1. Chao-Lin Kuo Stanford Physics/SLAC
ACBAR
Chao-Lin Kuo
Stanford Physics/SLAC

2. CMB power spectrum, as of 03/04/08
mK2

3. ACBAR – power spectrum final results
On the preprint arxiv: 01/10/08 (astro-ph )
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

4. Arcminute Cosmology Bolometer Array Receiver (2001-2005)
corrugated
feed horns
South pole
2 meter Telescope
@ South Pole
Cooled to 240mK
He3/He3/He4
Fridge
Bolometers
2 meter mirror
+ 150 GHz =
High resolution (4.8’)
Map = 11x2.5 deg
The largest scale structures
(>1 deg) have been filtered
All structures are real,
larger than the beam size
sum
diff

5. 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

6. Sky Coverage Year observed: 2001 2002 2005
Kuo, 2004; khours ; 63 deg2
Kuo, 2007; khours ; 137 deg2
Reichardt 2008; 85.4 khours ; 710 deg2
Year observed:

7. 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

8. Foregrounds Calibration FDS (1) Galactic dust 0.5%
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:
2.2 (/2600)2 K2
(done by C Reichardt)
ACBAR
2.3%
(3) High-z galaxies
Estimated residual::
9-16 (/2600)2 K2

9. 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)
CBI/BIMA:
355  103 K2
at 30 GHz*
ACBAR
34  20 K2
at 150 GHz
High-l
CBI excess is not primordial*

10. 1D likelihoods WMAP3 WMAP3+ ACBAR CMBall More details:
No major surprises. (Very consistent with WMAP3 model!)
Adding ACBAR’s small scale information shifts c &  by 1 .
More details:
astro-ph/

11. Where the constraining power is coming from- The 3rd peak..
ACBAR
WMAP
BOOM
Slosar

12. 2-D parameter contours q ns

13. Lensing with ACBAR Lensed Unlensed Method 1: Power spectrum:
* ACBAR’s band-power’s are consistent with a 6-parameter CDM 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

14. The Quest for “B”
BICEP & future
ACBAR
QUAD/DASI/SPUD
BICEP

15. CMB polarization and current measurements
E-mode
B-mode
(gravity waves)
(lensing)
Re-ionization
r = 0.05 E B →
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
The re-ionization bump (early re-ionization )
The E-mode polarization – adiabatic vs isocurvature modes

16. Ongoing @ South Pole: the BICEP Experiment
H. Chiang
Small telescope
Cold, stable refractive optics

17. Bolometric Polarimeters
The state-of-the-art (QUAD, BICEP):
The future:
Co-locating dual-polarization polarimeter
High optical efficiency, wide band
Extremely stable
Nice beam/band
Low polarization artifacts
Discrete elements: feeds, filters, detectors
To integrate all these components on a Si
wafer → mass production
Higher packing density
TES enables SQUID multiplexed read-out
30 cm
8 cm
Antenna-coupled TES array (64 detector pairs)
BICEP focal plane (98 detectors)

18. Enabling Technology: lithographic detectorsAl
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

19. 2008