Exotica: Discovering new physics with
gravitational waves
Neil J. Cornish
Montana State University
“It would be unprecedented in
the history of astronomy if the
gravitational radiation window
being opened up by LISA does
not reveal new, enigmatic
sources”
Outline
• Exotic sources of gravitational waves
• How to detect the unexpected?
• Testing General Relativity
Imagined
Exotic Sources
Topological defects
Pre-heating/Re-heating
Phase transitions- bubble nucleation,
cavitation, collisions
Un-Imagined
Burst sources?
Warped extra dimensions
Braneworlds
Detecting the Unmodeled and Unexpected
Is this a signal or an instrumental artifact?
Detecting the Unmodeled and Unexpected
Is this a signal or an instrumental artifact?
a.k.a.
Guano or Gold?
Exotica Detection
• Multiple channels for signal/noise separation
• Time delays for signal/noise separation
• Angular resolution & EM counterparts
Three arms are better than two
Three arms are better than two
Z
X
Y
Three arms are better than two
Z
X
3
S+ =
X
2
1
S = (X + 2Y )
2
1
S = (X + Y + Z)
3
Y
}
}
Instantaneous measurement of
both polarization states and
increased signal-to-noise
Null channel to monitor average
low frequency instrument noise
Triangulation- Source Localization
Triangulation- Source Localization
Separating Burst Signals from Noise
Noise delays
L
t=n
c
Signal delays
L k̂ · L
t=n +
c
c
Separating Burst Signals from Noise: LIGO heritage
H
H
L
L
V
V
Separating Burst Signals from Noise: LIGO heritage
H
L
L
V
8e-21
8e-21
8e-21
6e-21
6e-21
6e-21
4e-21
4e-21
4e-21
2e-21
2e-21
2e-21
0
h
0
h
h
H
V
0
-2e-21
-2e-21
-2e-21
-4e-21
-4e-21
-4e-21
-6e-21
-6e-21
-8e-21
-6e-21
-8e-21
60
61
62
63
64
t
65
66
67
68
-8e-21
60
61
62
63
64
t
65
66
67
68
60
61
62
63
64
t
65
66
67
68
LIGO Burst reconstruction: BayesWave
(Mock LISA Data Challenge heritage here)
[Cornish & Littenberg 14]
Detecting a Stochastic Background
1e-11
A, E Channel
T Channel
1e-12
1e-13
1e-14
h (Hz1/2)
1e-15
1e-16
1e-17
1e-18
1e-19
1e-20
1e-21
1e-05
0.0001
0.001
f (Hz)
0.01
0.1
Detecting a Stochastic Background: (e)LISA
[Adams & Cornish 14]
Burst detection with LISA/eLISA?
LISA
eLISA
Up-scoping!
Cross
Flip
Up-scoping!
Dual
Trio
Burst Angular Resolution
f = 0.5f
13, 000 deg2
SNR = 100
Burst Angular Resolution
f = 0.5f
13, 000 deg2
300 deg2
SNR = 100
Burst Angular Resolution
f = 0.5f
13, 000 deg2
300 deg2
3 deg2
SNR = 100
Burst Angular Resolution
f = 0.5f
13, 000 deg2
300 deg2
3 deg2
SNR = 100
0.8 deg2
Burst Angular Resolution
f = 0.5f
SNR = 100
13, 000 deg2
0.8 deg2
300 deg2
0.5 deg2
3 deg2
Burst Angular Resolution
f = 0.5f
SNR = 100
13, 000 deg2
0.8 deg2
300 deg2
0.5 deg2
3 deg2
0.1 deg2
How to pay for it?
