Finding gravitational waves from the early Universe
Eiichiro Komatsu
[Max Planck Institute for Astrophysics]
Colloquium, AEI Potsdam, February 7, 2020
Full-dome movie for planetarium Director: Hiromitsu Kohsaka
E and B mode
• E mode
: Polarisation directionsparallel or perpendicular
to the wavevector• B mode
: Polarisation directions45 degree tilted
with respect to the wavevector
Parity
• E mode
: Parity even• B mode
: Parity oddParity
• E mode
: Parity even• B mode
: Parity oddB-mode polarisation from gravitational lensing
E-mode polarisation from sound waves
Temperature fluctuations from sound waves
B-mode from GW
Power spectrum, explained
B-mode from gravitational lensing E-mode
from sound waves
Temperature from sound waves
B-mode from GW
Seven or ders of magnitude in power in “just” 25 years
CMB Stages
4
Detectors are a big challenge,
2000 2005 2010 2015 2020
10−4 10−3 10−2 10−1
WMAP
Planck
CMB
−S4
Year
Approximate raw experimental sensitivity (µK)
Space based experiments Stage−I − ≈ 100 detectors Stage−II − ≈ 1,000 detectors Stage−III − ≈ 10,000 detectors Stage−IV − ≈ 100,000 detectors
Approximate raw experimental noise (µK)
Figure by Clem Pryke for 2013 Snowmass documents
then
now
What comes next?
Advanced Atacama Cosmology Telescope
South Pole Telescope “3G”
CLASS
BICEP/Keck Array
Not just gravitational waves…
Ground-based CMB polarisation experiments measuring the E-mode polarisation from sound waves precisely will provide independent assessments of H0 inferred
from CMB, which has been derived mostly from temperature anisotropy so far.
H0liCOW Collaboration
E-mode
from sound waves
Temperature from sound waves
B-mode from GW
Another two or ders of magnitude in the next 10–15 years
B-mode from gravitational lensing
We want this!!
ESA
2025– [proposed]
JAXA
LiteBIRD
+ participations from USA, Canada, Europe
Polarisation satellite dedicated to measure CMB polarisation from
primordial GW, with a few thousand TES bolometers in space
2028–
ESA
2025– [proposed]
JAXA
LiteBIRD
May 21: JAXA has chosen LiteBIRD as the strategic large-class mission.
We will go to L2!
+ participations from USA, Canada, Europe
Selected!
2028–
A Remarkable Story
• Observations of the cosmic microwave background and their interpretation
taught us that galaxies, stars, planets, and ourselves originated from tiny
fluctuations in the early Universe
• But, what generated the initial
fluctuations?
Leading Idea
•
Quantum mechanics at work in the early Universe•
“We all came from quantum fluctuations”•
But, how did quantum fluctuations on the microscopic scales become macroscopic fluctuations over largedistances?
•
What is the missing link between small and large scales?Mukhanov & Chibisov (1981); Hawking (1982); Starobinsky (1982); Guth & Pi (1982);
Bardeen, Turner & Steinhardt (1983)
Cosmic Inflation
•
Exponential expansion (inflation) stretches the wavelength of quantum fluctuations to cosmological scalesStarobinsky (1980); Sato (1981); Guth (1981); Linde (1982); Albrecht & Steinhardt (1982)
Quantum fluctuations on microscopic scales
Inflation!
Inflationary Predictions
•
Fluctuations we observe today in CMB and the matter distribution originate from quantum fluctuations during inflationζ
scalar mode
h ij
tensor mode
•
There should also be ultra long-wavelength gravitational waves generated during inflationGrishchuk (1974) Starobinsky (1979) Mukhanov&Chibisov (1981) Guth & Pi (1982)
Hawking (1982)
Starobinsky (1982)
Bardeen, Steinhardt&Turner (1983)
We measure distortions in space
•
A distance between two points in spaced`
2= a
2(t)[1 + 2⇣ (x, t)][
ij+ h
ij(x, t)]dx
idx
jX
i
h
ii= 0
•
ζ : “curvature perturbation” (scalar mode)•
Perturbation to the determinant of the spatial metric•
hij : “gravitational waves” (tensor mode)•
Perturbation that does not alter the determinantMeasuring GW
d`
2= dx
2= X
ij
ij
dx
idx
jd`
2= X
ij
(
ij+ h
ij)dx
idx
j•
GW changes distances between two pointsLaser Interferometer
Mirror
Mirror
detector No signal
Laser Interferometer
Mirror
Mirror
Signal!
detector
LIGO detected GW from a binary blackholes, with the wavelength
of thousands of kilometres
But, the primordial GW affecting the CMB has a wavelength of
billions of light-years!! How do
we find it?
