The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic...
-
Upload
isabel-preston -
Category
Documents
-
view
213 -
download
0
Transcript of The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic...
![Page 1: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/1.jpg)
![Page 2: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/2.jpg)
2The Cosmic Background Imager – ATCA, 19 Oct 2004
CMB Polarization Results from the
Cosmic Background ImagerSteven T. Myers
National Radio Astronomy Observatory
Socorro, NM
![Page 3: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/3.jpg)
3The Cosmic Background Imager – ATCA, 19 Oct 2004
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
![Page 4: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/4.jpg)
4The Cosmic Background Imager – ATCA, 19 Oct 2004
The CMB Landscape
![Page 5: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/5.jpg)
5The Cosmic Background Imager – ATCA, 19 Oct 2004
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 2.725 K– Anisotropies ≤10-5
![Page 6: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/6.jpg)
6The Cosmic Background Imager – ATCA, 19 Oct 2004
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/a3 ; radiation density 1/a4
• 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”
za
1
1
![Page 7: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/7.jpg)
7The Cosmic Background Imager – ATCA, 19 Oct 2004
Thermal History of the Universe
Courtesy Wayne Hu – http://background.uchicago.edu
““First 3 minutes”:First 3 minutes”:very hot (10 million very hot (10 million °°K)K)like interior of Sunlike interior of Sunnucleosynthesis!nucleosynthesis!
After “recombination”:After “recombination”:cooler, transparent, cooler, transparent, neutral hydrogen gasneutral hydrogen gas
Before “recombination”:Before “recombination”:hot (3000hot (3000°°K)K)like surface of Sun like surface of Sun opaque, ionized plasmaopaque, ionized plasma
““Surface of last scattering” Surface of last scattering” TT≈≈30003000°°K zK z≈≈10001000THIS IS WHAT WE SEE AS THIS IS WHAT WE SEE AS THE CMB!THE CMB!
![Page 8: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/8.jpg)
8The Cosmic Background Imager – ATCA, 19 Oct 2004
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– CMB @ a = 0.001 density fluctuations ~ 0.001
• NOTE: density higher in past, but density fluctuations smaller!
Courtesy Wayne Hu – http://background.uchicago.edu
![Page 9: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/9.jpg)
9The Cosmic Background Imager – ATCA, 19 Oct 2004
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
![Page 10: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/10.jpg)
10The Cosmic Background Imager – ATCA, 19 Oct 2004
CMB Acoustic Peaks
• Compression driven by gravity, resisted by radiation≈ “j ladder” series of harmonics + projection corrections
peaks: ~ peaks: ~ llss jjtroughs: ~ troughs: ~ llss ( (jj ±± ½½))
![Page 11: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/11.jpg)
11The Cosmic Background Imager – ATCA, 19 Oct 2004
CMB Primary Anisotropies
• Low l (<100)– primordial power spectrum (+ S-W, tensors, etc.)
• Intermediate l (100-2000)– 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 (2000-5000+)– realm of the secondaries (e.g. SZE)
Courtesy Wayne Hu – http://background.uchicago.edu
![Page 12: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/12.jpg)
12The Cosmic Background Imager – ATCA, 19 Oct 2004
only transverse only transverse polarization can be polarization can be transmitted on scattering!transmitted on scattering!
