gravitational antennae for probing the dark side of the...

Gravitational Antennae for Probing the Dark Side of the Universe

Rana X Adhikari (Caltech)

Gravitational Waves

Einstein’s Equations:When matter moves, or changes its configuration, its gravitational

field changes. This change propagates outward asa ripple in the curvature of space-time: a gravitational wave.

“Mass tells space-time how to curve,and space-time tells mass how to move.”

--- John Wheeler

NASA/Dana Berry, Sky Works Digital

Gµ⌫ = 8⇡G

c4Tµ⌫

10�43

q Gravitational Waves = “Ripples in space-time”q Two transverse polarizations - quadrupolar: + and x

Gravitational Waves:

GW amplitude is a strain: ∆L / L ∆L = strain x L

we need a large L !

q Compact binary inspirals: “chirp”Ø NS-NS waveforms are well described. R ~ 300 Mpc Ø inspiral is a standard candle.Ø BH-BH merger simulations exist! R ~ 1500 Mpc

q Supernovae / Mergers: “burst” Ø Short signals. Waveforms not well known.Ø Search in coincidence between two or more interferometers and possibly

with electromagnetic and/or neutrinos signals. R ~ 0.03 Mpc

q Spinning NS: “continuous”Ø search for signals from observed pulsars R ~ 0.1 Mpc Ø all-sky search computing challenging R ~ 0.01 Mpc

q Cosmic Background: “stochastic”Ø Metric fluctuations amplified by inflation, phase transitions in early universe,

topological defects too weak to measure (on the earth)Ø Unresolved background sources (BH/BH mergers)

GW Sources in LIGO Band 10 - 5000

Caltech/Cornell - SXS

Adam Burrows

Timeline of the GW Field1. GR 1915 2. Einstein 1916 3. Einstein 1918 4. Chapel Hill (1957) 5. Pirani 6. Gertenstein & Pustovit 7. PPN Formalism 8. Thorne 1968 - 2014 9. Chandrasekhar &

Detweiler (1975) 10.Pretorius (2005)

1. Michelson (1881) 2. Weber (1965) 3. Weiss 1971 4. 1987 LIGO Proposal 5. MIT 1-5m 1982-1998 6. CIT 40m 1981-> 7. iLIGO 1997 - 2007 8. eLIGO 2007 - 2010 9. aLIGO 2010 -> 10.First lock 5/2014 11.O1 start 9/2015 12. GW150914

How the Michelson Interferometer Works:

Mirror motion -> Optical Phase -> Light Power

The Michelson Interferometer

Anti-Symmetric (Dark) Port

Ly

LxReflected Port

P ∝ PBS x sin2(ϕ)

dP/dϕ ∝ PBS x sin(ϕ)cos(ϕ)

ϕ = 2π (δLy - δLx) / λdϕ/dh ∝ L

Laser

Phase Shift ∝ Length

Signal ∝ BS Power

BS

dP ∝ sqrt(P)Shot Noise

Poisson Statistics...

200 WLASER

!m

EndTestMass

T = 5 ppm

InputTestMass

T = 1.4%PowerRecycling

MirrorT = 3%

Beam-Splitter Pcav = 800 kW

3995 mSignalRecycling

MirrorT = 20%

100 kW

22 W

T = 30%

Photodetector

BeamSplitter

Power Recycling

Laser

Source100 kW Circulating Power

b)

a)

Signal Recycling

Test Mass

Test Mass

Test Mass

Test Mass

Lx = 4 km

20 W

H1

L1

10 ms light

travel time

L y =

4 k

m

c

c

cw

wp

p

p

p

p

w

Sep. 14 th

LIGO Hanford Control Room

Phys. Rev. Lett. 116, 061102

shifted by 7.3 ms

Numerical Sim of the merger on a bright background

SXS collaboration

More Quantitative Simulation

What do the colors and arrows represent?

