GRAVITATIONAL WAVES: FROM DETECTION TO NEW …...• Gravitational Wave Signals Outline for Today 6 • If there is a light axion (scalar/ vector) with compton wavelength comparable

GRAVITATIONAL WAVES: FROM DETECTION TO NEW PHYSICS SEARCHES

Masha Baryakhtar

New York University

Lecture 3 July 2. 2020

Superradiance and Black Holes

or

How to Extract Energy from Black Holes and

Discover New Particles

• Superradiance and rotating BHs

• Gravitational Atoms

• Signs of New Particles

• Black Hole Spindown

• Gravitational Wave Signals

Outline for Today

3






Outline for Today

4

• Rotational, or Zeldovich, superradiance: extraction of an object’s rotational energy by an incident wave in the presence of dissipation

• Rotating (Kerr) black holes can superradiance and lose energy and angular momentum






Outline for Today

5

• Ultralight fields can form macroscopic gravitationally bound states with astophysical black holes, or ``gravitational atoms’’

• Bosonic fields can form states with exponentially large occupation values which grow spontaneously through superradiance






Outline for Today

6

• If there is a light axion (scalar/vector) with compton wavelength comparable to astrophysical BH sizes, it will cause astrophysical black holes to spin down

• The resulting bound states of light particles will source gravitational wave radiation that is observable by LIGO

Motivation

7

• Ultralight scalar particles often found in theories beyond the Standard Model

• E.g. the QCD axion solves the `strong-CP’ problem

• As already discussed, ultralight scalars can make up the DM

10-14 10-12 10-10 10-8 10-6 10-4 10-2 1

1018

1016

1014

1012

1010

108

106

108 106 104 102 1 10-2 10-4 10-6

CASTSN1987A

HAYSTAC

ADMX

Telescopes

axion

SN1987A

ALP dark matter

QCD axion

Plan

ck s

cale

30 M⦿ black hole radius

GWs,BH spindown

• Black holes in our universe provide nature’s laboratories to search for light particles

• Set a typical length scale, and are a huge source of energy

• Sensitive to QCD axions with GUT- to Planck-scale decay constants fa

Astrophysical Black Holes and Ultralight Particles

8

tt

Amplitude

frequency

kHz−1t

100 km

for a 10-12 eV particle:

103kmx

Amplitude

black hole (30 M☉)

compton wavelength

Ball incident on cylinder with lossy surface slows down due to friction

9

• A an object scattering off a rotating cylinder can increase in angular momentum and energy.

• Effect depends on dissipation, necessary to change the velocity

Superradiance: gaining from dissipation

10

If the cylinder is rotating at angular velocity equal to the angular velocity of the ball about the axis, the relative velocity at the point of contact is zero: no energy loss




⌦i = v�,i

<latexit sha1_base64="NdkuuF5HYynWh2KwTlXzrXyj/iA=">AAAB/nicbVBNS8NAEJ34WetXVDx5WSyCBymJFNSDUPTizQr2A5oQNtttu3Q3CbubQgkF/4oXD4p49Xd489+4bXPQ1gcDj/dmmJkXJpwp7Tjf1tLyyuraemGjuLm1vbNr7+03VJxKQusk5rFshVhRziJa10xz2kokxSLktBkObid+c0ilYnH0qEcJ9QXuRazLCNZGCuxD717QHg4YukbDIPOSPjtj48AuOWVnCrRI3JyUIEctsL+8TkxSQSNNOFaq7TqJ9jMsNSOcjoteqmiCyQD3aNvQCAuq/Gx6/hidGKWDurE0FWk0VX9PZFgoNRKh6RRY99W8NxH/89qp7l76GYuSVNOIzBZ1U450jCZZoA6TlGg+MgQTycytiPSxxESbxIomBHf+5UXSOC+7lfLVQ6VUvcnjKMARHMMpuHABVbiDGtSBQAbP8Apv1pP1Yr1bH7PWJSufOYA/sD5/AEZZlRI=</latexit>

11

If the cylinder is rotating even faster,




Ball scattering off rapidly rotating cylinder with lossy surface speeds up!

