Constraints on the neutrino mass

by future precise CMB polarization

and 21cm line observationsYoshihiko Oyama

The Graduate University for Advanced Studies

KEK cosmophysics group

CollaboratorsMasashi Hazumi (KEK CMB group)Kazunori Kohri (KEK cosmophysics group)

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SKA Phase1, Phase2

POLARBEAR-2 or Simons Array

＋

Planck＋

temperature, E-mode, B-mode

E-mode, B-mode

21cm line brightness temperature （ z=7-10 ）

We studied their sensitivities to constraints on the sum of the neutrino masses and the mass hierarchy.

◇ Focused experiments

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SKA Phase1, Phase2

POLARBEAR-2 or Simons Array

＋

Planck＋

temperature, E-mode, B-mode

E-mode, B-mode

21cm line brightness temperature （ z=7-10 ）

◇ Focused experiments

＋Baryon Acoustic Oscillation (BAO)

2. Effects of neutrinos on the growth of the density fluctuations

4

contents

1. 21cm line observations

3. Future constraints on the neutrino mass by CMB and 21 cm line

4. Summary

2. Effects of neutrinos on the growth of the density fluctuations

5

contents

1. 21cm line observations

3. Future constraints on the neutrino mass by CMB and 21 cm line

4. Summary

6

・ Introduction

・ 21cm line brightness temperature and the power spectrum

1. 21cm line observations

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21cm line results from hyperfine splitting of neutral hydrogen.

Spin =0singlet

Spin =1triplet

proton

electron

eV

cm

1S state

◇ 21cm line

𝝂21=𝟏 .𝟒𝟐𝐆𝐇𝐳

S.G. Djorgovski et al. & Digital Media Center, Caltech.

◇ Cosmological 21 cm radiation

We particularly focused on the epoch of reionization ( 7 z 10 )

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The epoch of reionization

Dark age

z1000CMB

Signals of the 21 cm line exist Cosmic dawn

(The late stage of the dark age)15 z 30

6 z 15

This signal has information of the matter distribution.

◇ 21cm line and cosmology

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We can constrain cosmological parameters (e.g. .)

(2006) Astrophys.J.653:815-830,2006M.McQuinn, O.Zahn, M.Zaldarriaga, L.Hernquist, S.R. Furlanetto

21 cmHI gas （ IGM

） 𝑇 21 cm

◇ Advantages of 21 cm line observations

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１ . Non-linear effects are small

Z=0 Z=3

𝑘 [hMpc−1] 𝑘 [hMpc−1]

𝑃(𝑘

)[h−

3Mpc

3]

𝑃(𝑘

)[h−

3Mpc

3]

linear

non linear

linear

non linear

２ . Broad redshift range・ A lot of independent Fourier modes.・ The time evolution of the density fluctuations

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・ Introduction

・ 21cm line brightness temperature and the power spectrum

1. 21cm line observations

≈27 𝑥HI (1+𝛿𝑏) ( Ω𝑏h2

0.023 )( 0.15Ω𝑚h2

1+𝑧10 )

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12

𝑇 𝑏❑( 𝜈211+𝑧

,𝒓 , 𝑧)

1. Peculiar velocity of gas2. Expansion of universe

×[1− 𝑇𝛾

𝑇 𝑆]¿

◇ Brightness temperature

Fluctuation of baryon

: Spin temp

: CMB temp

: Neutral fraction

𝑻 𝑺>𝑻 𝜸 emission （ 6 z 15 ）

𝑻 𝑺<𝑻 𝜸 absorption （ 15 z ）

2. Effects of neutrinos on the growth of the density fluctuations

13

contents

1. 21cm line observations

3. Future constraints on the neutrino mass by CMB and 21 cm line

4. Summary

This effect erases their own fluctuations within such scales. 　

◇ Effects of neutrinos on the growth of the density fluctuations

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When neutrinos are relativistic ,

neutrinos run up to the horizon scale(Free-streaming)

~ Horizon scale𝝂

CDM

baryon

Matter power spectrum𝑷 (𝒌 )= ⟨|𝜹𝒌|𝟐 ⟩

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Total mass 　

𝒁=𝟎

Heavier neutrino mass

This suppression becomes larger.

The free-streamingeffects of neutrinos

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Polarization of CMB

Total mass 　

Power spectra of CMB polarization (lensing B-mode )𝑪𝒍

𝑩𝑩

The free-streamingeffects of neutrinos

By observation of CMB polarization, we can constrain the neutrino mass.

