ICTS at 10 January 7, 2018 Gravitational Wave Detections by LIGO and Virgo: The Birth of a Revolution in Astronomy David Reitze LIGO Laboratory California Institute of Technology For the LIGO Scientific Collaboration and the Virgo Collaboration LIGO-G1702466-v1 LIGO-G1702466 Image Credit: Aurore Simmonet/SSU GW150914: The First Binary Black Hole Merger Andy Bohn, François Hébert, and William Throwe, SXS Collaboration Abbott, et al. ,LIGO Scientific Collaboration and Virgo Collaboration, “Observation of Gravitational Waves from a Binary Black Hole Merger” Phys. Rev. Lett. 116, 061102 (2016) 2 LIGO-G1702466 Outline l Motivations, Detectors l Binary Black Hole Mergers l The First Binary Neutron Merger Dawn of Multi- messenger Astronomy with Gravitational Waves l (A Few Slides About the Future) 3 LIGO-G1702466 Some of the Questions That Gravitational Waves Can Answer l Outstanding Questions in Fundamental Physics Black Hole Merger and Ringdown » Is General Relativity the correct theory of gravity? » How does matter behave under extreme conditions? » No Hair Theorem: Are black holes truly bald? l Outstanding Questions in Astrophysics, Astronomy, Cosmology Image credit: W. Benger » Do compact binary mergers cause GRBs? » What is the supernova mechanism in core-collapse of massive Neutron Star Formation stars? » How many low mass black holes are there in the universe? » Do intermediate mass black holes exist? » How bumpy are neutron stars? » Can we observe populations of weak gravitational wave Image credit: NASA sources? » Can binary inspirals be used as “standard sirens” to measure GW Upper limit map the local Hubble parameter? » Are LIGO/Virgo’s binary black holes a component of Dark Matter? » Do Cosmic Strings Exist? Credit: LIGO Scientific Collaboration 4 LIGO-G1702466 Gravitational-wave Interferometry Advanced LIGO l Ground-based GW detectors uses enhanced Michelson interferometry » With suspended (‘freely falling’) mirrors l Passing GWs stretch and compress the distance between the end test mass and the beam splitter l The interferometer acts as a transducer, turning GWs into photocurrent » A coherent detector! 2X improvement in sensitivity == 8X increase in detection rate 5 LIGO-G1702466 Advanced LIGO Interferometer Active Seismic Isolation Pre-stabilized Laser 40 kg ‘Test Mass’ Mirror 200W , 1064 nm Input Optics Output Mode Cleaner Auxiliary Laser 6 LIGO-G1702466 LIGO - G1702466 D L ~ 3 x10 ~ L LIGO Livingston Advanced LIGO Sensitivity Advanced - 19 70.6 m Mpc BNS Range) 175 10-19 L1, O1 (2015 October 24, 22 W ) L1, O2 (2017 July 20, 29 W, 98.2 Mpc BNS range) aLIGO Target Sensitivity Design (125 W, 193 Mpc BNS range) -20 ] 10 2 / 1 z H / -21 ) 10 m / m ( [ 7 1 0 inclinations) orbital and positions sky over all (averaged 1.4 can detecta an interferometer to which distance star) range neutron BNS (binary -22 2 - n g i 10 u A - a 3 2 r - n t o 1.4 M 1.4 s S n i a r t s l a i c i -23 f f 10 o e n i b m o BNS merger with an SNR SNR of 8 an with merger BNS c -19 y b H1, O1 (2015 October 24, 22 W, 75.9 Mpc BNS range) 10 d e t a H1, O2 (2016 December 2016, 29 W, 70.6 Mpc BNS range) e r 10-24 c aLIGO Target Design Sensitivity (125 W, 193 Mpc BNS range) 101 102 103 -20 Frequency [Hz] ] 10 2 / 1 z H / -21 ) 175 10 m / m ( - [ 7 1 the 0 -22 2 - n g i 10 u A - a 3 2 r ‘average’ ‘average’ n t o s S n i a r t s l a i c i -23 f f 10 o e n i b m o c y b d e t a e r 10-24 c 7 101 102 103 Frequency [Hz] Virgo LIGO Hanford Observatory Observatory Italy Washington, USA LIGO Livingston KAGRA Observatory (2019) Observatory Japan Louisiana, USA LIGO-India (2025) LIGO Laboratory 8 LIGO-G1702466 LIGO-India LIGO-India Project l LIGO-India Project – a collaboration between India and the USA to build a LIGO interferometer in India. » Identical to the two USA LIGO detectors IndIGO - LSC » India lead agencies: DAE&DST; US lead agency: NSF l Good progress made in the past two years » Formal MOU between DAE and NSF in place » Site has been selected; land acquisition is proceeding » $23M (US equivalent) released to lead institutions for site acquisition, site studies and prep, vacuum prototyping, human resource development » A large of India institutions (including ICTS!) and researchers are joining the IndIGO collaboration l Baseline LIGO-India Project schedule » Site preparation: 2018 – 2019 » Observatory Construction: 2020-2022 » Interferometer installation and commissioning: 2022-2024 » Observatory operations scheduled to begin in 2025 LIGO-India Proposed Site9 LIGO-G1702466 The First Gravitational Wave Detections: Binary Black Holes 10 LIGO-G1702466 Astrophysical Parameters of the Detected BBH Mergers GW150914 GW151226 LVT151012 GW170814 GW170608 GW170104 11 LIGO-G1702466 l we Most Recent Binary Black Hole Merger Reported on Nov 15: GW170608: Observation of a 19-solar-mass Binary Black Hole Coalescence, Astrophys. J. Lett 851:L35 (2017). 