Detecting GW by CMB
Isotropic electro-magnetic fields
Detecting GW by CMB
GW propagating in isotropic electro-magnetic fields
h + ij
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h ⇥ ij
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Detecting GW by CMB
Space is stretched => Wavelength of light is also stretched
h + ij
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h ⇥ ij
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Detecting GW by CMB Polarisation
electron electron
Space is stretched => Wavelength of light is also stretched
h + ij
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h ⇥ ij
<latexit sha1_base64="NwsD1SgjkJfMeVFacsNc7+DBIRA=">AAAB+HicbVBNS8NAEJ34WetHox69BIvgqSQi6LHoxWMF+wFtDZvtpl272YTdiVBDfokXD4p49ad489+4bXPQ1gcDj/dmmJkXJIJrdN1va2V1bX1js7RV3t7Z3avY+wctHaeKsiaNRaw6AdFMcMmayFGwTqIYiQLB2sH4euq3H5nSPJZ3OElYPyJDyUNOCRrJtysjP+MP+X3WQx4xnft21a25MzjLxCtIFQo0fPurN4hpGjGJVBCtu56bYD8jCjkVLC/3Us0SQsdkyLqGSmK29LPZ4blzYpSBE8bKlERnpv6eyEik9SQKTGdEcKQXvan4n9dNMbzsZ1wmKTJJ54vCVDgYO9MUnAFXjKKYGEKo4uZWh46IIhRNVmUTgrf48jJpndU8t+bdnlfrV0UcJTiCYzgFDy6gDjfQgCZQSOEZXuHNerJerHfrY966YhUzh/AH1ucPjLyTpw==</latexit><latexit sha1_base64="NwsD1SgjkJfMeVFacsNc7+DBIRA=">AAAB+HicbVBNS8NAEJ34WetHox69BIvgqSQi6LHoxWMF+wFtDZvtpl272YTdiVBDfokXD4p49ad489+4bXPQ1gcDj/dmmJkXJIJrdN1va2V1bX1js7RV3t7Z3avY+wctHaeKsiaNRaw6AdFMcMmayFGwTqIYiQLB2sH4euq3H5nSPJZ3OElYPyJDyUNOCRrJtysjP+MP+X3WQx4xnft21a25MzjLxCtIFQo0fPurN4hpGjGJVBCtu56bYD8jCjkVLC/3Us0SQsdkyLqGSmK29LPZ4blzYpSBE8bKlERnpv6eyEik9SQKTGdEcKQXvan4n9dNMbzsZ1wmKTJJ54vCVDgYO9MUnAFXjKKYGEKo4uZWh46IIhRNVmUTgrf48jJpndU8t+bdnlfrV0UcJTiCYzgFDy6gDjfQgCZQSOEZXuHNerJerHfrY966YhUzh/AH1ucPjLyTpw==</latexit><latexit sha1_base64="NwsD1SgjkJfMeVFacsNc7+DBIRA=">AAAB+HicbVBNS8NAEJ34WetHox69BIvgqSQi6LHoxWMF+wFtDZvtpl272YTdiVBDfokXD4p49ad489+4bXPQ1gcDj/dmmJkXJIJrdN1va2V1bX1js7RV3t7Z3avY+wctHaeKsiaNRaw6AdFMcMmayFGwTqIYiQLB2sH4euq3H5nSPJZ3OElYPyJDyUNOCRrJtysjP+MP+X3WQx4xnft21a25MzjLxCtIFQo0fPurN4hpGjGJVBCtu56bYD8jCjkVLC/3Us0SQsdkyLqGSmK29LPZ4blzYpSBE8bKlERnpv6eyEik9SQKTGdEcKQXvan4n9dNMbzsZ1wmKTJJ54vCVDgYO9MUnAFXjKKYGEKo4uZWh46IIhRNVmUTgrf48jJpndU8t+bdnlfrV0UcJTiCYzgFDy6gDjfQgCZQSOEZXuHNerJerHfrY966YhUzh/AH1ucPjLyTpw==</latexit><latexit sha1_base64="NwsD1SgjkJfMeVFacsNc7+DBIRA=">AAAB+HicbVBNS8NAEJ34WetHox69BIvgqSQi6LHoxWMF+wFtDZvtpl272YTdiVBDfokXD4p49ad489+4bXPQ1gcDj/dmmJkXJIJrdN1va2V1bX1js7RV3t7Z3avY+wctHaeKsiaNRaw6AdFMcMmayFGwTqIYiQLB2sH4euq3H5nSPJZ3OElYPyJDyUNOCRrJtysjP+MP+X3WQx4xnft21a25MzjLxCtIFQo0fPurN4hpGjGJVBCtu56bYD8jCjkVLC/3Us0SQsdkyLqGSmK29LPZ4blzYpSBE8bKlERnpv6eyEik9SQKTGdEcKQXvan4n9dNMbzsZ1wmKTJJ54vCVDgYO9MUnAFXjKKYGEKo4uZWh46IIhRNVmUTgrf48jJpndU8t+bdnlfrV0UcJTiCYzgFDy6gDjfQgCZQSOEZXuHNerJerHfrY966YhUzh/AH1ucPjLyTpw==</latexit>
hot
hot
cold
cold
cold cold
hot hot
Detecting GW by CMB Polarisation
Space is stretched => Wavelength of light is also stretched
