S.Klimenko, December 18, 2010, Miami, LIGO-G v3 Credit: AEI, CCT, LSU From Initial to Advanced gravitational wave interferometers: results, challenges and prospects. Sergey Klimenko, University of Florida for the LIGO and Virgo collaborations

S.Klimenko, December 18, 2010, Miami, LIGO-G v3 Gravitational Waves after a decade of experiments with the initial (1G) GW interferometers, the advanced (2G) detectors are targeting detection of GWs in ~2016 – 100 years after their prediction. J.Weber: ”When I decided to search for gravitational waves some 14 years ago, most physicists applauded our but felt that success – detection of gravitational radiation – would require a century of experimental work.” ( Popular Science May W.Churchill: “Courage is going from failure to failure without losing enthusiasm” space-time perturbations propagating at the speed of light predicted by A.Einstein in 1916 as part of his theory of General Relativity

S.Klimenko, December 18, 2010, Miami, LIGO-G v3 Gravitational Waves: the evidence PSR Neutron Binary System Separated by 10 6 miles, m 1 = 1.4m  ; m 2 = 1.36m  ; Prediction from general relativity spiral in by 3 mm/orbit merge in 300 million years Emission of gravitational waves time of periastron relative to that expected if the orbital separation remained constant. Hulse & Taylor

S.Klimenko, December 18, 2010, Miami, LIGO-G v3 GW Detectors LIGO, VIRGO, GEO, TAMA: breakthrough in the GW experiment Interferometers wideband (~10000 Hz) ALLEGRO, AURIGA, EXPLORER, NAUTILUS, NIOBE, … Bars narrowband (~1Hz) recent improvements (~10Hz) UF graduate student Kate Dooley inspecting a LIGO optic. J.Weber working on the bar

S.Klimenko, December 18, 2010, Miami, LIGO-G v3 Sensitivity of 1G Interferometers strain noise:

S.Klimenko, December 18, 2010, Miami, LIGO-G v3 LIGO Observatory Initial LIGO detectors (1G) were in operation for a decade  6 data taking runs (~1.5 years of 2D live time)  reached its design sensitivity during the S5 run: Virgo detector joined in May 2007 (VSR1 run)  run enhanced configuration during the s6 run: 2009 – 2010  decommissioned in October 2010 started to constrain source models (analysis of data continues) paved road for aLIGO 2G detectors established conceptually new GW data analysis began integration of GW experiment and astronomy Livingston, LA (LLO) L1: 4km x 4km Hanford, WA (LHO) H1: 4km x 4km H2: 2km x 2km

S.Klimenko, December 18, 2010, Miami, LIGO-G v3 Gravitational Wave Sources and other violent astrophysical sources.. Credit: Chandra X-ray Observatory Casey Reed, Penn State NS-NS Credit: AEI, CCT, LSU binary neutron stars binary black holes pulsars supernovae gamma ray bursts soft gamma repeaters

S.Klimenko, December 18, 2010, Miami, LIGO-G v3 Compact Binary Coalescence: NS-NS PRD 82 (2010) S5 l NS-NS – LIGO standard candle (1G horizon ~30Mpc))  large expected signal, inspiral in the sweet spot ( Hz)  challenges: get physics at merger phase (~1.5kHz) l CL – cumulative luminosity (370L 10 ) l T – observation time (~1 year) l measured rate limit: <3.2 / year: l expected rates: ~0.01 / year inspiral: PN GR merger: NR GR BH ringdown L 10 = L ,B (1 Milky Way = 1.7 L 10 )

S.Klimenko, December 18, 2010, Miami, LIGO-G v3 Black Holes

S.Klimenko, December 18, 2010, Miami, LIGO-G v3 BH binary coalescence: BH-BH & BH-NS l BH searches  low mass BH & NS (<25Mo)  search with inspiral templates  high mass BH-BH (25-100Mo)  search with IMR templates  massive BH-BH ( Mo)  burst searches l high mass CBC (>25Mo) are better detected via their merger and ring-down waves ( in progress). C hallenges:  need merger waveforms (Numerical Relativity calculations)  background due to non-stationary detector noise M<20M o Background: S5/VSR1 burst search event strength

S.Klimenko, December 18, 2010, Miami, LIGO-G v3 Low Mass CBC BH search l S5/VSR1 run (T~1year): PRD 82 (2010) l Measure rate limits: l Expected rates NS(1.35Mo)-BH BH-BH BH(5Mo)-NS: C L = 1600L 10 BH(5Mo)-BH(5Mo): C L = 8300L 10 CQG. 27 (2010)

All-Sky Burst Searches model independent, however sensitive to a wide class of sources: binary mergers, SN, SGR,.. use ad-hoc waveforms (Sine-Gaussian, Gaussian, etc.) to determine detection sensitivity Challenges: affected by detector glitches  need smart network search algorithms and very detail understanding of the detector noise Sine-Gaussian waveforms, Q=8.9 PRD 72(2005) CQG 24(2007) CQG 25(2008)

S.Klimenko, December 18, 2010, Miami, LIGO-G v3 Supernova Karachentsev et al. 2004; Cappellaro et al l GW from supernova  Several Core-Collapse SN Mechanisms  Direct “live” information from the supernova engine. 1/50 yr - Milky Way Ott, et al.

