Towards fundamental physics from the cosmic microwave background - PowerPoint PPT Presentation

Towards fundamental physics from the cosmic microwave background Hiranya V. Peiris UCL and Stockholm

(Part of) the Planck team

C REDIT : BICEP / K ECK C OLLABORATIONS

Temperature quadrupole at surface of last scattering creates polarisation… C REDIT : BICEP / K ECK C OLLABORATIONS

Radial (tangential) pattern around hot (cold) spots. Measurement Cold spot Hot spot I Q I Q Cold spot Hot spot Theory prediction Planck Collaboration (2013)

C REDIT : ESA / P LANCK

Compress the CMB map to study cosmology Express sky as: � δ T ( θ , φ ) = a lm Y lm ( θ , φ ) l,m 0.06% of map 5 deg X 1 deg +/- 32 uK 1 � Angular power spectrum | a lm | 2 C l = 2 ℓ + 1 m

WMAP “first light” spectrum power larger smaller scales scales

Planck 2015 Temperature Credit: Planck Collaboration

Planck 2015 TE Polarization Credit: Planck Collaboration

Planck 2015 EE Polarization Credit: Planck Collaboration

Radical data compression! 50 million pixels... 2500 multipoles... six cosmological parameters!

Planck TT + lowP cosmological parameters Planck EE+lowP Planck TE+lowP ~directly measured Planck TT+lowP Planck TT,TE,EE+lowP Ω b h 2 = 0.02222 ± 0.00023 0.0275 0.0250 Ω b h 2 Ω c h 2 = 0.1197 ± 0.0022 0.0225 0.0200 n s = 0.9655 ± 0.0062 0.13 0.12 Ω c h 2 0.11 τ = 0.078 ± 0.019 0.10 3.20 ln(10 10 A s ) 3.12 ln(10 10 A s ) = 3.089 ± 0.036 3.04 2.96 1.02 derived 0.99 n s 0.96 0.93 H 0 = 67.31 ± 0.96 km/s/Mpc 0.16 0.12 τ Ω Λ = 0.685 ± 0.013 0.08 0.04 1.038 1.040 1.042 0.0200 0.0225 0.0250 0.0275 0.10 0.11 0.12 0.13 2.96 3.04 3.12 3.20 0.93 0.96 0.99 1.02 0.04 0.08 0.12 0.16 100 θ MC Ω b h 2 Ω c h 2 ln(10 10 A s ) n s τ σ 8 = 0.829 ± 0.014 Cosmological parameters not “directly measured”; details depend on models [“priors”]

C REDIT : ESA / P LANCK

Deflections are ~ 2 arcmin C REDIT : ESA / P LANCK

CMB lensing potential reconstruction Credit: Planck Collaboration

CMB lensing potential power spectrum Detected at ~40 σ (nearly doubled 2013 sensitivity): breaks parameter degeneracies from primary CMB alone; new window on growth of cosmic structure Credit: Planck Collaboration

CMB lensing potential reconstruction 2500 sq. deg. map of gravitational lensing potential projected along the line of sight 
 (South Pole Telescope 150 GHz + Planck 143 GHz) Omori et al (SPT Collaboration, 2017)

Cross-correlations with large-scale structure probes • Secondary CMB contributions 
 Integrated Sachs-Wolfe effect, thermal / kinetic Sunyaev-Zel’dovich effect, lensing, cosmic infrared background…. 
 • Cross-correlations with non-CMB “tracers” 
 Galaxy surveys, clusters, weak lensing mass maps, velocity reconstructions… 
 • Reveals interplay of dark and light matter in evolved universe 
 Intracluster gas, “missing” baryons, star formation history, halo masses…

Cross-correlations with large-scale structure probes WL x CMB lensing DESxSPT, DESxPlanck (Kirk et al 2015) Original detection of kSZ kSZ (4.2 σ ) ACT x BOSS cluster positions DES clusters x SPT-SZ (Hand et al 2012) (Soergel et al 2016) Hill, Spergel (2014), Van Waerbeke et al (2014), Ferraro et al (2016), Soergel et al (2016), Hill et al (2016), Schaan et al (2015), Planck Collaboration (XIX 2013, XXXVII 2015), Hand et al (2012), Harnois-Deraps et al (2016), Kirk et al. (2015), Liu, Hill (2015), Omori, Holder (2015), Ma et al (2015), Hand et al (2014), Serra et al (2014), Giannantonio et al (2015), Hurier et al (2017)

Geometry & Topology of the Universe - Einstein’s General Relativity explains local curvature of spacetime but doesn’t tell us global geometry and topology of Universe. - No evidence for non-trivial geometry or topology, tight constraints on models. Simulated Bianchi CMB contributions Best fit Bianchi component to Planck Planck Collaboration (2015)


 
 
 How isotropic is the Universe? Anisotropic expansion • Tested full Bianchi freedom to E S V 2 - p × o l p × m 6 e + T 0 conduct general test of isotropy. 
 = Temp × 5 Pol × 150 Temp × 5 Pol × 150 0 • Highly constraining polarisation + + 6 × l o p - B T reg T irr data used for the first time. 
 Rotate Stochastic fluctuations e E E r - u p 2 - p t o × a o l r l × p e × p m 1 m 6 0 e T 0 e 0 • Vectors: 
 T + ( σ V /H ) 0 < 4 . 7 × 10 − 11 (95% CL) 0 0 0 6 1 × × l l o o p p - - B B E p Tensors: 
 o e l +0.25 mK r a r Collins and Hawking (1973) u i t z a a r t e i p o m n × e (95% CL) T ( σ T /H ) 0 < 1 . 0 × 10 − 6 3 0 = • Anisotropic expansion of the 0 3 × n Universe disfavoured by 120,000:1. o i t a z i r a l o p Total CMB sky B –0.25 mK Saadeh, Feeney, Pontzen, Peiris, McEwen (PRL, 2016)

