GW150914: The Advanced LIGO Detectors in the Era of First Discoveries

B. P. Abbott et al.∗

(LIGO Scientific Collaboration and Virgo Collaboration)(February 12, 2016)

Following a major upgrade, the two advanced detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) held their first observation run between September 2015 and January

2016. With a strain sensitivity of 10−23/√

Hz at 100 Hz, the product of observable volume and mea-surement time exceeded that of all previous runs within the first 16 days of coincident observation.On September 14th, 2015 the Advanced LIGO detectors observed a transient gravitational-wavesignal determined to be the coalescence of two black holes [1], launching the era of gravitational-wave astronomy. The event, GW150914, was observed with a combined signal-to-noise ratio of 24 incoincidence by the two detectors. Here we present the main features of the detectors that enabledthis observation. At full sensitivity, the Advanced LIGO detectors are designed to deliver anotherfactor of three improvement in the signal-to-noise ratio for binary black hole systems similar inmasses to GW150914.

PACS numbers: 04.80.Nn, 95.55.Ym, 95.75.Kk, 07.60.Ly

Introduction — On September 14th, 2015, both Ad-vanced LIGO detectors in the USA, H1 in Hanford,Washington and L1 in Livingston, Lousiana, made thefirst direct measurement of gravitational waves [1]. Theevent, GW150914, was determined to be the mergerof two black holes, with masses of 36M� and 29M�,into a black hole of approximately 62M� [2]. 3.0 so-lar masses of energy (' 5.4 × 1047 J) was radiated ingravitational waves. The gravitational waves from thisevent, which occurred at a distance of ' 410 Mpc '1.3×109 light years, changed the separation between thetest masses by '4×10−18 m, about one 200th of a protonradius.

The Advanced LIGO detectors, multi-kilometerMichelson-based interferometers [3], came online inSeptember 2015, after a major upgrade targeting a factorof 10 sensitivity improvement over initial detectors [4, 5].While not yet at design sensitivity during their first ob-servation run, they have already exceeded the strain sen-sitivity of the initial detectors across the entire frequencyband, significantly surpassing the past discovery poten-tial [6–10]. This paper describes the Advanced LIGOdetectors, as well as their current and final design sensi-tivity, at the inception of gravitational-wave astronomy.

Astrophysical Reach — In general relativity, a gravita-tional wave far from the source can be approximated asa time-dependent perturbation of the space-time metric,expressed as a pair of dimensionless strain polarizations,h+ and h× [12]. An interferometric gravitational-wavedetector acts as a transducer to convert these space-timeperturbations into a measurable signal [13]. The inter-ferometer mirrors act as ‘freely falling’ test masses. Ad-vanced LIGO measures linear differential displacementalong the arms which is proportional to the gravitational-wave strain amplitude. We define the differential dis-placement as ∆L = δLx − δLy, where Lx = Ly = L arethe lengths of two orthogonal interferometer arms. The

gravitational-wave strain and the interferometer displace-ment are related through the simple equation ∆L = hL,where h is a linear combination of h+ and h×.

The tiny displacements induced by astrophysicalevents demand that the interferometer mirrors be freefrom environmental disturbances and require a highlysensitive interferometric transducer—designed to be lim-ited only by disturbances arising from fundamentalphysics consideration. Since the interferometer re-sponse to displacement, or equivalently gravitational-wave strain, is frequency dependent, it is necessary torepresent the limiting detector noises as functions of fre-quency normalized by the interferometer response.

The left panel of Figure 1 shows the amplitude spectraldensity of the total strain noise in units of strain per√

Hz during the first observation run (O1 run) and, forcomparison, during the final science run of the initialLIGO detectors (S6 run). In the detectors’ most sensitivefrequency band between 100 Hz and 300 Hz, the O1 strainnoise is 3 to 4 times lower than achieved in the S6 run.At 50 Hz, the improvement is nearly a factor of 100.

The right panel of Figure 1 shows the single detec-tor signal-to-noise ratio (SNR) for an optimally orientedcompact binary system consisting of two 30M� blackholes as a function of redshift z, and for different in-terferometer configurations. The observed strain ampli-tude is largest for a source whose orbital plane is parallelto the detector’s plane and is located straight above orbelow; we refer to such a source as optimally oriented.The SNR is computed in the frequency domain [14] us-ing standard cosmology [15] and phenomenological wave-forms which account for inspiral, merger and ringdown,but not spins [16].

A Michelson interferometer lacks good directional sen-sitivity to gravitational waves. The antenna pattern cov-ers approximately half the sky, both above and beneaththe plane of the detector. Moreover, the antenna patterns

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FIG. 1. The left plot shows the strain sensitivity during the first observation run (O1) of the Advanced LIGO detectors andduring the last science run (S6) of the initial LIGO detectors. The O1 strain noise curve is shown for H1 (dark red) and L1(light red); the two detectors have similar performance. The Advanced LIGO design sensitivity as well as a possible futureupgrade [11] are shown to highlight the discovery potential in the coming years. The right plot shows the single detectorsignal-to-noise ratio (SNR) under optimal orientation as function of redshift z—for two merging black holes with mass 30M�each. GW150914 was not optimally orientated and was detected with a single detector SNR of 13 to 20 at z = 0.09; this eventwould not have been seen in S6.

of the two LIGO detectors are aligned to maximize thecoincident detection of gravitational-wave signals, con-strained to the 10 ms inter-site propagation time. Thecoincidence constraint substantially rejects non-Gaussiannoise and vetoes local transients.