12 LIGO-G1702466 Astrophysical Implications of LIGO- Virgo Black Hole Mergers l Stellar mass binary black hole systems exist. l Stellar mass binary black hole systems can merge in less than a Hubble time. l First observation of ‘heavy’ stellar mass (> 25 M) black holes l Heavy mass BBH system most likely formed in a low-metallicity environment: < ½-¼ Z What to expect in the future: Abbott, et al., LIGO Scientific Collaboration and Virgo Collaboration, “Astrophysical Implications of the Binary l Determination of mass and spin spectrum of black holes Black Hole Merger GW150914” Astrophys. J. Lett 818:L22 » Confirm or rule out dark matter scenarios (2016) l Determine preferred formation channels: isolated binary evolution vs dynamical capture in dense stellar environments Abbott, et al. ,LIGO Scientific Collaboration and Virgo Collaboration, “Astrophysical Implications of the Binary Black-Hole Merger GW150914”, ApJL, 818, L22, 2016 ;”The Rate of Binary Black Hole Mergers Inferred from Advanced LIGO Observations Surrounding GW150914”, arXiv:1602.03842 13 LIGO-G1702466 The Newest Detection: A Binary Neutron Star Merger 14 LIGO-G1702466 Abbott, et al. ,LIGO Scientific Collaboration and Virgo Collaboration, “GW170817: Observation of Gravitational Waves from a Binary Neutron Star GW170817: Inspiral” Phys. Rev. Lett. 161101 (2017) The First Detected Binary Neutron Star Merger 15 LIGO-G1702466 » wqwe 16 LIGO-G1702466 LIGO-G1702466 LIGO-G1702466 LIGO Scientific Collaboration and Virgo Collaboration, Gravitational Waves and Gamma-Rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A” Astrophys. J. Lett., 848:L13, (2017) LIGO-G1702466 Observations Across the Electromagnetic Spectrum NGC 4993 D=1.3 x 108 ly Credit: European Southern Observatory Very Large Telescope Abbott, et al. ,LIGO Scientific Collaboration and Virgo Collaboration, “Multi-messenger Observations of a Binary Neutron Star Merger” Astrophys. J. Lett., 848:L12, (2017) 20 LIGO-G1702466 Are Gravitons Massless? l GW170817 provides a stringent test of the speed of gravitational waves Dt = 1.7 s l Dt =1.74 +/- 0.05 s l D ≈ 26 Mpc » Conservative limit – use 90% confidence level lower limit on GW source from parameter estimation l GW170814 also puts limits on violations of Lorentz Invariance and Equivalence Principle LIGO Scientific Collaboration and Virgo Collaboration, Gravitational Waves and Gamma-Rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A” Astrophys. J. Lett., 848:L13, (2017) 21 LIGO-G1702466 Binary Neutron Star Mergers Produce Kilonovae Kasliwal et al. 2017, l Electromagnetic follow-up of GW170817 Science, DOI: https://doi.org/10.1126/science.aap9455 provides strong evidence for kilonova model » kilonova - isotropic thermal emission produced by radioactive decay of rapid neutron capture (‘r-process’) elements synthesized in the merger ejecta l Spectra taken over 2 week period across all electromagnetic bands consistent with kilonova models » “Blue” early emission dominated by Fe-group and light r-process formation; later “red” emission dominated by heavy element (lanthanide) formation Cowpersthwaite, et al. 2017, l Recent radio data prefers ‘cocoon’ model to Ap. J. Lett. DOI: https://doi.org/10.3847/2041-8213/aa8fc7 classical short-hard GRB production! LIGO-G1702466 A gravitational-wave standard siren measurement of the Hubble constant l Gravitational waves are ‘standard sirens’, providing absolute measure of luminosity distance dL l can be used to determine H0 directly if red shift is known: c z = H0 dL l … without the need for a cosmic distance ladder! H0 = 70 (+12, - 8) km/s/Mpc Abbott, et al., LIGO-Virgo Collaboration, 1M2H, DeCAM GW-EM & DES, DLT40, Las Cumbres Observatory, VINRO UGE, MASTER Collaborations, A gravitational-wave standard siren measurement of the Hubble constant”, Nature 551, 85–88 (2017). 23 LIGO-G1702466 The Future of GW Astrophysics: Beyond Advanced LIGO 24 LIGO-G1702466 ‘A+’ Advanced LIGO Mid-scale Upgrade l An upgrade to aLIGO that leverages existing technology and infrastructure, with minimal new investment and moderate risk l Target: average 1.7 increase in range over aLIGO ~ 5 greater event rate than Advanced LIGO; ~ 40 times better than current Advanced LIGO sensitivity l A+ is a stepping stone to future detector technologies l Timescale – begin upgrade in 2021; back online in 2023 A+ key parameters: 12dB injected squeezing 15% readout loss » Assumes funding begins in 2019 100 m filter cavity (FC) l LIGO-India is planned to come 20 ppm round trip FC loss Coating Thermal Noise half online in the A+ configuration of aLIGO LIGO-G1702466 LIGO Science is Sensitivity Driven 1) Rates Binary Neutron Stars running at O2 sensitivity N = <R>VT ) 3 events 1 10 running at O3 sensitivity 825X O running at aLIGO O4 sensitivity no A+ upgrade f <R>: average astrophysical o A+ upgrade s 230X rate t i V: volume of the universe n u 3 102 probed (Range) n i 120X ( T: coincident observing time e m i 45X 2) Many sources T x 1 require higher SNR to e 10 m uncover new u l o astrophysics V - tidal disruption in BNS mergers 100 - tests of alternative theories 2016 2018 2020 2022 2024 2026 of gravity Calendar year - Black hole ringdowns - Stochastic background - Isolated neutron stars - Galactic supernova - ...