constraining gravitational waves from inflation · 2019-08-07 · brief intro + current bounds....
TRANSCRIPT
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Constraining Gravitational Waves from Inflation
Ema DimastrogiovanniThe University of New South Wales
BEYOND19 - Warsaw— July 5th 2019
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Outline
Brief intro + current bounds
Particle sources during inflation
Tensor fossils
Polarized Sunyaev–Zeldovich tomography
1810.09463 - Deutsch, ED, Fasiello, Johnson, Muenchmeyer1707.08129 - Deutsch, ED, Johnson, Muenchmeyer, Terrana
1806.05474 - ED, Fasiello, Hardwick, Assadullahi, Koyama, Wands
1608.04216 - ED, Fasiello, Fujita 1411.3029 - Biagetti, ED, Fasiello, Peloso
1708.01587 - Biagetti, ED, Fasiello1407.8204 - ED, Fasiello, Jeong, Kamionkowski
1504.05993 - ED, Fasiello, Kamionkowski
1906.07204 - ED, Fasiello, Tasinato
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Outline
Particle sources during inflation
Tensor fossils
Polarized Sunyaev–Zeldovich tomography
Brief intro + current bounds
![Page 4: Constraining Gravitational Waves from Inflation · 2019-08-07 · Brief intro + current bounds. ... pl k k ⇤ n s 1 2.2 ⇥ 109 0.968 ± 0.006 [k ⇤ =0.05Mpc1, 68%C.L.] from Planck](https://reader033.vdocuments.us/reader033/viewer/2022043023/5f3ef8e2b190ea08ab07a663/html5/thumbnails/4.jpg)
about 13.8 billion years
The universe over time
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P⇣(k) =1
8⇡2
1
✏
H2
M2pl
✓k
k⇤
◆ns�1
2.2⇥ 10�9
0.968± 0.006
[k⇤ = 0.05Mpc�1, 68%C.L.]
from Planck measurements of CMB anisotropies
�� ! ⇣ ! �T
Two-point statistics of primordial perturbations: scalars
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�ii = @i�ij = 0 two polarization states of the graviton
Gravitational waves
ds2 = �dt2 + a2(t) (�ij + �ij) dxidxj
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• homogeneous solution: GWs from vacuum fluctuations
GW background from inflation
• inhomogeneous solution: GWs from sources
⇧TTij /
scalars
{@i�@j�}TT
vectors
{EiEj +BiBj}TT
tensors
{�ij}TT
anisotropic stress-energy
tensor�Tij(from )
�ij + 3H �ij + k2�ij = 16⇡G⇧TT
ij
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red tilt: amplitude decreases
as we go towards smaller scales
energy scale of inflation
Pvacuum� (k) =
2
⇡2
H2
M2pl
✓k
k⇤
◆nT
nT = �r/8
• homogeneous solution: GWs from vacuum fluctuations
and non-chiral!!!
GW background from inflation
r ⌘ P�
P⇣
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10�1610�18 10�14 10�12 10�10 10�8 10�6 10�4 10�2 1 102wave
frequency (Hz)
space-based interferometers
terrestrialinterfer.
