Gravitational Waves and LIGO

§ Physics of gravitational waves § Astrophysical sources of GWs § The LIGO project and its sister projects § LIGO Interferometry § Advanced LIGO § Recent science running § Finding gravitational wave signals in the LIGO data

Alan Weinstein, Caltech

AJW, LIGO Project, SURF03-1 Gravitational Waves

Static gravitational fields are described in General Relativity as a curvature or warpage of space-time, changing the distance between space-time events. Shortest straight-line path of a nearby test-mass is a ~Keplerian orbit. If the source is moving (at speeds close to c), eg, because it’s orbiting a companion, the “news” of the changing gravitational field propagates outward as gravitational radiation – a wave of spacetime curvature

AJW, LIGO Project, SURF03-1 Einstein’s Theory of Gravitation experimental tests

bending of light Mercury’s orbit “Einstein Cross” As it passes in the vicinity perihelion shifts forward The bending of light rays of massive objects twice Post-Newton theory gravitational lensing

First observed during the solar Mercury's elliptical path around the Sun Quasar image appears around the eclipse of 1919 by Sir Arthur shifts slightly with each orbit central glow formed by nearby Eddington, when the Sun was such that its closest point to the Sun galaxy. Such gravitational lensing silhouetted against the Hyades star (or "perihelion") shifts forward images are used to detect a ‘dark cluster with each pass. matter’ body as the central object

AJW, LIGO Project, SURF03-1 Strong-field

•Most tests of GR focus on small deviations from Newtonian dynamics (post-Newtonian weak-field approximation) •Space-time curvature is a tiny effect everywhere except: ØThe universe in the early moments of the big bang ØNear/in the horizon of black holes •This is where GR gets non-linear and interesting! •We aren’t very close to any black holes But we can search for (weak-field) (fortunately!), and can’t see them with light gravitational waves as a signal of their presence and dynamics

AJW, LIGO Project, SURF03-1 Nature of Gravitational Radiation

Ripples of curvature in the fabric of spacetime, predicted by General Relativity •transverse space-time distortions, freely h = DL / L propagating at speed of light • mass of graviton = 0 • Stretches and squeezes space between “test masses” – strain h = DL/L • GW is a tensor field (EM are vector fields): two polarizations: plus (Å) and cross (Ä) (EM: two polarizations, x and y ) Spin of graviton = 2 Contrast with EM dipole radiation: •Conservation laws: )) • cons of energy Þ no monopole radiation xˆ (( )) yˆ • cons of momentum Þ no dipole radiation )) • lowest multipole is quadrupole wave (spin 2) AJW, LIGO Project, SURF03-1 Contrast EM and GW information

E&M GW space as medium for field Space-time itself incoherent superpositions of atoms, molecules coherent motions of huge masses (or energy)

wavelength small compared to sources - wavelength ~large compared to sources - images poor spatial resolution absorbed, scattered, dispersed by matter very small interaction; no shielding

106 Hz and up 103 Hz and down

measure amplitude (radio) or intensity (light) measure amplitude

detectors have small solid angle acceptance detectors have large solid angle acceptance

• Very different information, mostly mutually exclusive • Difficult to predict GW sources based on E&M observations • GW astronomy is a totally new and unique window on the universe AJW, LIGO Project, SURF03-1 Sources of GWs

§ Accelerating charge Þ electromagnetic radiation (dipole) § Accelerating mass Þ gravitational radiation (quadrupole) § Amplitude of the gravitational wave (dimensional analysis): 2G 4p 2GMR2 f 2 h = I&& Þ h » orb mn c4r mn c4 r § && = second derivative Imn of mass quadrupole moment (non-spherical part of kinetic energy – tumbling dumb-bell) § G is a small number! § Need huge mass, relativistic km velocities, nearby. § For a binary neutron star pair, 10m light-years away, solar masses moving at 15% of speed of light: Terrestrial sources TOO WEAK!

AJW, LIGO Project, SURF03-1 Observing the Galaxy with Different Electromagnetic Wavelengths http://antwrp.gsfc.nasa.gov/apod/ image/SagSumMW _dp_big.gif l = 5 x 10 -7 m

http://antwrp.gsfc.nasa.gov/apod /image/xallsky_rosat_big.gif l = 5 x 10 -10 m http://antwrp.gsfc.nasa.gov/apod /image/comptel_allsky_1to3_big.gif l = 6 x 10 -13 m

http://www. gsfc.nasa.gov/astro/cobe l = 2 x 10 -6 m

http://cossc.gsfc.nasa.gov/cossc/ egret/ //rsd-www. nrl.navy.mil/7213/lazio/GC/ l = 1 x 10 -14 m l = 9 x 10 -1 m AJW, LIGO Project, SURF03-1 What will we see?

