LIGO: Laser Interferometer Gravitational-wave Observatory

3 0 3 ( ± 0 1 k 0 m m s ) LIGO: Laser Interferometer Gravitational-wave Observatory 4 km & 2 km WA MIT Caltech • Managed and operated by Caltech & MIT with funding from NSF • Ground breaking 1995 • 1st interferometer lock 2000 • LIGO Scientific collaboration: 45 institutions, world-wide LA 4 km March 2, 2007 R Frey

General Relativity • Some predictions: • Gravity influences both mass and energy • e.g. bending of light in regions with gravitational field • 1919 Eddington; Gravitational lensing: Einstein Cross • Many small deviations from Newtonian gravity in “weak” fields • Gravitational “redshift” (e.g. clocks on satellites are faster) • Perihelion advance of mercury • Global Positioning System would not work without GR corrections • “Strong” field effects • Black holes; Rs = 2GM/c2 • Spacetime structure of universe – evolution of spacetime from Big Bang • the “big stretch” • And gravitational radiation (gravitational waves) March 2, 2007 R Frey

GWs in GR March 2, 2007 R Frey

Required Gravitational Wave Sensitivity • GW emission requires time varying quadrupole moment of mass distribution • Strain estimate (h = L/ L): March 2, 2007 R Frey

GW Interferometer Principle GW strain: h = L/ L March 2, 2007 R Frey

S5 Science Run: LIGO at Design Sensitivity March 2, 2007 R Frey

Science runs and sensitivity March 2, 2007 R Frey

Coalescing Compact Binaries NS-NS, BH-BH, (BH-NS) binary systems Matched filter Template-less Matched filter March 2, 2007 R Frey

Gravitational Radiation and Gamma-ray Bursts BATSE • Long-duration GRBs • Stronger afterglows → z • SNe or “hypernovae” • mean z  2.5 GSFC • Short-duration GRBs • Until 2005, no measured z’s → enter Swift • Now: a few z’s → “compact binary mergers” GRB030329 HETE-2 • mergers are efficient GW radiators • much smaller z’s (mean  0.4) Oct 6, 2005 March 2, 2007 R Frey

2006 2007 2008 2009 2010 2011 2012 2013 2014 The Future: Enhanced and Advanced LIGO Enhanced LIGO (S6) • readout noise; laser power • Commission AdLIGO readout with real IFOs • reduce AdLIGO startup time Advanced LIGO • Major upgrades: optics, lasers, suspensions, ... • 10 better sensitivity S5 Run S7 S6 LIGO enhanced LIGO AdvancedLIGO News flash: Advanced LIGO is in the FY08 President’s budget build hardware installation science March 2, 2007 R Frey

Advanced LIGO reach (example) NS-NS inspiral search NS-NS sources (h sensitivity)2.7 h sensitivity will improve by 10, with improved bandwidth March 2, 2007 R Frey

LIGO: Laser Interferometer Gravitational-wave Observatory

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