CMB Polarization
• Due to quadrupolar intensity field at scattering
Courtesy Wayne Hu – http://background.uchicago.edu
NOTE: polarization maximum NOTE: polarization maximum when velocity is maximum when velocity is maximum (out of phase with compression (out of phase with compression maxima)maxima)
![Page 13: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/13.jpg)
13The Cosmic Background Imager – ATCA, 19 Oct 2004
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 – http://background.uchicago.edu
![Page 14: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/14.jpg)
14The Cosmic Background Imager – ATCA, 19 Oct 2004
Polarization Power Spectrum
Hu & Dodelson ARAA 2002
Planck “error boxes”Planck “error boxes”
Note: polarization peaks Note: polarization peaks out of phase w.r.t. out of phase w.r.t. intensity peaksintensity peaks
![Page 15: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/15.jpg)
15The Cosmic Background Imager – ATCA, 19 Oct 2004
The Gold Standard: WMAP + “ext”WMAP
ACBAR
![Page 16: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/16.jpg)
16The Cosmic Background Imager – ATCA, 19 Oct 2004
The Cosmic Background Imager
![Page 17: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/17.jpg)
17The Cosmic Background Imager – ATCA, 19 Oct 2004
The Instrument
• 13 90-cm Cassegrain antennas– 78 baselines
• 6-meter platform– Baselines 1m – 5.51m
• 10 1 GHz channels 26-36 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
![Page 18: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/18.jpg)
18The Cosmic Background Imager – ATCA, 19 Oct 2004
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
![Page 19: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/19.jpg)
19The Cosmic Background Imager – ATCA, 19 Oct 2004
Traditional Inteferometer – The VLA• The Very Large Array (VLA)
– 27 elements, 25m antennas, 74 MHz – 50 GHz (in bands)– independent elements Earth rotation synthesis
![Page 20: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/20.jpg)
20The Cosmic Background Imager – ATCA, 19 Oct 2004
CMB Interferometer – The CBI• The Cosmic Background Imager (CBI)
– 13 elements, 90 cm antennas, 26-36 GHz (10 channels)– fixed to 3-axis platform telescope rotation synthesis!
![Page 21: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/21.jpg)
21The Cosmic Background Imager – ATCA, 19 Oct 2004
Other CMB Interferometers: DASI, VSA
• DASI @ South Pole
• VSA @ Tenerife
![Page 22: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/22.jpg)
22The Cosmic Background Imager – ATCA, 19 Oct 2004
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+– 2000 January routine observing begins– 2001 first paper; 2002 first year results; 2003 2yrs; 2004 pol– 2002 continued NSF funding to end of 2004– exploring funding prospects to operate until end of 2005
![Page 23: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/23.jpg)
23The Cosmic Background Imager – ATCA, 19 Oct 2004
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
![Page 24: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/24.jpg)
24The Cosmic Background Imager – ATCA, 19 Oct 2004
CBI Site – Northern Chilean Andes
• Elevation 16500 ft.!
![Page 25: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/25.jpg)
25The Cosmic Background Imager – ATCA, 19 Oct 2004
CBI Instrumentation
![Page 26: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/26.jpg)
26The Cosmic Background Imager – ATCA, 19 Oct 2004
CBI in Chile
![Page 27: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/27.jpg)
27The Cosmic Background Imager – ATCA, 19 Oct 2004
The CBI Adventure…
• sunset
![Page 28: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/28.jpg)
28The Cosmic Background Imager – ATCA, 19 Oct 2004
The CBI Adventure…
• Steve Padin wearing the cannular oxygen system– because you never know when you
need to dig the truck out!