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・ : sum of the neutrino masses

・ : neutrino number of species 　

(68%CL)

WMAP 9-year + ACT + SPT + BAO + H0

eV (95%CL)

◇ Current neutrino mass constraints

Planck (temperature) + WMAP polarizations ＋ ACT + SPT + BAO

eV (95% C.L),

2. Effects of neutrinos on the growth of the density fluctuations

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contents

1. 21cm line observations

3. Future constraints on the neutrino mass by CMB and 21 cm line

4. Summary

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◆ CMB, 21cm, BAO 観測実験

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We took account of combinations ofabove 2 experiments and Planck satellite.

KEK CMB group is developing these experiments.

◆ POLARBEAR-2 ◆ Simons Array

POLARBEAR-2 × 395, 150, 220 GHz

95, 150 GHz

◇ CMB polarization experiments

◇ 21cm line experiment

◆ SKA (Square kilometer Array)

http://www.skatelescope.org/

SKA low frequency 　(Australia)

Construction of Phase1 will start in 2018.

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We took account of Phase1 and Phase2 (Phase2 has 10 times larger collecting area.)

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◆ Dark Energy Spectroscopic Instrument (DESI)

・ Galaxy survey (2018 年から観測開始 )

◇ BAO Observation

Survey solid angle : square degree

Redshift range :

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◆ Constraints on the sum of the neutrino masses and neutrino number of species

◆ Constraints on neutrino number of species

95% C.L. Contour, eV

90% C.L 90% C.L

CMB + DESI (BAO) + 21cm line

By Planck + Simons Array + SKA,the neutrino total mass is detectable at 95%C.L.

CMB+DESI+SKASimons

Array + DESI

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◆ With residual foregrounds

Motivation:How much is it necessary to remove foregrounds?

◆ Constraints on neutrino number of species with residual foregrounds

90% C.L 90% C.L

Because constraints from CMB become weaker,combinations of CMB and SKA is more important.

CMB + DESI (BAO) + 21cm line

CMB+DESI+SKA

Simons Array + DESI

95% C.L. Contour, eV

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◆ Constraints on the neutrino mass hierarchy

◇ The neutrino mass hierarchy

Normal hierarchy

𝒎𝟐

eV

𝒎𝟏

𝛥𝑚23

𝛥𝑚12

𝒎𝟑

Inverted hierarchy

𝒎𝟐

𝒎𝟏

𝒎𝟑

𝛥𝑚23

𝛥𝑚12

eV

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Each neutrino becomes non-relativistic () at different time.

◇ Effects of the mass hierarchy

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Ratios of matter power spectra (at z = 8)

Normal

Inverted

The differences due to the mass hierarchy

becomes smaller

larger

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◆ Parameterization of the mass hierarchy

𝒓𝝂≡𝒎𝟑−𝒎𝟏

𝜮𝒎𝝂 Inverted T. Jimenez, T. Kitching, C. Pena-Garay, L. Verde, 　 JCAP 1005:035,2010

Normal

Behaviors of

Dotted lines express allowed regions by oscillation experiments

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◆ Contours of 95% C.L. forecasts in - plane

In the inverted case, SKA phase1 + Simons Array + Planck has enough sensitivity to determine the mass hierarchy.

Normal hierarchy Inverted hierarchy

CMB+DESI+SKA1

SKA2CMB+DESI+SKA1

SKA2

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◆ Contours of 95% C.L. forecasts in - plane

In the inverted case, SKA phase1 + Simons Array + Planck has enough sensitivity to determine the mass hierarchy.

Normal hierarchy Inverted hierarchy

CMB+DESI+SKA1

SKA2CMB+DESI+SKA1

SKA2

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◆ Contours of 95% C.L. forecasts in - plane with residual foregrounds

In the inverted case, SKA phase2 + Simons Array + Planck has enough sensitivity to determine the mass hierarchy.

Inverted hierarchy

CMB+DESI+SKA1

SKA2

Normal hierarchy

CMB+DESI+SKA1

SKA2

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◆ Contours of 95% C.L. forecasts in - plane with residual foregrounds

In the normal case, SKA phase2 + Simons Array + Planck has enough sensitivity to determine the mass hierarchy.

Inverted hierarchy

CMB+DESI+SKA1

SKA2

Normal hierarchy

CMB+DESI+SKA1

SKA2

2. Effects of neutrinos on the growth of the density fluctuations

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contents

1. 21cm line observations

3. Future constraints on the neutrino mass by CMB and 21 cm line

4. Summary

■ We studied sensitivities of 21cm line (SKA) + CMB polarization observations (POLARBEAR-2, Simons Array) to the neutrino total mass.

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■ Planck + Simons Array + SKA phase1 can detect the neutrino total mass at 2σ (if eV.)

5. Summary

■ Planck + Simons Array + SKA may determine the neutrino mass hierarchy.

◆ Back up slide

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