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, “GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral” Phys. Rev. Lett. 161101 (2017)
36 LIGO-G1800682 LIGO-G1800682 LIGO-G1800682 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-G1800682 Kilonovae • ADD A SLIDE ON KILONOVAE
LIGO-G1800682 Brian D. Metzger and Edo Berger, 2012 Astrophysical Parameters of the Detected BBH Mergers
GW150914 GW151226 LVT151012
GW170814
GW170104 41 LIGO-G1800682 Searching for Compact Binary Coalescences
This source: Buried in this noise stream: Binary BH-BH system
Produces this waveform:
We use different methods (in this case h optimal Wiener filtering using matched templates) to pull these signals from the noise: “Chirp” waveform
The problem is that non-astrophysical sources also produces signals (false positives) 42 LIGO-G1800682 Assessing Statistical Significance: Modeled Search
Abbott, et al., LIGO Scientific Collaboration and Virgo Collaboration, “Binary Black Hole Mergers in the first Advanced LIGO Observing Run”, Phys. Rev. X 6, 041015 (2016).
43 LIGO-G1800682 Can a binary black hole merger produce a detectable EM transient? l We don’t expect a stellar-mass binary black hole system to have enough matter around for the final BH to accrete and form a relativistic jet [e.g., Lyutikov, arXiv:1602.07352] — or can it? Various models have been proposed: » Single star: collapse of a very massive, rapidly rotating stellar core, which fissions into a pair of black holes which then merge [Fryer+ 2001; Reisswig+ 2013; Loeb 2016, ApJL 819]; but see Woosley, arXiv:1603.00511v2 for modeling that does not support this idea » Instant BBH: massive star-BH binary triggers collapse of star to BH, then immediate inspiral and merger; final BH can be kicked into circumbinary disk and accrete from it [Janiuk+ 2013, A&A 560; arXiv:1604.07132]
» BBH with fossil disk: activates and accretes long-lived cool disk [Perna+ 2016, ApJL 821] » BBH embedded in AGN disk: binary merger assisted by gas drag and/or 3-body interactions in AGN disk, which provides material to accrete [Bartos+, arXiv:1602.03831; Stone+ 2016, MNRAS] » Third body: tidal disruption of a star in a hierarchical triple with the BBH at time of merger [Seto&Muto 2011, cited in Murase+ 2016, ApJL 822] » Charged BHs: Merging BHs with electric (or magnetic monopole!) charge could produce a detectable EM transient [Zhang 2016, ApJL 827; Liebling&Palenzuela 2016, PRD 84]
» Magnetic reconnection [Fraschetti, arXiv:1603.01950] l Also models for high-energy neutrino and ultra-high energy cosmic ray emission 44 LIGO-G1800682 The Heart of Advanced LIGO:
The Detector Noise Budget O2 Noise Budget Noise O2
Effler alog33552llo LIGO-G1800682 Gravitational Waves
Physically, h is a strain: DL/L 1 G hmn » 4 Imn transverse to the propagation direction of the gravitational wave r c
10M Binary Black Hole System h+ hx worb 8GM R2w 2 h » orb ~10-21 4 M rc R
46 LIGO-G1800682 Advanced LIGO Interferometer
200W , 1064 nmLIGO Test Mass Mirror stabilized laser
Actively Controlled Seismic Isolation
47 LIGO-G1800682 Enabling multi-messenger astronomy with gravitational waves
Interferometers are ‘omni-directional SwiftSwift microphones’!!
Polarization-averaged antenna pattern for an interferometer Limit:
qGW ~lGW / dearth ~ few degrees
LIGO Hanford
t1 Virgo t2 Coherent Detector t3 LIGO Livingston Network
Image: http://earthobservatory.nasa.gov/ Abadie, et al, (LSC & Virgo Collaborations) Astron. Astrophys. 541 (2012) A155. 48 LIGO-G1800682 Virgo LIGO Hanford Observatory Observatory Italy Washington, USA
LIGO Livingston KAGRA Observatory (2019) Observatory Japan Louisiana, USA
LIGO-India (2025)
LIGO Laboratory 49 LIGO-G1800682 Binary Neutron Star Merger Localization: Hanford-Livingston-Virgo
3 site network x denotes blind spots
S. Fairhurst, “Improved source localization with LIGO India”, J. Phys.: Conf. Ser. 484 012007
50 LIGO-G1800682 Binary Neutron Star Merger Localization: Hanford-Livingston-Virgo-India
4 site network
S. Fairhurst, “Improved source localization with LIGO India”, J. Phys.: Conf. Ser. 484 012007
51 LIGO-G1800682 LILIGOGO-G1800682G1702186 Advanced LIGO Front-end Stabilized 200W Laser
• Stabilized in power and frequency – using techniques developed for time references • Uses a Nd:YAG monolithic master oscillator followed by two-stage amplification
• 35W Nd:YVO4 MOPA • 200 W injection-locked Nd:YAG rod ring amplifier
Collaboration w/ MPG Albert Einstein Institute; Laser Zentrum Hannover Compact NeoLase 70W amplifier
53 P. Kwee,et al., Opt. Exp. 20, 10617-10634 (2012). LIGO-G1800682 Squeezing: Reducing Shot Noise
• Electromagnetic fields are H. P. Yuen, Phys. Rev. A13, 2226 (1976) quantized: C. M. Caves, Phys. Rev. D26, 1817 (1982) Wu, Kimble, Hall, Wu, PRL (1986) ˆ ˆ ˆ E = X1 coswt +iX2 sinwt 3.5 dB squeezing • Quantum fluctuations exist in Typical noise without squeezing (1.5X reduced noise) Squeezing-enhanced sensitivity the vacuum state:
Main Laser
Coherent State
Faraday Squeezed Isolator Squeezed Vacuum Vacuum x State 2 Source 2.1 dB squeezing │E │ Photodiode(1.27X reduced noise) x ϕ 1
Aasi, et al., (LIGO Scientific Collaboration), Nature Physics, 7, 962 (2011); Nature Photonics 7 613 (2013).