h + ij
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h ⇥ ij
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horizontally polarised
Photo Credit: TALEX
Photo Credit: TALEX
Physics of CMB Polarisation
• Necessary and sufficient conditions for generating polarisation in CMB:
• Thomson scattering
• Quadrupolar temperature anisotropy around an electron
By Wayne Hu
propagation direction of GW h
+=cos(kx)
Polarisation directions perpendicular/parallel to the
wavenumber vector -> E mode polarisation
propagation direction of GW h
x=cos(kx)
Polarisation directions 45 degrees tilted from to the
wavenumber vector -> B mode polarisation
E-mode!
E-mode!
Pol on the horizon is 1/2
of the zenith
B-mode!
Pol on the horizon vanishes
Gravitational waves as the quantum vacuum fluctuation in spacetime
•
Quantising the gravitational waves in de Sitter space in vacuum
Grishchuk (1974); Starobinsky (1979)
⇤ h ij = 0
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gives
k 3 h h ij (k)h ij ⇤ (k 0 ) i
= (2⇡ ) 3 D (k k 0 ) 8 M pl 2
✓ H 2⇡
◆ 2
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scale-invariant spectrum
Propagation of GW
•
In an expanding Universe,
⇤ h ij = 0
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gives
h ¨ ij + 3 ˙ a
a h ˙ ij + k 2
a 2 h ij = 16⇡ GT ij GW
<latexit sha1_base64="XLil458Y+U4bzO29KFAWiBIo6hk=">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</latexit>
expansion of the Universe affects h
ij=3H
GW Evolution
•
Super-horizon scales [k << aH]•
The amplitude of GW is conserved (i.e., hij = constant)•
Sub-horizon scales [k >> aH]•
The amplitude of GW decays (i.e., hij ~ 1/a)Therefore, the long-wavelength
GW preserves the initial condition:
the beginning of the Universe!
GW “entering the horizon”
•
This is a tricky concept, but it is important•
Suppose that GWs were created at all wavelengths•
As the Universe expands, the horizon size grows and we can see longer and longer wavelengths•
Fluctuations “entering the horizon”10 Gpc today 1 Gpc today 100 Mpc today
10 Mpc today 1 Mpc today
“enter the horizon”
Radiation Era Matter Era
a k
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Theoretical energy density
Watanabe & EK (2006)GW entered the horizon during the radiation era
GW entered the horizon during the matter era
Spectrum of GW today
Spectrum of GW today
Watanabe & EK (2006)
CMB PTA Interferometers
Wavelength of GW
~ Billions of light years!!!
Theoretical energy density
Tensor-to-scalar Ratio
•
We really want to find this! The current upper bound is r<0.06 (95%CL)r ⌘ h h ij h ij i h ⇣ 2 i
BICEP2/Keck Array Collaboration (2018)
WMAP(temp+pol)+ACT+SPT+BAO+H
0
WMAP(pol) + Planck + BAO ruled
out!
WMAP Collaboration
WMAP(temp+pol)+ACT+SPT+BAO+H
0
WMAP(pol) + Planck + BAO ruled
out!
ruled out!
ruled out!
ruled out!
ruled out!
