Probing the Universe for Gravitational Waves LIGO Caltech

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Probing the Universe for Gravitational Waves LIGO / Caltech LIGO Barry Barish Caltech 5

Probing the Universe for Gravitational Waves LIGO / Caltech LIGO Barry Barish Caltech 5 -June-03 LIGO-G 030284 -00 -M 5 -June-03 Caltech Colloquium

Gravitational Waves sources and detection Gravitational Wave Astrophysical Source Terrestrial detectors LIGO, TAMA, Virgo,

Gravitational Waves sources and detection Gravitational Wave Astrophysical Source Terrestrial detectors LIGO, TAMA, Virgo, AIGO Detectors in space LISA 5 -June-03 Caltech Colloquium 2

Detecting a passing wave …. Free masses 5 -June-03 Caltech Colloquium 3

Detecting a passing wave …. Free masses 5 -June-03 Caltech Colloquium 3

Detecting a passing wave …. Interferometer 5 -June-03 Caltech Colloquium 4

Detecting a passing wave …. Interferometer 5 -June-03 Caltech Colloquium 4

Interferometer Concept § Laser used to measure § Arms in LIGO are 4 km

Interferometer Concept § Laser used to measure § Arms in LIGO are 4 km relative lengths of two § Measure difference in orthogonal arms length to one part in 1021 or 10 -18 meters …causing the interference pattern to change at the photodiode 5 -June-03 As a wave passes, the arm lengths change in different ways…. Caltech Colloquium 5

The Laboratory Sites Laser Interferometer Gravitational-wave Observatory (LIGO) Hanford Observatory Livingston Observatory 5 -June-03

The Laboratory Sites Laser Interferometer Gravitational-wave Observatory (LIGO) Hanford Observatory Livingston Observatory 5 -June-03 Caltech Colloquium 6

LIGO: A View from the Bulldozers 5 -June-03 Caltech Colloquium 7

LIGO: A View from the Bulldozers 5 -June-03 Caltech Colloquium 7

From Bulldozers to First Results 5 -June-03 Caltech Colloquium 8

From Bulldozers to First Results 5 -June-03 Caltech Colloquium 8

Construction in Washington 5 -June-03 Caltech Colloquium 9

Construction in Washington 5 -June-03 Caltech Colloquium 9

Flooding in Louisiana 5 -June-03 Caltech Colloquium 10

Flooding in Louisiana 5 -June-03 Caltech Colloquium 10

LIGO Facilities beam tube enclosure • minimal enclosure • reinforced concrete • no services

LIGO Facilities beam tube enclosure • minimal enclosure • reinforced concrete • no services

LIGO I the noise floor § Interferometry is limited by three fundamental noise sources

LIGO I the 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 5 -June-03 Caltech Colloquium 12

Dirt Moving to Mechanical arches and beam tubes Concrete Arches beamtube transport girth welding

Dirt Moving to Mechanical arches and beam tubes Concrete Arches beamtube transport girth welding beamtube install 5 -June-03 Caltech Colloquium 13

LIGO beam tube § LIGO beam tube under constructi § 65 ft spiral welded

LIGO beam tube § LIGO beam tube under constructi § 65 ft spiral welded sections § girth welded in portable clean roo 1. 2 m diameter - 3 mm stainless 50 km of weld 5 -June-03 Caltech Colloquium NO LEAKS !! 14

LIGO I the noise floor § Interferometry is limited by three fundamental noise sources

LIGO I the 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 5 -June-03 Caltech Colloquium 15

Beam Tube bakeou • I = 2000 amps for ~ 1 week • no

Beam Tube bakeou • I = 2000 amps for ~ 1 week • no leaks !! • final vacuum at level where not limiting noise, even for future detectors 5 -June-03 Caltech Colloquium 16

LIGO I the noise floor § Interferometry is limited by three fundamental noise sources

LIGO I the 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 5 -June-03 Caltech Colloquium 17

Vacuum Chambers vibration isolation systems » Reduce in-band seismic motion by 4 - 6