A NEW WINDOW ON THE UNIVERSE WILL OPEN UP FOR EXPLORATION. BE THERE!

AJW, LIGO Project, SURF03-1 Astrophysical Sources of Gravitational Waves

Coalescing compact binaries (neutron stars, black holes)

Non-axi-symmetric supernova collapse

Non-axi-symmetric pulsars (rotating, beaming neutron star)

Stochastic background relic from the Big Bang

AJW, LIGO Project, SURF03-1 Hulse-Taylor binary pulsar

Neutron Binary System PSR 1913 + 16 -- Timing of pulsars

17 / sec · • A rapidly spinning pulsar (neutron star beaming EM radiation at us 17 x / sec) • orbiting around an ordinary star with 8 hour period • Only 7 kpc away · • discovered in 1975, orbital parameters ~ 8 hr measured • continuously measured over 25 years!

AJW, LIGO Project, SURF03-1 GWs from Hulse-Taylor binary

emission of gravitational waves by compact binary system

§ Only 7 kpc away § period speeds up 14 sec from 1975-94 § measured to ~50 msec accuracy § deviation grows quadratically with time § Merger in about 300M years § (<< age of universe!) § shortening of period Ü orbital energy loss § Compact system: § negligible loss from friction, material flow § beautiful agreement with GR prediction § Apparently, loss is due to GWs! § Nobel Prize, 1993

AJW, LIGO Project, SURF03-1 GWs from coalescing compact binaries (NS/NS, BH/BH, NS/BH)

Compact binary mergers

AJW, LIGO Project, SURF03-1 Chirp signal from Binary Inspiral

determine •distance from the earth r •masses of the two bodies •orbital eccentricity e and orbital inclination I •Over-constrained parameters: TEST GR AJW, LIGO Project, SURF03-1 The sound of a chirp

BH-BH collision, no noise

The sound of a BH-BH collision, Fourier transformed over 5 one-second intervals (red, blue, magenta, green, purple) along with expected IFO noise (black)

AJW, LIGO Project, SURF03-1 Astrophysical sources: Thorne diagrams

LIGO I (2002-2005)

LIGO II (2007- )

Advanced LIGO

AJW, LIGO Project, SURF03-1 How many sources can we see?

Improve amplitude sensitivity by a factor of 10x, and… Þ Number of sources goes up 1000x! Virgo cluster

LIGO I LIGO II

AJW, LIGO Project, SURF03-1 Estimated detection rates for compact binary inspiral events

LIGO I

LIGO II

V. Kalogera (population synthesis)

AJW, LIGO Project, SURF03-1 Supernova collapse sequence

§ Within about 0.1 second, the core collapses and gravitational waves Gravitational waves are emitted. § After about 0.5 second, the collapsing envelope interacts with the outward shock. Neutrinos are emitted. § Within 2 hours, the envelope of the star is explosively ejected. When the photons reach the surface of the star, it brightens by a factor of 100 million. § Over a period of months, the expanding remnant emits X-rays, visible light and radio waves in a decreasing fashion.

AJW, LIGO Project, SURF03-1 Gravitational Waves from Supernova collapse

Non axisymmetric collapse ‘burst’ signal

Rate 1/50 yr - our galaxy 3/yr - Virgo cluster

AJW, LIGO Project, SURF03-1 Zwerger-Müller SN waveforms

§ astrophysically-motivated waveforms, computed from simulations of axi-symmetric SN core collapses. § Almost all waveforms have duration < 0.2 sec § A “menagerie”, revealing only crude systematic regularities. Inappropriate for matched filtering or other model-dependent approaches. » Their main utility is to provide a set of signals that one could use to compare the efficacy of different filtering techniques. § Absolute normalization/distance scale.