Curvature
Tests of General Relativity
Field Strength
Will, Liv. Rev. 2005
Psaltis, Liv. Rev. 2008
Siemens & Yunes, Liv. Rev. 2012
Gravitational Wave Tests of General Relativity
• Internal (self consistency checks)
•
•
BH spectroscopy - ringdowns
BH mapping - EMRIs, IMRIs
• External (comparison to alternative theories)
•
Specific theories (e.g. scalar-tensor, Chern-Simons)
•
•
•
•
Polarization states
Graviton mass
Null tests, coherent residuals
Parameterized models (e.g. ppE)
Gravitational Wave Tests of General Relativity
Fitting Factor and Bayes Factor Related:
Mismatch and Bayes Factor Related:
log BF
MM
1
(1
2
FF )SNR
2
2
Cornish, Sampson,
Yunes, Pretorius 2011
log BF
SNR2
aLIGO detection with SNR =10
Can measure 10% departure from GR
LISA detection with SNR =1000
Can measure 0.001% departure from GR
(> “4 sigma” detection)
Alternative Theories Predict Additional Polarization States
(
4)
(
3)
(
2
22
(
4)
(
3)
4)
(
2
22
(
3)
4)
(
3)
LISA sensitivity to alternative
polarization states
[Tinto, da Silva Alves 2010]
Speed Gravity = Speed Light?
Massive Graviton
Dark Matter Emulators
Desai, Kahya & Woodard 08
Braneworlds
vg2 = c2 (1
(mg /Eg )2 )
vg2 > c2
(photons and gravitons
“see” different metrics)
vg2 < c2
(gravitons propagate
off the brane)
Speed Gravity = Speed Light?
Massive Graviton
Dark Matter Emulators
Desai, Kahya & Woodard 08
Braneworlds
Optical Counterparts
vg2 = c2 (1
(mg /Eg )2 )
vg2 > c2
(photons and gravitons
“see” different metrics)
vg2 < c2
(gravitons propagate
off the brane)
Speed Gravity = Speed Light?
Massive Graviton
Dark Matter Emulators
Desai, Kahya & Woodard 08
Braneworlds
Optical Counterparts
vg2 = c2 (1
(mg /Eg )2 )
vg2 > c2
(photons and gravitons
“see” different metrics)
vg2 < c2
(gravitons propagate
off the brane)
Chirp “squeezing”
Post-Newtonian Waveforms
h(f ) = A(f ) ei
(f )
Post-Newtonian Waveforms
h(f ) = A(f ) ei
Leading order inspiral waveform
(f )
u = ( Mf )
1/3
v
c
Post-Newtonian Waveforms
h(f ) = A(f ) ei
(f )
u = ( Mf )
1/3
Leading order inspiral waveform
M2 Q( , , , )
AGR (f ) = 7/2
DL
u
GR (f )
= 2 f tc
c
/4 +
(
k=0
k
uk
5
+
lk
uk ln u)
v
c
Modified Waveforms
Variable G
(f ) = 2 f tc
+
c
3
+
u
4
128
3715 55
+
756
9
5
2/5 2
u
1
Scalar Field
25
ĠMu
1536
16
3/5 3
u
8
128
3
5 S2
84 BD
3/5
u
2
2
DM 2
u +...
2 (1 + z)
g
Massive Graviton
A(f ) =
5 M5/6
f
2/3
96 D
7/6
1
5
ĠMu
512
Variable G
8
+
743 11
+
672
8
u + ...
2/5 2
Parameterized Post Einsteinian
[Yunes-Pretorius ’09]
h(f ) = A(f ) ei
(f )
u = ( Mf )1/3
A(f ) = AGR (f ) (1 +
(f ) =
GR (f )
Theory
1+
ua )
ub
a
General Relativity
0
-
Brans-Dicke
0
-
Chern-Simons
1
b
0
-7
0
-
Extra-Dimensions
0
-
-13
Qaudratic Curvature
0
-
-1
-8
-13
-
-3
Variable G
Massive Graviton
0
Covers almost all theories (certain massive scalar field and spontaneous scalarization scenarios are exceptions )
LISA vs. Current Pulsar Bounds
(Cornish, Sampson, Yunes & Pretorius 2011)
10000
100
Brans Dicke LISA Exclusion
1
Excluded
0.01
Quadratic Curvature 0.0001
1e-06
Massive Graviton 1e-08
-2.5
Pulsar
LISA BH
-2
-6
-1.5
-1
-3
-0.5
b
00
0.5
31
Back of the envelope bounds
Useful cycles
Bayes Factor
[Damour, Iyer, Sathyaprakash ’00]
[Sampson et al ’14]
Alternative Gravity Multipliers: Butterfly Effect
[Cornish ??]
EMRI resonances
[Brink, Geyer, Hinderer 13]
[Ruangsri, Hughes 13]
Alternative Kerr Spacetimes
[Yagi, Yunes, Tanaka 12]