Vacuum Chambers vibration isolation systems » Reduce in-band seismic motion by 4 - 6 orders of magnitude » Compensate for microseism at 0. 15 Hz by a factor of ten » Compensate (partially) for Earth tides 5 -June-03 Caltech Colloquium 18

Seismic Isolation springs and masses damped spring cross section 5 -June-03 Caltech Colloquium 19

Seismic Isolation springs and masses damped spring cross section 5 -June-03 Caltech Colloquium 19

Seismic Isolation performance HAM stack in air 102 100 10 -2 10 -6 10

Seismic Isolation performance HAM stack in air 102 100 10 -2 10 -6 10 -4 Horizontal 10 -6 BSC stack in vacuum 5 -June-03 Caltech Colloquium 10 -8 Vertical 10 -10 20

LIGO vacuum equipment 5 -June-03 Caltech Colloquium 21

LIGO vacuum equipment 5 -June-03 Caltech Colloquium 21

LIGO Livingston Observatory 5 -June-03 Caltech Colloquium 22

LIGO Livingston Observatory 5 -June-03 Caltech Colloquium 22

Welcome to Louisiana pet alligator collecting bullet holes 5 -June-03 Caltech Colloquium 23

Welcome to Louisiana pet alligator collecting bullet holes 5 -June-03 Caltech Colloquium 23

LIGO Hanford Observatory 5 -June-03 Caltech Colloquium 24

LIGO Hanford Observatory 5 -June-03 Caltech Colloquium 24

Gliches at Hanford a view from the bridge LIGO as a car stop desert

Gliches at Hanford a view from the bridge LIGO as a car stop desert on fire LIGO as a fire break 5 -June-03 Caltech Colloquium 25

Seismic Isolation suspension system suspension assembly for a core optic • support structure is

Seismic Isolation suspension system suspension assembly for a core optic • support structure is welded tubular stainless steel • suspension wire is 0. 31 mm diameter steel music wire • fundamental violin mode frequency of 340 Hz 5 -June-03 Caltech Colloquium 26

LIGO Optic Substrates: Si. O 2 25 cm Diameter, 10 cm thick Homogeneity <

LIGO Optic Substrates: Si. O 2 25 cm Diameter, 10 cm thick Homogeneity < 5 x 10 -7 Internal mode Q’s > 2 x 106 Polishing Surface uniformity < 1 nm rms Radii of curvature matched < 3% Coating Scatter < 50 ppm Absorption < 2 ppm Uniformity <10 -3 5 -June-03 Caltech Colloquium 27

Core Optics installation and alignment 5 -June-03 Caltech Colloquium 28

Core Optics installation and alignment 5 -June-03 Caltech Colloquium 28

LIGO Construction Complete 5 -June-03 Caltech Colloquium 29

LIGO Construction Complete 5 -June-03 Caltech Colloquium 29

LIGO Inauguration Whitcomb Caltech Boss 5 -June-03 Sanders The masses Caltech Colloquium Lazzarini NSF

LIGO Inauguration Whitcomb Caltech Boss 5 -June-03 Sanders The masses Caltech Colloquium Lazzarini NSF Boss 30

Locking the Interferometers 5 -June-03 Caltech Colloquium 31

Locking the Interferometers 5 -June-03 Caltech Colloquium 31

LIGO “first lock” Composite Video Y Arm Laser X Arm signal 5 -June-03 Caltech

LIGO “first lock” Composite Video Y Arm Laser X Arm signal 5 -June-03 Caltech Colloquium 32

Watching the Interferometer Lock Y arm X arm 2 min Y Arm Reflected light

Watching the Interferometer Lock Y arm X arm 2 min Y Arm Reflected light Anti-symmetric port Laser X Arm signal 5 -June-03 Caltech Colloquium 33

Lock Acquisition Matt Evans Caltech grad student 5 -June-03 Caltech Colloquium 34

Lock Acquisition Matt Evans Caltech grad student 5 -June-03 Caltech Colloquium 34

Detecting Earthquakes From electronic logbook 2 -Jan-02 An earthquake occurred, starting at UTC 17:

Detecting Earthquakes From electronic logbook 2 -Jan-02 An earthquake occurred, starting at UTC 17: 38. 5 -June-03 Caltech Colloquium 35

Detecting the Earth Tides Sun and Moon Eric Morgenson Caltech Sophomore Summer ‘ 99

Detecting the Earth Tides Sun and Moon Eric Morgenson Caltech Sophomore Summer ‘ 99 5 -June-03 Caltech Colloquium 36

Making LIGO Work 5 -June-03 Caltech Colloquium 37

Making LIGO Work 5 -June-03 Caltech Colloquium 37

Tidal Compensation Data Tidal evaluation on 21 -hour locked section of S 1 data

Tidal Compensation Data Tidal evaluation on 21 -hour locked section of S 1 data Predicted tides Feedforward Feedback Residual signal on voice coils Residual signal on laser 5 -June-03 Caltech Colloquium 38

Controlling angular degrees of freedom 5 -June-03 Caltech Colloquium 39

Controlling angular degrees of freedom 5 -June-03 Caltech Colloquium 39

LIGO Control Room 5 -June-03 Caltech Colloquium 40

LIGO Control Room 5 -June-03 Caltech Colloquium 40

LIGO DESIGN CONSTRUCTION OPERATION Detector R&D SCIENCE LIGO Laboratory LIGO Science Collaboration MIT +

LIGO DESIGN CONSTRUCTION OPERATION Detector R&D SCIENCE LIGO Laboratory LIGO Science Collaboration MIT + Caltech 44 member institutions ~140 people > 400 scientists Director: Barry Barish Spokesperson: Rai Weiss UK Germany Japan Russia India Spain Australia $ National Science Foundation 5 -June-03 Caltech Colloquium 41

Worldwide Network simultaneously detect signal LIGO GEO decompose the polarization of detection locate theconfidence

Worldwide Network simultaneously detect signal LIGO GEO decompose the polarization of detection locate theconfidence sources gravitational waves 5 -June-03 Caltech Colloquium Virgo TAMA AIGO 42

Improving the Sensitivity • Seismic noise & vibration limit at low frequencies • Atomic

Improving the Sensitivity • Seismic noise & vibration limit at low frequencies • Atomic vibrations (Thermal Noise) inside components limit at mid frequencies • Quantum nature of light (Shot Noise) limits at high frequencies • Myriad details of the lasers, electronics, etc. , can make problems above these levels 5 -June-03 Caltech Colloquium 43

LIGO Sensitivity Livingston 4 km Interferometer First Science Run 17 days - Sept 02

LIGO Sensitivity Livingston 4 km Interferometer First Science Run 17 days - Sept 02 May 01 Jan 03 Second Science Run 59 days - April 03 5 -June-03 Caltech Colloquium 44

The First Science Run s 1 5 -June-03 Caltech Colloquium 45

The First Science Run s 1 5 -June-03 Caltech Colloquium 45

Sensitivity during S 1 LIGO S 1 Run -----“First Upper Limit Run” § 23

Sensitivity during S 1 LIGO S 1 Run -----“First Upper Limit Run” § 23 Aug– 9 Sept 2002 § 17 days §All interferometers in power recycling configuration LHO 2 Km LHO 4 Km LLO 4 Km GEO in S 1 RUN -----Ran simultaneously In power recycling Lesser sensitivity 5 -June-03 Caltech Colloquium 46

Astrophysical Sources signatures § Compact binary inspiral: “chirps” » NS-NS waveforms are well described

Astrophysical Sources signatures § Compact binary inspiral: “chirps” » NS-NS waveforms are well described » BH-BH need better waveforms » search technique: matched templates § Supernovae / GRBs: “bursts” » burst signals in coincidence with signals in electromagnetic radiation » prompt alarm (~ one hour) with neutrino detectors § Pulsars in our galaxy: “periodic” » search for observed neutron stars (frequency, doppler shift) » all sky search (computing challenge) » r-modes § Cosmological Signals “stochastic background” 5 -June-03 Caltech Colloquium 47