Polarsiation limit added:
r<0.07 (95%CL)
Planck Collaboration (2015); BICEP2/Keck Array Collaboration (2016)
WMAP(temp+pol)+ACT+SPT+BAO+H
0
WMAP(pol) + Planck + BAO ruled
out!
ruled out!
ruled out!
ruled out!
ruled out!
Planck Collaboration (2015); BICEP2/Keck Array Collaboration (2016)
BICEP2/Keck Array Collaboration (2018)
r<0.06 (95%CL)
2018
Polarsiation limit added:
r<0.07 (95%CL)
ESA
2025– [proposed]
JAXA
LiteBIRD
+ participations from USA, Canada, Europe
Selected!
2028–
Target: δr<0.001 (68%CL)
• Polarized foregrounds
• Synchrotron radiation and thermal emission from inter-galactic dust
• Characterize and remove foregrounds
• 15 frequency bands between 40 GHz - 400 GHz
• Split between Low Frequency Telescope (LFT) and High Frequency Telescope (HFT)
• LFT: 40 GHz – 235 GHz
• HFT: 280 GHz – 400 GHz
Foreground Removal
7
Polarized galactic emission (Planck X) LiteBIRD: 15 frequency bands
Slide courtesy Toki Suzuki (Berkeley)
LiteBIRD
LiteBIRD Spacecraft
LiteBIRD for B-mode from Space
2018/7/21 11
LFT (5K)
HG-antenna HFT (5K)
V-groove
radiators SVM/BUS
PLM 200K100K30K
JAXA
H3 LFT (Low frequency telescope) 34 – 161 GHz : Synchrotron + CMB HFT (high frequency telescope) 89 – 448 GHz : CMB + Dust
4.5 m
Focal plane 0.1K
Slide courtesy Yutaro Sekimoto (ISAS/JAXA)
European Contribution
LiteBIRD Collaboration
LiteBIRD Collaboration
But, wait a minute…
Are GWs from vacuum fluctuation in spacetime, or from sources?
•
Homogeneous solution: “GWs from vacuum fluctuation”•
Inhomogeneous solution: “GWs from sources”•
Scalar and vector fields cannot source tensorfluctuations at linear order (possible at non-linear level)
•
SU(2) gauge field can!⇤ h ij = 16⇡ G⇡ ij
Maleknejad & Sheikh-Jabbari (2013); Dimastrogiovanni & Peloso (2013);
Adshead, Martinec & Wyman (2013); Obata & Soda (2016); …
Many papers by Sorbo, Peloso, and others
Important Message
•
Do not take it for granted if someone told you thatdetection of the primordial gravitational waves would be a signature of “quantum gravity”!
•
Only the homogeneous solution corresponds to thevacuum tensor metric perturbation. There is no a priori reason to neglect an inhomogeneous solution!
•
Contrary, we have several examples in which detectable B-modes are generated by sources [U(1) and SU(2)]⇤ h ij = 16⇡ G⇡ ij
Experimental Strategy
Commonly Assumed So Far
1. Detect CMB polarisation in multiple frequencies, to make sure that it is from the CMB (i.e., Planck spectrum)
2. Check for scale invariance: Consistent with a scale invariant spectrum?
•
Yes => Announce discovery of the vacuum fluctuation in spacetime•
No => WTF?New Experimental Strategy:
New Standard!
1. Detect CMB polarisation in multiple frequencies, to make sure that it is from the CMB (i.e., Planck spectrum)
2. Consistent with a scale invariant spectrum?
3. Parity violating correlations consistent with zero?
4. Consistent with Gaussianity?
•
If, and ONLY IF Yes to all => Announce discovery of the vacuum fluctuation in spacetimeNew Experimental Strategy:
New Standard!
1. Detect CMB polarisation in multiple frequencies, to make sure that it is from the CMB (i.e., Planck spectrum)
2. Consistent with a scale invariant spectrum?
3. Parity violating correlations consistent with zero?
4. Consistent with Gaussianity?
•
If, and ONLY IF Yes to all => Announce discovery of the vacuum fluctuation in spacetimeIf not, you may have just discovered new physics
during inflation!
Further Remarks
•
“Guys, you are complicating things too much!”• No.
These sources (eg., gauge fields) should beubiquitous in a high-energy universe. They have every right to produce GWs if they are around
•
Sourced GWs with r>>0.001 can be phenomenologically more attractive than the vacuum GW from the large-field inflation [requiring super-Planckian field excursion]. Better radiative stability, etc•
Rich[er] phenomenology: Better integration with the Standard Model; reheating; baryon synthesis vialeptogenesis, etc. Testable using many more probes!
