Report

Constraints on the neutrino mass by future precise CMB polarization and 21cm line observations Yoshihiko Oyama The Graduate University for Advanced Studies KEK cosmophysics group Collaborators Masashi Hazumi (KEK CMB group) Kazunori Kohri (KEK cosmophysics group) ◇ Focused experiments Plancktemperature, E-mode, B-mode ＋ POLARBEAR-2 or Simons Array E-mode, B-mode ＋ SKA Phase1, Phase2 21cm line brightness temperature（z=7-10） We studied their sensitivities to constraints on the sum of the neutrino masses and the mass hierarchy. 2 ◇ Focused experiments Plancktemperature, E-mode, B-mode ＋ POLARBEAR-2 or Simons Array E-mode, B-mode ＋ SKA Phase1, Phase2 21cm line brightness temperature（z=7-10） ＋ Baryon Acoustic Oscillation (BAO) 3 contents 1. 21cm line observations 2. Effects of neutrinos on the growth of the density fluctuations 3. Future constraints on the neutrino mass by CMB and 21 cm line 4. Summary 4 contents 1. 21cm line observations 2. Effects of neutrinos on the growth of the density fluctuations 3. Future constraints on the neutrino mass by CMB and 21 cm line 4. Summary 5 1. 21cm line observations ・Introduction ・21cm line brightness temperature and the power spectrum 6 ◇ 21cm line 21cm line results from hyperfine splitting of neutral hydrogen. 1S state = cm 21 = . Spin =1 triplet proton electron Spin =0 singlet = . × − eV 7 ◇ Cosmological 21 cm radiation S.G. Djorgovski et al. & Digital Media Center, Caltech. CMB z~1000 Dark age Cosmic dawn 15 ≲ z ≲ 30 (The late stage of the dark age) The epoch of reionization 6 ≲ z ≲ 15 We particularly focused on the epoch of reionization ( 7 ≲ z ≲ 10 ) 8 ◇ 21cm line and cosmology = 21 cm 21cm This signal has information of the matter distribution. We can constrain cosmological parameters (e.g. ΩCDM .) M.McQuinn, O.Zahn, M.Zaldarriaga, L.Hernquist, S.R. Furlanetto (2006) Astrophys.J.653:815-830,2006 9 ◇ Advantages of 21 cm line observations Z=0 linear non linear [ℎ Mpc −1 ] () [ℎ−3 Mpc 3 ] () [ℎ−3 Mpc 3 ] １. Non-linear effects are small Z=3 linear non linear [ℎ Mpc −1 ] ２. Broad redshift range ・ A lot of independent Fourier modes. ・ The time evolution of the density fluctuations 10 1. 21cm line observations ・Introduction ・21cm line brightness temperature and the power spectrum 11 ◇ Brightness temperature 21 , , ≈ 27HI 1 + 1+ Ω ℎ 2 0.023 Fluctuation of baryon × 1 − 0.15 1 + Ω ℎ2 10 1 2 ()/(1 + ) || /|| 1. Peculiar velocity of gas 2. Expansion of universe : Spin temp : CMB temp HI : Neutral fraction > emission（6 ≲ z ≲ 15） < absorption（15 ≲ z ） 12 contents 1. 21cm line observations 2. Effects of neutrinos on the growth of the density fluctuations 3. Future constraints on the neutrino mass by CMB and 21 cm line 4. Summary 13 ◇ Effects of neutrinos on the growth of the density fluctuations ~ Horizon scale When neutrinos are relativistic ≪ , neutrinos run up to the horizon scale (Free-streaming) This effect erases their own fluctuations within such scales. 14 Matter power spectrum = = The free-streaming effects of neutrinos Heavier neutrino mass This suppression becomes larger. Total mass Σ = 1 + 2 + 3 15 Polarization of CMB Power spectra of CMB polarization (lensing B-mode ) The free-streaming effects of neutrinos By observation of CMB polarization, we can constrain the neutrino mass. Total mass Σ = 1 + 2 + 3 16 ◇ Current neutrino mass constraints WMAP 9-year + ACT + SPT + BAO + H0 ・ : sum of the neutrino masses < 0.44 eV (95%CL) ・ : neutrino number of species = 3.84 ± 0.40 (68%CL) Planck (temperature) + WMAP polarizations ＋ ACT + SPT + BAO < 0.28 eV (95% C.L), = 3.32+0.54 −0.52 17 contents 1. 