Energy increase comes from cylinder slowing down, losing energy and angular momentum

⌦i > v�,i

<latexit sha1_base64="zSLbg60Wn7vua3LOSB3eUeunfSg=">AAAB/nicbVBNS8NAEJ34WetXVDx5WSyCBymJFNSLFL14s4L9gCaEzXbbLt1Nwu6mUELBv+LFgyJe/R3e/Ddu2xy09cHA470ZZuaFCWdKO863tbS8srq2Xtgobm5t7+zae/sNFaeS0DqJeSxbIVaUs4jWNdOcthJJsQg5bYaD24nfHFKpWBw96lFCfYF7EesygrWRAvvQuxe0hwOGrtEwyLykz87YOLBLTtmZAi0SNyclyFEL7C+vE5NU0EgTjpVqu06i/QxLzQin46KXKppgMsA92jY0woIqP5ueP0YnRumgbixNRRpN1d8TGRZKjURoOgXWfTXvTcT/vHaqu5d+xqIk1TQis0XdlCMdo0kWqMMkJZqPDMFEMnMrIn0sMdEmsaIJwZ1/eZE0zstupXz1UClVb/I4CnAEx3AKLlxAFe6gBnUgkMEzvMKb9WS9WO/Wx6x1ycpnDuAPrM8fR+iVEw==</latexit>

• Scalar perturbations scattering off of rotating cylindrical medium with absorption

� = �(r)e�i!t+im'

v',i < ⌦i ! !/m < ⌦

⌦


The amplitude of the field will increase for

superradiance condition

12

• A wave scattering off a rotating object can increase in amplitude by extracting angular momentum and energy.

• Growth proportional to probability of absorption when rotating object is at rest: dissipation necessary to increase wave amplitude

Angular velocity of wave slower than angular velocity of BH horizon,

⌦a < ⌦BH

Superradiance condition:

Zel’dovich; Starobinskii; Misner 13


• A wave scattering off a rotating object can increase in amplitude by extracting angular momentum and energy.

• Growth proportional to probability of absorption when rotating object is at rest: dissipation necessary to change the wave amplitude


⌦a < ⌦BH


Zel’dovich; Starobinskii; Misner 14Numerical GR simulation by Will East

Gravitational wave amplified when scattering from a rapidly rotating black hole

Superradiance

14

⌦a < ⌦BH

What is the `angular velocity’ of the BH horizon?

15

Superradiance condition for Black Holes


Kerr Metric

16

Kerr Metric

17

v

Kerr Metric

18

v

v

Horizon: coordinate singularity:

Kerr Metric

19

Ergoregion:

Kerr Metric

20

Ergoregion:

Surface beyond which there are no stationary observers

⌦a < ⌦BH

What is the `angular velocity’ of the BH horizon?

21



`Blackboard’

⌦a < ⌦BH

For a scalar field mode with energy and angular momentum ,ω m

22



� = �(r)e�i!t+im'

⌦a < ⌦BH


23



� = �(r)e�i!t+im'

And a Kerr black hole,!

m<

1

2rg

a⇤

1 +p

1� a2⇤

<latexit sha1_base64="+5q5llJh/g0/fRSL1DoPoEhO/3g=">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</latexit>

⌦a < ⌦BH


24



� = �(r)e�i!t+im'

And a Kerr black hole,!

m<

1

2rg

a⇤

1 +p

1� a2⇤

<latexit sha1_base64="+5q5llJh/g0/fRSL1DoPoEhO/3g=">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</latexit>

For a nonrelativistic field with mass and angular momentum , the SR condition isμ m

µrgm

<1

2

a⇤

1 +p

1� a2⇤<

1

2

<latexit sha1_base64="w9Dngca0TImFqBKyJK/XjsnPIMA=">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</latexit>






Outline for Today

25

• Ultralight fields can form macroscopic gravitationally bound states with astophysical black holes, or ``gravitational atoms’’

• Bosonic fields can form states with exponentially large occupation values which grow spontaneously through superradiance

“Black hole bomb” exponential instability when surround BH by a mirror

Kinematic, not resonant condition

Particles/waves trapped in orbit around the BH repeat this process continuously

Press & Teulkosky


⌦a < ⌦BH


26

Superradiance

“Black hole bomb”: exponential instability when surround BH by a mirror

Kinematic, not resonant condition

Particles/waves trapped in orbit around the BH repeat this process continuously

Press & Teulkosky

⌦a < ⌦BH


27

Superradiance


[Zouros & Eardley’79; Damour et al ’76; Detweiler’80; Gaina et al ’78][Arvanitaki, Dimopoulos, Dubovsky, Kaloper, March-Russell 2009; Arvanitaki, Dubovsky 2010]

