ProbingProbing InflationInflation withwith CMBPolCMBPol Gary Hinshaw, NASA/GSFC Presentation to NRC Beyond Einstein Program Assessment Committee November 7, 2006 Gary Hinshaw, NRC-BEPAC, 11/7/06 TheThe ConceptConcept StudyStudy TeamTeam • Chuck Bennett (GFSC) • Barth Netterfield (U. Toronto) • Mark Devlin (U. Penn) • Angelica Oliviera-Costa (U. Penn) • Dale Fixsen (GSFC) • Lyman Page (Princeton) • Gary Hinshaw (GSFC, PI) • John Ruhl (Case Western) • Wayne Hu (U. Chicago) • Uros Seljak (Princeton) • Kent Irwin (NIST/Boulder) • David Spergel (Princeton) • Norm Jarosik (Princeton) • Suzanne Staggs (Princeton) • Alan Kogut (GSFC) • Max Tegmark (U. Penn) • Arthur Kosowsky (Rutgers) • Bruce Winstein (U. Chicago) • Michele Limon (GSFC) • Ed Wollack (GSFC) • Steve Meyer (U. Chicago) • Ned Wright (UCLA) • Amber Miller (Columbia) • Matias Zaldarriaga (Harvard) • Harvey Moseley (GSFC) • Cliff Jackson (GSFC) • Barth Netterfield (U. Toronto) Gary Hinshaw, NRC-BEPAC, 11/7/06 1965:1965: PenziasPenzias && WilsonWilson DiscoverDiscover thethe CMBCMB ArnoArno Robert PenziasPenzias Wilson Microwave Receiver- Bell Labs Full sky image, green represents the CMB New Jersey 1978 Nobel Prize in Physics 19891989--1993:1993: COBECOBE UnleashesUnleashes thethe CMBCMB COBE-FIRAS spectrum JohnJohn George of the CMB MatherMather Smoot COBE-DMR anisotropy of the CMB 2006 Nobel Prize COBE Spacecraft in Physics Gary Hinshaw, NRC-BEPAC, 11/7/06 2006:2006: PrecisionPrecision MeasurementsMeasurements ofof thethe CMBCMB Tremendous progress has been made! ΔT ~ 0.1 K in 1965 ΔT ~ 0.1 μK in 2005 Advances in space - largely based on experience gained in numerous balloon and ground-based campaigns. Gary Hinshaw, NRC-BEPAC, 11/7/06 ProbingProbing InflationInflation withwith thethe CMBCMB COBE WMAP Planck CMBPol The only thing standing between the CMB and inflation is a thin layer of warm plasma. Gary Hinshaw, NRC-BEPAC, 11/7/06 SixSix TestsTests ofof InflationInflation (after(after Steinhardt)Steinhardt) • The following are “generic” predictions of inflation, phenomena for which we had little evidence when inflation was introduced in 1980: – nearly-scale-invariant fluctuations • spectral index - measured with ~20% precision by COBE – flat universe • position of 1st acoustic (BAO) peak - measured by TOCO, Boomerang, WMAP1 – adiabatic fluctuations • coherence of acoustic (BAO) peaks - measured by Boomerang, …, WMAP1 – gaussian fluctuations • limits on fNL, measured by WMAP1 – super-horizon fluctuations • TE anti-correlation on >2° scales, measured by WMAP1 – spectral tilt, ns < 1 • favored by WMAP3 – gravity waves (a.k.a. tensor fluctuations) • measured by the Inflation Probe… Gary Hinshaw, NRC-BEPAC, 11/7/06 InflationInflation andand GravityGravity WavesWaves -- II • Inflation predicts two forms of fluctuations: – Scalar modes (density perturbations) with slope ns: • generate CMB anisotropy and lead to structure formation – Tensor modes (gravity waves) with slope nt: • generate CMB anisotropy but do not contribute to structure formation • Gravity wave amplitude, r, proportional to energy scale of inflation: 1/4 2 4/1 Vφ Einfl ()ΔT tensor r ∝ = 16 with r ≡ 2 3m .pl 3 10× GeV ()ΔT scalar • Both types of fluctuations contribute to CMB temperature anisotropy: Gary Hinshaw, NRC-BEPAC, 11/7/06 InflationInflation ParameterParameter MeasurementsMeasurements c.2006c.2006 0 .ns = 960± 0 . 016 Spergel et al., 2006 r < 3.0 16 E 2 .infl< 6 10 × GeV • “Generic” HZ model: (ns,r) = (1,0) disfavored at ~ 95% CL. • Slow roll inflation models relate ns and r, as shown. • ns<1 suggests r should be observable. “We find that, except for (inflation models) with numerous unnecessary degrees of fine-tuning, n < 0.98, measurably • Knox et al. estimate r ~ 0.13 s is the lowest amplitude different from exact HZ. Furthermore, if ns > ~0.95, in accord with current measurements, the tensor/scalar ratio satisfies r > ~10─2, detectable with temperature data. a range that should be detectable in proposed CMB polarization experiments.” • Further progress requires Boyle, Steinhardt, Turok (2005) polarization. Gary Hinshaw, NRC-BEPAC, 11/7/06 InflationInflation andand GravityGravity WavesWaves –– IIII • Both types of fluctuations contribute to CMB polarization anisotropy: – Scalar modes produce only “E-mode” polarization patterns, by symmetry – Tensor modes produce both “E-mode” and “B-mode” polarization patterns (see below) • The observation of B-mode polarization uniquely separates scalar and tensor modes from inflation and measures the energy scale of inflation. • Only known probe of physics at E ~ 1016 GeV… 12 orders of magnitude higher than planned accelerators! E – scalar+tensor B – tensor only Gary Hinshaw, NRC-BEPAC, 11/7/06 TaskTask ForceForce onon CMBCMB ResearchResearch (TFCR)(TFCR) • The