time between wave peaks
(age of the universe) (hours) (secs) (millisecs)
CMB anisotropies
Scales — Experiments
(years)
pulsar timing arrays (PTA)
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Observational bounds/sensitivities
Implications for model building:
threshold for large field inflation
��
Mpl&
⇣r⇤8
⌘1/2N⇤ &
⇣ r⇤0.01
⌘1/2
H . 5⇥ 1013 GeVupper bound on the
energy scale of inflation
r[0.05Mpc�1] < 0.06
BICEP2/KECK+Planck
Next generation:BICEP, SPT-3G,
Simons Obs., LiteBIRD, CMB-S4,
PICO
�(r) ! 0.0005
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Observational bounds/sensitivities
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Outline
Particle sources during inflation
Tensor fossils
Polarized Sunyaev–Zeldovich tomography
Brief intro + current bounds
![Page 13: Constraining Gravitational Waves from Inflation · 2019-08-07 · Brief intro + current bounds. ... pl k k ⇤ n s 1 2.2 ⇥ 109 0.968 ± 0.006 [k ⇤ =0.05Mpc1, 68%C.L.] from Planck](https://reader033.vdocuments.us/reader033/viewer/2022043023/5f3ef8e2b190ea08ab07a663/html5/thumbnails/13.jpg)
�ij + 3H �ij + k2�ij = 16⇡G⇧TT
ij
INFLATON SPECTATOR SECTOR+
negligible energy density compared to the inflaton
P tot� = P vacuum
� + P spectator�
• inhomogeneous solution: GWs from sources
GW background from inflation
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Why additional fields?
Interesting for phenomenology: qualitatively different signatures w.r.t. basic single-field inflation testable!
Natural from a top-down perspective: plenty of candidates from string theory (e.g. moduli fields, axions, Kaluza-Klein modes, gauge fields…)
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Scalar field (I)
Spectator fields with small sound speed
P (X,�)
subdominant at the background levelrelevant for perturbations
[Biagetti, Fasiello, Riotto 2012, Biagetti, ED, Fasiello, Peloso 2014, Fujita, Yokoyama, Yokoyama, 2014]
�ij + 3H �ij + k2�ij = 16⇡G⇧TT
ij
Pspectator� / 1
cns
H4
M4P
Sourced may be comparable to vacuum fluctuations
Breaking standard r—H relation: r = f(✏, cs)
small sound speed: from integrating out heavy fields
c2s =PX
PX + �20PXX
< 1
X ⌘ � (@�)2
/ @i�@j�
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Scalar field (II)
[Chung et al., 2000, Senatore et al, 2011, Pearce et al, 2017]
Auxiliary scalars with time-varying mass
graviton (and scalar fluctuations!) production
g2
2(�� �⇤)
2 �2
particle burst when inflaton crosses over value�⇤
features in the power spectra
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Axion-Gauge fields models: genesis
✏ ⌘M2
p
2
V
0
V
!2
, ⌘ ⌘ M2pV
00
V
… but flatness may be spoiled by radiative corrections!
Generic requirement for inflation: nearly flat potential: ✏, |⌘| ⌧ 1
� ! �+ c
V (') = ⇤4 [1� cos ('/f)]
Flatness protected by axionic shift symmetryNatural Inflation [Freese, Frieman, Olinto 1990]
f & MPAgreement with observations requires:
undesirable constraint on the theory[Kallosh, Linde, Susskind, 1995, Banks et al, 2003]
V (�)
�
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Axion-Gauge fields models: motivation
naturally light inflaton
��
4fF F
sub-Planckian axion decay constant
support reheating
Anber - Sorbo 2009, Cook - Sorbo 2011, Barnaby - Peloso 2011, Barnaby - Namba - Peloso 2011Adshead - Wyman 2011, Maleknejad - Sheikh-Jabbari, 2011, ED - Fasiello - Tolley 2012ED - Peloso 2012, Namba - ED - Peloso 2013, Adshead - Martinec -Wyman 2013, ED - Fasiello - Fujita 2016Agrawal - Fujita - Komatsu 2017, Thorne - Fujita - Hazumi - Katayama - Komatsu - Shiraishi ’17Caldwell - Devulder 2017, …