![Page 29: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/29.jpg)
29The Cosmic Background Imager – ATCA, 19 Oct 2004
The CBI Adventure…
• the snow in Chile falls mainly on the road! 2 winters/yr
![Page 30: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/30.jpg)
30The Cosmic Background Imager – ATCA, 19 Oct 2004
The CBI Adventure…• Volcan Lascar (~30 km away) erupts in 2001
![Page 31: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/31.jpg)
31The Cosmic Background Imager – ATCA, 19 Oct 2004
CMB Interferometry
![Page 32: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/32.jpg)
32The Cosmic Background Imager – ATCA, 19 Oct 2004
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
e)(~
)(~
e)()()(
22
)(22
p
p
i
ip
eIAd
eIAdV
xv
xxu
vvuv
xxxxu
![Page 33: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/33.jpg)
33The Cosmic Background Imager – ATCA, 19 Oct 2004
The uv plane
• The projected baseline length gives the angular scale
multipole:multipole:
ll = 2 = 2B/B/λ λ = 2= 2uuijij||
shortest CBI baseline:shortest CBI baseline:
central hole 10cmcentral hole 10cm
![Page 34: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/34.jpg)
34The Cosmic Background Imager – ATCA, 19 Oct 2004
CBI Beam and uv coverage
• Over-sampled uv-plane– excellent PSF– allows fast gridded method (Myers et al. 2000)
primary beam transform:primary beam transform:
θθpripri= 45= 45' ' ΔΔll ≈ 4D/ ≈ 4D/λλ ≈ 360 ≈ 360
mosaic beam transform:mosaic beam transform:
θθmosmos= = nn××4545' ' ΔΔll ≈ 4D/ ≈ 4D/nnλλ
![Page 35: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/35.jpg)
35The Cosmic Background Imager – ATCA, 19 Oct 2004
Mosaicing in the uv plane
offset & add
phase gradients
![Page 36: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/36.jpg)
36The Cosmic Background Imager – ATCA, 19 Oct 2004
Polarization of radiation
• Electromagnetic Waves– Maxwell: 2 independent linearly polarized waves
– 3 parameters (E1,E2,) polarization ellipse
Rohlfs & Wilson
![Page 37: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/37.jpg)
37The Cosmic Background Imager – ATCA, 19 Oct 2004
Polarization of radiation
• Electromagnetic Waves– Maxwell: 2 independent linearly polarized waves
– 3 parameters (E1,E2,) polarization ellipse
• Stokes parameters (Poincare Sphere):– intensity I (Poynting flux) I2 = E1
2 + E22
– linear polarization Q,U (m I)2 = Q2 + U2
– circular polarization V (v I)2 = V2
Rohlfs & Wilson
The Poincare SphereThe Poincare Sphere
![Page 38: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/38.jpg)
38The Cosmic Background Imager – ATCA, 19 Oct 2004
Polarization of radiation
• Electromagnetic Waves– Maxwell: 2 independent linearly polarized waves
– 3 parameters (E1,E2,) polarization ellipse
• Stokes parameters (Poincare Sphere):– intensity I (Poynting flux) I2 = E1
2 + E22
– linear polarization Q,U (m I)2 = Q2 + U2
– circular polarization V (v I)2 = V2
• 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)
![Page 39: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/39.jpg)
39The Cosmic Background Imager – ATCA, 19 Oct 2004
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
V
U
Q
I
eie
eie
VI
eUiQ
eUiQ
VI
ee
ee
ee
ee
ii
ii
i
i
LL
RL
LR
RR
1001
00
00
1001
22
22
2
2
*
*
*
*
![Page 40: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/40.jpg)
40The Cosmic Background Imager – ATCA, 19 Oct 2004
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°)
RLij
iijij
RLij
RRijijij
RRij
ijeUiQPdV
IPdV
e)(~
)(~
)()(
e)(~
)()(
22
2
vvvvu
vvvu
ijiijijij eAP xvvuv
2)(~
)(
01tan ijijijij uv
![Page 41: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/41.jpg)
41The Cosmic Background Imager – ATCA, 19 Oct 2004
E and B modes
• A useful decomposition of the polarization signal is into “gradient” and “curl modes” – E and B:
uv1tan v
vvvvv χieBiEUiQ 2)(~
)(~
)(~
)(~
RLij
iijij
RLij
ijeBiEPdV
e)](~
)(~
[)()( )(22 vvvvvu
E & B response smeared by phase variation over aperture A
interferometer “directly” measures (Fourier transforms of) E & B!