Detweiler & Chandrasekhar

(1975)

fring ' 32 kHz

✓M�M

◆h1� 0.63(1� a)3/10

i

Qring ' 2p1� a

GW150914 Baseball Cardm1= 36; m2 = 29

mfinal = 62; spin = 0.67

distance = 410 Mpc; z ~ 0.09

EGW = 3 M; Lpeak ~ 3x1049 W (1023 suns)

Public data release: https://losc.ligo.org/events/GW150914/

Christmas Night

KAGRA..

LIGO India

some interesting topicsthe next decade of LIGO upgrades

Quantum Revolution ‘15

mirrors with “no” thermal noise

new Indian LIGO

Mystery Noise ?

Deep Learning for technical noise regression

direct dark matter detection with LIGO

tests of emergent gravity

short, space interferometer for cosmography (in prep.)

https://arxiv.org/abs/1605.01103

https://arxiv.org/abs/1504.02545

What’s next for LIGO?2016: increase laser power, reduce low frequency noise

take ~6 months of data

2017: install squeezed light system

2019: improved mirrors

2025: Cryogenic silicon mirrors

~2030-2035: New (40 km) Facility

Vacuum Fluctuationsof EM Field

Radiation Pressure -- Photon Fluctuations

Residual Gas➢ random phase fluctuations

ThermodynamicMirror SurfaceFluctuations

Seismic/Gravitational

Vibrations

GW Readout

Laser

Shot Noise --Photon Fluctuations

Calculated LIGO Noise Anatomy

Newtonian gravity noise (a.k.a. Gravity Gradients)

Filtered Seismic

Glass Suspension Thermal Noise

Mirror Coating Thermal Noise

Quantum Noise: Radiation Pressure / Shot Noise

initial LIGO (2007)

Advanced LIGO

estimated Noise Budget (Louisiana, Feb. 2016)

“mystery” noise

Where do we come from?What are we?Where are we going? -- Paul Gauguin

How can we eat?Why do we eat?Where shall we have lunch? -- Douglas Adams

Ira Thorpe

What’s next for LIGO?2016: increase laser power, reduce low frequency noise

take ~6 months of data

2017: install squeezed light system

2019: improved mirrors

2025: Cryogenic silicon mirrors

~2030-2035: New (40 km) Facility

Frequency [Hz]10

110

210

3

Str

ain

[1/

Hz]

10-24

10-23

10-22

cre

ate

d u

sin

g g

win

c.m

on

31-J

an

-2016 b

y r

an

a o

n S

ilver7

80.lo

cal

Adv LIGO

A+

Quantum: Pin = 145 W; ζsqz = 10 dBSeismic: aLIGONewtonian Gravity: 10x subtractionSusp Thermal: 123 K Si blades and ribbonsCoat Brown: α− Si : SiO2 Φcoat = 6.5e-05Coating ThermoOptic: ωbeam = 5.9 8.4 cmSub Brown: Si mirror (T = 123 K, mmirror = 204 kg)Residual Gas: 3 nTorr of H2

Sub Thermo-RefractiveCarrier Density: 1013/cm3

Total

Sep 2015

Total Mass (M⊙)101 102 103

Redshift

10-1

100

101

Redshift v. Black Hole mass for LIGO Voyager

Cryo LIGOAdv LIGO

Our view of the Universe (circa 1998)

Fermi / 1 GeV (2012)

PlanckHFI/LFI (2010)

– James T. Kirk

“Space, the Final Frontier”

Why Space?

Earth based detectors limited by seismic / gravity noise below ~5 Hz. Enormous challenges going to 1 Hz or below (cf. MANGO report: http://arxiv.org/abs/1308.2074)

Strain Sensitivity ~1/Larm. Hard to beat 100 km on Earth (cf. LUNGO report http://arxiv.org/abs/1410.0612)

Different astrophysical signals at low frequencies: massive black holes, white dwarf binaries (cf. numerous LISA science case reports, as well as BBO & DECIGO)

[1] C. Cutler and D. E. Holz, Physical Review D 80, 104009 (2009) [2] L. Randall and G. Servant, arXiv hep-ph, (2006). [3] K. Yagi and T. Tanaka, arXiv gr-qc, (2009).

