Status and Prospects for LIGO Barry C. Barish Caltech 17-March-06 St Thomas, Virgin Islands Crab Pulsar

17-March-06Confronting Gravity - St Thomas2 LIGO Livingston, Louisiana 4 km

17-March-06Confronting Gravity - St Thomas3 LIGO Hanford Washington 4 km 2 km

17-March-06Confronting Gravity - St Thomas4 Interferometer optical layout laser various optics 10 W 6-7 W 4-5 W W9-12 kW vacuum photodetector suspended, seismically isolated test masses GW channel 200 mW mode cleaner 4 km

17-March-06Confronting Gravity - St Thomas5 LIGO Beam Tube 1.2 m diameter - 3mm stainless 50 km of weld 65 ft spiral welded sections Girth welded in portable clean room in the field Minimal enclosure Reinforced concrete No services

17-March-06Confronting Gravity - St Thomas6 LIGO vacuum equipment

17-March-06Confronting Gravity - St Thomas7 Core Optics installation and alignment

17-March-06Confronting Gravity - St Thomas8 LIGO Optics fused silica Caltech dataCSIRO data  Surface uniformity < 1 nm rms  Scatter < 50 ppm  Absorption < 2 ppm  ROC matched < 3%  Internal mode Q’s > 2 x 10 6

17-March-06Confronting Gravity - St Thomas9 Interferometer Noise Limits Thermal (Brownian) Noise LASER test mass (mirror) Beam splitter Residual gas scattering Wavelength & amplitude fluctuations photodiode Seismic Noise Quantum Noise "Shot" noise Radiation pressure

17-March-06Confronting Gravity - St Thomas10 What Limits LIGO Sensitivity?  Seismic noise limits low frequencies  Thermal Noise limits middle frequencies  Quantum nature of light (Shot Noise) limits high frequencies  Technical issues - alignment, electronics, acoustics, etc limit us before we reach these design goals

17-March-06Confronting Gravity - St Thomas11 Commissioning /Running Time Line Now Inauguration E2 Engineering E3 E5 E9E10 E7 E8 E11 First LockFull Lock all IFO First Science Data S1 S4 Science S2 Runs S3S5S K strain noiseat 150 Hz [Hz -1/2 ] 4x10 -23

17-March-06Confronting Gravity - St Thomas12 Evolution of LIGO Sensitivity  S1: 23 Aug – 9 Sep ‘02  S2: 14 Feb – 14 Apr ‘03  S3: 31 Oct ‘03 – 9 Jan ‘04  S4: 22 Feb – 23 Mar ‘05  S5: 4 Nov ‘05 -

17-March-06Confronting Gravity - St Thomas13 Initial LIGO - Design Sensitivity

17-March-06Confronting Gravity - St Thomas14 Rms strain in 100 Hz BW: 0.4x Sensitivity Entering S5 …

17-March-06Confronting Gravity - St Thomas15 S5 Run Plan and Outlook  Goal is to “collect at least a year’s data of coincident operation at the science goal sensitivity”  Expect S5 to last about 1.5 yrs  S5 is not completely ‘hands-off’ RunS2S3S4 S5 Target SRD goal L137%22%75%85%90% H174%69%81%85%90% H258%63%81%85%90% 3- way 22%16%57%70%75% Interferometer duty cycles

17-March-06Confronting Gravity - St Thomas16 Sensitivity Entering S5 … Hydraulic External Pre-Isolator

17-March-06Confronting Gravity - St Thomas17 Locking Problem is Solved

17-March-06Confronting Gravity - St Thomas18 What’s after S5?

17-March-06Confronting Gravity - St Thomas19 “Modest” Improvements Now – 14 Mpc Then – 30 Mpc

17-March-06Confronting Gravity - St Thomas20 Astrophysical Sources  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 Signal “stochastic background”

17-March-06Confronting Gravity - St Thomas21 Our Searches BNS PBH Spin is important “High mass ratio” Coming soon Mass Inspiral-Burst S4  Several inspiral searches are performed currently: »Primordial black holes binaries (PBHB) »Binary Neutron Stars (BNS) »Binary Black Holes (BBH)  Other searches in progress »Spinning Black Holes »Coincidences with GRB »Black Hole Ringdown »Inspiral-Burst BBH

17-March-06Confronting Gravity - St Thomas22 Template Bank  Covers desired region of mass param space  Calculated based on L1 noise curve  Templates placed for max mismatch of  = templates Second-order post-Newtonian

17-March-06Confronting Gravity - St Thomas23 Binary Neutron Star Search Results (S2) cumulative number of events signal-to-noise ratio squared Rate < 47 per year per Milky-Way-like galaxy Physical Review D

17-March-06Confronting Gravity - St Thomas24 Binary Black Hole Search

17-March-06Confronting Gravity - St Thomas25 From Limit Setting to Detections

17-March-06Confronting Gravity - St Thomas26 Improving Sensitivities Effective distance of L1 improved – S3  S4 8 Mpc to 40 Mpc

17-March-06Confronting Gravity - St Thomas27 Binary Inspiral Search: LIGO Ranges Image: R. Powell binary neutron star range binary black hole range

17-March-06Confronting Gravity - St Thomas28 Astrophysical Sources  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 Signal “stochastic background”

17-March-06Confronting Gravity - St Thomas29 ‘Unmodeled’ Bursts search for waveforms from sources for which we cannot currently make an accurate prediction of the waveform shape. GOAL METHODS Time-Frequency Plane Search ‘TFCLUSTERS’ Pure Time-Domain Search ‘SLOPE’ frequency time ‘Raw Data’Time-domain high pass filter 0.125s 8Hz

17-March-06Confronting Gravity - St Thomas30 Burst Search Results  Blind procedure gives one event candidate »Event immediately found to be correlated with airplane over-flight

17-March-06Confronting Gravity - St Thomas31 Burst Source - Upper Limit

17-March-06Confronting Gravity - St Thomas32 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 Signal “stochastic background”

17-March-06Confronting Gravity - St Thomas33 Detection of 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.

17-March-06Confronting Gravity - St Thomas34 Directed Pulsar Search 28 Radio Sources

17-March-06Confronting Gravity - St Thomas35 LIGO Pulsar Search using home pc’s BRUCE ALLEN Project Leader Univ of Wisconsin Milwaukee LIGO, UWM, AEI, APS ALL SKY SEARCH enormous computing challenge

17-March-06Confronting Gravity - St Thomas36 All Sky Search – Final S3 Data NO Events Observed

17-March-06Confronting Gravity - St Thomas37 Astrophysical Sources  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 Signal “stochastic background”

17-March-06Confronting Gravity - St Thomas38 Signals from the Early Universe  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: Overlap Reduction Function

17-March-06Confronting Gravity - St Thomas39 Stochastic Background Search (S3) Fraction of Universe’s energy in gravitational waves: (LIGO band)

17-March-06Confronting Gravity - St Thomas40 Results – Stochastic Backgrounds

17-March-06Confronting Gravity - St Thomas41 Conclusions  LIGO works!  Data Analysis also works for broad range of science goals. Now making transition from limit setting to detection based analysis  Data taking run (S5) to exploit Initial LIGO is well underway and will be complete within ~ 1.5 years  Incremental improvements to follow S5 are being developed. (improve sensitivity ~ x2)  Advanced LIGO fully approved by NSF and NSB and funding planned to commence in (design will improve sensitivity ~ x20)  R&D on third generation detectors is underway