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LspectatorP�,vacuum P�,sourced
L = Linflaton � 1
2(@�)2 � U(�)� 1
4FF +
��
4fF F
Inflaton field dominates energy density of the universe
Spectator sector contribution to curvature fluctuations negligible
[ED-Fasiello-Fujita 2016]
Axion-Gauge fields models: SU(2)
Aa0 = 0
Aai = aQ�ai
slow-roll background attractor solution
�Aai = tai + ... TT-component A �
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One helicity of the gauge field fluctuations is amplified from coupling with axion the same helicity of the tensor mode is amplified
�R
tRgauge field(L)
�
A
[ED-Fasiello-Fujita 2016]
Axion-Gauge fields models: SU(2)
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Axion-Gauge fields models: signatures
Non-Gaussianity
Chirality
Scale dependence
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Scale-dependence
basic single-field inflation axion-gauge fields models
nT ' �r/8
(nearly flat spectrum)
[ED-Fasiello-Fujita 2016, Thorne et al, 2017]
detectably large and running nT
bump may occur at small scales
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Chirality
basic single-field inflation axion-gauge fields models
�L = �R �L 6= �Rnon-chiral chiral
hTBi, hEBi 6= 0hTBi, hEBi = 0(parity conservation)
Detectable at 2 by LiteBIRD for r > 0.03 [Thorne et al, 2017]
�
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basic single-field inflation axion-gauge fields models
�L = �R �L 6= �Rnon-chiral chiral
Interferometers: need advanced design with multiple (non co-planar) detectors [Thorne et al. 2017, Smith-Caldwell 2016]
Chirality
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Non-Gaussianity: beyond the power spectrum
k1
k2
k3
h��1k1��2k2��3k3i = (2⇡)3�(3)(k1 + k2 + k3)B
�1�2�3� (k1, k2, k3)
tensor bispectrum
shape:
amplitude: fNL =B
P 2⇣
![Page 26: Constraining Gravitational Waves from Inflation · 2019-08-07 · Brief intro + current bounds. ... pl k k ⇤ n s 1 2.2 ⇥ 109 0.968 ± 0.006 [k ⇤ =0.05Mpc1, 68%C.L.] from Planck](https://reader033.vdocuments.us/reader033/viewer/2022043023/5f3ef8e2b190ea08ab07a663/html5/thumbnails/26.jpg)
Tensor non-Gaussianity
k1
k2
k3
from interactions of the tensors with other fields or from self-interactions
�
�
�
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[Agrawal - Fujita - Komatsu 2017]detectable by upcoming CMB space missions
axion-gauge fields models
�
�
� �
�
�
AA
A
A A
basic single-field inflation
fNL = O(r2)
too small for detection
�
�
�
Tensor non-Gaussianity
fNL = r2 · 50✏B
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Mixed (scalar-tensor) non-Gaussianity
testing interactions of tensors and matter fields
A
�
� ⇣
[ED - Fasiello - Hardwick - Koyama - Wands 2018, Fujita - Namba - Obata 2018]
potentially observable!
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Inflationary GWs from vacuum fluctuations
One or more of these predictions may be easily violated beyond
the minimal set-up!
• Energy scale of inflation: V 1/4infl ⇡ 1016GeV (r/0.01)1/4
• Scalar field excursion (Lyth bound): ��/MP & (r/0.01)1/2
• Non-chiral:
H ⇡ 2⇥ 1013p
r/0.01GeV
nT ' �2✏ = �r/8• Red tilt:
• Nearly Gaussian: fNL ⌧ 1
PL = PR
![Page 30: Constraining Gravitational Waves from Inflation · 2019-08-07 · Brief intro + current bounds. ... pl k k ⇤ n s 1 2.2 ⇥ 109 0.968 ± 0.006 [k ⇤ =0.05Mpc1, 68%C.L.] from Planck](https://reader033.vdocuments.us/reader033/viewer/2022043023/5f3ef8e2b190ea08ab07a663/html5/thumbnails/30.jpg)
