1. 21cm line observations

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
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