Cosmic Background Imager – ATCA, 19 Oct 2004 26 CBI in Chile

27. The Cosmic Background Imager – ATCA, 19 Oct 2004 27 The CBI Adventure… sunset

28. The Cosmic Background Imager – ATCA, 19 Oct 2004 28 The CBI Adventure… Steve Padin wearing the cannular oxygen system –because you never know when you need to dig the truck out!

29. The Cosmic Background Imager – ATCA, 19 Oct 2004 29 The CBI Adventure… the snow in Chile falls mainly on the road! 2 winters/yr

30. The Cosmic Background Imager – ATCA, 19 Oct 2004 30 The CBI Adventure… Volcan Lascar (~30 km away) erupts in 2001

31. The Cosmic Background Imager – ATCA, 19 Oct 2004 31 CMB Interferometry

32. The Cosmic Background Imager – ATCA, 19 Oct 2004 32 The CMB and Interferometry The sky can be uniquely described by spherical harmonics –CMB power spectra are described by multipole l For small (sub-radian) scales the spherical harmonics can be approximated by Fourier modes –The conjugate variables are (u,v) as in radio interferometry –The uv radius is given by |u| = l / 2  An interferometer naturally measures the transform of the sky intensity in l space convolved with aperture

33. The Cosmic Background Imager – ATCA, 19 Oct 2004 33 The uv plane The projected baseline length gives the angular scale multipole: l = 2  B/λ = 2  u ij | shortest CBI baseline: central hole 10cm

34. The Cosmic Background Imager – ATCA, 19 Oct 2004 34 CBI Beam and uv coverage Over-sampled uv-plane –excellent PSF –allows fast gridded method (Myers et al. 2000) primary beam transform: θ pri = 45' Δ l ≈ 4D/λ ≈ 360 mosaic beam transform: θ mos = n×45' Δ l ≈ 4D/nλ

35. The Cosmic Background Imager – ATCA, 19 Oct 2004 35 Mosaicing in the uv plane offset & add phase gradients

36. The Cosmic Background Imager – ATCA, 19 Oct 2004 36 Polarization of radiation Electromagnetic Waves –Maxwell: 2 independent linearly polarized waves –3 parameters (E 1,E 2,  )  polarization ellipse Rohlfs & Wilson

37. The Cosmic Background Imager – ATCA, 19 Oct 2004 37 Polarization of radiation Electromagnetic Waves –Maxwell: 2 independent linearly polarized waves –3 parameters (E 1,E 2,  )  polarization ellipse Stokes parameters (Poincare Sphere): –intensity I (Poynting flux) I 2 = E 1 2 + E 2 2 –linear polarization Q,U (m I) 2 = Q 2 + U 2 –circular polarization V (v I) 2 = V 2 Rohlfs & Wilson The Poincare Sphere

38. The Cosmic Background Imager – ATCA, 19 Oct 2004 38 Polarization of radiation Electromagnetic Waves –Maxwell: 2 independent linearly polarized waves –3 parameters (E 1,E 2,  )  polarization ellipse Stokes parameters (Poincare Sphere): –intensity I (Poynting flux) I 2 = E 1 2 + E 2 2 –linear polarization Q,U (m I) 2 = Q 2 + U 2 –circular polarization V (v I) 2 = V 2 Coordinate system dependence: –I independent –V depends on choice of “handedness” V > 0 for RCP –Q,U depend on choice of “North” (plus handedness) Q “points” North, U 45 toward East EVPA  = ½ tan -1 (U/Q) (North through East)

39. The Cosmic Background Imager – ATCA, 19 Oct 2004 39 Polarization – Stokes parameters CBI receivers can observe either RCP or LCP –cross-correlate RR, RL, LR, or LL from antenna pair CMB intensity I plus linear polarization Q,U important –CMB not circularly polarized, ignore V (RR = LL = I) –parallel hands RR, LL measure intensity I –cross-hands RL, LR measure complex polarization P=Q+iU R-L phase gives electric vector position angle  = ½ tan -1 (U/Q) rotates with parallactic angle of detector  on sky

40. The Cosmic Background Imager – ATCA, 19 Oct 2004 40 Polarization Interferometry Parallel-hand & Cross-hand correlations –for antenna pair i, j and frequency channel : –where kernel P is the aperture cross-correlation function –and  the baseline parallactic angle (w.r.t. deck angle 0°)

41. The Cosmic Background Imager – ATCA, 19 Oct 2004 41 E and B modes A useful decomposition of the polarization signal is into “gradient” and “curl modes” – E and B: E & B response smeared by phase variation over aperture A interferometer “directly” measures (Fourier transforms of) E & B!