Inhomogeneous nonlinear (ultra)-large scale cosmology • Dawn of numerical relativity in cosmology . CMB-related examples: 
 Constraining ultra-large scale inhomogeneities with CMB quadrupole 
 Testing eternal inflation with cosmic bubble collisions imprint on the CMB Inflation Numerical GR 0 . 5 Gaussian � ends early C obs 0 . 4 2 � ˆ � � 0 . 3 log 10 ( A φ ) 0 . 2 2 α = 0 . 1 � 300 P 0 . 0 − 6 − 5 − 4 − 3 log 10 ( A φ ) ultra large scale structure amplitude ︎ Bentivegna, Bruni (2016), Mertens, Giblin, Starkman (2016), East, Kleban, Linde, Senatore (2015) ︎ Wainwright, Johnson, Peiris, Aguirre, Lehner, Leibling (2014), Johnson, Peiris, Lehner (2012) ︎ Adamek, Daverio, Durrer, Kunz (2016), Braden, Johnson, Peiris, Aguirre (2016), GRChombo (2015)

H 0: Cosmological vs distance ladder measurements Figure: Science Magazine

Cosmic (in)consistency: real or “tension in a teapot”? Systematics? astrophysics? (new) physics? Freedman (2017) adapted from Beaton et al (2016)

“No one trusts a model except the person who wrote it; everyone trusts an observation, except the person who made it”. paraphrasing H. Shapley

Raw data : ~quadrillion samples over 29 months (HFI), 50 months (LFI) Maps : ~50 million pixels over 9 frequencies Planck (2015)

Emission at frequency = CMB + astrophysical sources along line of sight. Planck observes in 9 bands over 30–850 GHz to disentangle cosmology from astrophysics C REDIT : ESA / P LANCK

Just beginning to characterise polarised foregrounds polarised polarised synchrotron dust Polarised FG complex & filamentary Planck Collaboration (2015), Planck intermediate results. XLIV. (2016)

Frequency dependence of Galactic foregrounds CMB obscured by astrophysical foregrounds at all frequencies Orders of magnitude worse for polarisation RMS brightness temperature (uK) 30 44 70 100 143 217 353 545 857 30 44 70 100 143 217 353 Sum fg Thermal dust Synchrotron RMS brightness temperature ( µ K) RMS brightness temperature ( µ K) 2 2 10 10 C M Thermal dust B 1 1 10 10 Sum fg F r 0 0 e 10 S 10 e CMB - p f CO 1-0 r e i e n n Synchrotron i n g d -1 -1 u 10 10 s t 10 30 100 300 1000 10 30 100 300 1000 Frequency (GHz) Frequency (GHz) Temperature Polarisation Planck Collaboration

What do we know about cosmic initial conditions? • Background: ‣ Spatial flatness (tested at <1% level!) • Perturbations: ‣ scalar fluctuations in the CMB temperature ✓ nearly but not exactly scale-invariant (>5 σ !) ✓ approximately Gaussian (at the 10 -4 level!) ✓ Adiabatic fluctuations ✓ Superhorizon perturbations ? primordial tensor fluctuations (stochastic gravitational waves)

Gravitational waves also create polarisation…. lensing creates B -mode polarisation from E -mode polarisation even if no tensors. C REDIT : BICEP / K ECK C OLLABORATIONS

CMB polarisation status A Measurement of the Cosmic Microwave Background B-Mode Polarization Power Spectrum at Sub- degree Scales with P OLARBEAR 
 The P OLARBEAR Collaboration 
 The Astrophysical Journal ( 2014 ) f =90% s Measurements of Sub-degree B-mode k y Polarization in the Cosmic Microwave Background from 100 Square Degrees of polarized SPTpol Data 
 dust + synchrotron R. Keisler et al. 
 The Astrophysical Journal, ( 2015 ) @ 100GHz lensing 
 B-modes Joint Analysis of BICEP 2 / 
 f =1% s k y Keck Array and Planck Data 
 P . Ade et al. 
 Physical Review Letters ( 2015 ) BICEP/Keck Array 95 GHz (2015) 
 r<0.09 (95%) Yuji Chinone / Josquin Errard

CMB polarisation status PolarBear Collaboration (2017)

The challenge Typical degree-scale brightness fluctuations (150GHz) T P Ground, Telescope mount etc 3-300 K 10 8 - 10 10 10 6 - 10 8 Atmosphere 30 mK - 3 K 10 4 - 10 6 Galaxy 0.3-30mK 10 3 CMB T anisotropies 30 μ K 10 Lensing B modes (at arcmin) 300 nK r=0.01 B-modes 30 nK noise you want to reach <10 nK Adapted ¡ ¡from ¡C. ¡Pryke

Polarisation is not going to be easy. • Planck/BICEP2/Keck: polarised dust and/or synchrotron important at all Galactic latitudes (1502.00612, 1502.01588) • Lensing additional “foreground” for tensors Errard, Feeney (joint first authors), Peiris, Jaffe (JCAP , 2016)