Future CMB observations: Can we break CDM? Christian Reichardt - PowerPoint PPT Presentation

Future CMB observations: Can we break Λ CDM? Christian Reichardt University of Melbourne

Outline • Cosmic microwave background (CMB): – What are the neutrino masses? – What caused inflation? • Future CMB experiments – Ground – Satellites

Λ CDM: 6 parameters fit all observations Percival et al 2010 Larson et al 2011 Amanullah et al 2010 Cosmic Microwave Background + Large Scale Structure + Supernovae We live in a flat universe whose expansion is accelerating!

But this can’t last… 1. What are the neutrino masses? 2. What caused inflation? among others — is the Dark sector fully explained by 2 parameters? Ω Λ + Ω c = 0.9539 ± 0.0015

Cosmic Timeline Large-Scale Structure, accelerated expansion Galaxies, many more stars Reionization, BBN, first stars Recombination, CMB Inflation? z=0 z~1000 z~10 z~4 Time z~1 300 kyr 0.5 Gyr 1.6 Gyr 6.0 Gyr 13.8 Gyr

CMB polarization can address these questions z=0 Gravitational lensing and the Sunyaev- CMB power spectrum: Zel’dovich (SZ) e ff ect: • What caused inflation? • What are the neutrino masses? • How many relativistic degrees etc. of freedom (ie neutrino species) are present? etc.

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!

The CMB is polarized 10 o • Any polarization pattern can be decomposed into “E” (grad) and “B” (curl) modes B-modes have a very low background! Smith et al 2008 • Density fluctuations at LSS do not produce “B” modes!

B-modes come from: Inflationary gravitational waves Gravitational lensing 9

Why look at Polarization? E ff ect of Lensing Small Changes Gravity Big wave Changes!!! signal

Lensing power spectrum

Lensing power spectrum 10 − 4 eg ACTpol, SPTpol, stage 2, EB POLARBEAR stage 2, TT 10 − 5 eg AdvACT, SPT-3G, Simons stage 3, EB Array stage 3, TT stage 4, EB CMB-S4 10 − 6 stage 4, TT C κκ 10 − 7 L 10 − 8 Sample variance limits: 10 − 9 * Planck L<40 * SPTpol, ACTpol, POLARBEAR: L < 200ish 10 − 10 500 1000 * CMB-S4: L <1000 ! L from CMB-S4 science book

Neutrinos mass from Lensing Short scales: Faster expansion Massive neutrinos reduce suppresses structure the lensing power spectrum CMB Lensing Potential Power (2D) relative 1.5 • 10 − 7 1.2 1.0 1.0 • 10 − 7 0.8 φφ / 2 π 0.6 m ν L 4 C L Long scales: 5.0 • 10 − 8 Faster expansion & 0.4 clustering cancel 0.2 (no net change) 0 0.0 0 200 400 600 800 10001200 1 10 100 1000 L L

Neutrinos mass forecasts from CMB-S4 science book

Takeaway 1: CMB lensing + BAO or H0 will measure sum of neutrino masses to 15 meV

B-modes come from: Inflationary gravitational waves Gravitational lensing 16

Tensor-to-scalar ratio (r) Scalar perturbations • Perturbations in the energy density. • The only perturbations which form structure due to gravitational instability (therefore only ones required in a minimal model) Tensor perturbations • Gravity waves - transverse-traceless metric perturbations • Generally predicted by inflation models; amplitude related to energy scale at which inflation occurs. r is the ratio of tensor to scalar power at a certain angular scale

Results since last Planck release from L Page

Results since last Planck release from L Page Approximate Planck BB foreground model Handling Galactic foregrounds is key!

Forecast Inflaton constraints includes degradation due 0.1 to foreground cleaning M=10 M P CMB-S4 M 0.03 = 2 0 M BK14/Planck P V ( 1- (φ/M) ) 4 0 M=12 M 2 0.01 P V tanh (φ/M) 0 2 2 r 47< N < 57 m φ * 3 μ φ 47< N < 57 * 0.003 10/3 2/3 47< N < 57 M=2 M μ φ * P Higgs N = 57 * 0.001 2 R N = 50 * 3 10 -4 × 0.955 0.960 0.965 0.970 0.975 0.980 0.985 0.990 0.995 1.00 n s from CMB-S4 science book Pushing limits to r~0.001 would rule out large field inflation models