42. The Cosmic Background Imager – ATCA, 19 Oct 2004 42 Power Spectrum of CMB Statistics of CMB field –Gaussian random field – Fourier modes independent –described by angular power spectrum –4 non-zero polarization covariances: TT,EE,BB,TE –EB, TB should be zero due to parity (but check on systematics)

43. The Cosmic Background Imager – ATCA, 19 Oct 2004 43 Errors: leakage instrumental polarization –“leaks” L into R, R into L (level ~1%-2%) –e.g. R obs = R + d L measure on bright source –use standard data analysis to determine d-terms to first order: –TT unaffected –TT leaks into TE & TB –TE & TB leak into EE, BB, EB include in correlation analysis –just complicates covariance matrix calculation

44. The Cosmic Background Imager – ATCA, 19 Oct 2004 44 CBI Polarization New Results! Brought to you by: A. Readhead, T. Pearson, C. Dickinson (Caltech) S. Myers, B. Mason (NRAO), J. Sievers, C. Contaldi, J.R. Bond (CITA) P. Altamirano, R. Bustos, C. Achermann (Chile) & the CBI team! astro-ph/0409569 (24 Sep 2004)

45. The Cosmic Background Imager – ATCA, 19 Oct 2004 45 CBI 2000+2001, WMAP, ACBAR, BIMA Readhead et al. ApJ, 609, 498 (2004) astro-ph/0402359 SZESecondary CMBPrimary

46. The Cosmic Background Imager – ATCA, 19 Oct 2004 46 2002 DASI & 2003 WMAP Polarization Courtesy Wayne Hu – http://background.uchicago.edu Carlstrom et al. 2003 astro-ph/0308478

47. The Cosmic Background Imager – ATCA, 19 Oct 2004 47 New: DASI 3-year polarization results! 16Sep04!Leitch et al. 2004 (astro-ph/0409357) 16Sep04! –EE 6.3 σ –TE 2.9 σ –consistent w/ WMAP+ext model –BB consistent with zero –no foregrounds (yet)

48. The Cosmic Background Imager – ATCA, 19 Oct 2004 48 CBI Current Polarization Data Observing since Sep 2002 (processed to May 2004) –compact configuration, maximum sensitivity

49. The Cosmic Background Imager – ATCA, 19 Oct 2004 49 CBI Polarization Upgrade CBI instrumentation –Use quarter-wave devices for linear to circular conversion –Single amplifier per receiver: either R or L only per element 2000 Observations –One antenna cross-polarized in 2000 (Cartwright thesis) –Only 12 cross-polarized baselines (cf. 66 parallel hand) –Original polarizers had 5%-15% leakage –Deep fields, upper limit ~8  K 2002 Upgrade –Upgrade in 2002 using DASI polarizers (J. Kovac) –Observing with 7R + 6L starting Sep 2002 –Raster scans for mosaicing and efficiency –New TRW InP HEMTs from NRAO

50. The Cosmic Background Imager – ATCA, 19 Oct 2004 50 Calibration from WMAP Jupiter Old uncertainty: 5% 2.7% high vs. WMAP Jupiter New uncertainty: 1.3% Ultimate goal: 0.5%

51. The Cosmic Background Imager – ATCA, 19 Oct 2004 51 CBI Polarization Mosaics Four mosaics  = 02 h, 08 h, 14 h, 20 h at  = 0° –02h, 08h, 14h 6 x 6 fields, 20h deep strip 6 fields [45’ centers]

52. The Cosmic Background Imager – ATCA, 19 Oct 2004 52 CBI observational issues short (100 ) baselines –can see the Sun if it is up  observe at night only –can see the Moon within 60  observe 60 from Moon CMB fields on equator  observe SZE clusters when blocked by moon! –far-field at 100m  atmosphere imaged along with CMB Atacama site very good, little data lost to clouds plus platform (no delay tracking) –need to reject common mode signals (which correlate) 120db isolation between antennas (shields + phase shifters) –strong (>1 Jy) ground signal (polarized) orientation dependence (see mountains around site!) removed by differencing (or scan projection)

53. The Cosmic Background Imager – ATCA, 19 Oct 2004 53 Calibration and Foreground Removal Ground emission removal –Strong on short baselines, depends on orientation –Differencing between lead/trail field pairs (8m in RA=2deg) Use scanning for 2002-2003 polarization observations

