Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.mrao.cam.ac.uk/projects/cmb/workshop_jul09/talks/challinor.pdf Дата изменения: Wed Jul 29 18:31:02 2009 Дата индексирования: Tue Aug 18 10:28:19 2009 Кодировка: Поисковые слова: южная атлантическая аномалия

CMB B -modes ­ science and systematics
Anthony Challinor Institute of Astronomy and Kavli Institute for Cosmology Cambridge and Depar tment of Applied Mathematics and Theoretical Physics University of Cambridge a.d.challinor@ast.cam.ac.uk

UK involvement in future ground-based B-mode and SZ experiments Cambridge, 20­21 July 2009


C U R R E N T O B S E RVAT I O N A L E V I D E N C E F O R I N FL AT I O N
· Inflation predicts: ­ A flat universe (c.f. -0.0178 < K < 0.0066 from WMAP5+BAO+SN) ­ Scalar fluctuations with percent-level deviations from scale-invariance (c.f. 014 ns = 0.963+0..015 from WMAP5 assuming r = 0) -0 ­ Gaussian fluctuations (c.f. |fN L| PR < 10-3) ­ Adiabatic fluctuations ­ Super-horizon fluctuations (c.f. T E anti-correlation for 5 > > 1) ­ Detectable gravity waves if inflation occurs at GUT scale

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T H E O R Y P O W E R S P E C T R A ( r = 0 .2 )

· Linear scalar fluctuations do not produce B -mode polarization
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G R AV I TAT I O N A L WAV E S I N T H E C M B

· Cosmic variance of dominant scalar fluctuations limits r = 0.07 from T and r = 0.02 if include E ­ Degeneracies make actual limits worse; WMAP5 alone r < 0.43 (95% CL)
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CURRENT CONSTRAINTS: T E AND EE

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T E AND EE FORECASTS FOR PLANCK

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CURRENT CONSTRAINTS: BB

· BICEP limit (Chiang et al. 2009) on r from B -modes alone: r < 0.73 (95% CL)
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W H AT W O U L D A D E T E C T I O N O F P R I M O R D I A L G R AV I T Y WAV E S T E L L U S ?
· Strong evidence that inflation happened · Power spectrum Ph(k) is model-independent measure of energy scale of inflation
4 H2 Einf 8 -11 = 1.92 в 10 Ph = 2 2 1016 GeV MPl ­ In terms of tensor-to-scalar ratio

r = 0.008(Einf /1016 GeV)4 ­ Detectable gravity waves (r > 0.01 say) would mean inflation occured at the GUT scale · In canonical single-field models (Lyth 1997) 8 d 2 r= 2 MPl dN ­ Field evolution over 60 e-folds: (r/0.002)1/2 ­ Detectable gravity waves means inflaton evolved through a super-Planckian distance ­ Smooth potential over > MPl problematic for effective field theor y with cut-off < MPl unless shift symmetry removes higher-order corrections
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C O N S T R A I N I N G T H E S H A P E O F T H E I N FL ATO N P OT E N T I A L
8 2 MPl H 2 H 2
2 2

P h (k ) P R (k )

r P R (k ) H
2

8 2 MPl

H 2

2

1 в 8M

2 Pl

V V

2

· r and power-law spectral index
2 ns - 1 2MPl[V /V - (3/2)(V /V )2 ]

probe slope and curvature of potential

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SENSITIVITIES REQUIRED
· Ground-based surveys probing recombination signal with P = 5 µK-arcmin require 1000 deg2 for (r) = 0.005 ­ Need array sensitivity to Q (and U ) of 15 µK s1/2 for one year of obser vations · Comparable sensitivity to Planck using the reionization signal

Kendrick Smith (r = 0 )
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WEAK LENSING OF THE CMB
· Smooths acoustic peaks in T and E · Generates additional small-scale power · Generates B -modes from primordial E -modes ­ Acts as a source of noise with P 5 µK-arcmin for detecting large-scale primordial B -modes

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L E N S I N G R E C O N S T RU C T I O N W I T H B - M O D E S
· Statistically reconstruct deflection field from higher-order lens-induced statistics · Polarization most powerful since more small-scale features and (for E -B ) no confusion from small-scale primordial B -modes ­ Reconstruction with polarization requires better than 5 µK-arcmin imaging

Kendrick Smith
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S C I E N C E F R O M L E N S E D C M B : m A N D w
· Oscillation data m > 0.05 eV · Not ver y contraining for dark energy (w) > 0.08 as CMB lensing most sensitive to z 2 ­ Interesting constraints in early dark energy models

Smith et al. (2008)
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S Y S T E M AT I C E FF E C T S
· Instrumental polarization ­ T P ­ beam size ­ gain ­ beam offset ­ beam shape ­ temporal response ­ spectral pass band ­ Far sidelobes · "Cross polarization" ­ E B ­ Co-rotation ­ Absolute pointing · Other ­ 1/f noise ­ Errors in noise estimation ­ Thermal variations ­ Magnetic pick-up

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M I T I G AT I O N O F R E D U C I B L E E FF E C T S
· Many systematics reducible with good angular coverage/modulation ­ E.g. gain fixed w.r.t. instrument but true polarization is spin 2 ­ E.g. differential pointing couples T to P and rotates like spin 1

Bock et al. (0906.1188)

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S Y S T E M AT I C E R R O R S I N B I C E P

Relative gain Diff. pointing Focal plane temp. stability Polarization orientation Optics temp. stability Differential ellipticity Pol. sidelobes (100, 150) Differential beam size Absolute pointing

Measured < 1.1% 1.3% 1 nK < 0.7% 0.7 µK < 0.2% -9, -4 dBi < 0.3% 0.2

Equiv. r < 0.15 0.05 0.01 < 0.01 0.003 < 0.002 0.002 < 0.0007 0.0002

Takahashi et al. (0906.4069) · "Old" technology (horns, PSBs etc) · No active modulation (cf. Maxipol)

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