Outline
Particle sources during inflation
Tensor fossils
Polarized Sunyaev–Zeldovich tomography
Brief intro + current bounds
![Page 31: Constraining Gravitational Waves from Inflation · 2019-08-07 · Brief intro + current bounds. ... pl k k ⇤ n s 1 2.2 ⇥ 109 0.968 ± 0.006 [k ⇤ =0.05Mpc1, 68%C.L.] from Planck](https://reader033.vdocuments.us/reader033/viewer/2022043023/5f3ef8e2b190ea08ab07a663/html5/thumbnails/31.jpg)
amplitude of long-wavelength modes coupled with amplitude of short-wavelength modes
long wavelength
short wavelength
short wavelengthk3 k2
k1
Squeezed non-Gaussianity
31
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Soft limits and fossils
squeezed 3pf affects the 2pf
• No squeezed non-Gaussianity h�~k1�~k2
i = �(3)(~k1 + ~k2)P (k1)diagonal
2p correlation
• Squeezed non-Gaussianity
~K ~k1
~k2
there is also a
off-diagonal
contribution!h�~k1
�~k2i ~K = �(3)(~k1 + ~k2 + ~K)
⇥f(~k1,~k2)A(K)
short-wavelength modes
long-wavelength mode
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[ED, Fasiello, Jeong, Kamionkowski - 2014, ED, Fasiello, Kamionkowski - 2015, Biagetti, ED, Fasiello - 2017]
Soft limits and fossils
�
⇣
⇣~K ~k1
~k2comes fromIf
constrain tensor modes amplitude/interactions with induced quadrupole anisotropy
super-Hubble K:
~k0
1~k
0
2
~k2
~k1~k
00
1
~k00
2
~k000
2
~k000
1
~K
estimate tensor modes amplitudefrom off-diagonal correlations
sub-Hubble K:
P⇣(k,xc)|�L = P⇣(k)⇣1 +Q`m(xc,k)k`km
⌘
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Soft limits and fossils
�~K ~k1
~k2from
constrain tensor modes amplitude/interactions with induced quadrupole anisotropy
super-Hubble K:
�
�
P�(k,xc)|�L = P�(k)⇣1 +Q`m(xc,k)k`km
⌘
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Soft limits and fossils
�~K ~k1
~k2from
constrain tensor modes amplitude/interactions with induced quadrupole anisotropy
super-Hubble K:
�
�
P�(k,xc)|�L = P�(k)⇣1 +Q`m(xc,k)k`km
⌘
Important remark: primordial bispectrum highly suppressed on small scales(superposition of signals from a large number of Hubble patches
+ Shapiro time-delay)[Bartolo, De Luca, Franciolini, Lewis, Peloso, Riotto 2018]
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[ED, Fasiello, Tasinato 2019]
Soft limits and fossils
�~K ~k1
~k2from
constrain tensor modes amplitude/interactions with induced quadrupole anisotropy
super-Hubble K:
�
�
Crucial observable for tensor non-Gaussianityat interferometer scales!
P�(k,xc)|�L = P�(k)⇣1 +Q`m(xc,k)k`km
⌘
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Why is squeezed non-Gaussianity
so important?
37
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kN+1
k1k2
k3
kN
limkN+1!0
⇠ 0[ ]SINGLE-FIELD (single-clock) inflation: soft-limits not observable
Intuitive understanding :
[Maldacena 2003, Creminelli, Zaldarriaga 2004]
Soft limits in inflation
Soft mode rescales background for hard modes Effect can be gauged away!
Super-horizon modes freeze-out Standard initial conditions
![Page 39: Constraining Gravitational Waves from Inflation · 2019-08-07 · Brief intro + current bounds. ... pl k k ⇤ n s 1 2.2 ⇥ 109 0.968 ± 0.006 [k ⇤ =0.05Mpc1, 68%C.L.] from Planck](https://reader033.vdocuments.us/reader033/viewer/2022043023/5f3ef8e2b190ea08ab07a663/html5/thumbnails/39.jpg)
Extra fields Soft limits reveal(extra) fields mediating
inflaton or graviton interactions
squeezed bispectrum delivers info on mass spectrum!!!