AJW, LIGO Project, SURF03-1 Pulsars and continuous wave sources

§ Pulsars in our galaxy »non axisymmetric: 10-4 < e < 10-6 »science: neutron star precession; interiors »“R-mode” instabilities »narrow band searches best

AJW, LIGO Project, SURF03-1 Gravitational waves from Big Bang

Cosmic microwave background

AJW, LIGO Project, SURF03-1 GWs probe the universe at earliest times after the Big Bang

AJW, LIGO Project, SURF03-1 Stochastic Background sensitivities

AJW, LIGO Project, SURF03-1 Ultimate Goals for the Observation of GWs

§ Tests of Relativity – Wave propagation speed (delays in arrival time of bursts) – Spin character of the radiation field (polarization of radiation from CW sources) – Detailed tests of GR in P-P-N approximation (chirp waveforms) – Black holes & strong-field gravity (merger, ringdown of excited BH) § Gravitational Wave Astronomy (observation, populations, properties): – Compact binary inspirals – Gravitational waves and gamma ray burst associations – Black hole formation – Supernovae in our galaxy – Newly formed neutron stars - spin down in the first year – Pulsars and rapidly rotating neutron stars – LMXBs – Stochastic background

AJW, LIGO Project, SURF03-1 Gravitational wave detectors

• Bar detectors • Invented and pursued by Joe Weber in the 60’s • Essentially, a large “bell”, set ringing (at ~ 900 Hz) by GW • Won’t discuss any further, here • Michelson interferometers • At least 4 independent discovery of method: • Pirani `56, Gerstenshtein and Pustovoit, Weber, Weiss `72 • Pioneering work by Weber and Robert Forward, in 60’s • Now: large, earth-based detectors. Soon: space-based (LISA).

AJW, LIGO Project, SURF03-1 Resonant bar detectors

§ AURIGA bar near Padova, Italy (typical of some ~6 around the world – Maryland, LSU, Rome, CERN, UWA) § 2.3 tons of Aluminum, 3m long; § Cooled to 0.1K with dilution fridge in LiHe cryostat § Q = 4´106 at < 1K § Fundamental resonant mode at ~900 Hz; narrow bandwidth § Ultra-low-noise capacitive transducer and electronics (SQUID)

AJW, LIGO Project, SURF03-1 Interferometric detection of GWs

GW acts on freely mirrors falling masses: laser

Beam For fixed ability to splitter Dark port measure DL, make L photodiode P = P sin2 (2kDL) as big as possible! out in

Antenna pattern: (not very directional!)

AJW, LIGO Project, SURF03-1 LIGO – the first Km- class GW detector

L - DL L + DL

AJW, LIGO Project, SURF03-1 International network

Simultaneously detect signal (within msec) GEO Virgo § detection LIGO TAMAconfidence § locate the sources

§ verify light speed propagation

§ decompose the polarization of gravitational waves

AIGO §Open up a new field of astrophysics! AJW, LIGO Project, SURF03-1 LIGO, VIRGO, GEO, TAMA …

GEO 600 LHO4K LHO2K

LLO TAMA 4K 300 VIRGO 3000

AJW, LIGO Project, SURF03-1 Event Localization With An Array of GW Interferometers

SOURCE SOURCE TAMA GEO VIRGO

LIGO Hanford LIGO Livingston

SOURCE SOURCE

cosq = dt / (c D12) Dq ~ 0.5 deg t/c d L = D q 1 D 2 AJW, LIGO Project, SURF03-1 The Laser Interferometer Space Antenna LISA

Three spacecraft in orbit The center of the triangle formation about the sun, will be in the ecliptic plane with 5 million km baseline 1 AU from the Sun and 20 degrees behind the Earth.

LISA (NASA/JPL, ESA) may fly in the next 10 years! AJW, LIGO Project, SURF03-1 Sensitivity bandwidth

§ EM waves are studied over ~20 orders of magnitude » (ULF radio -> HE g rays)

§ Gravitational Waves over ~10 orders of magnitude » (terrestrial + space)

AJW, LIGO Project, SURF03-1 LIGO sites

4 km Hanford + 2 km Observatory (H2K and H4K)

Hanford, WA (LHO) • located on DOE reservation • treeless, semi-arid high desert • 25 km from Richland, WA • Two IFOs: H2K and H4K Livingston, LA (LLO) • located in forested, rural area Livingston 4 km Both sites are relatively • commercial logging, wet climate Observatory • 50km from Baton Rouge, LA seismically quiet, • One L4K IFO low human noise

AJW, LIGO Project, SURF03-1 LIGO Livingston (LLO)