In-Lock Data Summary from S 1 H 1: 235 hrs H 2: 298 hrs

In-Lock Data Summary from S 1 H 1: 235 hrs H 2: 298 hrs Red lines: integrated up time L 1: 170 hrs 3 X: 95. 7 hrs Green bands (w/ black borders): epochs of lock • August 23 – September 9, 2002: 408 hrs (17 days). • H 1 (4 km): duty cycle 57. 6% ; Total Locked time: 235 hrs • H 2 (2 km): duty cycle 73. 1% ; Total Locked time: 298 hrs • L 1 (4 km): duty cycle 41. 7% ; Total Locked time: 170 hrs • Double coincidences: • L 1 && H 1 : duty cycle 28. 4%; Total coincident time: 116 hrs • L 1 && H 2 : duty cycle 32. 1%; Total coincident time: 131 hrs • H 1 && H 2 : duty cycle 46. 1%; Total coincident time: 188 hrs Triple Coincidence: L 1, H 1, and H 2 : duty cycle 23. 4% ; total 95. 7 hours 5 -June-03 Caltech Colloquium 48

Compact binary collisions “chirps” » Neutron Star – waveforms are well described » Black

Compact binary collisions “chirps” » Neutron Star – waveforms are well described » Black Hole – need better waveforms » Search: matched templates 5 -June-03 Caltech Colloquium 49

Searching Technique binary inspiral events § § Use template based matched filtering algorithm Template

Searching Technique binary inspiral events § § Use template based matched filtering algorithm Template waveforms for non-spinning binaries » 2. 0 post-Newtonian approx. s(t) = (1 Mpc/D) x [ sin(a) h. Is (t-t 0) + cos(a) I (t-t 0)] h D: effective distance; a: c phase Discrete set of templates labeled by I=(m 1, m 2) » 1. 0 Msun < m 1, m 2 < 3. 0 Msun » 2110 templates » At most 3% loss in SNR 5 -June-03 Caltech Colloquium 50

Sensitivity neutron binary inspirals Star Population in our Galaxy § Population includes Milky Way,

Sensitivity neutron binary inspirals Star Population in our Galaxy § Population includes Milky Way, LMC and SMC § Neutron star masses in range 1 -3 Msun § LMC and SMC contribute ~12% of Milky Way Reach for S 1 Data § Inspiral sensitivity Livingston: <D> = 176 kpc Hanford: <D> = 36 kpc § Sensitive to inspirals in » Milky Way, LMC & SMC 5 -June-03 Caltech Colloquium 51

Loudest Surviving Candidate § § Not NS/NS inspiral event 1 Sep 2002, 00: 38:

Loudest Surviving Candidate § § Not NS/NS inspiral event 1 Sep 2002, 00: 38: 33 UTC S/N = 15. 9, c 2/dof = 2. 2 (m 1, m 2) = (1. 3, 1. 1) Msun What caused this? § Appears to be saturation of a photodiode 5 -June-03 Caltech Colloquium 52

Results of Inspiral Search Upper limit binary neutron star coalescence rate LIGO S 1

Results of Inspiral Search Upper limit binary neutron star coalescence rate LIGO S 1 Data R < 160 / yr / MWEG § Previous observational limits » Japanese TAMA R < 30, 000 / yr / MWEG » Caltech 40 m R < 4, 000 / yr / MWEG § Theoretical prediction R < 2 x 10 -5 / yr / MWEG Detectable Range for S 2 data will reach Andromeda! 5 -June-03 Caltech Colloquium 53

Burst Sources signatures § Known sources -- Supernovae & GRBs » Coincidence with observed

Burst Sources signatures § Known sources -- Supernovae & GRBs » Coincidence with observed electromagnetic observations. » No close supernovae occurred during the first science run » Second science run – We are analyzing the recent very bright and close GRB 030329 NO RESULT YET § Unknown phenomena » Emission of short transients of gravitational radiation of unknown waveform (e. g. black hole mergers). 5 -June-03 Caltech Colloquium 54

‘Unmodelled’ Bursts GOAL search for waveforms from sources for which we cannot currently make