![Page 42: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/42.jpg)
42The Cosmic Background Imager – ATCA, 19 Oct 2004
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)
)'()'(~
)(~
2)'()'(*~
)(~
2
2
vvvv
vvvvv
CTT
CTT
)'()'(*~
)(~
)'()'(*~
)(~
)'()'(*~
)(~
)'()'(*~
)(~
)'()'(*~
)(~
)'()'(*~
)(~
22
22
22
vvvvvvvv
vvvvvvvv
vvvvvvvv
EBTB
BBTE
EETT
CBECBT
CBBCET
CEECTT
![Page 43: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/43.jpg)
43The Cosmic Background Imager – ATCA, 19 Oct 2004
Errors: leakage
• instrumental polarization– “leaks” L into R, R into L (level ~1%-2%)
– e.g. Robs = 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
![Page 44: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/44.jpg)
44The Cosmic Background Imager – ATCA, 19 Oct 2004
CBI PolarizationNew 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/0409569 (24 Sep 2004)
![Page 45: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/45.jpg)
45The Cosmic Background Imager – ATCA, 19 Oct 2004
CBI 2000+2001, WMAP, ACBAR, BIMA
Readhead et al. ApJ, 609, 498 (2004)Readhead et al. ApJ, 609, 498 (2004)
astro-ph/0402359astro-ph/0402359
SZE SZE SecondarySecondaryCMB CMB
PrimaryPrimary
![Page 46: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/46.jpg)
46The Cosmic Background Imager – ATCA, 19 Oct 2004
2002 DASI & 2003 WMAP Polarization
Courtesy Wayne Hu – http://background.uchicago.edu
Carlstrom et al. 2003 astro-ph/0308478
![Page 47: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/47.jpg)
47The Cosmic Background Imager – ATCA, 19 Oct 2004
New: DASI 3-year polarization results!
• Leitch et al. 2004 (astro-ph/0409357) 16Sep04! 16Sep04! – EE 6.3 σ – TE 2.9 σ – consistent w/ WMAP+ext model– BB consistent with zero– no foregrounds (yet)
![Page 48: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/48.jpg)
48The Cosmic Background Imager – ATCA, 19 Oct 2004
CBI Current Polarization Data
• Observing since Sep 2002 (processed to May 2004)– compact configuration, maximum sensitivity
![Page 49: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/49.jpg)
49The Cosmic Background Imager – ATCA, 19 Oct 2004
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
Ka-band Receiver
0
2
4
6
8
10
12
14
16
18
20
26 28 30 32 34 36 38 40
Frequency (GHz)
No
ise
Tem
per
atu
re (
K)
![Page 50: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/50.jpg)
50The Cosmic Background Imager – ATCA, 19 Oct 2004
Calibration from WMAP Jupiter
• Old uncertainty: 5%• 2.7% high vs. WMAP Jupiter• New uncertainty: 1.3%• Ultimate goal: 0.5%
![Page 51: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/51.jpg)
51The Cosmic Background Imager – ATCA, 19 Oct 2004
CBI Polarization Mosaics
• Four mosaics = 02h, 08h, 14h, 20h at = 0°– 02h, 08h, 14h 6 x 6 fields, 20h deep strip 6 fields [45’ centers]
![Page 52: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/52.jpg)
52The Cosmic Background Imager – ATCA, 19 Oct 2004
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)
![Page 53: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/53.jpg)
53The Cosmic Background Imager – ATCA, 19 Oct 2004
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 2002-2003 polarization observations
![Page 54: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/54.jpg)
54The Cosmic Background Imager – ATCA, 19 Oct 2004
Before ground subtraction:
• I, Q, U dirty mosaic images:
![Page 55: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/55.jpg)
55The Cosmic Background Imager – ATCA, 19 Oct 2004
After ground subtraction:
• I, Q, U dirty mosaic images (9m differences):
![Page 56: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/56.jpg)
56The Cosmic Background Imager – ATCA, 19 Oct 2004
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
![Page 57: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/57.jpg)
57The Cosmic Background Imager – ATCA, 19 Oct 2004
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
![Page 58: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/58.jpg)
58The Cosmic Background Imager – ATCA, 19 Oct 2004
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
![Page 59: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/59.jpg)
59The Cosmic Background Imager – ATCA, 19 Oct 2004
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 14h field (in North Polar Spur) 50% worse
• Rely on CBI frequency leverage (26-36 GHz)– synchrotron spectrum -2.7 vs. thermal
– also l2 vs. CMB in power spectrum
![Page 60: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/60.jpg)
60The Cosmic Background Imager – ATCA, 19 Oct 2004
CBI & DASI Fields
galactic projection – image WMAP “synchrotron” (Bennett et al. 2003)
![Page 61: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/61.jpg)
61The Cosmic Background Imager – ATCA, 19 Oct 2004
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
![Page 62: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/62.jpg)
62The Cosmic Background Imager – ATCA, 19 Oct 2004
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!
