LIGO Update

Transcription

1 LIGO Update The Search for Gravitational Waves Barry Barish Caltech Trustees 10-Sept-02

2 ! Goals Laser Interferometer Gravitational-wave Observatory» First direct detection of gravitational waves» Open new window on the universe gravitational wave astronomy! NSF funded construction in 1994 for $296M» Caltech has fiduciary responsibility» Joint Caltech/MIT technical and scientific team» Construction completed in both Louisiana and Washington in 2000! Commissioning, Operations and Scientific Programs» First Interferometer locked (Oct 2000)» First coincidence running of both sites (Dec 2001)» First scientific data run upper limits (Sept 2002)» Search for gravitational waves (2003 through 2006)! We propose to install Advanced LIGO in 2007» Cost ~ $125M total -- international collaboration 10-Sept-02 Caltech Board of Trustees 2

3 LIGO Scientific Collaboration Member Institutions LSC Membership 35 institutions > 350 collaborators University of Adelaide ACIGA Australian National University ACIGA California State Dominquez Hills Caltech LIGO Caltech Experimental Gravitation CEGG Caltech Theory CART University of Cardiff GEO Carleton College Cornell University University of Gainesville Glasgow University GEO University of Hannover GEO Harvard-Smithsonian India-IUCAA IAP Nizhny Novgorod Iowa State University Joint Institute of Laboratory Astrophysics LIGO Livingston LIGOLA LIGO Hanford LIGOWA Louisiana State University Louisiana Tech University MIT LIGO Max Planck (Garching) GEO Max Planck (Potsdam) GEO University of Michigan Moscow State University NAOJ - TAMA University of Oregon Pennsylvania State University Exp Pennsylvania State University Theory Southern University Stanford University University of Texas@Brownsville University of Western Australia ACIGA University of Wisconsin@Milwaukee International India, Russia, Germany, U.K, Japan and Australia. The international partners are involved in all aspects of the LIGO research program. 10-Sept-02 Caltech Board of Trustees 3

4 Livingston Optical Telescope broad outreach/education program Draft building concept utilizes surplus beam tube enclosures on raised footings with roll-off off roof Proposed telescope location on fire access road gives clear view to south Telescope facts: 16 inch Richey Chretien telescope built by Optical Guidance Systems Telescope provided by state funds via LSU. LIGO provides site and internet connection and incorporates telescope use into outreach program. Internet accessible to facilitate classroom use 10-Sept-02 Caltech Board of Trustees 4

5 Budget LIGO Operations (2002 thru 2006)! Operations of LIGO funded beginning in 2002 for 5 years at a total funding of $160M! We function as one distributed laboratory (LIGO Laboratory)» Caltech (85 staff); MIT (25staff); Hanford (25 staff); Livingston (25 staff)! Advanced LIGO construction (not included) to be proposed next year Operations Advanced R&D FY 2002 ($M) $24 $4 + $5M FY 2003 ($M) $29 $4 FY 2004 ($M) $30 10-Sept-02 Caltech Board of Trustees 5 $3 FY 2005 ($M) $30 $3 FY 2006 ($M) $30 $3

6 ! Faculty LIGO at Caltech» Barish, Drever, Libbrecht, Prince and Weinstein (Exp) & Thorne(Th)! Scientists/Postdocs/Students» PhD theses; talented junior and senior scientists! LIGO Management» Directorate, Administration! LIGO Technical» Engineering center precision engineering; controls; electronics» 40 meter prototype; Optical laboratories, etc! LIGO Data Analysis and Computing» Simulations; Analysis infrastructure, Networking, Data Archive» Scientific data analysis efforts! Source Simulations Numerical Relativity 10-Sept-02 Caltech Board of Trustees 6

7 Einstein s Theory of Gravitation gravitational waves Newton s Theory instantaneous action at a distance Einstein s Theory information carried by gravitational radiation at the speed of light A necessary consequence of Special Relativity with its finite speed for information transfer Time dependent gravitational fields come from the acceleration of masses and propagate away from their sources as a space-time warpage at the speed of light 10-Sept-02 Caltech Board of Trustees 7

8 Direct Detection astrophysical sources Gravitational Wave Astrophysical Source Detectors in space LISA Terrestrial detectors LIGO, TAMA, Virgo,AIGO 10-Sept-02 Caltech Board of Trustees 8

9 International network (LIGO, Virgo, GEO, TAMA, AIGO) of suspended mass Michelson-type interferometers on earth s surface detect distant astrophysical sources Interferometers terrestrial free masses free masses suspended test masses 10-Sept-02 Caltech Board of Trustees 9

10 Suspended Mass Interferometer the concept! An interferometric gravitational wave detector» A laser is used to measure the relative lengths of two orthogonal cavities (or arms) Arms in LIGO are 4km» Current technology then allows one to measure h = δl/l ~ which turns out to be an interesting target causing the interference pattern to change at the photodiode As a wave passes, the arm lengths change in different ways. 10-Sept-02 Caltech Board of Trustees 10

11 How Small is Meter? One meter, about 40 inches 10, , ,000 1,000 Human hair, about 100 microns Wavelength of light, about 1 micron Atomic diameter, meter Nuclear diameter, meter LIGO sensitivity, meter 10-Sept-02 Caltech Board of Trustees 11