• 30 miles from Baton Rouge, LA (LSU) • forested, rural area •Commercial logging, wet climate • need moats (with alligators) •Seismically quiet, low human noise level

AJW, LIGO Project, SURF03-1 LIGO Hanford (LHO)

• DOE nuclear reservation • treeless, semi-arid high desert • 15 miles from Richmond, WA •Seismically quiet, low human noise level

AJW, LIGO Project, SURF03-1 LIGO I configuration

Power-recycled Michelson with Fabry-Perot arms:

•Fabry-Perot optical cavities in the two arms store the light for many (~200) round trips •Michelson interferometer: change in arm lengths destroy destructive interference, light emerges from dark port •Normally, light returns to bright port laser at bright port •Power recycling mirror sends the light back in (coherently!) to be reused dark port (GW signal)

AJW, LIGO Project, SURF03-1 Interferometric phase difference

The effects of gravitational waves appear as a deviation in the phase differences between two orthogonal light paths of an interferometer.

For expected signal strengths, The effect is tiny: Phase shift of ~10-10 radians

The longer the light path, the larger the phase shift… Make the light path as long as possible!

AJW, LIGO Project, SURF03-1 Light storage: folding the arms

How to get long light paths without making huge detectors: Fold the light path!

Simple, but requires large mirrors; (LIGO design) tstor~ 3 msec

limited tstor More compact, but harder to control

AJW, LIGO Project, SURF03-1 Suspended test masses

• To respond to the GW, test masses must be “free falling” • On Earth, test masses must be supported against DC gravity field • The Earth, and the lab, is vibrating like mad at low frequencies (seismic, thermal, acoustic, electrical); •can’t simply bolt the masses to the table (as in typical ifo’s in physics labs) • So, IFO is insensitive to low frequency GW’s • Test masses are suspended on a pendulum resting on a seismic isolation stack •“fixed” against gravity at low frequencies, but •“free” to move at frequencies above ~ 100 Hz

“Free” mass: pendulum at f >> f0

AJW, LIGO Project, SURF03-1 Seismic displacement noise

Motion of the earth •driven by wind, volcanic/seismic activity, ocean tides, humans •requires e.g., roughly 109 attenuation at 100 Hz •~300 micron tidal motion, microseismic peak at 0.16 Hz. • At low frequencies, motion is correlated over two mirrors Approaches to limiting seismic noise •careful site selection •far from ocean, significant human activity, seismic activity •active control systems (only microseismic peak for now) •seismometers, regression, feedback to test masses •simple damped harmonic oscillators in series •`stacks', constrained layer springs and SS masses •one or more low-loss pendulums for final suspension •gives 1/f2 for each pendulum

AJW, LIGO Project, SURF03-1 Seismic isolation stacks

AJW, LIGO Project, SURF03-1 Noise from imperfect Optics

Highly efficient optical system: ~50 ppm lost per round-trip • optics are 25 cm diameter, 10 cm thick fused silica cylinders • light beam ~10 cm diameter; 1ppm scattered, ~1ppm absorbed Constraints on optical surface due to noise requirements: • minimize scatter (power loss Þ phase noise) • minimize absorption (thermal distortions, lensing Þ phase noise) • minimize scattering out of beam, onto tube, back into beam (phase noise) • minimize wavefront distortions (contrast defect at dark port Þ phase noise) Results

• l/800 over central 10 cm (~1 nm rms); fine scale `superpolish‘ •Sophisticated baffling AJW, LIGO Project, SURF03-1 LIGO Optics mirrors, coating and polishing

§ SUPERmirrors: » High uniformity fused silica quartz » reflectivity as high as 99.999% » losses < 1 ppm in coating, 10 ppm in substrate » polished with mircoroughness < l/1800 » 0.5 nm » and ROC within spec. » (dR/R < 5%, except for BS) § Suspensions: hang 10kg optic by a single loop of wire, and hold it steady with feedback system

AJW, LIGO Project, SURF03-1 Residual gas in beam tube

Light must travel 4 km without attenuation or degradation • refractive index fluctuations in gas cause variations in optical path, phase noise • residual gas scatters light out of, then back into, beam; phase noise • Residual gas pressure fluctuations buffet mirror; displacement noise • Contamination: low-loss optics can not tolerate surface ‘dirt’; High circulating powers of ~10-50 kW burns dirt onto optic surface

requirement for vacuum in 4 km tubes:

