Cosmology with CMB polarization: current
status and future prospects
Kiyotomo ICHIKI (Nagoya)Refs.: KI, Kanai, Katayama & Komatsu, PTEP ‘19Liu, KI, Tashiro & Sugiyama, MNRAS Letters ‘16
Planck 2018 results V, Meyers+, PRD ‘18
Pagano+(arxiv:1908.09856)

1 / 40Contents●Large scale CMB polarization and optical depth●Next generation CMB polarization satellite: LiteBIRD●Future prospects●–Constraints on reionization history–Reconstruct of density fluctuations through cluster CMB polarization

Summary2 / 40

Cosmic Microwave Background(Relic of the Big-Bang, 3K black body)
remove the monopole& dipole

Penzias and Wilson (1965)

temperaturepolarization(Planck collaboration, 2013)3 / 40Optical depth tau from CMB Emode polarization
Thomson scattering produces linear polarization
if there is quadrupole anisotropy in CMB
intensity around the free electrons
冷熱熱
冷

see W. Hu’s tutrial

Pol. angle

Polarization angle follows the CMB quadrupole
seen by the electron
4 / 40E-mode & B-mode

5 / 40from BICEP2 web page

CMB polarization
Polarization image generated by stacking the polarization pattern around hot spotsof temperature anisotropies (clear indication of the sound horizon at recombination)
Real data

LCDM prediction

Parity even pattern (E-mode)
[rad]

[rad]

6 / 40Large angle polarization from reionization
Last scattering surfacesof electrons
free electrons at re-ionization see
almost the same CMB quadropole
over 0.55 Gpc scale

Thus polarization pattern is coherent
over:Corresponding multipole isreionization(z=6.5)LARGE ANGULAR SCALE!

recombination(last scattering surface of us)

7 / 40Planck 2018 results+
Large-scale E-mode power spectrum

Planck 2018 power spectrum

8 / 40what’s next?

P.Bull+, 2016

9 / 40Planck 2018 results+

10 / 40

11 / 40

12 / 40

15 frequency bands from 40GHz to 400GHz
Mission of Opportunity, A. Lee

Combined,

FWHM = 30arcmin

13 / 40

Yuji Chinone

inflation GWs

naoittaiv
grangisnl ler < 0.065 (95% C.L.)

14 / 40

Yuji Chinone

inflation GWs

LiteBIRDng
isenllnaoittaiv
gra

mission requirement ：s(r) < 1 x 10-3 (for r=0)2 ≤ ≤ 200

15 / 40

Yuji Chinone

inflation GWs

taiv
grasinnl leationg= Effective noise
5 muK arcmin

LiteBIRD

16 / 40

Yuji Chinone

inflation GWs

r=0.001 B-mode

taiv
grangisenllation= Effective noise
5 muK arcmin

17 / 40

Yuji Chinone

inflation GWs

ngisenllnaoittaiv= Effective noisegra
5 muK arcmin

Foregrounds@100GHz18 / 40CMB and foregrounds

AME?

B-mode CMB

19 / 40

Planck 2015 results. X

A Message from S-PASS
Synchrotron … S-PASS
Dust … Planck 353

Foreground removal is essential

Krachmalnicoff+, arxiv: 1802.01145

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From KK2011 to Deltamap (Katayama & Komatsu, ApJ, ‘11)
S-PASS (Krachmalnicoff+, arxiv: 1802.01145)

Three Issues
1. varying spectral parameters
Internal template had to assume that spectral
parameters are uniform over the full sky(e.g. Katayama&Komatsu, ApJ, 2011)
2. De-correlation effect(e.g., Tassis+, MNRAS, ‘15)
3. unknown AME component

We resolve these issues(ICHIKI+, PTEP, ‘19)

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Results (KI+, PTEP, ‘19)
Work in Nside=4 resolution
6 or 7 bands used
# of parameters =4

Appealing points
・ internal & simple
・ accounting for spatiallyvarying foreground params
to 1st order・ AME is supported
・ decorrelation is supported
・ unbiased

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Even if no GWs were detected“A cosmic variance limited measurement of EE on large angular scales will be an important,and guaranteed, legacy for LiteBIRD.” (external international science review)

LiteBIRD
Robertson+, ApJL, 201523 / 40

Even if no GWs were detected“A cosmic variance limited measurement of EE on large angular scales will be an important,and guaranteed, legacy for LiteBIRD.” (external international science review)

LiteBIRD

Breaking degeneracy between

anddetection of neutrino mass
24 / 40“Science from LiteBIRD” , Bucher,Komatsu,Hazumi et al., See also Calabrese+, PRD, ‘16

