Stephen, Gary, and the first gravita1onal wave detec1ons Bruce Allen Max Planck Ins1tute for Gravita1onal Physics (Albert Einstein Ins1tute, AEI)
MIT Undergraduate 1976-80 DAMTP October 1980 Undergrad thesis, June 1980, CMB experiment 2 Cambridge 4.7.2017
Cambridge 1980-83 3 Cambridge 4.7.2017
Weber GW “detec1on” Phys. Rev. Le9. 22, 1320, 1969 4 Cambridge 4.7.2017
Weber GW “detec1on” Phys. Rev. Le9. 24, 276, 1970 5 Cambridge 4.7.2017
Weber GW “detec1on” The Detec1on of Gravita1onal Waves , by Joseph Weber The existence of such waves is predicted by the theory of rela7vity. Experiments designed to detect them have recorded evidence that they are being emi<ed in bursts from the direc7on of the galac7c center” 6 Cambridge 4.7.2017
DAMTP Silver Street 7 Cambridge 4.7.2017
PRD 4, 2191–2197 (1971) cited 64 Imes: Astone , Billing, Blair , Caves, Dewey, Drever , Hamilton , Hough , Isaacson, Lobo, Michelson, Misner, Pizzella, Press, Ruffini, Sathyaprakash , Saulson , Schutz , Thorne , Trimble, Vinet , Weber, Winkler 8 Cambridge 4.7.2017
• Merger of “collapsed objects” and “neutron stars”. Does not contain the words “black hole” • Correct Ime-scales and energy esImates (msec per solar mass) when objects approach O(Schwarzschild radius) • Concept of matched filtering (not with that name) to “dig into the noise”. x12 be9er sensiIvity • Precision of arrival-Ime determinaIon, use of triangulaIon to determine direcIon to source • Does not menIon orbital behaviour (head-on collision?) • Amusing typos (“Earth orbiIng around the sun radiates 1kW at a frequency of 3 cycles/year.”) 9 Cambridge 4.7.2017
Glasgow, 1971 Ron Drever Jim Hough (L) and Stuart Cherry (R) 10 Cambridge 4.7.2017
PHYSICAL REVIEW LETTERS VOLUME 26, NUMBER 21 24 Mwv 1971 Institute for Atomic Physics, 0 Permanent address: tion from the obsemed 2+-level den- neutron-capture Bucharest, sity at 7. 6-MeV excitation. Rumania. G. C. Kyker, Jr. , E. G. T. H. Kruse, M. E. Williams, J. A. ~See, e. g., G. A. Keyworth, ~N. Williams, Nucl. Phys. 89, 590 (1966). and G. L. Miller, Bilpuch, and H. W. Newson, Fenton, to be published. K. Ozawa, F. Fujimoto, K. Tsukada, and R. H. Lemmer, M. Maruyama, H. Feshbach, A. K. Kerman, and T. Sakurai, K. Komaki, Nucl. Phys. (New York) 41, 280 (1967); R. A. Ferrell M. Mannami, Ann. Phys. A145, 581 (1970). Phys. Rev. Lett. 16, 187 (1966). and W. M. MacDonald, D. W. Mingay, J. P. St~cthe in Nuclear Reactions, W. M. Gibson, M. Maruyama, edited Intermediate F. Sellschop, and R. Van Bree, Bull. by H. P. Kennedy and R. Schrils (University G. M. Temmer, of Kentucky Amer. Phys. Soc. 16, 557 (1971). Press, Ky. , 1968). Lexington, J. D. Moses, thesis, D. W. Mingay, G. M. Temmer, M. Maruyama, Duke University, 1970 (unpub- and R. Van Bree, Bull. Amer. Phys. Soc. M. Petrascu, lished). ~3D. P. Lindstrom, H. W. Newson, E. G. Bilpuch, 16, 182 (1971). and L. H. Goldman, G. E. Mitchell, Phys. Rev. 165, 1203 (1968). to be published. W. Darcey, J. Fenton, T. H. Kruse, J. C. Browne, and M. E. Will- E. G. Bilpuch, H. W. Newson, and G. E. Mitchell, iams, Nucl. Phys. A153, 481 (1970). unpublished. ~5J. D. Mosey, private R. Van Bree, unpublished based computer program communication. in part on B. Teitelman Z. Vager, R. E. Segel, and G. M. Temmer, Phys. Rev. L. Meyer-Schutzmeister, and P. P. Singh, 177, 1656 (1969), Appendix. This program does nof; Nucl. Phys. A108, 180 (1968). G. C. Kyker, Jr. , E. G. Bilpuch, spins and parities, and the fit is ~YJ. A. Farrell, allow for identical and Phys. Lett. 17, 286 (1965). therefore very tentative. H. W. Newson, J. R. Huizenga, J. E. Monahan and A. J. Elwyn, This re- Phys. Rev. Lett. 20, Hawking’s Area Theorem PRL 21, 1344 (1971) communication. private using a slight extrapola- 1119 (1968). the best estimate, presents from Colliding Black Holes Gravitational Radiation S. W. Hawking Institute of Theoretical of Cambridge, Astronomy, University Cambridge, England (Received 11 March 1971) It is shown that there is an upper bound to the energy of the gravitational radiation In the case of two objects with emitted when one collapsed object captures another. m and zero intrinsic bound is (2-W2) m. equal masses this upper angular momenta, Weber' ' has recently on the ef- mea- collapsed objects. Up to now no limits reported coinciding radia- ficiency of the processes of short bursts have been known. surements of gravitational The object of this Letter is to show that there is a tion at a frequency of 1660 Hz. These occur at a limit for the second process. rate of about one per day and the bursts For the case of appear to be coming