54. The Cosmic Background Imager – ATCA, 19 Oct 2004 54 Before ground subtraction: I, Q, U dirty mosaic images:

55. The Cosmic Background Imager – ATCA, 19 Oct 2004 55 After ground subtraction: I, Q, U dirty mosaic images (9 m differences):

56. The Cosmic Background Imager – ATCA, 19 Oct 2004 56 Foregrounds – Sources Foreground radio sources –Predominant on long baselines –Located in NVSS at 1.4 GHz, VLA 8.4 GHz –Measured at 30 GHz with OVRO 40m new 30 GHz GBT receiver available late 2004

57. The Cosmic Background Imager – ATCA, 19 Oct 2004 57 Foregrounds – Sources Foreground radio sources –Predominant on long baselines –Located in NVSS at 1.4 GHz, VLA 8.4 GHz –Measured at 30 GHz with OVRO 40m new 30 GHz GBT receiver available late 2004 “Projected” out in power spectrum analysis –list of NVSS sources (extrapolation to 30 GHz unknown) –3727 total for TT  many modes lost, sensitivity reduced –use 557 for polarization (bright OVRO + NVSS 3  pol) –need 30 GHz GBT measurements to know brightest

58. The Cosmic Background Imager – ATCA, 19 Oct 2004 58 CBI Calibration & Foregrounds Calibration on TauA (Crab) & Jupiter –use TauA to calibrate R-L phase (26 Jy of polarized flux!) –secondary calibrators also (3C274, Mars, Saturn, …) Scan subtraction/projection –observe scan of 6 fields, 3m apart = 45’ –lose only 1/6 data to differencing (cf. ½ previously) Point source projection –list of NVSS sources (extrapolation to 30 GHz unknown) –3727 total for TT  many modes lost, sensitivity reduced –use 557 for polarization (bright OVRO + NVSS 3  pol) –need 30 GHz GBT measurements to know brightest

59. The Cosmic Background Imager – ATCA, 19 Oct 2004 59 CBI Diffuse Foregrounds Mid-High galactic latitudes (25°– 50° vs. 60° DASI) Galactic cosmic rays (synchrotron emission) –from WMAP template (Bennett et al. 2003) –mean, rms, max not significantly worse than in DASI fields –except 14 h field (in North Polar Spur) 50% worse Rely on CBI frequency leverage (26-36 GHz) –synchrotron spectrum -2.7 vs. thermal –also l 2 vs. CMB in power spectrum

60. The Cosmic Background Imager – ATCA, 19 Oct 2004 60 CBI & DASI Fields galactic projection – image WMAP “synchrotron” (Bennett et al. 2003)

61. The Cosmic Background Imager – ATCA, 19 Oct 2004 61 New: CBI Polarization Power Spectra 7-band fits (  l = 150 for 600< l <1200) bin positions well-matched to peaks & valleys offset bins run also narrower bins (  l = 75) – scatter from F -1 bin resolution limited by signal-to-noise

62. The Cosmic Background Imager – ATCA, 19 Oct 2004 62 Data Tests Test robustness to systematic effects, such as: –instrumental effects (amplitude, polarization) –foregrounds (synchrotron, free-free, dust) Numerous  2 and noise tests –few discrepant days found  no difference to results Conduct series of splits and “jack-knife” tests, e.g.: –primary vs. secondary calibrators (calibration consistency) –first half vs. second half of data (time-variable instrument) –“jack-knife” on antennas (bad single antenna) –“jack-knife” on fields (bad single field) –high vs. low frequency channels (e.g. foregrounds) NO SIGNIFICANT DEVIATIONS FOUND!

63. The Cosmic Background Imager – ATCA, 19 Oct 2004 63 Shaped C l fits Use WMAP’03 best-fit Cl in signal covariance matrix –bandpower is then relative to fiducial power spectrum –compute for single band encompassing all l s Results for CBI data (sources projected from TT only) –q B = 1.22 ± 0.21 (68%) –EE likelihood vs. zero : equivalent significance 8.9 σ Conservative - project subset out in polarization also –q B = 1.18 ± 0.24 (68%) –significance 7.0 σ

