PolarBear in Chile Measurements of CMB Polarization SPT Keck Array Bicep2 Christian Reichardt University of Melbourne
Outline • CMB polarization & Gravitational Lensing • First detection of lensing B-modes • Future prospects (SPT-3G, Simons Array) – What are the neutrino masses? • Energy injection from dark matter - z ~ O(100): Temperature-polarization correlation - z ~ O(10 7 ): Spectral Distortion
Things left out • only touch upon gravity waves from Inflation � • Temperature probes: • thermal Sunyaev-Zel’dovich e ff ect: • Competitive constraints on dark energy from galaxy clusters • kinetic Sunyaev-Zel’dovich e ff ect (cross- correlated with optical surveys) • Test modified gravity models at ~200 Mpc scales
Temperature is very well measured
CMB is linearly polarized at 10% level by Thompson scattering.
10% Polarized Photons/electrons Thompson scatter at last scattering surface Local radiation quadrupole leads to a preferred direction Electron hot$ Oscillation cold$ cold$ Polarization hot$ direction Net linear polarization!
The CMB is polarized 10 o • Any polarization pattern can be decomposed into “E” (grad) and “B” (curl) modes � � � � � � � � � Smith et al 2008 � � • Density fluctuations at LSS do not produce “B” modes!
B-modes come from: Inflationary gravity waves Gravitational lensing 8
RMS deflection 2.5’; coherent on degree scales T (ˆ n ) ! T (ˆ n + r φ (ˆ n )) Z χ ∗ d χ f K ( χ ∗ − χ ) φ (ˆ n ) = − 2 f K ( χ ∗ ) f K ( χ ) Ψ ( χ ˆ n ; η 0 − χ ) 0
CMB is a unique lensing source � 1. Low systematic uncertainties: � • Gaussian, well-understood power spectrum � • Known, unique redshift � � 2. High redshift � • No higher-z source �
Weighing the Hubble Volume work being led by O. Zahn Planck map of full sky (30 σ ) SPT map of 6% of matter in observable Universe (20 σ ) ACT and SPT temperature measurements are now sample/foreground limited. Only way to get more information is to cover more sky or go to polarization.
E ff ect of Lensing Small Changes Gravity Big wave Changes!!! signal B-modes very important once noise is below ~ 8 uk-arcmin
Outline CMB polarization & Gravitational Lensing • First detection of lensing B-modes • Future prospects (SPT-3G, Simons Array) – What are the neutrino masses? • Energy injection from dark matter - z ~ O(100): Temperature-polarization correlation - z ~ O(10 7 ): Spectral Distortion
Detecting Lensing B-modes • Lens reconstruction in polarization can be thought of as a process of template fitting. • Cross correlations guard against systematics φ B lens E
Correlation with the Cosmic Infrared Background (CIB) Smith+, 2007 Herschel/SPIRE 250, 350, 500 um � May 2012: Map deepest 100 deg 2 of SPT survey to the confusion limit. • Redshift kernel of lensing peaks z~2 � • Well-matched to CIB (80% correlation)
Detecting Lensing B-modes • Lens reconstruction in polarization can be thought of as a process of template fitting. • Cross correlations guard against systematics φ B lens E Herschel CIB!
Detection of B -mode Polarization in the Cosmic Microwave Background with Data from the South Pole Telescope Duncan Hanson et al., PRL 2013 E (SPTpol) Density (SPIRE) Predicted B SPTpol: First detection of lensing B modes ( 7.7 σ ) Uses three-point EB ɸ from SPTpol + Herschel-SPIRE maps of the cosmic infrared background. PolarBear also detects polarized lensing in two ways: 4.0 / 4.2 σ
lensing B-mode Power Spectrum Consistent results using: ‣ 90GHz E-modes. Power (µK 2 x10 4 ) ‣ Temperature-derived E-modes. ‣ TT, TE, EE, EB lensing estimators. � No signal seen using: ‣ Curl-mode null test. ‣ E-modes from di ff . map. ‣ B-modes from di ff . map. Angular Frequency (multipole) Not yet a test of gravity waves (GW) • Cross-correlation eliminates GW signal • Wrong angular scales (GW in blue region)
Outline CMB polarization & Gravitational Lensing Lensing B-modes (first detected in 2013) • Future prospects (SPT-3G, Simons Array) – What are the neutrino masses? • Energy injection from dark matter - z ~ O(100): Temperature-polarization correlation - z ~ O(10 7 ): Spectral Distortion
E ff ect of Lensing Small Changes Gravity Big wave Changes!!! signal B-modes very important once noise is below ~ 8 uk-arcmin
Go big! credit: B. Benson 2001: ACBAR � 16 detectors Stage-2 2007: SPT � 960 detectors 2012: SPTpol � ~1600 detectors � Stage-3 2012: PB � 2016: SPT-3G � 1500 detectors ~15,200 detectors � Simons Array: � Stage-4 30k detectors 2020?: CMB-S4 � 100,000+ detectors Pol Pol Detector sensitivity has been limited by photon “shot” noise for last ~15 years; further Pol improvements are made only by making more detectors!