Why NOT Space?Its expensive: 1000-2000 M$ for LISA. ~5000 M$ for JWST.

There’s no parts replacement in space: if the suspensions or lasers break, its game over.

It takes FOREVER: LISA concept started ~1975. As of 2014, the earliest launch would be in 2034.

except: Hubble mirror spherical aberration

Space Detectors

LISA, NGO, eLISA, SGO

BBO

DECIGO

AGIS

LAGRANGE(s)

OMEGA

http://pcos.gsfc.nasa.gov/studies/gravitational-wave-mission.phpRFI in 2011, Workshop in early 2012

10−4

10−3

10−2

10−1

100

101

10−25

10−24

10−23

10−22

10−21

10−20

10−19

10−18

10−17

Frequency [Hz]

Str

ain

[1

/√H

z]

Adv LIGOEinstein TelescopeDECIGOLISABasic AGISBBO

Recent Workshop

J. Harms, D. Shaddock, R. Adhikari, M. Ando, L. Barsotti, Y. Chen, H. Müller (Nov 5-9)

Explore geosynchronous, heliocentric, squeezing, cavities, HP lasers, corner cubes, etc.

Aim for the 0.01 - 10 Hz band (between LISA and LIGO)

10−4

10−3

10−2

10−1

100

101

10−25

10−24

10−23

10−22

10−21

10−20

10−19

10−18

10−17

Frequency [Hz]

Str

ain [

1/√

Hz]

Adv LIGOEinstein Telescope (D)DECIGOLISABasic AGISBBOUNOGO

⌦GW=2⇥

10 �15

Compare Space Detectors

DECIGO / BBOL = 1000 km

dmirror = 1 m

mmirror = 100 kg

Laser: 10 W, 532 nm

Finesse = 10

Noise: 5 x 10-19 (m/s2)/rHz

DECIGO Pathfinder not selected in JAXA down-select

Try something else…

Simple Michelson: Plaser = 5 W, wavelength = 532 nm

L = 100 km, m = 10 kg, dmirror = 0.35 m

no transponders(?) in remote satellites

Technical laser noise cancellation

Squeezed Light: 2x reduction of quantum noise

Orbits

NGO/eLISA orbit (NGO “Yellow Book”, http://lisa.nasa.gov/documentation.html)

• Hughes, S. P., & Bauer, F. H. (2002). Preliminary optimal orbit design for the laser interferometer space antenna (LISA)

• NGO “Yellow Book”, http://lisa.nasa.gov/documentation.html• Y. Xia, G. Y. Li, G. Heinzel, A. Rüdiger, and Y. J. Luo, “Orbit design for the Laser Interferometer Space Antenna”, Science China Physics (2010)

• Helio ETO very stable. ~kW of solar energy.• For short baseline and high acc noise reqs, can place orbit closer to Earth• Does the relative velocity of SCs require remote transponders?• How much $ savings by closer orbit? Lower initial velocities?

LISA Noise BudgetingAcceleration Noise: 10�16(m/s2)/

pHz

“Current error estimates for LISA spurious accelerations”Stebbins, Bender, Hanson, Hoyle, Schumaker, & Vitale, CQG, (2004)

Frequency [Hz]10-3 10-2 10-1 100 101 102 103

Str

ain

[1

/H

z]

10-24

10-23

10-22

10-21

10-20

10-19

10-18UNGO Noise Budget

Total noiseMagneticCosmic raysResidual gasLaser RPRadiometerThermal RPNewtonianThrusterLocal Sensor Backaction

LIGO

ConclusionsNeed more serious noise analysis (SC thermal, Doppler effects with realistic orbits, beam jitter,…)

Science case: how to exploit 6 decades of frequency space

Possible to get launch, rocket costs from JAXA/ISRO?

What is the real cost savings on payload?

Quantum!Mechanical Limits

Heisenberg!Uncertainty!Principle!

Electric!Field!of Empty Space

Carl%Caves,%PhD%‘79%

Yanbei%Chen%PhD%‘03%

Kip%Thorne%BS%’62%

Vladimir%Braginsky%