Optical depth and beyond●●●

In most CMB analyses, one usually assumes a tanh-like reionization
history with a single reionization redshift zre and dzre (=0.5)
In Watts+ (1910.00590), the authors investigate how the future large-scaleE-mode polarization can constrain xe(z) (Millea&Bouchet, ‘18)
Significant xemin can be expectede.g., from– PopIII BBH (Inayoshi+, ‘16)
– QSOs (Ewall-Wice+, ‘18)
– annihilating particles(Mapelli+, ‘06)

25 / 40

Future constraints on xe(z) (Watts+,1910.00590)
only from Large-scale E-mode polarization

CLASS (on-going) after fore. removal

LiteBIRD (future)

26 / 40

Further precision cosmology using CMBpolarization
Can we reduce CMB error bars smaller than the cosmic variance?
Yes! Cluster polarization can be used to reduce the cosmic variance
Original ideas can be found in, e.g.,
Kamionski & Loeb, PRD, ‘97; Seto & Sasaki, PRD, ‘00
In fact, Meyers+ showed that cluster polarization can be used to constrain
the CMB optical depth beyond the cosmic variance to reachσ(τ) = 0.0002 (Meyers+, PRD, ‘18)

Kamionkowski & Loeb method
CMB last scattering
surface of us

平面波

CMB photon

銀河団

CMB surface seenfrom the cluster

Linearly polarized according
to the CMB quadrupole seenby the cluster

Liu, KI, Tashiro, Sugiyama, MNRAS Letter, ‘16
3D Initial
density fluctuation
Direct CMB observation

銀河団

predict by using
remote quadrupole

We showed that CMB polarization
at distant clusters can be used topredict the CMB sky viewed by us!

Measure cosmological density fieldtwice
Remote quadrupole can be reconstructedby cluster CMB polarizations (K&L, PRD,‘97)
and 21cm circular polarization (Hirata+, PRD, ‘18)
The quadrupole evolve in time and cross ourlight-cone, and hence it can be directly
observed at different redshifts from place
to place.
We may be able to observe the same place twice
to beat the cosmic variance (under investigation)

summary●●●●●Large-scale E-mode polarization is a clear signature of cosmicreionization
LiteBIRD is a CMB satellite that aims to detect inflationary GWs withr>10-3 and has been selected by JAXA as strategic large mission
A cosmic variance limited E-mode measurement on large scales will bea legacy for LiteBIRD, giving a detection of neutrino mass with
Our new internal template foreground removal method supports
spatially varying foreground spectra, AME, and dust de-correlation
Cluster CMB polarization measurements may enable us to observe the31 / 40
density field twice to beat the cosmic varianceCMB satellites and telescopes

LiteBIRD

1990s

2000s

2010s

2020s

Perfect B.B. confirmed
large scale fluctuation Clear detection ofacoustic peaks
LCDM model confirmed Finer angular resolution (x3)→ more info. (x9)large scale E-mode

32 / 40

TT

QMASK
PlanckWMAP
COBE

MAXIMACBIBooMERanG

EE

WMAP

DASI

CAPMAPQUad

BICEP2BKP

POLARBEAR
SPTpolLens B
GWs B

33 / 40

TTPlanck

SPTpol
ACTpolEE Planck

BKP

POLARBEAR
SPTpolLens B
GWs B

34 / 40

Another two ordersSevenof magnitude
orders of magnitudeimprovement in theimprovement
next 10 yearsin power in 25 years

TTEE

Lens B
GWs B

35 / 40

Optical depth and beyond

36 / 40

Krachmalnicoff+, arxiv: 1802.01145

S-PASS results

Parkes 64m (2.3GHz)
FWHM = 9’σbeam = 1muK

The S-PASS experiment has observed
synchrotron emission of our galaxy, anddetermined synchrotron spectral index

WMAP 9yr

S-PASS

Fuskeland+, ApJ 2014

Krachmalnicoff+, arxiv: 1802.01145

37 / 40

Delta-map method(Taylor expansion)

Delta-map: two new “foreground maps”&from spatial variation of spectal parameters,
whose frequency dependence does not depend onsky direction.
Now we can remove them by linearly combining
different frequency maps

Synchrotron running:→ absorb AME

38 / 40

Let’s talk about de-correlation
We show that the multiple dust clouds with different temperatures can be treatedas if Q and U had slightly different dust temperature:(one dust cloud)Our recipe:

39 / 40

Meyers+, PRD, ‘18

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