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

The Cosmic Background Imager – ATCA, 19 Oct 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

The Cosmic Background Imager – ATCA, 19 Oct The CMB Landscape

The Cosmic Background Imager – ATCA, 19 Oct 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 K –Anisotropies ≤10 -5

The Cosmic Background Imager – ATCA, 19 Oct 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”

The Cosmic Background Imager – ATCA, 19 Oct Thermal History of the Universe Courtesy Wayne Hu – “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!

The Cosmic Background Imager – ATCA, 19 Oct 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 a =  density fluctuations ~ NOTE: density higher in past, but density fluctuations smaller! Courtesy Wayne Hu –

The Cosmic Background Imager – ATCA, 19 Oct 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

The Cosmic Background Imager – ATCA, 19 Oct 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)

The Cosmic Background Imager – ATCA, 19 Oct CMB Primary Anisotropies Low l (<100) –primordial power spectrum (+ S-W, tensors, etc.) Intermediate l ( ) –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 ( ) –realm of the secondaries (e.g. SZE) Courtesy Wayne Hu –

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

The Cosmic Background Imager – ATCA, 19 Oct 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 –

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

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

The Cosmic Background Imager – ATCA, 19 Oct The Cosmic Background Imager

The Cosmic Background Imager – ATCA, 19 Oct The Instrument cm Cassegrain antennas –78 baselines 6-meter platform –Baselines 1m – 5.51m 10 1 GHz channels 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

The Cosmic Background Imager – ATCA, 19 Oct 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

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

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

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

The Cosmic Background Imager – ATCA, 19 Oct 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 January routine observing begins –2001 first paper; 2002 first year results; yrs; 2004 pol –2002 continued NSF funding to end of 2004 –exploring funding prospects to operate until end of 2005

The Cosmic Background Imager – ATCA, 19 Oct 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

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

The Cosmic Background Imager – ATCA, 19 Oct CBI Instrumentation

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

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

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

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

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

The Cosmic Background Imager – ATCA, 19 Oct CMB Interferometry

The Cosmic Background Imager – ATCA, 19 Oct 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

The Cosmic Background Imager – ATCA, 19 Oct 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

The Cosmic Background Imager – ATCA, 19 Oct 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

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

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

The Cosmic Background Imager – ATCA, 19 Oct 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 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

The Cosmic Background Imager – ATCA, 19 Oct 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 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)

The Cosmic Background Imager – ATCA, 19 Oct 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

The Cosmic Background Imager – ATCA, 19 Oct 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°)

The Cosmic Background Imager – ATCA, 19 Oct 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!

The Cosmic Background Imager – ATCA, 19 Oct 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)

The Cosmic Background Imager – ATCA, 19 Oct 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

The Cosmic Background Imager – ATCA, 19 Oct 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/ (24 Sep 2004)

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

The Cosmic Background Imager – ATCA, 19 Oct DASI & 2003 WMAP Polarization Courtesy Wayne Hu – Carlstrom et al astro-ph/

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

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

The Cosmic Background Imager – ATCA, 19 Oct 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

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

The Cosmic Background Imager – ATCA, 19 Oct 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]

The Cosmic Background Imager – ATCA, 19 Oct 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)

The Cosmic Background Imager – ATCA, 19 Oct 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 polarization observations

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

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

The Cosmic Background Imager – ATCA, 19 Oct 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

The Cosmic Background Imager – ATCA, 19 Oct 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

The Cosmic Background Imager – ATCA, 19 Oct 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

The Cosmic Background Imager – ATCA, 19 Oct 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

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

The Cosmic Background Imager – ATCA, 19 Oct 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

The Cosmic Background Imager – ATCA, 19 Oct 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!

The Cosmic Background Imager – ATCA, 19 Oct 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

The Cosmic Background Imager – ATCA, 19 Oct  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:

The Cosmic Background Imager – ATCA, 19 Oct 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]

The Cosmic Background Imager – ATCA, 19 Oct 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 TT (Readhead et al. 2004a) NOTE: parameter constraints dominated by higher precision TT from CBI data!

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

The Cosmic Background Imager – ATCA, 19 Oct 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)

The Cosmic Background Imager – ATCA, 19 Oct Example: Acoustic Overtone Pattern Sound crossing angular size at photon decoupling –fiducial model WMAP+ext : θ 0 = 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)

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

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

The Cosmic Background Imager – ATCA, 19 Oct 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

The Cosmic Background Imager – ATCA, 19 Oct 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

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

The Cosmic Background Imager – ATCA, 19 Oct 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

The Cosmic Background Imager – ATCA, 19 Oct 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

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

The Cosmic Background Imager – ATCA, 19 Oct 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)

The Cosmic Background Imager – ATCA, 19 Oct 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)

The Cosmic Background Imager – ATCA, 19 Oct 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

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

The Cosmic Background Imager – ATCA, 19 Oct 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!)

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

The Cosmic Background Imager – ATCA, 19 Oct 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.