energy
Hm�
�⇣, �
⇣, �
⇣, �
39
Soft limits in inflation
![Page 40: Constraining Gravitational Waves from Inflation · 2019-08-07 · Brief intro + current bounds. ... pl k k ⇤ n s 1 2.2 ⇥ 109 0.968 ± 0.006 [k ⇤ =0.05Mpc1, 68%C.L.] from Planck](https://reader033.vdocuments.us/reader033/viewer/2022043023/5f3ef8e2b190ea08ab07a663/html5/thumbnails/40.jpg)
probe for (extra) fields, pre-inflationary dynamics, (non-standard) symmetry patterns
Non-Bunch Davies initial states[Holman - Tolley 2007, Ganc - Komatsu 2012, Brahma - Nelson - Shandera 2013, …]
Broken space diffs (e.g. space-dependent background)[Endlich et al. 2013, ED - Fasiello - Jeong - Kamionkowski 2014, …]
[Chen - Wang 2009, ED - Fasiello - Kamionkowski 2015, ED - Emami 2016, Biagetti - ED - Fasiello 2017, …]
Extra fields
40
Soft limits in inflation
![Page 41: Constraining Gravitational Waves from Inflation · 2019-08-07 · Brief intro + current bounds. ... pl k k ⇤ n s 1 2.2 ⇥ 109 0.968 ± 0.006 [k ⇤ =0.05Mpc1, 68%C.L.] from Planck](https://reader033.vdocuments.us/reader033/viewer/2022043023/5f3ef8e2b190ea08ab07a663/html5/thumbnails/41.jpg)
Learning about primordial gravitational waves through non-Gaussian effects
Local observables affected by long modes (anisotropic effects / off-diagonal correlations)
Effects from “squeezed” tensor-scalar-scalar bispectrum particularly effective at constraining inflation!
Tensor fossils
Quadrupole anisotropy crucial observable for tensor non-Gaussianity at interferometer scales
![Page 42: Constraining Gravitational Waves from Inflation · 2019-08-07 · Brief intro + current bounds. ... pl k k ⇤ n s 1 2.2 ⇥ 109 0.968 ± 0.006 [k ⇤ =0.05Mpc1, 68%C.L.] from Planck](https://reader033.vdocuments.us/reader033/viewer/2022043023/5f3ef8e2b190ea08ab07a663/html5/thumbnails/42.jpg)
Outline
Particle sources during inflation
Tensor fossils
Polarized Sunyaev–Zeldovich tomography
Brief intro + current bounds
![Page 43: Constraining Gravitational Waves from Inflation · 2019-08-07 · Brief intro + current bounds. ... pl k k ⇤ n s 1 2.2 ⇥ 109 0.968 ± 0.006 [k ⇤ =0.05Mpc1, 68%C.L.] from Planck](https://reader033.vdocuments.us/reader033/viewer/2022043023/5f3ef8e2b190ea08ab07a663/html5/thumbnails/43.jpg)
Large scale structure surveys
Primordial Gravitational Waves
CMB polarization
Interferometers
![Page 44: Constraining Gravitational Waves from Inflation · 2019-08-07 · Brief intro + current bounds. ... pl k k ⇤ n s 1 2.2 ⇥ 109 0.968 ± 0.006 [k ⇤ =0.05Mpc1, 68%C.L.] from Planck](https://reader033.vdocuments.us/reader033/viewer/2022043023/5f3ef8e2b190ea08ab07a663/html5/thumbnails/44.jpg)
Polarized Sunyaev-Zel’dovich effect
• Polarization from Thomson scattering of (quadrupolar) radiation by free electrons
• Used to obtain a map of the remote (= locally observed) CMB quadrupole