-6 -9 • H2 at 10 torr initial, 10 torr ultimate -7 -10 • H2O at 10 torr initial, 10 ultimate • Hydro-, flourocarbons < 10-10 torr • vacuum system, 1.22 m diameter, ~10,000 m3 • strict control on in-vacuum components, cleaning AJW, LIGO Project, SURF03-1 LIGO Beam Tube

Beam light path must be high vacuum, to minimize “phase noise” due to fluctuations in index of refraction § LIGO beam tube under construction in January 1998 § 65 ft spiral welded sections § girth welded in portable clean room in the field

AJW, LIGO Project, SURF03-1 Mirror control

§ Seismic isolation system, and pendulum, keep the mirror motion to a minimum. § Now the mirrors are not being kicked around by the environment (at high frequencies); § But, being free, they may not be where you need them to be to keep the laser resonant in the cavities! § Need active control system to keep mirrors at set points (at/near DC), to keep F-P cavities resonant, § Without injecting noise at high frequencies § Þ Carefully designed feedback servo loops

AJW, LIGO Project, SURF03-1 LIGO I Suspensions

AJW, LIGO Project, SURF03-1 OSEMs

• Five magnets glued to fused Si optic •(this ruins the thermal noise properties of the optic – a big problem!) •LED/PD pair senses position • Coil pushes/pulls on magnet, against pendulum

AJW, LIGO Project, SURF03-1 Suspension control system

• Each suspension controller handles one suspension (5 OSEMs) • Local velocity damping • Input from LSC and ASC to fix absolute position, pitch, yaw of mirror to keep cavity in resonance

AJW, LIGO Project, SURF03-1 Suspension controller (local analog version)

AJW, LIGO Project, SURF03-1 Cavity control

Pound-Drever (reflection) locking used to control lengths of all the optical cavities in LIGO

• Phase modulate incoming laser light, producing RF sidebands • Carrier is resonant in cavity, sidebands are not • Beats between carrier and sidebands provide error signal for cavity length

AJW, LIGO Project, SURF03-1 Phase modulation of input beam

Phase modulation adds sidebands to the beam:

i(w t+GcosWt) iw t iWt -iWt Einc = Elasere » Elasere (J 0 (G) + J +1 (G)e + J -1 (G)e ) W = RF modulation frequency (W /2p ~ 30 MHz) G = modulation depth

Ji = Bessel functions; J ±1 » ± G/2 for G<1 ref ref iWt ref -iWt iw t Eref = (E0 + E+1 e + E-1 e )e Arrange the length of the cavity, and the value of W, so that •carrier is resonant in FP cavity, sidebands are not, •so they have different reflection coefficients •phase of carrier is sensitive to length changes in cavity, sidebands are not

AJW, LIGO Project, SURF03-1 Demodulation

2 2 2 S = çæ E + E + E ÷ö + 2 Re((E*E + E E* )eiWt )+ 2 Re(E*E ei2Wt ) ref è 0 + - ø 0 + 0 - + -

Use an electronic “mixer” to multiply this by cosWt or sinWt, average over many RF cycles, to get: * * • In-phase demodulated signal n I = 2 Re(E0 E+ + E0 E- ) • Quad-phase demodulated signal * * n Q = 2 Im(E0 E+ + E0 E- ) Which are sensitive to length of cavity (very near resonance) And can be used as an error signal to control cavity length

Sideband resonant - error signal has wrong sign

AJW, LIGO Project, SURF03-1 Schnupp Asymmetry

GW signal ( L- ) is measured using light transmitted to dark port. Signal power is quadratic in L- ; not as sensitive as linear dependence. To keep the dark port dark for the main (carrier) laser light, use Schnupp (tranmission) locking as opposed to reflection locking, for l- signal. • In absence of GW, dark port is dark; carrier power ~ sin2(Df) , quadratic in Df = 2k l- for small signal

• Add Schnupp (Michelson) asymmetry: l1 ¹ l2 (l- ¹ 0); port still dark for carrier (l1 = l2 mod lc ), but sidebands leak out to dark port PD to act as * * local oscillator for RF-detection of GW signal. n Q = 2 Im(E0 E+ + E0 E- ) • Error signal is then linearly proportional to amount of carrier light (GW signal) AJW, LIGO Project, SURF03-1 The control problem in LIGO