‘Unmodelled’ Bursts GOAL search for waveforms from sources for which we cannot currently make an accurate prediction of the waveform shape. METHODS ‘Raw Data’ Time-domain high pass filter frequency Time-Frequency Plane Search ‘TFCLUSTERS’ Pure Time-Domain Search ‘SLOPE’ 8 Hz 0. 125 s time 5 -June-03 Caltech Colloquium 55

Determination of Efficiency To measure our Efficiency measured for ‘tfclusters’ algorithm efficiency, we must

Determination of Efficiency To measure our Efficiency measured for ‘tfclusters’ algorithm efficiency, we must pick a waveform. 1 ms Gaussian burst amplitude h 0 0 time (ms) 5 -June-03 10 Caltech Colloquium 56

Upper Limit 1 ms gaussian bursts Result is derived using ‘TFCLUSTERS’ algorithm Upper limit

Upper Limit 1 ms gaussian bursts Result is derived using ‘TFCLUSTERS’ algorithm Upper limit in strain compared to earlier (cryogenic bar) results: 90% confidence • IGEC 2001 combined bar upper limit: < 2 events per day having h=1 x 10 -20 per Hz of burst bandwidth. For a 1 k. Hz bandwidth, limit is < 2 events/day at h=1 x 10 -17 • Astone et al. (2002), report a one sigma excess of one event per day at strain level of h ~ 2 x 10 -18 5 -June-03 Caltech Colloquium 57

Astrophysical Sources periodic sources § Pulsars in our galaxy: “periodic” » search for observed

Astrophysical Sources periodic sources § Pulsars in our galaxy: “periodic” » search for observed neutron stars » all sky search (computing challenge) » r-modes § Frequency modulation of signal due to Earth’s motion relative to the Solar System Barycenter, intrinsic frequency changes. §Amplitude modulation due to the detector’s antenna pattern. An afterlife of stars 5 -June-03 Caltech Colloquium 58

Directed searches NO DETECTION EXPECTED at present sensitivities Crab Pulsar Limits of detectability for

Directed searches NO DETECTION EXPECTED at present sensitivities Crab Pulsar Limits of detectability for rotating NS with equatorial ellipticity e = d. I/Izz: 10 -3 , 10 -4 , 10 -5 @ 8. 5 kpc. PSR J 1939+2134 5 -June-03 Caltech Colloquium 1283. 86 Hz 59

Two Search Methods Frequency domain Time domain • Best suited for large parameter space

Two Search Methods Frequency domain Time domain • Best suited for large parameter space searches • Maximum likelihood detection method + frequentist approach • Best suited to target known objects, even if phase evolution is complicated • Bayesian approach First science run --- use both pipelines for the same search for cross-checking and validation 5 -June-03 Caltech Colloquium 60

The Data time behavior days 5 -June-03 Caltech Colloquium days 61

The Data time behavior days 5 -June-03 Caltech Colloquium days 61

The Data frequency behavior 5 -June-03 Hz Hz Caltech Colloquium 62

The Data frequency behavior 5 -June-03 Hz Hz Caltech Colloquium 62

PSR J 1939+2134 Frequency domain Injected signal in LLO: h = 2. 83 x

PSR J 1939+2134 Frequency domain Injected signal in LLO: h = 2. 83 x 10 -22 • Fourier Transforms of time series • Detection statistic: F , maximum likelihood ratio wrt unknown parameters • use signal injections to measure F’s pdf Measured F statistic • use frequentist’s approach to derive upper limit 5 -June-03 Caltech Colloquium 63

PSR J 1939+2134 Data Time domain Injected signals in GEO: h=1. 5, 2. 0,

PSR J 1939+2134 Data Time domain Injected signals in GEO: h=1. 5, 2. 0, 2. 5, 3. 0 x 10 -21 • time series is heterodyned • noise is estimated • Bayesian approach in parameter estimation: express result in terms of posterior pdf for parameters of interest 5 -June-03 95% h = 2. 1 x 10 -21 Caltech Colloquium 64

Results: Periodic Sources J 1939+2134 § No evidence of continuous wave emission from PSR

