LISHEP 2018, Salvadore, Bahia, Brazil, 10 Sept 2018 A New Era of Collisions: Gravitational-wave Detection Meets Astrophysics David Reitze LIGO Laboratory California Institute of Technology For the LIGO Scientific Collaboration and the Virgo Collaboration LIGO-G1800xxx-v1 LIGO-G1800682 Image Credit: Aurore Simmonet/SSU Talk Roadmap l Gravitational Waves and GW Astrophysics l The NSF LIGO Detectors l Binary Black Hole Mergers l Multi-messenger Astronomy: Discovery of a Binary Neutron Star Merger l The Future of Ground-based Gravitational-wave Astronomy 2 LIGO-G1800682 General Relativity and Gravitational Waves General Relativity: 8pG Einstein Field Gmn = 4 Tmn Equations c Weak field approximation -- Free Space: space-time is slightly -43 perturbed from flat Tmn = 0 ~ 10 space-time: gmn » hmn +hmn Physically, h is a strain: 2 DL/L æ 2 1 ¶ ö Wave equation for h çÑ - ÷hmn = 0 mn è c2 ¶t 2 ø 3 LIGO-G1800682 An Abridged Astrophysical Gravitational-Wave Source Catalog Coalescing Binary Systems Transient‘Burst’ • Black hole – black Sources hole • asymmetric core •Black hole – neutron collapse supernovae star • cosmic strings • Neutron star – neutron star (Unmodeled • White dwarf binaries waveform) (modeled waveform) Credit: Chandra X-ray Observatory Credit: Bohn, Hébert, Throwe, SXS And possibly the unknown… Stochastic Continuous Background Sources • residue of the Big Bang • Spinning neutron • incoherent sum of stars unresolved ‘point’ (monotone waveform) sources Credit: Planck Collaboration (stochastic, incoherent noise background) Credit: Casey Reed, Penn State 4 LIGO-G1800682 NSF’s LIGO Gravitational Wave Detectors 5 LIGO-G1800682 4 km LIGOLIGO Livingston Hanford ObservatoryObservatory 4 km 4 km 4 km LIGO Laboratory 6 LIGO-G1800682 Precision Gravitational-wave Interferometry Advanced LIGO l LIGO 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! 7 LIGO-G1800682 Precision Interferometry = Understanding Measurement Noises Fundamental Noises: Advanced LIGO Design Noise Budget I. Displacement Noises DL(f) Photon Statistics Radiation Pressure • Seismic noise Sensitivity ~ 1/√PLaser • Radiation Pressure •Thermal noise Dissipative Dynamics Photon Statistics • Suspensions ‘kT physics’ Shot Noise Sensitivity ~ √P • Optics Laser II. Sensing Noises Dtphoton(f) Residual Gas Scattering • Shot Noise • Residual Gas Technical Noises: Hundreds of them… Seismic Motion 8 LIGO-G1800682 Advanced LIGO Suspensions Force Displacement Concept: 4 StageTransfer Transfer Function Function: Harmonic 1010 Model vs. Measured Oscillator 105 100 Implementation: Collaboration w/ U. Glasgow X -5 / x 10 10-10 10-15 10-20 0.01 0.1 1 10 100 1000 10000 Frequency (Hz) Upper ‘ear’ Lower ‘ear’ 9 LIGO-G1800682 Binary Black Hole Mergers 10 LIGO-G1800682 Modeled Template-based Searches l Matched filter search: X-correlation of L1, H1 data streams l Background computed from time-shifting coincident data in 100 ms steps » For GW150914, 51.5 days 5x106 years Simulation: Reed Essick, LIGO MIT Abbott, et al., LIGO Scientific Collaboration and Virgo Collaboration, “Binary Black Hole 11 LIGO-G1800682 Mergers in the first Advanced LIGO Observing Run”, Phys. Rev. X 6, 041015 (2016). Modeled Template-based Searches l Matched filter search: X-correlation of L1, H1 data streams l Background computed from time-shifting coincident data in 100 ms steps » For GW150914, 51.5 days 5x106 years Simulation: Reed Essick, LIGO MIT Abbott, et al., LIGO Scientific Collaboration and Virgo Collaboration, “Binary Black Hole 12 LIGO-G1800682 Mergers in the first Advanced LIGO Observing Run”, Phys. Rev. X 6, 041015 (2016). 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) 4 x 10-18 m 13 LIGO-G1800682 Black hole mergers of known mass detected by LIGO & VIRGO l we LIGO-Virgo O2 Catalog paper coming soon! 14 LIGO-G1800682 A Revolution in Black Hole Physics l First direct detection of gravitational waves l First observational confirmation that black holes can form in a binary system and merge in less than a Hubble time l First observational confirmation that ‘heavy’ stellar mass black holes exist l Strong Evidence that LIGO’s black holes form in low metallicity environments l Still many open questions! » (Binary) Black hole mass spectrum? » Spins? Formation channels? » Primordial black holes? Dark matter component? Abbott, et al., LIGO Scientific Collaboration and Virgo Collaboration, “Astrophysical Implications of the Binary Black Hole Merger GW150914” Astrophys. J. Lett 818:L22 (2016) 15 LIGO-G1800682 Gravitational-wave Multi-messenger Astronomy: Discovery of a Binary Neutron Star Merger 16 LIGO-G1800682 Multi-messenger Astronomy with Gravitational Waves Binary Neutron Star Merger X-rays/Gamma-rays Gravitational Waves Visible/Infrared Light Neutrinos Radio Waves LIGO-G1800682 The Global Ground-based Gravitational-wave Detector Network 2019 2025 LIGO-G1800682 Virgo, Cascina, Italy LIGO, Livingston, LA LIGOLIGO,-G1800682 Hanford, WA 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 20 LIGO-G1800682 A Multi- messenger Astronomical Revolution! 