AJW, LIGO Project, SURF03-1 Interferometer locking

Two optical cavities inside a third. end test mass

Optical cavities must be in resonance, to build up light, amplifying effect of Light bounces back GW on phase shift as if the arms were and forth along 150 times longer. arms about 150 times Requires test masses to be held in position to 10-10-10-13 meter, using many digital servo loops: input test mass “Locking the interferometer” Laser Light is “recycled” signal about 50 times

AJW, LIGO Project, SURF03-1 LIGO I noise floor

§ Interferometry is limited by three fundamental noise sources Ø seismic noise at the lowest frequencies Ø thermal noise at intermediate frequencies Ø shot noise at high frequencies

§Many other noise sources lurk underneath and must be controlled as the instrument is improved

AJW, LIGO Project, SURF03-1 LIGO schedule

1995 NSF funding secured ($360M) 1996 Construction Underway (mostly civil) 1997 Facility Construction (vacuum system) 1998 Interferometer Construction (complete facilities) 1999 Construction Complete (interferometers in vacuum) 2000 Detector Installation (commissioning subsystems) 2001 Commission Interferometers (first coincidences) 2002 Sensitivity studies (initiate LIGO I Science Run) 2003+ LIGO I data run (one year integrated data at h ~ 10-21)

2006… Begin Advanced LIGO upgrade installation 2007… Begin Advanced LIGO observations…

AJW, LIGO Project, SURF03-1 Advanced LIGO

§ Keep the same vacuum system & lab § Reduce seismic noise: Active seismic isolation systems § Reduce seismic & thermal noise: multiple pendulum stages, fused silica suspension fibers § Reduce thermal noise: advanced mirror materials (single crystal sapphire, 40 kg) § Reduce shot noise: high powered laser (10 Þ 200 watts), advanced optical configuration § Reduce thermal distortions: thermal compensation techniques

AJW, LIGO Project, SURF03-1 Advanced LIGO prototyping

§ Caltech LIGO 40 Meter §Thermal Noise Interferometer Gravitational Wave (Libbrecht) Interferometer (Weinstein) » Direct measurement of thermal » Full engineering prototype of the noise in mirrors made of advanced Advanced LIGO optical configuration materials and controls

AJW, LIGO Project, SURF03-1 Advanced LIGO R&D

§ Development of multiple pendulum suspensions with silica fibers » Willems et al § Development of advanced seismic isolation and suspension systems » de Salvo et al § Advanced interferometer techniques at the Drever laboratory § Simulations of complex interferometer behavior » Yamamoto et al § Quantum-nondemolition optical techniques to reduce quantum readout noise » Whitcomb et al

AJW, LIGO Project, SURF03-1 Commissioning History

-17 -18 -19 -20 -21 L4k strain noise @ 150 Hz [Hz -1/2] 10 10 10 10 10

1999 2000 2001 2002 2003 4Q 1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q 1Q

Inauguration E1 E2 E3 E4 E5 E6 E7 E8 E9 One Arm S1 S2 Power Recycled Michelson Science Science Recombined Interferometer Run Run

Full Interferometer

Washington 2K First Lock Louisiana 4k Washington LHO 2k wire Washington 4K Now earthquake accident

Fritschel AJW, LIGO Project, SURF03-1 Science Running plan

§ Two “upper limit” runs S1 and S2, interleaved with commissioning, at “publishable” sensitivity levels » S1 Aug 23 – Sep 9, 2002; duration 2 weeks » S2 Feb 14 – Apr 14, 2003; duration 8 weeks

§ First “search” run S3 will be performed in Fall 2003 (~ 6 months)

AJW, LIGO Project, SURF03-1 Steady Improvement over time

AJW, LIGO Project, SURF03-1 S1-Run Sensitivities for the Three LIGO Interferometers

AJW, LIGO Project, SURF03-1 Progress continues…

Similar At LLO; and… all 60 Hz harmonics lines gone!