Tech directions Multichroic pixels Multiplexing Keck Array Simons Array Multiple dewars / telescopes
CMB Experimental Stages Space based experiments − 1 Stage − I − ≈ 100 detectors 10 Approximate raw experimental sensitivity ( µ K) Stage − II − ≈ 1,000 detectors Stage − III − ≈ 10,000 detectors WMAP Stage − IV − ≈ 100,000 detectors Stage-IV CMB − 2 10 experiment = Today e.g., � CMB-S4 SPT-3G � ~200x faster Simons Array � Planck Adv ACTpol than today’s − 3 e.g., � 10 Stage 2 SPTpol � experiments POLARBEAR � ACTpol C M B − S 4 − 4 10 2000 2005 2010 2015 2020 Year Snowmass: CF5 Neutrinos Document � arxiv:1309.5383
Much more to come! adapted from B. Sherwin Lensing B-modes have been detected by: SPTpol, P OLARBEAR Stage 3 160$ ! Signal'to'Noise-on-Lensing-Power-Spectrum- Current best: � 140$ Planck: 30 σ � 120$ Taking data now (Stage 2): � 100$ SPTpol / P OLARBEAR / ACTpol : ~ 45 σ � 80$ 5! Stage 2 60$ t! Data-taking starts ~2016 40$ (Stage 3): � SPT-3G / Simons Array / Adv 20$ ACTpol: ~ 150 σ � 0$ � SPTpol � SPT-3G � ACT-1 SPT-1 ACT-full Planck-1 SPT-full Polarbear � Simons Array � Stage 4 ~ early 2020s ACTpol Adv ACTpol
Neutrinos as seen by Structure Matter power spectrum today m ν Long Short P(k) @ z=0 scales: scales: Faster Faster ∑ m ν = 0 eV expansion expansion & suppresses ∑ m ν = 0.94 eV clustering structure cancel (no net change) k (Mpc -1 ) 100 meV changes BB power by up to 5% There are 3-4 sigma ‘detections’ at ~300 meV
Predictions for neutrino masses Planck + DESI (BAO) Simons + Planck Simons + Planck + DESI (BAO) σ ( ∑ m ν ) =18 meV Also: x1.8 improvement on (22 meV for SPT3G) N e ff vs Planck
An aside: Inflation Constraints 1 BICEP2 r=0.20 +0.07-0.05 0.1 Stage 3: x5-10 better than Δϕ ¡ ≳ ¡m pl BICEP2 � 0.01 Δϕ ¡ ≲ ¡m pl � Stage 4: � 0.001 x50 better than BICEP2 � 0.0001 � Both stage 3/4 0.00001 include multiple frequencies for foreground control Snowmass: CF5 Inflation Document � arxiv:1309.5381
Outline CMB polarization & Gravitational Lensing Lensing B-modes (first detected in 2013) Future prospects (SPT-3G, Simons Array) – What are the neutrino masses? • Looking for energy injection from dark matter - z ~ O(100): Temperature-polarization correlation - z ~ O(10 7 ): Spectral distortion
Extra O(100) GeV positrons PAMELA (2008); confirmed by AMS (2013) What could produce these? - Exotic pulsars? - Dark matter? - None of the above. AMS collaboration e ± energy [GeV] from Doug Finkbeiner
from Doug Finkbeiner Modifies ionization history • WIMP annihilation/decay injects high-energy particles & photons into the gas at z~O(100). 1 Padmanabhan & Finkbeiner 2005 10 -1 x e 10 -2 10 -3 Increases ionization fraction 10 4 and temperature 10 3 T mat (K) 10 2 10 1 10 0 10 100 1000 Redshift
from Doug Finkbeiner Detectable in the CMB � Slatyer, et al. 2009 • Increased ionization fraction broadens 2 1 “last-scattering” 5 Ruled out by WMAP5 8 3 4 – weakens T-P 6 7 correlations; 10 Sampling of 9 strengthens PP 11 PAMELA models 12 1 XDM µ + µ - 2500 GeV, BF = 2300 correlations 13 2 µ + µ - 1500 GeV, BF = 1100 3 XDM µ + µ - 2500 GeV, BF = 1000 4 XDM e + e - 1000 GeV, BF = 300 5 XDM 4:4:1 1000 GeV, BF = 420 • Measure total Planck 6 e + e - 700 GeV, BF = 220 forecast 7 µ + µ - 1500 GeV, BF = 560 CVL energy injection 8 XDM 1:1:2 1500 GeV, BF = 400 9 XDM µ + µ - 400 GeV, BF = 110 10 µ + µ - 250 GeV, BF = 81 which constrains 11 W + W - 200 GeV, BF = 66 12 XDM e + e - 150 GeV, BF = 16 WIMP properties 13 e + e - 100 GeV, BF = 10 PAMELA/AMS models predict similar energy injection, can be ruled out with Planck polarization data soon!
from Kogut et al. 2011 Light Dark Matter? (neutralino/gravitinos) Electromagentic Energy Release BBN limits Decay/annihilation add energy in early Universe: 10 6 < z < 10 8 Energy release: Δ E ~ Ω DM 𝛥 Δ m Chemical potential: μ ~ Δ E/E Plot for gravitinos Lifetime ==> Distortion in the CMB black-body spectrum
from Kogut et Measuring distortion al. 2011 PIXIE is a proposed nulling Fourier Transform Spectrometer � see also PRISM, LiteBird PIXIE forecast: PIXIE forecast: μ < 1e-8 (95%CL) x10,000 better than COBE /FIRAS Also excellent at disentangling foregrounds and inflationary gravity waves
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