• For a massive particle, e.g. axion, gravitational potential barrier provides trapping

• For high superradiance rates, compton wavelength should be comparable to black hole radius:

�a ⇠ 3 km 6⇥10�11eVµa

28

Superradiance

V(r) = −GNMBHμa

r

t

μ−1a

rg ≲ μ−1a

rg

• Particles/waves trapped near the BH repeat this process continuously

Gravitational Atoms?

Axion Gravitational Atoms

29

n = 1, ℓ = 0, m = 0 n = 2, ℓ = 1, m = 1 n = 3, ℓ = 2, m = 2V(r) = −

GNMBHμa

r

&

Gravitational Atoms?


30

n = 1, ℓ = 0, m = 0 n = 2, ℓ = 1, m = 1 n = 3, ℓ = 2, m = 2V(r) = −

GNMBHμa

r

&

&

Gravitational Atoms


31

α ≡ GNMBHμa ≡ rgμa

`Fine structure constant`

n = 1, ℓ = 0, m = 0 n = 2, ℓ = 1, m = 1 n = 3, ℓ = 2, m = 2V(r) = −

GNMBHμa

r

Gravitational potential similar to hydrogen atom

Constraint on from SR condition:α↵

m<

1

2

a⇤

1 +p1� a2⇤

<1

2

<latexit sha1_base64="d4dMFMzG5k2W+qTG1DWMeRc8MSg=">AAACMXicbVDLSgMxFM3UV62vqks3wSKIYpkpBRVcFN10WcE+oFPLnTTThmYeJhmhhPklN/6JuOlCEbf+hOljodUDgZNzziW5x4s5k8q2x1ZmaXlldS27ntvY3Nreye/uNWSUCELrJOKRaHkgKWchrSumOG3FgkLgcdr0hjcTv/lIhWRReKdGMe0E0A+ZzwgoI3XzVdcXQLQLPB5AqoMUX+GZ5KS6lM4odE9S7Zy68kEo7ZyZ630pXUh28wW7aE+B/xJnTgpojlo3/+L2IpIENFSEg5Rtx45VR4NQjHCa5txE0hjIEPq0bWgIAZUdPd04xUdG6WE/EuaECk/VnxMaAilHgWeSAaiBXPQm4n9eO1H+RUezME4UDcnsIT/hWEV4Uh/uMUGJ4iNDgAhm/orJAEwLypScMyU4iyv/JY1S0SkXL2/Lhcr1vI4sOkCH6Bg56BxVUBXVUB0R9IRe0Rt6t56tsfVhfc6iGWs+s49+wfr6Bs3pqfA=</latexit>

Gravitational Atoms


32



n = 1, ℓ = 0, m = 0 n = 2, ℓ = 1, m = 1 n = 3, ℓ = 2, m = 2V(r) = −

GNMBHμa

r


rc ≃n2

α μa∼ 4 − 400rg

Radius Occupation number

N ∼ 1075 − 1080


33



n = 1, ℓ = 0, m = 0 n = 2, ℓ = 1, m = 1 n = 3, ℓ = 2, m = 2V(r) = −

GNMBHμa

r


rc ≃n2

α μa∼ 4 − 400rg

Radius Occupation number

N ∼ 1075 − 1080

Boundary conditions at horizon give imaginary frequency: exponential growth for rapidly rotating black holes

E ≃ μ (1 −α2

2n2 ) + iΓsr

Gravitational Atoms

Cloud size

Superradiance Timescales

BH lightcrossing time

Superradiance time

Annihilation time

Particle wavelength

34

rg

rc ⇠n

↵2rg

µ�1 =rg↵

�EM =e2

4�� = GNMBHµa = Rgµa . m

2a⇤

.01 ms

.1 ms

ms

⌧sr ⇠cn`m

(m⌦BH � µ)r+

1

↵4`+2j+5rg

<latexit sha1_base64="dj1UqTBaa30NrpXbGDDX4lNT+sE=">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</latexit>