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) 21 LIGO-G1800682 A Revolution in Multi-messenger Astronomy Observations by > 70 observatories across the EM Cowpersthwaite, et al. 2017, spectrum + neutrinos! Ap. J. Lett. DOI: https://doi.org/10.3847/2041-8213/aa8fc7 O(1000) papers have been published on this event. l First observation of a binary neutron star merger & First observation of a BNS collision in GW & EM l First confirmation of the BNS - GRB link l First solid evidence for BNS/r-process link; that BNS mergers are the Universe’s ‘foundry’ for producing heavy elements l Best constraint on the graviton mass l Best constraint on NS radius Kasliwal et al. 2017, l Closest short hard GRB ever observed Science, DOI: https://doi.org/10.1126/science.aap9455 l First measurement of the Hubble constant using gravitational waves l Still Many Open Questions: » Is the remnant a black hole or supermassive neutron star? » Why a subluminous GRB? Off-axis jet or cocoon or ? » What is the opening jet angle? 22 LIGO-G1800682 Measurements of the GW170817 BNS Radii and EoS l Reanalysis of LIGO-Virgo data assuming components were NSs described by single EOS and consistent with EM observations Abbott, et al., LIGO-Virgo Collaboration, “GW170817: l R = 11.9 (+/- 1.4) km; R = 11.9 (+/- 1.4) km Measurements of neutron 1 2 star radii and equation of l Also constrain NS pressure-density relationship state” arXiv:1805.11581v1, PRL (to appear). p @ 2X nuclear saturation density = 3.5x1034 dyn/cm2 23 LIGO-G1800682 Ground-based Gravitational-wave Detectors in the Next Decade and Beyond 24 LIGO-G1800682 2024: Advanced LIGO + l ‘Mid-scale’ upgrade of the Advanced LIGO interferometers l Sensitivity improvement over ALIGO: » 1.4/1.4 M BNS inspiral range by ~ 1.9 to 325 Mpc » 30/30 M binary black hole inspiral range by ~1.6 to > 2.5 Gpc ~ 5 greater event rate than Advanced LIGO Higher SNR CBC events l Employs frequency-dependent squeezing & lower thermal noise mirror coatings l Currently planning for a 1.5 - 2 year run duration in beginning in 2024 or 2025 LIGO-G1800682 LIGO Voyager – the Ultimate LIGO Detector l A 4 km design to exploit the LIGO Observatory facilities limits » Ultimately determined by arm length and vacuum base pressure l Uses new technologies … » Silicon test masses » 123 K operating temperature » 2 mm 150 W laser, higher quantum efficiency photodiodes l ... but reuses key Advanced LIGO components » Vacuum system » Seismic isolation l Cost: O($108M) l Time Scale: not before late 2020s Shapiro, Brett, et al. "Cryogenically cooled ultra low vibration silicon mirrors for gravitational wave observatories." Cryogenics 81 (2017): 83-92. LIGO Laboratory26 LIGO-G1800682 ‘Third Gen’ Ground-based Observatories: Einstein Telescope and Cosmic Explorer l qw Einstein Telescope Concept (Europe) Cosmic Explorer Concept (USA) 27 LIGO-G1800682 OBSERVING EARLIEST MOMENTS OF FORMA T I O N O F STARS AND STRUCTURE l wq Evan Hall 28 LIGO-G1800682 5 Summary: a Gravitational-wave Astronomical Revolution • Merging binary black hole and neutron star systems have been observed for the first time, producing a wealth of information • Advanced LIGO and Advanced Virgo will be back online in Feb/March 2019 with better sensitivity • Future ground-based GW detectors will be able to see the entire star-forming Stay Tuned… universe LIGO-G1800682 LIGO Scientific Collaboration LIGO-G1800682 Constraining the Neutron Star Equation of State with GW170817 l Gravitational waveforms contain information about NS tidal deformations allows us to constrain NS equations of state (EOS) Ozel and l Tidal deformability parameter: Friere (2016) l GW170817 data consistent with softer EOS more compact NS Low Spin High Spin Abbott, et al. ,LIGO Scientific Collaboration and Virgo Collaboration,