64. The Cosmic Background Imager – ATCA, 19 Oct 2004 64  k  b  cdm n s    m h  CBI Mosaic Observation 2.5 o THE PILLARS OF INFLATION 1) super-horizon (>2°) anisotropies 2) acoustic peaks and harmonic pattern (~1°) 3) damping tail (<10') 4) Gaussianity 5) secondary anisotropies 6) polarization 7) gravity waves But … to do this we need to measure a signal which is 3x10 7 times weaker than the typical noise! geometry baryonic fraction cold dark matter primordial dark energy matter fraction Hubble Constant optical depth of the protons, neutrons not protons and fluctuation negative press- size & age of the to last scatt- universe neutrons spectrum ure of space universe ering of cmb The CBI measures these fundamental constants of cosmology:

65. The Cosmic Background Imager – ATCA, 19 Oct 2004 65 New: CBI Polarization Parameters use fine bins (  l = 75) + window functions (  l = 25) cosmological models vs. data using MCMC –modified COSMOMC (Lewis & Bridle 2002) Include: –WMAP TT & TE –WMAP + CBI’04 TT & EE (Readhead et al. 2004b = new!) –WMAP + CBI’04 TT & EE l 1000 (Readhead et al. 2004a) [overlaps ‘04]

66. The Cosmic Background Imager – ATCA, 19 Oct 2004 66 New: CBI Polarization Parameters use fine bins (  l = 75) + window functions (  l = 25) Include: –WMAP TT & TE –CBI 2004 Pol TT, EE (Readhead et al. 2004b = new) –CBI 2001-2002 TT (Readhead et al. 2004a) NOTE: parameter constraints dominated by higher precision TT from CBI 2001-2002 data!

67. The Cosmic Background Imager – ATCA, 19 Oct 2004 67 New: CBI Polarization Parameters NOTE: parameter constraints dominated by higher precision TT from CBI 2001-2002 (and to lesser extent 2002-2004) data! To discern what polarization data is adding, will need to be more subtle…

68. The Cosmic Background Imager – ATCA, 19 Oct 2004 68 Cosmology from EE Polarization Standard Cosmological Model ™ –EE “predictable” from TT –constraints dominated by more precise TT measurements Beyond the Standard Model –derive key parameters from EE alone – check consistency –add new ingredients (e.g. isocurvature)

69. The Cosmic Background Imager – ATCA, 19 Oct 2004 69 Example: Acoustic Overtone Pattern Sound crossing angular size at photon decoupling –fiducial model WMAP+ext : θ 0 = 1.046 WMAP WMAP+CBI’04 WMAP+CBI’04+CBI’02 grand unified: θ = 1.044±0.005 θ/θ 0 =0.998±0.005 θ/θ 0 = 0.998±0.005(WMAP+CBI’04+CBI’02)

70. The Cosmic Background Imager – ATCA, 19 Oct 2004 70 Example: Acoustic Overtone Pattern Sound crossing angular size at photon decoupling –fiducial model WMAP+ext : θ 0 = 1.046 –CBIPol + WMAP + “ext” : θ/θ 0 = 0.998 ± 0.005 Overtone pattern –equivalent to “j ladder” –TT extrema spaced at j intervals –EE spaced at j+½ (plus corrections)

71. The Cosmic Background Imager – ATCA, 19 Oct 2004 71 New: CBI EE Polarization Phase Parameterization 1: envelope plus shiftable sinusoid –fit to “WMAP+ext” fiducial spectrum using rational functions

72. The Cosmic Background Imager – ATCA, 19 Oct 2004 72 New: CBI EE Polarization Phase Peaks in EE should be offset one-half cycle vs. TT –fix amplitude a=1 and allow phase  to vary slice at: a=1  = 25°±33° rel. phase (   2 =1)   2 (1, 0°)=0.56

73. The Cosmic Background Imager – ATCA, 19 Oct 2004 73 New: CBI EE Polarization Phase Peaks in EE should be offset one-half cycle vs. TT –allow amplitude a and phase  to vary best fit: a=0.94  = 24°±33° (   2 =1)   2 (1, 0°)=0.56

74. The Cosmic Background Imager – ATCA, 19 Oct 2004 74 New: CBI EE Polarization Phase Scaling model: spectrum shifts by scaling l –same envelope f,g as before fiducial model: θ 0 = 1.046 (“WMAP+ext”) θ sound crossing angular scale

75. The Cosmic Background Imager – ATCA, 19 Oct 2004 75 New: CBI EE Polarization Phase Scaling model: spectrum shifts by scaling l –allow amplitude a and scale θ to vary overtone 0.67 island: a=0.69±0.03 excluded by TT and other priors other overtone islands also excluded