value of CMB polarization measurements was emphasized in the last National Academy of Science Decadal Survey. • The 2003 National Research Council report, Connecting Quarks with the Cosmos, recommended that NASA, NSF, and DoE: – “Measure the polarization of the cosmic microwave background with the goal of detecting the signature of inflation” and “undertake research and development to bring the needed experiments to fruition.” • OSTP response to the CPU report: – "The three agencies (NASA, NSF, DoE) will work together to develop by 2005 a roadmap for decisive measurements of both types of CMB polarization. The road map will address needed technology development and ground-based, balloon-based, and space-based CMB polarization measurements." • TFCR Report (“The Weiss Report”) was issued Fall 2005 – “We recommend that NASA, NSF and DoE carry out a phased program of ground-, balloon- and space-based measurements of the CMB polarization anisotropy, with a primary emphasis on mapping the B-mode (gravity wave) signal to a sensitivity limited only by our ability to model and subtract the astrophysical foregrounds.” Gary Hinshaw, NRC-BEPAC, 11/7/06 TaskTask ForceForce MembershipMembership • Task Force: • Agency Observers: – Rainer Weiss (chair), MIT – Beverley Berger, NSF – James Bock, Caltech / JPL – Vladimir Papitashvili, NSF – Sarah Church, Stanford University – Michael Salamon, NASA/HQ – Mark Devlin, University of Pennsylvania – Nigel Sharp, NSF – Gary Hinshaw, NASA / GSFC – Kathy Turner, DoE – Andrew Lange, Caltech – Adrian Lee, U.C. Berkeley / LBNL – Lyman Page, Princeton University – Bruce Partridge, Haverford College – John Ruhl, Case Western Reserve – Max Tegmark, Penn. / MIT – Peter Timbie, University of Wisconsin – Bruce Winstein, University of Chicago – Matias Zaldarriaga, Harvard University Gary Hinshaw, NRC-BEPAC, 11/7/06 PredictedPredicted PolarizationPolarization Signal,Signal, r=1.00r=1.00 Temperature spectrum (as before) Observed=scalar+tensor E-mode polarization spectrum, scalar (blue) & tensor (red) terms B-mode polarization spectrum, Observed=tensor (+lensing) tensor (red) & gravitational lensing (green) terms Gary Hinshaw, NRC-BEPAC, 11/7/06 PredictedPredicted PolarizationPolarization Signal,Signal, r=0.10r=0.10 Temperature spectrum (as before) Observed=scalar+tensor E-mode polarization spectrum, scalar (blue) & tensor (red) terms B-mode polarization spectrum, Observed=tensor (+lensing) tensor (red) & gravitational lensing (green) terms Gary Hinshaw, NRC-BEPAC, 11/7/06 PredictedPredicted PolarizationPolarization Signal,Signal, r=0.01r=0.01 Temperature spectrum (as before) Observed=scalar+tensor E-mode polarization spectrum, scalar (blue) & tensor (red) terms B-mode polarization spectrum, Observed=tensor (+lensing) tensor (red) & gravitational lensing (green) terms Gary Hinshaw, NRC-BEPAC, 11/7/06 CurrentCurrent PolarizationPolarization DataData –– WMAP3WMAP3 Page et al., 2006 TT – temperature anisotropy TE – temperature – polarization correlation, (measured in 1st year data) E-mode polarization, (measured in 3-year data) B-mode polarization (data upper limit from 3-year data, model upper limit from TT data) Gary Hinshaw, NRC-BEPAC, 11/7/06 BBBB CloseClose--UpUp Green - lensing foreground (EE→BB from scalars), frequency independent r=0.3 Red - gravity wave signal: r=0.3: current upper limit r=0.01 r=0.01: target sensitivity for CMBPol Gary Hinshaw, NRC-BEPAC, 11/7/06 10001000 BackgroundBackground--LimitedLimited DetectorsDetectors Grey shaded band - 1-sigma sensitivity for 1000-channel system with 1-yr observing and 1°FWHM resolution. r=0.3 r=0.01 Gary Hinshaw, NRC-BEPAC, 11/7/06 SensitivitySensitivity && ForegroundForeground EstimatesEstimates Blue band - Galactic foreground estimate from WMAP3, frequency dependent Green line - Lensing (EE→BB), frequency independent Red lines - r=0.3 Gravity wave signal(s) Grey shaded band - 1-sigma sensitivity for r=0.01 1000-channel system with 1-yr integration, 1°FWHM resolution Gary Hinshaw, NRC-BEPAC, 11/7/06 TheThe RoadRoad toto nanoKelvinnanoKelvin MeasurementsMeasurements Measuring CMB polarization at the nanoKelvin level requires: • Sensitivity: – Employ ~1000 background-limited detectors. – Mostly a fabrication problem, not a fundamental one. • Removal of foreground signals: – Employ multiple frequencies, roughly 30-300 GHz. – Details of frequency coverage depend on complexity of foreground signals. VPM • Control of systematic errors: (few sec) – Modulate polarization signal on multiple time scales Annual Spin to reject unpolarized light. (1 year) (few min) – Control polarized stray light. Orbit (1+ hr) → hardware design and scan strategy. – Monitor gain fluctuations to a level commensurate with modulation strategy. → calibration strategy Gary Hinshaw,