Cloud size



Superradiance time

Annihilation time

Particle wavelength

35

rg

rc ⇠n

↵2rg

µ�1 =rg↵

�EM =e2


2a⇤

�scalarsr ⇠

Z

r=rg

⇤ · dA / (8⇡rgr+)1

r3c

✓r

rc

◆2`

|r=rg / ↵4`+6r�1gFlux into horizon:

.01 ms

.1 ms

ms

100 s

ma=6*10-13eV

20 40 60 80 100 120 1400.0

0.2

0.4

0.6

0.8

1.0

Black Hole Mass HMüL

BlackHoleSpina *

⌦ a<⌦ B

H

⌧SR >

100 ⌧BH

A black hole is born with spin a* = 0.95, M = 40 M⦿.

36

Superradiance: a stellar black hole history


Particle wavelength

0.2 msec (60 km)

1 msec (300 km)

t

BH rotates quickly enough to superradiate

ℓ = 1 ℓ = 2

ℓ = 3

ma=6*10-13eV

20 40 60 80 100 120 1400.0

0.2

0.4

0.6

0.8

1.0


BlackHoleSpina *

~ 1 year (~180 superradiance times)

BH spins down and fastest-growing level is formed


37


Particle wavelength

0.2 msec (60 km)

1 msec (300 km)

t

Cloud radius6 msec (2000 km)Once BH angular velocity matches that of the level, growth stops

no longer satisfies l=1 SR condition

ma=6*10-13eV

20 40 60 80 100 120 1400.0

0.2

0.4

0.6

0.8

1.0


BlackHoleSpina *


~ 1 year

Cloud can carry up to a few percent of the black hole mass: huge energy density

38

~1078 particles


{black hole angular momentum decreases by

1078 ℏ






Outline for Today

39

• If there is a light axion (scalar/vector) with compton wavelength comparable to astrophysical BH sizes, it will cause astrophysical black holes to spin down

• The resulting bound states of light particles will source gravitational wave radiation that is observable by LIGO

Five currently measured black holes combine to set limit:

Black Hole Spins

10-10

QCD axion

2s exclusion

1

2

35

45: GRS 1915+1054: Cyg X-13: GRO J1655-402: LMC X-11: M33 X-7

-13 -12 -11 -10 -9-20

-18

-16

-14

-12

-75

-70

-65

-60

Log@maêeVD

Log@G

eVêf aD

Log@lH10-10eVêm aL2 D

10-12 10-11 10-910-13 (eV)µa

41

Many BH-BH mergers detected

Each detection comes with

a measurement of the initial

black hole masses, and, to a

lesser extent, spins

Black Hole Spins

Initial Spin!actual"

0 20 40 60 80 1000.0

0.2

0.4

0.6

0.8

1.0

Black Hole Mass !M!"

BlackHoleSpina !

9-240 BBHs/Gpc3/yr. : 1000s of BHs merging in low-redshift universe

at LIGO

42

at LIGOBlack Hole Spins

If light axion exists, many initial BHs would have low spin due to superradiance, limited by age and radius of binary system

ma = 6 x 10-13 eVHactualL

0 20 40 60 80 1000.0

0.2

0.4

0.6

0.8

1.0


BlackHoleSpina *

l=1 l=2l=3

10 billion years

43

• Transitions between levels

• Annihilations to gravitons

• Signals coherent, monochromatic, last hours to millions of years

Gravitational Wave Signals

44

45

ma=6*10-13eV

20 40 60 80 100 120 1400.0

0.2

0.4

0.6

0.8

1.0


BlackHoleSpina *

~ 106 years

~ 1 year


• BH spins down: next level formed; annihilations to GWs deplete first level

• Next level has a superradiance rate exceeding age of BH

N211

N322

��

��

��

��

��

��

��

��

��

��

fa ∼ 1019 GeV

l=1 l=2

Num

ber o

f axio

ns

l=1

l=2



46

• Gravitational wave strain emitted from a time-varying energy density


47


• We have a field described by


48



• With stress-energy components of the form


49



• With stress-energy components of the form

Blackboard estimate for annihilations

⌧sr ⇠cn`m

(m⌦BH � µ)r+

1

↵4`+2j+5rg

<latexit sha1_base64="dj1UqTBaa30NrpXbGDDX4lNT+sE=">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</latexit>