from the center of the galaxy. It two colliding collapsed objects, each of mass m seems likely'4 and zero angular of ener- that the probability of a burst the amount momentum, between %eber's detectors gy that can be carried causing a coincidence or away by gravitational is less than, . If one allows for this and assumes is less than (2-v 2)m. any other form of radiation that the radiation is broadband, of the Carter-Israel I assume con- one finds that the the validity jucture'' that the metric outside a collapsed ob- radiation must be at energy flux in gravitational day. 4 This would imply a least 10'c erg/cm' ject settles down to that of one of the Kerr family mass loss from the center of the galaxy of about of solutions' with positive mass m and angular It is therefore possible that the 20 000M o/yr. a per unit mass less than or equal to momentum (I am using units in which G=c =1. ) Each of m. mass of the galaxy might have been considerably in the past than it is now. ' event hori- This makes it these solutions contains a nonsingular higher sections of which are topo- to estimate the efficiency with which zon, two-dimensional important with area' rest-mass into gravita- spheres can be converted graphically energy - Clearly nuclear reactions are tional radiation. a) ' ]. 8wm[m+(m since they release only about 1% of insufficient The event horizon is the boundary the rest mass. of the region The efficiency might be higher from which particles or photons of space-time in either the nonspherical gravitational collapse I shall consider and coalescence can escape to infinity. of a star or the collision of two only 1344 11 Cambridge 4.7.2017
Hawking’s Area Theorem PRL 21, 1344 (1971) Non-spinning area A = 4 π r S2 = 16 π m 2 A 1 + A 2 ≤ A 3 Saturate: 2m 2 = M 2 m Efficiency: (2m - M)/2m = M (2 - √ 2)/2 = m 29.3 % of energy + GWs in GWs 12 Cambridge 4.7.2017
New Scien1st, 11.12.1975 13 Cambridge 4.7.2017
Fast-forward 45 years, from 1971 to 2016…
First Detec1on 14 September 2015: Advanced LIGO records merger of a 29 and 36 solar mass BH References: PRL 116, 061102 (2016); PRX 6, 041015 (2016); Ann. Phys. 529, 1600209 (2017); PRL 118, 221101 (2017) 15 Cambridge 4.7.2017
GW150914 • First observing run (O1, science operaIons) start scheduled 18 September 2015 • Event at 09:50 UTC on 14 September 2015, four days before O1 start 16 Cambridge 4.7.2017
AEI Hannover, September 14, 2015 Marco Drago Andrew Lundgren • 11:50 Monday morning in Germany • At 12:54, Marco sent an email to the (02:50 in Hanford, 04:50 in Livingston) collaboraIon, asking for confirmaIon that it’s not a hidden test signal • Event database had ~1000 entries (hardware injecIon) • Marco and Andy checked injecIon • Next hours: flurry of emails, decision flags and logbooks, data quality, made to lock down sites, freeze instrument Qscans of LHO/LLO data. state • Contacted LIGO operators: “everyone’s gone home” 17 Cambridge 4.7.2017
The Chirp -0.5 1 ORBIT 1 ORBIT 1 ORBIT 1 -21 1 ORBIT Strain (10 -21 ) 0 Δ L/L H1 measured strain, bandpassed -1 L1 measured strain, bandpassed 0.2 0.25 0.3 0.35 0.4 0.45 Time (seconds) 18 Cambridge 4.7.2017
Gravita1onal waves from orbi1ng masses m orbital angular frequency ⍵ m r Newton : Gm 2 = m ω 2 � r ⇒ r 3 = 2 Gm � r 2 ω 2 2 = − G 2 / 3 m 5 / 3 � 2 − Gm 2 = − Gm 2 E mechanical = 1 � ω r � 2 +1 � ω r ω 2 / 3 2 m 2 m 2 4 / 3 2 2 r 2 r 5 c 5 m 2 r 4 ω 6 = 2 13 / 3 G 7 / 3 m 10 / 3 � d 3 �� d 3 in GW Luminosity = G = 8 G ω 10 / 3 � dt 3 Q ab dt 3 Q ab 5 c 5 5 c 5 dt E mechanical = G 2 / 3 m 5 / 3 in GW Luminosity = − d 3 · 2 1 / 3 ω − 1 / 3 d ω dt get mass from GW frequency dt = 3 · 2 14 / 3 G 5 / 3 m 5 / 3 d ω ω 11 / 3 frequency and its f = 4 π ⍵ 5 c 5 rate of change! 19 Cambridge 4.7.2017
Masses from the rate of frequency increase 5 � 3 / 5 ( m 1 m 2 ) 3 / 5 ( m 1 + m 2 ) 1 / 5 = c 3 96 π � 8 / 3 f � 11 / 3 ˙ = 30 M ⦿ M = f G 20 Cambridge 4.7.2017
Can only be two black holes! • Chirp mass M ~ 30 M ⦿ => m 1, m 2 ~ 35 M ⦿ => Sum of Schwarzschild radii ≥ 206km -21 • At peak f GW = 150 Hz, orbital frequency = 75 Hz separaIon of Newtonian point masses 346 km 6 km in size (merge • Ordinary stars are 10 4 km (merge at mHz). White dwarfs are 10 at 1 Hz). They are too big to explain data! H1 measured strain, bandpassed • Neutron stars are also not possible: L1 measured strain, bandpassed m 1 = 4 M ⦿ => m 2 =600 M ⦿ 0.3 0.35 0.4 0.45 =>Schwarzschild radius 1800km => too Time (seconds) big! Among known objects, only black holes are heavy enough and small enough! 21 Cambridge 4.7.2017
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