1. Tests of Cosmic Inflation with Measurements of
Cosmic Microwave Background Polarization
LiteBIRD
POLARBEAR
Masashi Hazumi
High Energy Accelerator Research Organization (KEK) and
Kavli Institute for Mathematics and Physics of the Universe, The University of Tokyo and
Graduate School for Advanced Studies (SOKENDAI) and
Institute of Space and Astronautical Science, JAXA 1
2. My research
history
2
1994-2008: B Factory at KEK
Discovery of CP violation in B decays
à Kobayashi-Maskawa Nobel 2008
2007: KEK CMB Group
officially established
2005: my “cosmic survey”
à chose CMB !
POLARBEAR
QUIET
2012 - Now
2008-2010
Telescopes in
Atacama, Chile
2014: Joined Kavli IPMU as a
Project Professor to promote
LiteBIRD satellite project
(80% KEK, 20% IPMU)
LiteBIRD
satellite
2024-25: Launch
2015: LiteBIRD Proposal
Now-2020s:
Simons Array
GroundBIRD
5. 5
Cosmic Ouroboros
http://www.cc.kyoto-su.ac.jp/department/physics/image/deptphys/hebi.png
Particle Cosmology seeks answers to the big questions
• How did our universe begin ?
• What fundamental laws governed the beginning of our universe ?
Deep connection
to our existence
Sense of wonder !
Joy of experiments
• You can invent new
instruments. Great
invention often changes
the world !
• You can see data that no
one else has ever seen.
6. A striking fact about particle physics
• We already have “rules with no exception (!)”, as long as
experiments on the ground are concerned
= the Standard Model of particle physics (Quantum
Physics !)
6
Many Nobel prizes awarded for the Standard Model
7. Breakdown of the Standard Model of particle physics
• Cosmological observations are incompatible with
the Standard Model of particle physics
1. Inflation (accelerating expansion of the early universe)
2. Matter anti-matter asymmetry of the universe
3. Dark matter
4. Dark energy
7
Big riddles are in front of us.
8. Particle physics perspective on the
beginning of our universe
• Our universe is governed by general theory of relativity
(GR) invented by Albert Einstein.
• GR is a classical theory with no quantum fluctuation.
• The Big Bang however points sizable
quantum fluctuations of space-time
in the very early universe.
8
Breakdown of GR ! à Quantum Gravity (e.g. Superstring theory)
9. • We have very interesting hypotheses about
quantum gravity (such as superstring theory),
but we do not yet know what it really is.
• Need clever measurements to observe effects
of quantum gravity !
• Cosmic Microwave Background (CMB)
polarization is our best hope !
9
11. 11
1929
1965
1915
1991
Spacetime curvature is
determined by matter
and radiation.
Our universe
is expanding !
Direct evidence
for Hot Big Bang !
General
relativity
(Einstein)
• Proof of
black-body radiation
• CMB anisotropy
à Indication of
cosmic inflation
now
COBE
Mather Smoot
Nobel
(2006)
Nobel (1978)
Cosmic
Microwave
Background
(CMB) Penzias Wilson
Red shift
of distant
galaxies
(Hubble)
Recent meas.
22. What is CMB temperature anisotropy ?
• CMB is the oldest light.
• The CMB anisotropy is regarded as
the “initial condition” of structure formation at later times.
• The Big Bang implies quantum fluctuations of space-time
in the very early universe (earlier than CMB generation)
• Therefore, CMB temperature anisotropy implies that the
origin of our existence is quantum fluctuations !
22
34. Inflation hypothesis (~1981)
34
Accelerating expansion before the hot big bang
Resolve outstanding problems of the naïve big bang model
• Horizon problem
• Flatness problem
• Structure formation
Impossible within the Standard Model of Particle Physics !
Katsuhiko Sato Alan Guth Andrei Linde Alexei Starobinsky
2014 Kavli Prize awarded to Guth,
Linde and Starobinsky for pioneering
the theory of cosmic inflation
36. What do we know about
time evolution of ?
36
a
The scale of our universe
is expressed by just one quantity a
37. Friedmann equation
• Einstein equation gives time evolution of metric gµν
from first principle.
• Imposing “Cosmological principle”: no special place
in the universe
37
gµ⌫ =
0
B
B
@
1 0 0 0
0 a2
(t) 0 0
0 0 a2
(t) 0
0 0 0 a2
(t)
1
C
C
A
energy density of
matter and radiation
In particular, Expanding universe !