Slam dunks in the next decade • 95% limit r < 0.001 (or detection) ℓ < 200 • Measure the sum of the neutrino masses to 15 meV. 200< ℓ < 4000 • Probes of dark energy from the abundance of galaxy clusters selected by the Sunyaev-Zel’dvich e ff ect • New tests of GR & the std. model through cross- correlations & growth of structure

Outline Cosmic microwave background (CMB): – What are the neutrino masses? – What caused inflation? • Future CMB experiments – Ground-based – Satellites

Snowmass: CF5 Neutrinos Document arxiv:1309.5383 CMB Experimental Stages Space based experiments Stage-III CMB − 1 Stage − I − ≈ 100 detectors 10 Approximate raw experimental sensitivity ( µ K) Stage − II − ≈ 1,000 detectors Stage − III − ≈ 10,000 detectors experiments are starting WMAP Stage − IV − ≈ 100,000 detectors now, e.g., BICEP3, CLASS, SPT-3G, − 2 10 AdvACT, Simons Array Today Planck Stage-IV CMB − 3 10 experiment = CMB-S4 ~200x faster than the C M Stage 2 experiments B − S 4 − 4 that just finished 10 2000 2005 2010 2015 2020 Year Enabling technologies: • First multichroic detectors on-sky in 2017. • Better multiplexing • Beginning to deploy tens of thousands of detectors

CMB-S4 CMB Experimental Stages: Science Book Science forecasts Order of magnitude improvements x70 x6 x10 x7 compared to today:

CMB-S4 CMB Experimental Stages: Science Book Science forecasts if in thermal Δ Ne ff ≥ 0.047 for spin 1/2, 1, or 3/2 Theoretical targets: equilibrium at some Δ Ne ff ≥ 0.027 for spin 0 point

AdvACT First light in 2017-2018 ~10-20k detectors SPT-3G focal plane P lanned freqs Chile 30, 40, 90, 150, 230 GHz AdvACT +Lens *Simons Array 90, 150, 220, 280 GHz +Lens CLASS 40, 90, 150 GHz *GroundBIRD - MKIDs 150, 220 GHz GroundBIRD Antarctica 90, 150, 220 GHz BICEP3 90, 150, 220 GHz SPT-3G +Lens Experiments finishing now have ~6000 detector-years The experiments starting now plan order 70,000 detector-years

First Light ~2020+ BICEP Array Also Balloons: SPIDER2 EBEX - IDS ~2020: Simons Observatory (Chile) Order 250,000 detector-years BICEP Array (Antartica) SPT-4G? (Antartica) early-mid 2020s Goal: 2 million detector-years CMB-S4 (Chile, Antartica)

LiteBIRD Future Satellites PIXIE concept 2,022$Bolometers$ • LiteBIRD (Japan) - launch in 10 years • PIXIE (recently reviewed for Phase B), CMBpol (concept study) (US) • COrE (EU)

LiteBIRD JAXA’s strategic large mission candidate ▪ In Phase-A1 (~2 years) for concept development Pol. modulator ▪ ▪ Crossed Dragone CMB polarization all-sky surveys for testing cosmic inflation Refractive LFT mirrors ▪ One of top-priority science goals in JAXA roadmap HFT ▪ δ r < 0.001 for full success (w/o delensing) TES array 1.8m ▪ Launch in 2026-27 w/ JAXA’s H3 rocket for 
 3-year observations at L2 ▪ Heritages from JAXA’s cryogenic satellites JAXA Phase-A1 team experience: ▪ ST/JT coolers ▪ X-ray satellites, CMB exp., large-scale projects 
 (in high energy physics, ALMA) Strong support from community in Japan ▪ ▪ Listed as a top-priority large-scale project in Master Plan 2017 of Science Council of Japan International project ▪ Expertise of US team in CMB projects ▪ Expertise of readout electronics in Canada ▪ Planck legacies/lessons learned (Europe+US) ▪ LiteBIRD (2 ≤ ell ≤ 200)

In conclusion • CMB experiments have detected the B-mode polarization signal, enabling: - Searches for inflationary gravitational waves “Smoking gun of inflation” • Must deal with Galactic foregrounds - Precision mass maps through gravitational lensing (neutrino masses) • Experimental sensitivities are improving rapidly with diverse technology base - Order of magnitude improvements with each generation