GW from Axion-SU(2) Dynamics
•
φ: inflaton field => Just provides quasi-de Sitter background•
χ: pseudo-scalar “axion” field. Spectator field (i.e., negligible energy density compared to the inflaton)•
Field strength of an SU(2) field :Dimastrogiovanni, Fasielo & Fujita (2017)
[I don’t want to touch this sector because I don’t understand inflaton]
[a=1,2,3; μ=0,1,2,3] self-interaction term
GW from Axion-SU(2) Dynamics
•
φ: inflaton field => Just provides quasi-de Sitter background•
χ: pseudo-scalar “axion” field. Spectator field (i.e., negligible energy density compared to the inflaton)•
Field strength of an SU(2) field :Dimastrogiovanni, Fasiello & Fujita (2017)
[I don’t want to touch this sector because I don’t understand inflaton]
A well-defined set up:
Axion-SU(2) gauge field dynamics in a given de-Sitter background.
Everything is calculable!
self-interaction term [a=1,2,3; μ=0,1,2,3]
Background and Perturbation
•
In an inflating background, the SU(2) field has anisotropic
background solution:A a i = [scale factor] ⇥ Q ⇥ i a
U: axion potential
•
Perturbations contain a tensor (spin-2) mode (as well as S&V)Maleknejad & Sheikh-Jabbari (2011)
A. Maleknejad (MPA)
Scenario
•
The SU(2) field contains 1 tensor, 2 vectors, and 3 scalars (9 DOF = 12 – 3)•
The tensor components are amplified strongly by a coupling to the axion field•
Only one helicity is amplified => GW is chiral (well- known result, also for U(1))•
New result: GWs sourced by this mechanism are strongly non-Gaussian!Agrawal, Fujita & EK, PRD, 97, 103526 (2018); JCAP 1806, 027 (2018)
Gravitational Waves
•
Defining canonically-normalised circular polarisation modes as•
The equations of motion for L and R modes are⇤ L,R 6 = 0
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Dimastrogiovanni, Fasiello & Fujita (2017)
Gravitational Waves
•
Defining canonically-normalised circular polarisation modes as•
The equations of motion for L and R modes are ( )= a few
(
spin-2 field
spin-2 field Dimastrogiovanni, Fasiello & Fujita (2017)
Spin-2 Field from SU(2)
•
The equations of motion for L and R modes of SU(2) arethe minus sign gives an instability -> exponential amplification of tR!
= a few
(
Dimastrogiovanni, Fasiello & Fujita (2017)
Spin-2 Field from SU(2)
•
The equations of motion for L and R modes of SU(2) arethe minus sign gives an instability -> exponential amplification of tR!
[Whittaker function]
(
•
The produced gravitational waves are totally chiral!•
The solution (when all the parameters are constant and the terms on the right hand side are ignored):Dimastrogiovanni, Fasiello & Fujita (2017)
Gravitational Waves
•
Defining canonically-normalised circular polarisation modes as•
The equations of motion for L and R modes are ( )•
Inhomogeneous solution:FE, FB: some complicated functions
Dimastrogiovanni, Fasiello & Fujita (2017)
•
This exponential dependence on mQ makes it possible to have Psourced >> Pvacuum= (2/π
2)H
2/M
2Pl• New Paradigm
Power Spectrum!
Dimastrogiovanni, Fasiello & Fujita (2017)
Phenomenology
•
The scale-dependence of the produced tensor modes is determined by how mQ changes with time•
E.g., Axion rolling faster towards the end of inflation:BLUE TILTED power spectrum! Therefore…
= a few
= …
(
the minus sign gives an instability -> exponential amplification of tR!
Not just CMB!
