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ACBAR Chao-Lin Kuo Stanford Physics/SLAC CMB power spectrum, as of 03/04/08 mK2 ACBAR – power spectrum final results On the preprint arxiv: 01/10/08 (astro-ph 08011491) For this data release, esp.: Christian Reichardt (Caltech→Berkeley) Bill Holzapfel Chao-Lin Kuo (Caltech→Stanford) Andrew Lange Carlo Contaldi Dick Bond Planning/ operation Cosmological parameters Arcminute Cosmology Bolometer Array Receiver (2001-2005) Cooled to 240mK He3/He3/He4 Fridge South pole corrugated feed horns 2 meter Telescope @ South Pole Bolometers 2 meter mirror + 150 GHz = High resolution (4.8’) • Map = 11x2.5 deg sum •The largest scale structures (>1 deg) have been filtered •All structures are real, larger than the beam size diff The CMB damping tail The damping scale measures the angular scale of Silk length at recombination: Silk length ~ 3.5 Mpc (m/ b)1/2 (mh2) -3/4 Dunkley et al, today Sky Coverage 2001 Year observed: 2002 2005 Kuo, 2004; 16.8 khours ; 63 deg2 Kuo, 2007; 23.0 khours ; 137 deg2 Reichardt 2008; 85.4 khours ; 710 2 ACBAR PS Releases R08 ACBAR 2004; differenced; 63 deg2; 10.% calibration (Temperature) ACBAR 2007; undifferenced; 137 deg2; 6.0% calibration Reichardt 2008; undifferenced ; 710 deg2; 2.3% calibration Foregrounds Calibration (1) Galactic dust CMB Dipole FDS (done by WMAP) 0.5% ACBAR favors a lower amplitude: 0.1±0.5 Good news for future polarization exp. (2) Radio point sources Estimated residual: (done by C Reichardt) ACBAR 2.3% 2.2 (/2600)2 mK2 (3) High-z galaxies Estimated residual:: 9-16 (/2600)2 mK2 Cosmological implications • The most important result: WMAP-3 model spectrum is a very good fit (flatness, L, CDM, …) This seriously limits non standard ingredients. •Important note: •Beam uncertainty (published function) •Calibration uncertainty (2.3% in T) High-l CBI/BIMA: 355 103 mK2 at 30 GHz* ACBAR 34 20 mK2 at 150 GHz CBI excess is not primordial* 1D likelihoods WMAP3 WMAP3+ ACBAR CMBall No major surprises. (Very consistent with WMAP3 model!) Adding ACBAR’s small scale information shifts c & by 1 . More details: astro-ph/08011491 Where the constraining power is coming fromThe 3rd ACBAR WMAP BOOM peak.. 500 1000 A. Slosar 1500 2000 2-D parameter contours ns Lensing with ACBAR Lensed Unlensed Method 1: Power spectrum: * ACBAR’s band-power’s are consistent with a 6-parameter LCDM model. * Lensed models are favored (~3.1) when ACBAR is added to WMAP3. Method 2: Higher order statistics – lens reconstruction * Generalize Hu’s quadratic estimator for a map with spatial filters and non-uniform coverage * ACBAR’s pixel-based maximum likelihood algorithm easy to generalize for lensing work. (CK, Dan Babich,..) * Maximum likelihood analysis by Hirata&Seljak serves as an important guide line The Quest for “B” BICEP & future QUAD/DASI/SPUD BICEP ACBAR CMB polarization and current measurements Re-ionization E E-mode B-mode (lensing) r = 0.05 B B-mode → (gravity waves) • The re-ionization bump (early re-ionization ) • The E-mode polarization – adiabatic vs isocurvature modes • The lensing B-mode – a probe of the large scale structure – – – Dark Energy – equation of state, evolution Absolute neutrino mass (down to ~0.05 eV) Geometry Ongoing @ South Pole: the BICEP Experiment •Small telescope •Cold, stable refractive optics H. Chiang Bolometric Polarimeters The state-of-the-art (QUAD, BICEP): •Co-locating dual-polarization polarimeter •High optical efficiency, wide band •Extremely stable •Nice beam/band •Low polarization artifacts •Discrete elements: feeds, filters, detectors 30 cm BICEP focal plane (98 detectors) The future: •To integrate all these components on a Si wafer → mass production •Higher packing density •TES enables SQUID multiplexed read-out 8 cm Antenna-coupled TES array (64 detector pairs) Enabling Technology: lithographic detectors Al Load resistor Ti Dual-Tc TES bolometer 7.5 mm (150 GHz) Dual-polarization antenna/summing network 25 % Bandwidth Compact LC Filter 0.8 mm 2008 2009-2010