Results: Periodic Sources J 1939+2134 § No evidence of continuous wave emission from PSR J 1939+2134. § Summary of 95% upper limits on h: IFO Frequentist FDS Bayesian TDS GEO (1. 94 0. 12)x 10 -21 (2. 1 0. 1)x 10 -21 LLO (2. 83 0. 31)x 10 -22 (1. 4 0. 1)x 10 -22 LHO-2 K (4. 71 0. 50)x 10 -22 (2. 2 0. 2)x 10 -22 LHO-4 K (6. 42 0. 72)x 10 -22 (2. 7 0. 3)x 10 -22 • Best previous results for PSR J 1939+2134: ho < 10 -20 (Glasgow, Hough et al. , 1983), 5 -June-03 Caltech Colloquium 65

Upper limit on pulsar ellipticity J 1939+2134 moment of inertia tensor gravitational ellipticity of

Upper limit on pulsar ellipticity J 1939+2134 moment of inertia tensor gravitational ellipticity of pulsar h 0 < 1 10 -22 e < 7. 5 10 -5 R (M=1. 4 Msun, r=10 km, R=3. 6 kpc) • assuming emission due to deviation from axisymmetry: . . 5 -June-03 Caltech Colloquium 66

Early Universe stochastic background ‘Murmurs’ from the Big Bang Cosmic Microwave background WMAP 2003

Early Universe stochastic background ‘Murmurs’ from the Big Bang Cosmic Microwave background WMAP 2003 5 -June-03 Caltech Colloquium 67

Stochastic Background § Strength specified by ratio of energy density in GWs to total

Stochastic Background § Strength specified by ratio of energy density in GWs to total energy density needed to close the universe: § Detect by cross-correlating output of two GW detectors: First LIGO Science Data Hanford - Livingston 5 -June-03 Hanford - Hanford Caltech Colloquium 68

Preliminary Limits: Stochastic Search Interferometer Pair 90% CL Upper Limit Tobs LHO 4 km-LLO

Preliminary Limits: Stochastic Search Interferometer Pair 90% CL Upper Limit Tobs LHO 4 km-LLO 4 km WGW (40 Hz - 314 Hz) < 72. 4 62. 3 hrs LHO 2 km-LLO 4 km WGW (40 Hz - 314 Hz) < 23 61. 0 hrs § Non-negligible LHO 4 km-2 km (H 1 -H 2) instrumental cross-correlation; currently being investigated. § Previous best upper limits: » Measured: Garching-Glasgow interferometers : » Measured: EXPLORER-NAUTILUS (cryogenic bars): 5 -June-03 Caltech Colloquium 69

Stochastic Background sensitivities and theory E 7 results projected S 1 S 2 LIGO

Stochastic Background sensitivities and theory E 7 results projected S 1 S 2 LIGO Adv LIGO 5 -June-03 Caltech Colloquium 70

Advanced LIGO improved subsystems Multiple Suspensions Active Seismic Sapphire Optics Higher Power Laser 5

Advanced LIGO improved subsystems Multiple Suspensions Active Seismic Sapphire Optics Higher Power Laser 5 -June-03 Caltech Colloquium 71

Advanced LIGO 2007 + • • Enhanced Systems laser suspension seismic isolation test mass

Advanced LIGO 2007 + • • Enhanced Systems laser suspension seismic isolation test mass Improvement factor in rate ~ 104 + narrow band optical configuration 5 -June-03 Caltech Colloquium 72

Probing the Universe with LIGO a glimpse at the science § LIGO commissioning is

Probing the Universe with LIGO a glimpse at the science § LIGO commissioning is well underway » Good progress toward design sensitivity § Science Running is beginning » Initial results from our first LIGO data run § Our Plan » Improved data “in the can” from second data run – S 2 » Our goal is to obtain one year of integrated data at design sensitivity before the end of 2006 » Advanced interferometer with dramatically improved sensitivity – 2007+ § LIGO should be detecting gravitational waves within the next decade ! 5 -June-03 Caltech Colloquium 73