Thorne, Fujita, Hazumi, Katayama, EK & Shiraishi, PRD, 97, 043506 (2018) LISABBO Planck
LiteBIRD
Example Tensor Spectra
Dimastrogiovanni, Fasiello & Fujita (2017) Thorne, Fujita, Hazumi, Katayama, EK & Shiraishi, PRD, 97, 043506 (2018)
•
Sourced tensor spectrum can also be bumpyExample Tensor Spectra
Tensor Power Spectrum, P(k) B-mode CMB spectrum, ClBB
Dimastrogiovanni, Fasiello & Fujita (2017) Thorne, Fujita, Hazumi, Katayama, EK & Shiraishi, PRD, 97, 043506 (2018)
•
The B-mode power spectrum still looks rather normalLarge bispectrum in GW from SU(2) fields
•
ΩA << 1 is the energy density fraction of the gauge field•
Bh/Ph2 is of order unity for the vacuum contribution•
Gaussianity offers a powerful test of whether the detected GW comes from the vacuum or sourcesB h RRR (k, k, k )
P h 2 (k ) ⇡ 25
⌦ A
Aniket Agrawal (MPA)
Tomo Fujita (Kyoto)
[Maldacena (2003); Maldacena & Pimentel (2011)]
Agrawal, Fujita & EK, PRD, 97, 103526 (2018)
NG generated at the tree level
•
This diagram generates second-order equation of motion for GW[GW]
[GW]
[GW]
[tensor SU(2)]
[tensor SU(2)]
[tensor SU(2)]
[mQ ~ a few]
~10
–2Agrawal, Fujita & EK, PRD, 97, 103526 (2018)
Result
•
This shape is similar to, but not exactly the same as, what was used by the Planck team to look for tensor bispectrumk 3 /k 1
k 2 /k 1
Agrawal, Fujita & EK, PRD, 97, 103526 (2018)
Parameter Scan
Agrawal, Fujita & EK, JCAP, 97, 103526 (2018)Schwinger Effect
Lozanov, Maleknejad & EK, arXiv:1805.09318Kaloian Lozanov
(MPA) Azadeh Maleknejad
(MPA)
Summary
•
Next frontier: Using CMB polarisation to find primordial GW. Critical test of the physics of the early Universe!•
With LiteBIRD we plan to reach r~10–3, i.e., 100 times better than the current bound•
GW from vacuum or sources? An exciting window to new physics•
Check not only for scale invariant, but also for chirality and non-GaussianityGround-based
Experiments
Advanced Atacama
Cosmology Telescope
South Pole Telescope “3G”
CLASS BICEP/Keck Array
CMB-S4(?)
The Biggest Enemy:
Polarised Dust Emission
•
The upcoming data will NOT be limited by statistics, but by systematic effects such as the Galactic contamination•
Solution: Observe the sky at multiple frequencies, especially at high frequencies (>300 GHz)•
This is challenging, unless we have a superb, high- altitude site with low water vapour• CCAT-p!
CCAT-p Collaboration
Frank Bertoldi’s slide from the Florence meeting
Frank Bertoldi’s slide from the Florence meeting
Cornell U. + German consortium + Canadian consortium + …
A Game Changer
• CCAT-p
: 6-m, Cross-dragone design, on Cerro Chajnantor (5600 m)• Germany makes great telescopes!
•
Design study completed, and the contract has been signed by“VERTEX Antennentechnik GmbH”
•
CCAT-p is a great opportunity for Germany to makesignificant contributions towards the CMB S-4 landscape (both US and Europe) by providing telescope designs and the “lessons learned” with prototypes.
Simons Observatory (USA)
in collaboration
South Pole?
Simons Observatory (USA)
in collaboration
South Pole?
This could be
“CMB-S4”
Current Limit on Tensor NG
•
The Planck team reported a limit on the tensor bispectrum in the following form:Planck Collaboration (2015)
f NL tens ⌘ B h +++ (k, k, k ) F scalar equil. (k, k, k )
•
The denominator is the scalar equilateral bispectrum template, givingF
scalarequil.(k, k, k ) = (18/5)P
scalar2(k)
•
The current 68%CL constraint isf
NLtens= 400 ± 1500
LiteBIRD would nail it!
Courtesy of Maresuke Shiraishi
ftens NL
in 1502.01592
tensor-to-scalar ratio r
RFG + LiteBIRD noise, 0% delens, fsky = 0.5 noiseless, 100% delens, fsky = 1 ( ftensNL = 100r3/2)
10-1 100 101 102
10-4 10-3 10-2 10-1
50% sky, no delensing, LiteBIRD noise, and residual foreground
CV limited
Err[f
NLtens] = a few!
SU(2), confronted
•
The SU(2) model of Dimastrogiovanni et al. predicts:•
The current 68%CL constraint is•
This is already constraining!f
NLtens= 400 ± 1500
Agrawal, Fujita & EK, PRD, 97, 103526 (2018)
Parity-violating Spectra
•
Angle mis-calibration can be distinguished easily!EB
TB
TB from anglemis-calibration
Thorne, Fujita, Hazumi, Katayama, EK & Shiraishi, PRD, 97, 043506 (2018)