ACT

1. ACT • Atacama Cosmology Telescope • Funded by NSF • Will measure CMB fluctuations on small angular scales • Probe the primordial power spectrum and the growth of structure

3. The MillimeterBolometric ArrayCamera: 3000 Detectors • Tricolor: • 145, 225, & 265 GHz • 3 independent 32x32 arrays • TES PUDs from GSFC • PUDs = Pop-Up Devices • TES = Transition Edge Sensor Each pixel: 1 mm x 1 mm • TDM Multiplexing • 2-stage 1x33 mux chips, followed by Series Array SQUIDs: SAs -- from NIST • Nyquist inductors -- from NIST • Mux servo electronics & DAQ from UBC (who provided these for SCUBA)

5. Princeton PENN CatÓlica Toronto Haverford CUNY ACT COLLABORATIONS Government Labs Museums Schools Kwa-Zulu Natal …united through research, education and public outreach.

6. Simulations of mm-wave data. Survey area High quality area 150 GHz SZ Simulation MBAC on ACT 1.7’ beam PLANCK 2X noise MAP PLANCK

7. Where will we be with CMB Bond et al. astro-ph/046195

8. Cosmic Timeline for ACT Science • First galaxies • Universe is reionized • Ostriker-Vishniac • Surveys of Sunyaev-Zel’dovich (SZ) clusters • Diffuse thermal SZ • Kinetic SZ signal Cosmic Microwave Background • N(mass,z) – Evolution of Cosmic Structure • Lensing of the CMB • The growth of structure is sensitive to w and mn • Additional cross-checks from correlations among effects • Extraction of cosmological parameters • Initial conditions for structure formation now z = 1000 t = 4 x 104 yrs z = 7 t = 3 x 106 yrs z = 1 t = 1 x 109 yrs z = .25 t = 12 x 109 yrs Primary CMB CMB Lensing OV/KSZ Diffuse Thermal SZ Cluster Surveys

9. SZ Signature Hot electron gas imposes a unique spectral signature 145 GHz decrement 220 GHz null 270 GHz increment NO SZ Contribution in Central Band 1.4°x 1.4°

10. Coordinated Cluster Measurements Identify and measure >500 clusters in an unbiased survey with multi-wavelength observations Galaxy Cluster Cosmic Microwave Background HOT Electrons • Mass limits of 3 x 1014 estimated from simulations • Science derived from N(mass,z)

11. Southern Africa Large Telescope World’s Largest Optical Telescope SALT has achieved 1” seeing SALT will survey the ACT strip in 4 colors and will then measure spectra for tens of galaxies per cluster

13. CMB Lensing of the CMB • Lensing arises from integrated mass fluctuations along the line of sight. • The CMB acts as a fixed distance source, removing the degeneracy inherent to other lensing measurements. • Signal at l = 1000-3000 • Image distortion – only a minor effect in the power spectrum. • Must have a deep, high fidelity map to detect this effect. -1850 (K) 0 1820 1.4°x 1.4°

14. Lensing of the CMB -34 (K) 0 34 • RMS signal well above noise floor. • Isolate from SZ and point sources spectrally. • Identify with distinctive 4-point function. Lensing Signal 2% of CMB RMS 1.4°x 1.4°

15. Where are the baryons? • Cross-correlate galaxy counts and kinetic SZ signal • KSZ signal proportional to tv • Measure TKSZ^2 as a function of galaxy position • Use redshift distribution to predict v, correlate density/velocity field and measure W • Estimates suggest high S/N detection for ACT and should be much better for 1 mm CCAT

16. ACT \REGION: Target for future lensing surveys ACT will begin surveying in 2006 We already plan deep multi-band imaging with SALT of low extinction part of ACT strip (200 square degrees) Would be a very interesting target for a lensing survey

17. ACT is but one of several next generation CMB experiments • APEX (Atacama Pathfinder Experiment) • UCB/MPI • 1.4mm and 2 mm obs. • SZ science • SPT (South Pole Telescope) • 8m at South Pole • Chicago group (2008) • Large area • Optimized for SZ/clusters