S.Klimenko, December 18, 2010, Miami, LIGO-G v3 Mass equivalent sensitivity l strain sensitivity can be converted to energy sensitivity assuming isotropic GW emission Capable to detect burst sources out to Virgo cluster if E GW is few % of Mo For lower energy output (like SNs, which also produce HF signals) need advanced detectors to see beyond our Galaxy 16Mpc 10kpc

S.Klimenko, December 18, 2010, Miami, LIGO-G v3 short GRB no gravitational waves detected APJ 681 (2008) % 50% 75% 90% D M31 ≈770 kpc Sky location consistent with Andromeda (M31) Possible progenitors:  NS-NS or BH-NS merger  Soft Gamma Repeater Inspiral search:  excludes binary progenitor in Andromeda at >99% confidence level  Exclusion of merger at larger distances Burst search:  Cannot exclude a Soft Gamma Repeater (SGR) at M31 distance  Upper limit: E GW <8x10 50 ergs (<4x10 -4 M o c 2 ) more GRB results: APJ 715 (2010) 1438 search for GWs from 137 GRBs in S5

S.Klimenko, December 18, 2010, Miami, LIGO-G v3 GWs from 116 known pulsars APJ. 713 (2010) 671 limits on GW amplitude S3/S4 S

S.Klimenko, December 18, 2010, Miami, LIGO-G v3 Beating the Crab Pulsar Spin Down Limit Young and rapidly spinning down GW frequency 59.6 Hz Experimental limits GW strength: h(95%CL) < 2.0 x the spin down limit (assuming restricted priors) ellipticity limit:  < 1.0 x GW energy upper limit: < 2% of radiated energy is in GWs Astrophys. J. 713 (2010) 671

S.Klimenko, December 18, 2010, Miami, LIGO-G v3 Stochastic Background LIGO S5 result:    6.9 x Nature., V460: 990 (2009).

S.Klimenko, December 18, 2010, Miami, LIGO-G v3 Multimessenger Astronomy lobservation and measurement of the same astrophysical event by different experiments  better confidence of GW event  extract physics of source engine lExternally triggered strategy  routinely used by LIGO lLook-Up strategy  close integration with astronomy: search for EM counterpart with optical and radio telescopes  need low latency (few min) source localization from GW detectors  rely on source reconstruction  In LIGO and Virgo carried out first EM followup experiments  analysis in progress

S.Klimenko, December 18, 2010, Miami, LIGO-G v3 Challenges of GW reconstruction If detection of GW signals is hard, the reconstruction even harder and not really addressed yet. incomplete or no source models dependence on antenna patterns & detector noise dependence on GW waveforms and polarization state reconstruction bias due to algorithmic assumptions reconstruction bias due to calibration errors high computational cost ….there are many ways to get it wrong  need smart algorithms  eventually need more detectors

S.Klimenko, December 18, 2010, Miami, LIGO-G v3 Source localization method Based on triangulation (  1,  2,  3,..)  3 or more sites lCoupled to reconstruction of GW waveforms  coherent analysis of data from all detectors in the network. 22 11 33 error region Probability map

S.Klimenko, December 18, 2010, Miami, LIGO-G v3 Antenna patterns & noise lnetwork sensitivity: lnetwork SNR ldetectors with small f k do not contribute to reconstruction  effectively deal with 2 detector network  lose triangulation  need more than 3 sites for robust reconstruction LIGO Virgo

S.Klimenko, December 18, 2010, Miami, LIGO-G v3 Waveforms & polarization Simulated signal ( SG235Q9 ) with linear polarization simulated signal ( WNB 250 Hz ) with two random polarizations V1, L1, H1 accuracy, degrees lFor linearly polarized signal effectively lose a detector lFor signals with random polarization, recover reconstruction due to the 2nd polarization lThis effect strongly depends on the sky location additional 4th site solves the problem

2G (advanced) detectors l x10 better sensitivity than for 1G l aLIGO Is being constructed  start operation in l aVirgo will emerge in about the same time after a series of upgrades which are in progress. l hopefully LIGO-A and LCGT will be constructed  huge increase in scientific output, make GW astronomy a reality. aLIGO LCGT aVIRGO LIGO-Australia (LIGO-A)

LIGO goes south? l Plans for relocation of one H detector to Australia, Gingin  5-10 times better sky resolution – compatible with FOV of telescopes  conditional approval from NSF LHHV LHVA network SNR Error angle in degrees longitude latitude Physics Today, Dec, 2010 committee report at LHHV LHVA

S.Klimenko, December 18, 2010, Miami, LIGO-G v3 Class. Quantum Grav. 27 (2010) G Astronomical Reach x10 better amplitude sensitivity  x1000 rate=(reach) 3 BH-BH y -1 NS-NS y -1 SN y -1 CQG. 27 (2010)