Friedmann Eq. for
flat universe
⇣ ˙a
a
⌘2
=
8⇡G
3
⇢
˙a > 0
38. Yet another Friedmann equation
38
¨a
a
=
4⇡G
3
(⇢ + 3p)
Pressure
>0 for matter and radiation
¨a < 0With known matter and radiation,
our universe should always be decelerating
39. Particle physics of inflation
39
• New particle called “Inflaton”
• Simplest model with just one inflaton
needs to be tested
• Inflation is so-to-speak
“standard model Higgs” in cosmology
40. Emission of primordial
gravitational waves
graviton
graviton
40
Quantum fluctuation
of space-time
Inflation
pulled apart
much faster
than any other
situation:
virtual particles
à real particles
Cf. Scientific American January 2001
Caldwell and Kamionkowski
49. 49
credit: New Scientist
hot electrons
emerged again
à rescattering and
additional B-mode with
larger angular scales
Reionization
50. Lensing B-mode – ``Another” B-mode
by Weak lensing
50
(image credit: ESA)
E-modes
B-modes at
sub-deg. scale
• Better ns from E-mode
• Sum of neutrino masses
• (Early) Dark energy
51. E mode
Primordial B mode
(not yet detected)
Reionization
dozens of degrees
Recombination
~2 degrees
Ground-based
large telescopes,
neutrino masses,
dark energy
Satellite !
Shed light on inflation energy scale
Determination of
r (tensor-scalar ratio)
51
CMB polarization power spectra
52. 52
Physics of CMB B-mode
• Direct evidence for cosmic inflation
• GUT-scale physics
• Arguably the first observation of quantum
fluctuation of space-time !
V 1/4
= 1.06 ⇥ 1016
⇥
✓
r
0.01
◆1/4
[GeV]
53. B-mode power spectrum measurements
53Figure by Yuji Chinone
Primordial
Gravitational waves
Lensing
57. Constraint on r
57
r < 0.07 at 95% C. L.
Symplest inflation model
is already ruled out !
Planck, WMAP,
BICEP2, Keck
58. B-mode projects (1) Ground and Balloons
South
Pole
Atacama,
Chile
Balloon Ground
In addition,
QUBIC at Dome C
SPIDER
In addition, ABS, CLASS
ACTPol
à Advanced ACTPol
POLARBEAR à Simons Array
In addition,
QUIJOTE in Canary island,
GroundBIRD in Canary island,
AMiBA in Hawaii
EBEX à EBEX6K
LSPE
PIPER
58
SPTPolà SPT3G
BICEP3
Simons Observatory
CMB-S4
59. B-mode projects (2): Satellites
• LiteBIRD
• Passed initial down-selection by ISAS/JAXA, in
phase-A stage
• US participation proposal for NASA MO also passed
initial down-selection, in phase-A stage
• Target launch in 2024-2025
• PIXIE
• NASA small PI-led mission proposal Feb 2011, not
selected
• Re-propose to next MIDEX AO (2016 Dec)
• Mission for ESA M5
• Proposal submitted in Oct 2016
• Planned launch date of 2029-2030
59
?
60. B-mode power spectrum measurements
60Figure by Yuji Chinone
Primordial
Gravitational waves
Lensing
61. 61 Figure by Yuji Chinone
B-mode power spectrum measurements
LiteBIRD
62. Scientific shopping list (1)
62
1) Cl
BB
– inflation and quantum gravity (r, nt )
– improvement w/ delensing
– lensing B-mode to very low l
2) Cl
EE
– reionization history
– better τ and sum of neutrino masses
63. Scientific shopping list (2)
63
3) Power spectrum deviation from ΛCDM
– parity violation in gravity
– quantum loop gravity
– primordial magnetic field
– new source fields for gravitational waves
4) Bi-spectrum (BBB etc.)
– tensor non-Gaussianity
– origin of gravitational waves
64. Scientific shopping list (3)
5) Non-standard patterns (e.g. bubbles) in the maps
à e.g. multiverse
6) Foreground science
7) Galactic magnetic field (in particular at large
galactic attitude)
8) Legacy all-sky multi-frequency maps of E-mode/
B-mode/Foregrounds
à various astronomical studies
64