⌧ann / 1

↵4`+11rg

Cloud size



Superradiance time

Annihilation time

Particle wavelength

50

rg

rc ⇠n

↵2rg

µ�1 =rg↵

�EM =e2


2a⇤

PGW ⇠ GN!2T ij(!, k)T

⇤ij(!, k) ⇠ GNµ2

��Z

Nµ 2j`(r!)dV

��2

Gravitational Wave Power:

.01 ms

.1 ms

ms

100 s

.1 year

Superradiance: gravitational wave emission

ma=6*10-13eV

20 40 60 80 100 120 1400.0

0.2

0.4

0.6

0.8

1.0


BlackHoleSpina *


~ 1 year

51

annihilation signal lasts 3000 years

Cloud of axions sources coherent, monochromatic gravitational waves

Gravitational wave frequency is set by twice the axion energy

Emission can be observed in LIGO continuous wave searches


Time-varying energy density sources gravitational waves: two bosons annihilating into gravitational waves

• coherent and monochromatic: • fit into searches for long, continuous, monochromatic gravitational

waves (“mountains” on neutron stars)Numerical GR simulation by Will East 52

• Weak, long signals last for ~ thousand- billion years, visible from our galaxy• Event rates up to 10,000 — can be observed and

studied in detail

time


h

gravitational wave strain (source frame)

53

Arvanitaki, MB, Huang (2015)Arvanitaki, MB, Dimopoulos, Dubovsky, Lasenby (2017)Brito et al (2017)


studied in detail

• Loud, short signals last for ~ days - months, observable from BBH or NS-NS merger events• Event rates <1/year at design aLIGO sensitivity, up

to 100's at future observatories

time


h


54

Arvanitaki, MB, Dimopoulos, Dubovsky, Lasenby (2017)Isi, Sun, Brito, Melatos (2019)


studied in detail

time


h


55

Arvanitaki, MB, Dimopoulos, Dubovsky, Lasenby (2017)Isi, Sun, Brito, Melatos (2019)

Zhu, MB, Papa, Tsuna, Kawanaka, Eggenstein (2020)

• Loud, short signals last for ~ days - months, observable from BBH or NS-NS merger events• Event rates <1/year at design aLIGO sensitivity, up

to 100's at future observatories

what are the near-term prospects of detection?

56

• Current searches for gravitational waves from asymmetric rotating neutron stars ongoing• Targeted as well as all-sky searches, reaching to very weak signals with large computational efforts

stra

in s

ensi

tivity

h0

Vela Pulsar Cambridge University Lucky Imaging Group

All-Sky O1 Upper Limits

Signal Frequency (Hz)

Abbott et al PRD 96, 122004 (2017)

Gravitational Wave Searches

• Up to 1000 signals above sensitivity threshold of Advanced LIGO searches today• See also papers by Brito et al on stochastic searches for these signals when many

signals are present

• Weak dependence on mass distribution except at low axion masses

• Very sensitive to number of rapidly rotating black holes

• Weak, long signals last for ~ million years, visible from our galaxy


57

• If ultralight axions (bosons) exist, black holes spin down.

• Measurement of high spin black holes places exclusion limits; LIGO will provide more data points

• Axion clouds produce monochromatic wave radiation; we are looking for these signals in LIGO data

New Physics with Gravitational Waves

5810-14 10-12 10-10 10-8 10-6 10-4 10-2 1

1018

1016

1014

1012

1010

108

106

108 106 104 102 1 10-2 10-4 10-6

CASTSN1987A

HAYSTAC

ADMX

Telescopes

axion

ALP dark matter

GWs,BH spindown

GRAVITATIONAL WAVES: FROM DETECTION TO NEW PHYSICS SEARCHES

Potentially new discoveries await!

• Detection at LIGO and physics of LIGO

• Pulsar timing for GWs and ultralight scalar DM

• Axion clouds around black holes and GWs

Documents

GRAVITATIONAL WAVES: FROM DETECTION TO NEW …...• Gravitational Wave Signals Outline for Today 6 • If there is a light axion (scalar/ vector) with compton wavelength comparable