AJW, LIGO Project, SURF03-1 S1 LIGO IFO duty cycle

§ L1: duty cycle 41.7% ; Total Locked time: 170 hrs H1: duty cycle 57.6% ; Total Locked time: 235 hrs H2: duty cycle 73.1% ; Total Locked time: 298 hrs Triple coincidence § Double coincidence: L1 and H1 duty cycle 28.4%; Total coincident time: 116 hrs Double coincidence: L1 and H2 duty cycle 32.1%; Total coincident time: 131 hrs Double Coincidence: H1 and H2 duty cycle 46.1%; Total coincident time: 188 hrs

§ Triple Coincidence: L1, H1, and H2 duty cycle 23.4% ;Total coincident time: 95.7 hrs

AJW, LIGO Project, SURF03-1 A variety of learning experiences

§ Computer crashes § Earthquakes § No fire or floods yet… § Logging at Livingston § Cars driving over cattle guards § Wind at Hanford § Snow in Louisiana

6 hrs AJW, LIGO Project, SURF03-1 Logging at Livingston

Less than 1 km away… Dragging big logs … Remedial measures at LIGO are in progress; this will not be a problem in the future.

AJW, LIGO Project, SURF03-1 Logging at Livingston

Before, as seen from lab. After.

Too close for comfort! BUT: by S2, we’ll have seismic pre- isolators which should solve the problem.

AJW, LIGO Project, SURF03-1 Earthquakes…

This one, on February 28, 2000 knocked out the H2K For months… Earthquakes have not been a problem for E7/S1, but we can “hear” them with the IFO From GEO Vanatu, 1/2/02, 6.3M

AJW, LIGO Project, SURF03-1 Time-frequency spectrogram of GW signal – stationary?

AJW, LIGO Project, SURF03-1 LIGO Data analysis

§ LIGO is a broad-band amplitude detector, measures waveforms. § The experimentalist thinks not in terms of astrophysical sources, but in terms of waveform morphologies. § Specific astrophysical sources suggest specific waveforms, but we don’t want to miss the unexpected! § Four different waveform morphologies being considered: » Bursts (of limited duration), for which we have models (binary inspiral chirps, ringdowns) » Bursts, for which we have no reliable models (supernovas, GRBs, BH mergers) » Continuous waves, narrow bandwidth - periodic (pulsars) » Continuous waves, broad bandwidth - stochastic (BB background) § Each requires radically different data analysis techniques. § Algorithms, implementation development is in its adolescence. § Marching into the unknown – look out for surprises!

AJW, LIGO Project, SURF03-1 “Upper Limits” S1,S2 Data Analysis Groups

§ LSC Upper Limit Analysis Groups » Typically ~25 physicists » One experimentalist / One theorist co-lead each group

§ Compact binary inspiral: “chirps”

§ Supernovae / GRBs: “bursts”

§ Pulsars in our galaxy: “periodic”

§ Cosmological Signal “stochastic background”

AJW, LIGO Project, SURF03-1 Frequency-Time Characteristics of GW Sources • Bursts are short duration, broadband events time • Chirps explore the greatest time- frequency area

Ringdowns • BH Ringdowns expected to be associated with chirps Broadband Background • CW sources have FM characteristics which depend on

Bursts position on the sky (and source

frequency CW (quasi-periodic) parameters) • Stochastic background is stationary and broadband Chirps

frequency •Optimal filter: time kernel µ 1/(noise power) time AJW, LIGO Project, SURF03-1 Optimal Wiener Filtering

§ Matched filtering (optimal) looks for best overlap Tˆ *( f ) sˆ ( f ) between a signal and a set of expected x t = p e-2piftc df p[ c ] ò ˆ (template) signals in the presence of the Sn ( f ) instrument noise -- correlation filter § Replace the data time series with an SNR time series § Look for excess SNR to flag possible detection

AJW, LIGO Project, SURF03-1 Summary and Plans for S1 upper limits

§ Good running for 17 days § Example expected “upper limit” sensitivities » Stochastic backgrounds

– upper limit W0 < 30 » Neutron binary inspiral – upper limit distance < 200 kpc » Periodic sources PSR J1939+2134 at 1283 Hz – Upper limit h < 10-23 90% CL § Results for presentation in early 2003 § S2 should be more than x10 more sensitive § S3 to last for 6 months § In parallel with science running, Intense R&D on AdvLIGO – aim to install in 2007-9 AJW, LIGO Project, SURF03-1 Einstein’s Symphony

§ Space-time of the universe is (presumably!) filled with vibrations: Einstein’s Symphony § LIGO will soon ‘listen’ for Einstein’s Symphony with gravitational waves, permitting » Basic tests of General Relativity » A new field of astronomy and astrophysics § A new window on the universe!

AJW, LIGO Project, SURF03-1