76. The Cosmic Background Imager – ATCA, 19 Oct 2004 76 New: CBI EE Polarization Phase Scaling model: spectrum shifts by scaling l –allow amplitude a and scale θ to vary best fit: a=0.93 slice along a=1: θ/θ 0 = 1.02±0.04 (   2 =1) zoom in: ± one-half cycle

77. The Cosmic Background Imager – ATCA, 19 Oct 2004 77 New: CBI, DASI, Capmap

78. The Cosmic Background Imager – ATCA, 19 Oct 2004 78 New: DASI EE Polarization Phase Use DASI EE 5-bin bandpowers (Leitch et al. 2004) –bin-bin covariance matrix plus approximate window functions a=0.5, 0.67 overtone islands: suppressed by DASI DASI phase lock: θ/θ 0 =0.94±0.06 θ/θ 0 = 0.94±0.06 a=0.5 (low DASI)

79. The Cosmic Background Imager – ATCA, 19 Oct 2004 79 New: CBI + DASI EE Phase Combined constraints on θ model: –DASI (Leitch et al. 2004) & CBI (Readhead et al. 2004) CBI a=0.67 overtone island: suppressed by DASI data other overtone islands also excluded CBI+DASI phase lock: θ/θ 0 =1.00±0.03 θ/θ 0 = 1.00±0.03 a=0.78±0.15 (low DASI)

80. The Cosmic Background Imager – ATCA, 19 Oct 2004 80 Conclusions CMB polarization interferometry (CBI,DASI) –straightforward analysis {RR,RL} → {TT,EE,BB,TE} –polarization systematics minimized CMB polarization results –EE power spectrum measured consistent with Standard Cosmological Model™ –EE acoustic spectrum peaks phase one-half cycle offset from TT sound crossing angular scale  independently consistent (3%) –BB null, no polarized foregrounds detected –TE difficult to extract in wide bins more data, narrower bins

81. The Cosmic Background Imager – ATCA, 19 Oct 2004 81 CBI Polarization Projections

82. The Cosmic Background Imager – ATCA, 19 Oct 2004 82 Future CBI –6 months more data in hand  finer l bins –more detailed papers: data tests, analysis, parameters –run to end of 2005 (pending funding) –also: SZE clusters (e.g. Udomprasert et al. 2004) Beyond CBI  QUIET –detectors are near quantum & bandwidth limit – need more! –but: need clean polarization (low stable instrumental effects) –large format (1000 els.) coherent (MMIC) detector array –polarization B-modes! (at least the lensing signal) Further Beyond –Beyond Einstein (save the Bpol mission!)

83. The Cosmic Background Imager – ATCA, 19 Oct 2004 83 SZE with CBI: z < 0.1 clusters P. Udomprasert thesis (Caltech)

84. The Cosmic Background Imager – ATCA, 19 Oct 2004 84 The CBI Collaboration Caltech Team: Tony Readhead (Principal Investigator), John Cartwright, Clive Dickinson, Alison Farmer, Russ Keeney, Brian Mason, Steve Miller, Steve Padin (Project Scientist), Tim Pearson, Walter Schaal, Martin Shepherd, Jonathan Sievers, Pat Udomprasert, John Yamasaki. Operations in Chile: Pablo Altamirano, Ricardo Bustos, Cristobal Achermann, Tomislav Vucina, Juan Pablo Jacob, José Cortes, Wilson Araya. Collaborators: Dick Bond (CITA), Leonardo Bronfman (University of Chile), John Carlstrom (University of Chicago), Simon Casassus (University of Chile), Carlo Contaldi (CITA), Nils Halverson (University of California, Berkeley), Bill Holzapfel (University of California, Berkeley), Marshall Joy (NASA's Marshall Space Flight Center), John Kovac (University of Chicago), Erik Leitch (University of Chicago), Jorge May (University of Chile), Steven Myers (National Radio Astronomy Observatory), Angel Otarola (European Southern Observatory), Ue-Li Pen (CITA), Dmitry Pogosyan (University of Alberta), Simon Prunet (Institut d'Astrophysique de Paris), Clem Pryke (University of Chicago). The CBI Project is a collaboration between the California Institute of Technology, the Canadian Institute for Theoretical Astrophysics, the National Radio Astronomy Observatory, the University of Chicago, and the Universidad de Chile. The project has been supported by funds from the National Science Foundation, the California Institute of Technology, Maxine and Ronald Linde, Cecil and Sally Drinkward, Barbara and Stanley Rawn Jr., the Kavli Institute,and the Canadian Institute for Advanced Research.