LIGO-G1800682 54 The Best of Both Worlds: Frequency Dependent Squeezing
Concept:Oelker, et Kimble, al., “Audio Levin,-band Matsko Frequency, Thorne,-dependent Vyatchanin , Phys.Squeezing”, Rev. D Phys. (2001) Rev. Lett. 116, 041102 (2016).
55 LIGO-G1800682 LIGO-G1800682 LIGO-G1800682 Multi-messenger Astronomy with Gravitational-waves and Light: The First Detection of a Binary Neutron Star Merger
58 LIGO-G1800682 Movie Credit: NASA Goddard Space Flight Center 59 LIGO-G1800682 LIGO Funding l 1984 LIGO founded as a Caltech/MIT project l 1990: LIGO Construction Project approved by NSF Hanford, WA l 1992: LIGO Construction Project funded by NSF LIGO Livingston l 1992 --1995: Site selection, vacuum prototyping l 1995 – 1999: LIGO facilities construction at Hanford and Livingston l 1998 – 2002: Installation/integration of initial LIGO interferometers Construction l 2002 - 2005: Interferometer commissioning interleaved with science runs (S1-S4) LIGO Hanford l Nov 4, 2005 – Sept 31, 2007: S5 science run » Design sensitivity reached Initial LIGO LIGO Hanford Observatory » 15 Mpc range; > 1 year of triple coincidence data Livingston, LA l 2007 – 2009: Enhanced LIGO instrument upgrade » Tests key Advanced LIGO technologies l July 7, 2009 – Oct 20, 2010: S6 science run LIGO Laboratory: » 18 Mpc range to merging binary neutron stars l April 2008: Advanced LIGO Construction begins 180 staff located at Caltech, MIT, l Dec 2011 – Advanced LIGO detector installation Hanford, Livingston begins Advanced LIGO l Mar 2015 - Advanced LIGO Construction complete LIGO Scientific Collaboration: l Sept 2015 – First Advanced LIGO Observing Run ‘O1’ ~ 1250 scientists, ~100 institutions, l Sept 14, 2015 – First binary black hole detection 16 countries l Nov 2016 – Advanced LIGO O2 run 60 LIGO-G1800682 Problems with High Laser Power: Parametric Instability
Acoustic mode Optical mode
fm = 15,539 Hz
Theory: V. B. Braginsky, S. E. Strigin, and S. P. Vyatchanin, Phys. Lett. A 305, 111 (2002) Experiment: C. Zhao, L. Ju, J. Degallaix, S. Gras, and D. G. Blair, Phys. Rev. Lett. 94, 121102 (2005); M. Evans, et al., “Observation of Parametric Instability in Advanced LIGO”, Phys. Rev. Lett. 114, 161102 (2015). 61 LIGO-G1800682 Parametric Instabilities (II) mechanical mode power in the arm cavity Q-factor spatial overlap Optical-mechanical mode Parametric Gain:
Mirror Acoustic mode optical mode mass frequency gain
62 LIGO-G1800682 Damping of Parametric Instabilities
End Reaction Mass (X, Y arms) 2) Active Electrostatic Damping of PI modes
1) Passive Thermal Tuning of the Mirror Radii of curvature via Ring Heater
3) Acoustic Mass Dampers
63 LIGO-G1800682 Third Gen Science Targets
The 3G Gravitational Wave Ground-based Network
Credit: B. Sathyaprakash, Dawn III Workshop, 64 LIGO-G1800682 https://wiki.ligo.org/LSC/LIGOworkshop2017/WebHome