21cm line observations 2. Effects of neutrinos on the growth of the density fluctuations 3. Future constraints on the neutrino mass by CMB and 21 cm line 4. Summary 18 ◆ CMB, 21cm, BAO観測実験 19 ◇ CMB polarization experiments ◆ POLARBEAR-2 95, 150 GHz ◆ Simons Array POLARBEAR-2 × 3 95, 150, 220 GHz KEK CMB group is developing these experiments. We took account of combinations of above 2 experiments and Planck satellite. 20 ◇ 21cm line experiment ◆ SKA (Square kilometer Array) SKA low frequency (Australia) Construction of Phase1 will start in 2018. http://www.skatelescope.org/ We took account of Phase1 and Phase2 (Phase2 has 10 times larger collecting area.) 21 ◇ BAO Observation ◆ Dark Energy Spectroscopic Instrument (DESI) ・Galaxy survey (2018年から観測開始) Redshift range : 0.1 < < 1.9 Survey solid angle : 14000 square degree 22 ◆ Constraints on the sum of the neutrino masses and neutrino number of species 23 ◆ Constraints on neutrino number of species 95% C.L. Contour, = . eV CMB + DESI (BAO) 90% C.L Simons Array + DESI + 21cm line 90 % C.L CMB+DESI +SKA By Planck + Simons Array + SKA, the neutrino total mass is detectable at 95%C.L. ◆ With residual foregrounds Motivation: How much is it necessary to remove foregrounds? 25 ◆ Constraints on neutrino number of species with residual foregrounds 95% C.L. Contour, = . eV CMB + DESI (BAO) 90% C.L Simons Array + DESI + 21cm line 90 % C.L CMB+DESI +SKA Because constraints from CMB become weaker, combinations of CMB and SKA is more important. ◆ Constraints on the neutrino mass hierarchy 27 ◇ The neutrino mass hierarchy Normal hierarchy ≫ > 23 12 Σ ≳ 0.05 eV ≫ Inverted hierarchy > ≫ 12 23 Σ ≳ 0.1eV 28 ◇ Effects of the mass hierarchy Ratios of matter power spectra (at z = 8) Normal Inverted Σ becomes smaller The differences due to the mass hierarchy larger 29 ◆ Parameterization of the mass hierarchy − ≡ T. Jimenez, T. Kitching, C. Pena-Garay, L. Verde, JCAP 1005:035,2010 Normal > Inverted < Behaviors of Dotted lines express allowed regions by oscillation experiments 30 ◆ Contours of 95% C.L. forecasts in - plane Normal hierarchy Inverted hierarchy SKA2 CMB+DESI +SKA1 CMB+DESI +SKA1 SKA2 In the inverted case, SKA phase1 + Simons Array + Planck has enough sensitivity to 31 determine the mass hierarchy. ◆ Contours of 95% C.L. forecasts in - plane Normal hierarchy Inverted hierarchy SKA2 CMB+DESI +SKA1 CMB+DESI +SKA1 SKA2 In the inverted case, SKA phase1 + Simons Array + Planck has enough sensitivity to 32 determine the mass hierarchy. ◆ Contours of 95% C.L. forecasts in - plane with residual foregrounds Normal hierarchy Inverted hierarchy SKA2 CMB+DESI +SKA1 CMB+DESI +SKA1 SKA2 In the inverted case, SKA phase2 + Simons Array + Planck has enough sensitivity to 33 determine the mass hierarchy. ◆ Contours of 95% C.L. forecasts in - plane with residual foregrounds Normal hierarchy Inverted hierarchy SKA2 CMB+DESI +SKA1 CMB+DESI +SKA1 SKA2 In the normal case, SKA phase2 + Simons Array + Planck has enough sensitivity to determine the mass hierarchy. 34 contents 1. 21cm line observations 2. Effects of neutrinos on the growth of the density fluctuations 3. Future constraints on the neutrino mass by CMB and 21 cm line 4. Summary 35 5. Summary ■ We studied sensitivities of 21cm line (SKA) + CMB polarization observations (POLARBEAR-2, Simons Array) to the neutrino total mass. ■ Planck + Simons Array + SKA phase1 can detect the neutrino total mass at 2σ (if ~. eV.) ■ Planck + Simons Array + SKA may determine the neutrino mass hierarchy. 36 37