![Page 63: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/63.jpg)
63The Cosmic Background Imager – ATCA, 19 Oct 2004
Shaped Cl 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 ls
• Results for CBI data (sources projected from TT only)– qB = 1.22 ± 0.21 (68%)
– EE likelihood vs. zero : equivalent significance 8.9 σ
• Conservative - project subset out in polarization also– qB = 1.18 ± 0.24 (68%)
– significance 7.0 σ
![Page 64: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/64.jpg)
64The Cosmic Background Imager – ATCA, 19 Oct 2004
k b cdm ns m h
CBI Mosaic Observation
2.5o
THE PILLARS OF INFLATION
1) super-horizon (>2°) anisotropies2) acoustic peaks and harmonic pattern (~1°)3) damping tail (<10')4) Gaussianity5) secondary anisotropies6) polarization7) gravity waves
But … to do this we need to measure a signal which is 3x107 timesweaker than the typical noise!
geometry baryonic fraction cold dark matter primordial dark energy matter fraction Hubble Constant optical depthof 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:
![Page 65: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/65.jpg)
65The Cosmic Background Imager – ATCA, 19 Oct 2004
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
+ CBI’02 TT l >1000 (Readhead et al. 2004a) [overlaps ‘04]
![Page 66: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/66.jpg)
66The Cosmic Background Imager – ATCA, 19 Oct 2004
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 2001-2002 TT (Readhead et al. 2004a)
• NOTE: parameter constraints dominated by higher precision TT from CBI 2001-2002 data!
![Page 67: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/67.jpg)
67The Cosmic Background Imager – ATCA, 19 Oct 2004
New: CBI Polarization Parameters
• NOTE: parameter constraints dominated by higher precision TT from CBI 2001-2002 (and to lesser extent 2002-2004) data!
• To discern what polarization data is adding, will need to be more subtle…
![Page 68: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/68.jpg)
68The Cosmic Background Imager – ATCA, 19 Oct 2004
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)
![Page 69: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/69.jpg)
69The Cosmic Background Imager – ATCA, 19 Oct 2004
Example: Acoustic Overtone Pattern
• Sound crossing angular size at photon decoupling– fiducial model WMAP+ext : θ0 = 1.046
WMAPWMAP
WMAP+CBI’04WMAP+CBI’04
WMAP+CBI’04+CBI’02WMAP+CBI’04+CBI’02
1 s
grand unified:grand unified:
θθ == 1.0441.044±0.005±0.005
θθ//θθ00 = = 0.998±0.0050.998±0.005(WMAP+CBI’04+CBI’02)(WMAP+CBI’04+CBI’02)
![Page 70: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/70.jpg)
70The Cosmic Background Imager – ATCA, 19 Oct 2004
Example: Acoustic Overtone Pattern
• Sound crossing angular size at photon decoupling– fiducial model WMAP+ext : θ0 = 1.046
– CBIPol + WMAP + “ext” : θ/θ0 = 0.998 ± 0.005
• Overtone pattern– equivalent to “j ladder” – TT extrema spaced at j intervals– EE spaced at j+½ (plus corrections)
21
j
j
sEEj
sTTj
![Page 71: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/71.jpg)
71The Cosmic Background Imager – ATCA, 19 Oct 2004
New: CBI EE Polarization Phase
• Parameterization 1: envelope plus shiftable sinusoid– fit to “WMAP+ext” fiducial spectrum using rational functions
kgfa
C EE
sin
1
![Page 72: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/72.jpg)
72The Cosmic Background Imager – ATCA, 19 Oct 2004
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: slice at: aa=1=1
== 2525°±°±3333°° rel. phase ( rel. phase (22=1)=1)
