Status and Prospects for LIGO

Transcription

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

2 LIGO Livingston, Louisiana 4 km 17-March-06 Confronting Gravity - St Thomas 2

3 LIGO Hanford Washington 4 km 2 km 17-March-06 Confronting Gravity - St Thomas 3

4 Interferometer optical vacuum layout suspended, seismically isolated test masses mode cleaner 4 km laser various optics 10 W 6-7 W 4-5 W W 9-12 kw 200 mw photodetector GW channel 17-March-06 Confronting Gravity - St Thomas 4

5 LIGO Beam Tube Minimal enclosure Reinforced concrete No services 1.2 m diameter - 3mm stainless 50 km of weld 65 ft spiral welded sections Girth welded in portable clean room in the field 17-March-06 Confronting Gravity - St Thomas 5

6 LIGO vacuum equipment 17-March-06 Confronting Gravity - St Thomas 6

7 Core Optics installation and alignment 17-March-06 Confronting Gravity - St Thomas 7

8 LIGO Optics fused silica Surface uniformity < 1 nm rms Scatter < 50 ppm Absorption < 2 ppm ROC matched < 3% Internal mode Q s > 2 x 10 6 Caltech data CSIRO data 17-March-06 Confronting Gravity - St Thomas 8

9 Interferometer Noise Limits Seismic Noise test mass (mirror) Quantum Noise Residual gas scattering "Shot" noise Radiation pressure LASER Wavelength & amplitude fluctuations Beam splitter photodiode 17-March-06 Confronting Gravity - St Thomas 9 Thermal (Brownian) Noise

10 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-06 Confronting Gravity - St Thomas 10

11 Commissioning /Running Time Line Inauguration First Lock Full Lock all IFO Now 4K strain noise x10-23 at 150 Hz [Hz -1/2 ] Engineering E2 Science E3 E5 E7 E8 E9 E10 E11 S1 S2 First Science Data S3 S4 S5 Runs 17-March-06 Confronting Gravity - St Thomas 11

12 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 March-06 Confronting Gravity - St Thomas 12

13 Initial LIGO - Design Sensitivity 17-March-06 Confronting Gravity - St Thomas 13

14 Sensitivity Entering S5 Equivalent strain noise (Hz -1/2 ) Rms strain in 100 Hz BW: 0.4x10-21 H1, 20 Oct 05 L1, 30 Oct 05 SRD curve Frequency (Hz) 17-March-06 Confronting Gravity - St Thomas 14

15 S5 Run Plan and Outlook Interferometer duty cycles 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 Run S2 S3 S4 S5 Target SRD goal L1 37% 22% 75% 85% 90% H1 74% 69% 81% 85% 90% H2 58% 63% 81% 85% 90% S5 is not completely hands-off 3- way 22% 16% 57% 70% 75% 17-March-06 Confronting Gravity - St Thomas 15

16 Sensitivity Entering S5 Hydraulic External Pre-Isolator 17-March-06 Confronting Gravity - St Thomas 16

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

18 What s after S5? 17-March-06 Confronting Gravity - St Thomas 18

19 Modest Improvements Now 14 Mpc Then 30 Mpc 17-March-06 Confronting Gravity - St Thomas 19

20 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-06 Confronting Gravity - St Thomas 20

21 Our Searches ass PBH BNS Inspiral-Burst S4 Spin is important High mass ratio Coming soon 10 BBH Several inspiral searches are performed currently: Mass» 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 17-March-06 Confronting Gravity - St Thomas 21

22 Template Bank Covers desired region of mass param space Calculated based on L1 noise curve Templates placed for max mismatch of δ = templates Second-order post-newtonian 17-March-06 Confronting Gravity - St Thomas 22

23 Binary Neutron Star Search Results (S2) Physical Review D cumulative number of events Rate < 47 per year per Milky-Way-like galaxy signal-to-noise ratio squared 17-March-06 Confronting Gravity - St Thomas 23

24 Binary Black Hole Search 17-March-06 Confronting Gravity - St Thomas 24

25 From Limit Setting to Detections 17-March-06 Confronting Gravity - St Thomas 25

26 Improving Sensitivities Effective distance of L1 improved S3 S4 8 Mpc to 40 Mpc 17-March-06 Confronting Gravity - St Thomas 26

27 Binary Inspiral Search: LIGO Ranges inary neutron star range inary black hole range 17-March-06 Confronting Gravity - St Thomas Image: R. Powell 27

28 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-06 Confronting Gravity - St Thomas 28

29 Unmodeled 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 Time-Frequency Plane Search TFCLUSTERS Pure Time-Domain Search SLOPE frequency 8Hz 0.125s time 17-March-06 Confronting Gravity - St Thomas 29

30 Blind procedure gives one event candidate» Event immediately found to be correlated with airplane over-flight Burst Search Results 17-March-06 Confronting Gravity - St Thomas 30

31 Burst Source - Upper Limit 17-March-06 Confronting Gravity - St Thomas 31

32 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-06 Confronting Gravity - St Thomas 32

33 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-06 Confronting Gravity - St Thomas 33

34 Directed Pulsar Search 28 Radio Sources 17-March-06 Confronting Gravity - St Thomas 34

35 ALL SKY SEARCH enormous computing challenge LIGO Pulsar Search using home pc s BRUCE ALLEN Project Leader Univ of Wisconsin Milwaukee LIGO, UWM, AEI, APS 17-March-06 Confronting Gravity - St Thomas 35

36 All Sky Search Final S3 Data NO Events Observed 17-March-06 Confronting Gravity - St Thomas 36

37 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-06 Confronting Gravity - St Thomas 37

38 Signals from the Early Universe Strength specified by ratio of energy density in GWs to total energy density needed to close the universe: Ω (f) GW = dρgw d(lnf) Detect by cross-correlating output of two GW detectors: ρ 1 critical Overlap Reduction Function 17-March-06 Confronting Gravity - St Thomas 38

39 Stochastic Background Search (S3) Fraction of Universe s energy in gravitational waves: (LIGO band) 17-March-06 Confronting Gravity - St Thomas 39

40 Results Stochastic Backgrounds 17-March-06 Confronting Gravity - St Thomas 40

41 LIGO works! Conclusions 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 17-March-06 Confronting Gravity - St Thomas 41