• Additional information w.r.t. primary CMB (scattered photons from off our past light cone)
![Page 45: Constraining Gravitational Waves from Inflation · 2019-08-07 · Brief intro + current bounds. ... pl k k ⇤ n s 1 2.2 ⇥ 109 0.968 ± 0.006 [k ⇤ =0.05Mpc1, 68%C.L.] from Planck](https://reader033.vdocuments.us/reader033/viewer/2022043023/5f3ef8e2b190ea08ab07a663/html5/thumbnails/45.jpg)
Notice:
(Q± iU)(ne)��pSZ
= �p6
10�T
Zd�e a(�e)ne(ne,�e) q
±e↵(ne,�e)
qme↵(ne,�e ! 0) = aT2m
qme↵(ne,�e) =
Zd2n
⇥⇥(ne,�e, n) +⇥T (ne,�e, n)
⇤Y ⇤2m(n)
q±e↵(ne,�) =2X
m=�2
qme↵(ne,�e)±2Y2m(ne)
“Remote” (observed at the location of the scatterer) CMB quadrupole
Polarized Sunyaev-Zel’dovich effect
![Page 46: Constraining Gravitational Waves from Inflation · 2019-08-07 · Brief intro + current bounds. ... pl k k ⇤ n s 1 2.2 ⇥ 109 0.968 ± 0.006 [k ⇤ =0.05Mpc1, 68%C.L.] from Planck](https://reader033.vdocuments.us/reader033/viewer/2022043023/5f3ef8e2b190ea08ab07a663/html5/thumbnails/46.jpg)
pSZ tomography
Reconstructing the remote quadrupole field from CMB-LSS cross-correlation:
tracer of electron number density
long-wavelength modulation of
small-scale power
ensemble average over small-scales
(q treated as a fixed deterministic field)
[Kamionkowski, Loeb 1997, Alizadeh, Hirata 2012, Deutsch, ED, Johnson, Muenchmeyer, Terrana - 2017]
D(Q± iU)
��pSZ
�(�e)E⇠ h� q± �i ⇠ q±(ne, �e)h� �i(�e)
![Page 47: Constraining Gravitational Waves from Inflation · 2019-08-07 · Brief intro + current bounds. ... pl k k ⇤ n s 1 2.2 ⇥ 109 0.968 ± 0.006 [k ⇤ =0.05Mpc1, 68%C.L.] from Planck](https://reader033.vdocuments.us/reader033/viewer/2022043023/5f3ef8e2b190ea08ab07a663/html5/thumbnails/47.jpg)
pSZ tomography
[A.-S. Deutsch, ED, M.C. Johnson, M. Muenchmeyer, A. Terrana - 2017]
Bin-averaged quadrupole field moments decomposition:
q±↵(ne) =X
`m
aq±↵`m ±2Y`m(ne)
aq,E ↵`m = �1
2
�aq+↵`m + aq�↵
`m
�
aq,B ↵`m = � 1
2i
�aq+↵`m � aq�↵
`m
�{ scalars/tensors
tensorsonly
Optimal unbiased estimator : X = E, B
aq,X ↵`m =
X
`1m1`2m2
⇣WX,E
`m`1m1`2m2aE`1m1
+WX,B`m`1m1`2m2
aB`1m1
⌘�⌧↵`2m2
binned density
field
![Page 48: Constraining Gravitational Waves from Inflation · 2019-08-07 · Brief intro + current bounds. ... pl k k ⇤ n s 1 2.2 ⇥ 109 0.968 ± 0.006 [k ⇤ =0.05Mpc1, 68%C.L.] from Planck](https://reader033.vdocuments.us/reader033/viewer/2022043023/5f3ef8e2b190ea08ab07a663/html5/thumbnails/48.jpg)
Primordial gravitational wave phenomenology with pSZ tomography
![Page 49: Constraining Gravitational Waves from Inflation · 2019-08-07 · Brief intro + current bounds. ... pl k k ⇤ n s 1 2.2 ⇥ 109 0.968 ± 0.006 [k ⇤ =0.05Mpc1, 68%C.L.] from Planck](https://reader033.vdocuments.us/reader033/viewer/2022043023/5f3ef8e2b190ea08ab07a663/html5/thumbnails/49.jpg)
[A.-S. Deutsch, ED, M. Fasiello, M.C. Johnson, M. Muenchmeyer - 2018]
full set of correlations between primary CMB and reconstructed remote quadrupole field