22(1, 0(1, 0°°)=0.56)=0.56
![Page 73: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/73.jpg)
73The Cosmic Background Imager – ATCA, 19 Oct 2004
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: best fit: aa=0.94=0.94
== 2424°±°±3333°° ( (22=1)=1)
22(1, 0(1, 0°°)=0.56)=0.56
![Page 74: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/74.jpg)
74The Cosmic Background Imager – ATCA, 19 Oct 2004
New: CBI EE Polarization Phase
• Scaling model: spectrum shifts by scaling l – same envelope f,g as before
0
0
sin
1
ss
EE
AAa
kgfa
C
fiducial model:fiducial model:
θθ00== 1.0461.046(“WMAP+ext”)(“WMAP+ext”)
θθ sound crossingsound crossingangular scaleangular scale
![Page 75: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/75.jpg)
75The Cosmic Background Imager – ATCA, 19 Oct 2004
New: CBI EE Polarization Phase
• Scaling model: spectrum shifts by scaling l – allow amplitude a and scale θ to vary
overtone 0.67 island: overtone 0.67 island: aa=0.69=0.69±±0.030.03
excluded by TTexcluded by TTand other priorsand other priors
other overtone islandsother overtone islands
also excludedalso excluded
![Page 76: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/76.jpg)
76The Cosmic Background Imager – ATCA, 19 Oct 2004
New: CBI EE Polarization Phase
• Scaling model: spectrum shifts by scaling l – allow amplitude a and scale θ to vary
best fit: best fit: aa=0.93=0.93
slice along a=1:slice along a=1:
θθ//θθ00== 1.021.02±±0.04 (0.04 (22=1)=1)
zoom in: zoom in:
± one-half cycle± one-half cycle
![Page 77: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/77.jpg)
77The Cosmic Background Imager – ATCA, 19 Oct 2004
New: CBI, DASI, Capmap
![Page 78: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/78.jpg)
78The Cosmic Background Imager – ATCA, 19 Oct 2004
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:a=0.5, 0.67 overtone islands:
suppressed by DASIsuppressed by DASI
DASI phase lock:DASI phase lock:
θθ//θθ00== 0.94±0.060.94±0.06a=0.5 (low DASI)a=0.5 (low DASI)
![Page 79: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/79.jpg)
79The Cosmic Background Imager – ATCA, 19 Oct 2004
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:CBI a=0.67 overtone island:
suppressed by DASI datasuppressed by DASI data
other overtone islandsother overtone islands
also excludedalso excluded
CBI+DASI phase lock:CBI+DASI phase lock:
θθ//θθ00== 1.00±0.031.00±0.03a=0.78a=0.78±0.15±0.15 (low DASI) (low DASI)
![Page 80: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/80.jpg)
80The Cosmic Background Imager – ATCA, 19 Oct 2004
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
![Page 81: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/81.jpg)
81The Cosmic Background Imager – ATCA, 19 Oct 2004
CBI Polarization Projections
![Page 82: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/82.jpg)
82The Cosmic Background Imager – ATCA, 19 Oct 2004
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!)
![Page 83: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/83.jpg)
83The Cosmic Background Imager – ATCA, 19 Oct 2004
SZE with CBI: z < 0.1 clusters
P. Udomprasert thesis (Caltech)
![Page 84: The Cosmic Background Imager – ATCA, 19 Oct 2004 2 CMB Polarization Results from the Cosmic Background Imager Steven T. Myers National Radio Astronomy.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649ecf5503460f94bdc8f1/html5/thumbnails/84.jpg)
84The Cosmic Background Imager – ATCA, 19 Oct 2004
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.