2-year Total Intensity Observations 2000+2001
1-year Polarization Observations 2003+2004
Cosmic Background Imager
Tony ReadheadZeldovich celebration
Moscow December 2004
Caltech:(Cartwright*)Dickinson(Keeney)(Mason)(Padin (project scientist))PearsonReadhead(Schaal)(Shepherd)(Sievers*)(Udomprasert*)(Yamasaki)
CITA:BondContaldi(Pen)Pogosyan(Prunet)
Chicago:CarlstromKovac*LeitchPryke
U. de Chile:Achermann*(Altamirano)BronfmanCasassusMayOyarce
Berkeley:(Halverson*)(Holzapfel)
NRAO:Myers
MSFC:(Joy)
* students altitude 16,800 feet
U. de ConcepcionBustos*Reeves*Torres
Polarization ObservationsPablo Altamirano, Ricardo Bustos, John Kovac
Rodrigo Reeves, Cristobal Achermann
CBI, 5080 m
APEX
1 meter
CBI Configuration for Polarization ObservationsVery close to a perfect matched filter to the expected polarization signal
LCP
RCP
v
u
D cos D sin
u.x
D=uE1(t) E2(t)
/2
complex correlator
Im Re
to ce
lestia
l sig
nal
cmb temperature variations T(x)
V(u)
_ie
e2iu x.
Q U
Thomson scattering gives rise to E-mode (curl-free) polarization (~10 % of T)
Gravitational waves and lensing also give rise to B-mode polarization (<1 % of T)
North
-Q
-U
CBI:78 baselines
10 frequency channels= 780 separateinterferometers
CBI Flux Density scale is tied to the WMAP Flux Density scale, absolute uncertainty = 1.3%
Page et al. ApJ 2003, 148, 39
Silk damping
CBI Polarization EE Observations
strategy: size of mosaics chosen so that at the end of 3-4 years the cosmic variance will equal the thermal noise in the center of the CBI l-range
If point sources were a factor we would see a l(l +1)x Cl dependence in both EE and BB
simulations with realistic point source contributions show that the first two
bins are expected to change by < 4 K2
significance of shaped fit is 8.9- without point source projection, or 7.0- with point source projection
2.1-3.4-
1.6-
CBI EE Polarization Phase
• Parameterization 1: envelope plus shiftable sinusoid– fit to “WMAP+ext” fiducial spectrum using
rational functions
( )( ) ( ) ( )[ ]φ++
+lll
ll l
kgfaC EE
sin1
slice at: slice at: aa=1=1== 2525°±°±3333°° rel. phase rel. phase
7.0- to 8.9- detection in amplitude of EE-mode polarizationand 3- rejection of “in phase” EE-TT spectra
Example: Acoustic Overtone Pattern• Sound crossing angular size at photon
decoupling
• Overtone pattern– TT extrema spaced at j intervals– EE spaced at j+1/2 (plus corrections)
( )21+∝
∝j
j
sEEj
sTTj
llll
ππ
1−≈ lθ
CBI EE Polarization Phase
• Parameterization 2: • Scaling model: spectrum shifts by scaling l
– allow amplitude a and scale l to vary
best fit: best fit: aa=0.93=0.93slice along a=1:slice along a=1:
//00== 1.021.02±±0.04 (0.04 (22=1)=1)
( )( ) ( ) ( )[ ]
0
0
sin1
ss
EE
AAa
kgfaC
==′
′′+′=+
θθlllll
ll l
• Scaling model: spectrum shifts by scaling l – allow amplitude a and scale l to vary
overtone 0.67 island: overtone 0.67 island: aa=0.69=0.69±±0.030.03excluded by TTexcluded by TT
and other priorsand other priors
other overtone islandsother overtone islandsalso excludedalso excluded
• DASI EE 5-bin bandpowers (Leitch et al. 2004)– bin-bin covariance matrix plus approximate
window functions
a=0.5, 0.67 overtone islands:a=0.5, 0.67 overtone islands:suppressed by DASIsuppressed by DASI
DASI phase lock:DASI phase lock://00== 0.94±0.060.94±0.06a=0.5 (low DASI)a=0.5 (low DASI)
CBI a=0.67 overtone island:CBI a=0.67 overtone island:suppressed by DASI datasuppressed by DASI data
other overtone islandsother overtone islandsalso excludedalso excluded
CBI+DASI phase lock:CBI+DASI phase lock://00== 1.00±0.031.00±0.03
a=0.78a=0.78±0.15±0.15 (low DASI) (low DASI)
slice at: slice at: aa=1=1== 2525°±°±3333°° rel. phase rel. phase
7.0- to 8.9- detection in amplitude of EE-mode polarizationand 3- rejection of “in phase” EE-TT spectra
a marginal result?I don’t think so!
apples & oranges: known uncertainties vs. blue-sky predictions of new technologies
Ey ~ Ea - Eb
Ex ~ Ea + Eb
Gx Gy (ExEy) ~ Gx Gy ( Ea2 - Eb
2 )
polarizers
Ga Ea2 Gb Eb
2
x
y
a b
EyEx
±
OMT
Correlation Polarimetry
Differencing Bolometers
Polarimetry Techniques
synchrotron 100 GHz
dust 100 GHz
WMAPBICEPQUIET1QUEST (QUaD)PlanckQUIET2
synchrotron 100 GHz
dust 100 GHz
Hivon