aT`m primary CMB temperature
E-mode remote quadrupole field
B-mode remote quadrupole field
aqE`m(�)
aqB`m(�)
primary CMB polarizationaB`m
aE`m
{
![Page 50: Constraining Gravitational Waves from Inflation · 2019-08-07 · Brief intro + current bounds. ... pl k k ⇤ n s 1 2.2 ⇥ 109 0.968 ± 0.006 [k ⇤ =0.05Mpc1, 68%C.L.] from Planck](https://reader033.vdocuments.us/reader033/viewer/2022043023/5f3ef8e2b190ea08ab07a663/html5/thumbnails/50.jpg)
chirality primordial tensorpower spectrum
[A.-S. Deutsch, ED, M. Fasiello, M.C. Johnson, M. Muenchmeyer - 2018]
![Page 51: Constraining Gravitational Waves from Inflation · 2019-08-07 · Brief intro + current bounds. ... pl k k ⇤ n s 1 2.2 ⇥ 109 0.968 ± 0.006 [k ⇤ =0.05Mpc1, 68%C.L.] from Planck](https://reader033.vdocuments.us/reader033/viewer/2022043023/5f3ef8e2b190ea08ab07a663/html5/thumbnails/51.jpg)
Fisher matrix forecast to derive exclusion bounds
• Our parameters:
amplitude
scale-dependence
chirality �c
r
nT
[A.-S. Deutsch, ED, M. Fasiello, M.C. Johnson, M. Muenchmeyer - 2018]
![Page 52: Constraining Gravitational Waves from Inflation · 2019-08-07 · Brief intro + current bounds. ... pl k k ⇤ n s 1 2.2 ⇥ 109 0.968 ± 0.006 [k ⇤ =0.05Mpc1, 68%C.L.] from Planck](https://reader033.vdocuments.us/reader033/viewer/2022043023/5f3ef8e2b190ea08ab07a663/html5/thumbnails/52.jpg)
• green: zero-noise cosmic variance limit using primary CMB T, E, B
• red: T, E, B, qE, qB with instrumental noise 1µK � arcmin
0.1µK � arcmin• blue: T, E, B, qE, qB with instrumental noise
• grey: T, E, B, qE, qB with no instrumental noise
Forecasted parameter constraints
[A.-S. Deutsch, ED, M. Fasiello, M.C. Johnson, M. Muenchmeyer - 2018]
![Page 53: Constraining Gravitational Waves from Inflation · 2019-08-07 · Brief intro + current bounds. ... pl k k ⇤ n s 1 2.2 ⇥ 109 0.968 ± 0.006 [k ⇤ =0.05Mpc1, 68%C.L.] from Planck](https://reader033.vdocuments.us/reader033/viewer/2022043023/5f3ef8e2b190ea08ab07a663/html5/thumbnails/53.jpg)
Observers: optimize future missions to go after these signals
improvements on constraints on phenomenological models of the tensor sector w.r.t. using the primary CMB (only)
pSZ tomography
![Page 54: Constraining Gravitational Waves from Inflation · 2019-08-07 · Brief intro + current bounds. ... pl k k ⇤ n s 1 2.2 ⇥ 109 0.968 ± 0.006 [k ⇤ =0.05Mpc1, 68%C.L.] from Planck](https://reader033.vdocuments.us/reader033/viewer/2022043023/5f3ef8e2b190ea08ab07a663/html5/thumbnails/54.jpg)
can lead to discovery of new physics
testable on a vast range of scales (and from cross-correlations of different probes!)
Primordial gravitational waves
different observables (amplitude, chirality, scale dependence, non-Gaussianity) to characterize them and identify their sources
a very important probe of inflation
Thank you!