12 Seismic noise & vibration limit at low frequencies What Limits Sensitivity of Interferometers? 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 10-Sept-02 Caltech Board of Trustees 12

13 Noise Floor 40 m prototype sensitivity demonstration displacement sensitivity in 40 m prototype. comparison to predicted contributions from various noise sources 10-Sept-02 Caltech Board of Trustees 13

14 LIGO long baseline interferometers (4 km) Laser Interferometer Gravitational-wave Observatory (LIGO) Hanford Observatory Livingston Observatory 10-Sept-02 Caltech Board of Trustees 14

15 LIGO Livingston Observatory 10-Sept-02 Caltech Board of Trustees 15

16 LIGO Hanford Observatory 10-Sept-02 Caltech Board of Trustees 16

17 LIGO beam tube! LIGO beam tube under construction in January 1998! 65 ft spiral welded sections! girth welded in portable clean room in the field 1.2 m diameter - 3mm stainless 50 km of weld NO LEAKS!! 10-Sept-02 Caltech Board of Trustees 17

18 LIGO vacuum equipment 10-Sept-02 Caltech Board of Trustees 18

19 Core Optics fused silica LIGO requirements! Surface uniformity < 1 nm rms! Scatter < 50 ppm! Absorption < 2 ppm! ROC matched < 3%! Internal mode Q s > 2 x 10 6 LIGO measurements central 80 mm of 4ITM06 (Hanford 4K) rms = 0.16 nm optic far exceeds specification. Surface figure = λ/ Sept-02 Caltech Board of Trustees 19

20 Core Optics installation and alignment 10-Sept-02 Caltech Board of Trustees 20

21 Interferometer locking Requires test masses to be held in position to meter: Locking the interferometer Light is recycled about 50 times end test mass Light bounces back and forth along arms about 150 times input test mass Laser signal 10-Sept-02 Caltech Board of Trustees 21

22 Lock Acquisition 10-Sept-02 Caltech Board of Trustees 22

23 LIGO watching the interferometer lock Composite Video Y Arm Laser signal X Arm 10-Sept-02 Caltech Board of Trustees 23

24 LIGO watching the interferometer lock Y arm X arm 2 min Y Arm Reflected light Anti-symmetric port Laser signal X Arm 10-Sept-02 Caltech Board of Trustees 24

25 Engineering Run detecting earthquakes From electronic logbook 2-Jan-02 An earthquake occurred, starting at UTC 17:38. The plot shows the band limited rms output in counts over the Hz band for four seismometer channels. We turned off lock acquisition and are waiting for the ground motion to calm down. 10-Sept-02 Caltech Board of Trustees 25

26 17:03:03 01/02/2002 ========================================================================= Seismo-Watch Earthquake Alert Bulletin No ========================================================================= Preliminary data indicates a significant earthquake has occurred: Regional Location: VANUATU ISLANDS Magnitude: 7.3M Greenwich Mean Date: 2002/01/02 Greenwich Mean Time: 17:22:50 Latitude: 17.78S Longitude: E Focal depth: 33.0km Analysis Quality: A Source: National Earthquake Information Center (USGS-NEIC) Seismo-Watch, Your Source for Earthquake News and Information. Visit ========================================================================= All data are preliminary and subject to change. Analysis Quality: A (good), B (fair), C (poor), D (bad) Magnitude: Ml (local or Richter magnitude), Lg (mblg), Md (duration), 10-Sept-02 Caltech Board of Trustees 26 =========================================================================

27 Detecting the Earth Tides Sun and Moon 10-Sept-02 Caltech Board of Trustees 27

28 10-Sept-02 Caltech Board of Trustees 28

29 LIGO Goals and Priorities! Interferometer performance» Integrate commissioning and data taking consistent with obtaining one year of integrated data at h = by end of 2006! Physics results from LIGO I» Initial upper limit results by early 2003» First search results in 2004» Reach LIGO I goals by 2007! Advanced LIGO» Prepare advanced LIGO proposal this fall» International collaboration and broad LSC participation» Advanced LIGO installation beginning by Sept-02 Caltech Board of Trustees 29

30 Preliminary 10-Sept-02 Caltech Board of Trustees 30

31 10-Sept-02 Caltech Board of Trustees 31

32 Astrophysical Sources the search for gravitational waves! 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 10-Sept-02 Caltech Board of Trustees 32

33 Stochastic Background cosmological signals Murmurs from the Big Bang signals from the early universe Cosmic microwave background 10-Sept-02 Caltech Board of Trustees 33

34 Stochastic Background coherence plot LHO 2K & LLO 4K 10-Sept-02 Caltech Board of Trustees 34

35 Stochastic Background projected sensitivities 10-Sept-02 Caltech Board of Trustees 35

36 Advanced LIGO Multiple Suspension Active Seismic Saphire Optics Higher Power Laser 10-Sept-02 Caltech Board of Trustees 36

37 Advanced LIGO Enhanced Systems improved laser suspension seismic isolation test mass material narrow band optics Improvement factor ~ Sept-02 Caltech Board of Trustees 37

38 Gravitational-wave Astronomy frequency range! EM waves are studied over ~20 orders of magnitude» (ULF radio > HE γ-rays) Audio band! Gravitational Waves over ~10 orders of magnitude» (terrestrial + space) LISA LIGO I ( ) Adv LIGO (2008 -) 10-Sept-02 Caltech Board of Trustees 38