The observed strain amplitude is inversely propor-tional to the luminosity distance. For small redshifts,z < 1, the observable volume, and thus the detectionrate, grows as the cube of the detector sensitivity. Thenumber of detected events is expected to scale with theproduct of observing volume and observing time. Be-tween September 12 and October 20 the H1 and L1 de-tectors had a duty cycle of 70% and 55%, respectively,while the observing time in coincidence was 48%. Af-ter data quality processing [17], 16 days of data wereanalyzed around GW150914, resulting in a time-volumeproduct of 0.1 Gpc3yr for binary black hole systems withmasses similar to GW150914 [18].

The Displacement Measurement — The current gener-ation of advanced detectors uses two pairs of test massesas coordinate reference points to precisely measure thedistortion of the space-time between them. A pair of in-put and end test masses is located in each of the two armsof a Michelson laser interferometer, as shown in Figure 2.The Advanced LIGO test masses are very pure and ho-mogeneous fused silica mirrors of 34 cm diameter, 20 cmthickness and 40 kg mass.

It is critical that the test masses be free from sources ofdisplacement noise, such as environmental disturbancesfrom seismic noise, or thermally driven motion. Thesenoise sources are most relevant at frequencies below100 Hz, while shot noise of the optical readout is dom-inant at high frequency. Figure 3 shows the measured

displacement noise of Advanced LIGO during the firstobserving run, together with the major individual con-tributions, as discussed below.

To minimize ground vibrations, the test masses aresuspended by multi-stage pendulums [19], thus actingas free masses well above the pendulum resonance fre-quency of 0.4 Hz. Monolithic fused silica fibers [20] areincorporated at the bottom stage to minimize suspensionthermal noise [21], which limits the useful frequencies to10 Hz and above. The Advanced LIGO test masses re-quire about 10 orders of magnitude suppression of groundmotion above 10 Hz. The multi-stage pendulum systemattenuates the ground motion by seven orders of magni-tude. It is mounted on an actively controlled seismic iso-lation platform which provides three orders of magnitudeof isolation of its own [22, 23]. Moreover, these platformsare used to reduce the very large displacements producedby tidal motion and microseismic activity. Tidal forcescan produce displacements up to several 100µm over amulti-kilometer baseline on time scales of hours. Thedominant microseismic activity is driven by ocean waves.The resulting ground motion can be as large as severalµm at frequencies around 0.15 Hz—even far inland.

The entire test mass assembly including the suspensionsystem and part of the seismic isolation system residesinside an ultra-high vacuum system, with pressures typi-cally below 1µPa over the 10, 000 m3 volume, to preventacoustic shorting of the seismic isolation systems and tominimize Rayleigh scattering in the optical readout.

The test masses are also susceptible to changes in thelocal gravitational field caused by changing mass distri-butions in their vicinity. While not limiting presently, atdesign sensitivity this time-dependent Newtonian noise

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FIG. 2. Interferometer configuration and test mass setup.Each arm of the Michelson interferometer includes two sus-pended test masses. The two test masses are placed 4 kmapart and form an optical resonator with a gain of 300. Thesuspension system is shown on the right, each test mass is atthe bottom of a quadruple pendulum. It provides high isola-tion above the resonance frequencies which range from 0.4 Hzto 13 Hz. The test mass is attached to the penultimate massthrough fused silica fibers providing a high mechanical qual-ity factor which lowers the thermal noise. The other stagesuse steel wire. The attachment point to the seismic isolationsystem as well as stages 1 and 2 implement cantilever springsfor vertical isolation. Each test mass is accompanied by itsown reaction chain to minimize actuation noise. Coil actu-ators are mounted to the upper stages of the reaction chainand an electrostatic actuator is implemented at the bottomstage. Shown on the left are the other optics of the Michelsoninterferometer with the beamsplitter and the perpendiculararm. The two optics at the interferometer input and outputport comprise the coupled resonator system which amplifiesthe response of the optical transducer.

source possibly becomes relevant below 20 Hz, and mightrequire active cancellation [24, 25].

Thermally driven motion is another important sourceof displacement noise. It includes the Brownian motion ofthe suspension system [26] as well as the test masses [27],and mechanical loss in the mirror optical coatings [28].The mirror coatings, a dielectric multilayer of silica andtitania-doped tantala [29, 30], were developed to providethe required high reflectivity while minimizing coatingthermal noise [31–33]; it limits the design sensitivity inthe central frequency band [3].

The predicted levels for seismic, thermal and Newto-nian noise sources are summarized in Figure 3 and com-pared to the total measured displacement noise. They arecurrently not limiting the sensitivity due to the presenceof other technical noise sources, as detailed in Ref. [34].

Quantum noise in the interferometer arises from thediscrete nature of photons and their Poisson-distributedarrival rate [35–37]. The momentum transfer of individ-ual photons hitting a test mass gives rise to radiation

pressure noise. Quantum radiation pressure noise scalesas 1/mf2, where m is the mass of the mirror and f thefrequency, and therefore it is most significant at lowerfrequencies.

Photon shot noise arises from statistical fluctuationsin the photon arrival time at the interferometer output,and it is a fundamental limit of the transducer in sensingchanges of the differential arm length. The importance ofshot noise decreases as the inverse square-root of the laserpower circulating in the interferometer arms. During thefirst observing run, Advanced LIGO was operating with100 kW of circulating laser power. The correspondingquantum noise curve, comprising both low frequency ra-diation pressure noise and high frequency shot noise, isshown in Figure 3; it is limiting at frequencies above100 Hz. In the upcoming years, we plan to increase thecirculating laser power up to 750 kW, and thus reducingthe shot noise contribution.

Coincident detection between the two LIGO obser-vatories is used to reject transient environmental dis-turbances. Both observatory sites deploy seismometers,accelerometers, microphones, magnetometers, radio re-ceivers, weather sensors, AC-power line monitors, anda cosmic ray detector for vetoes and characterization ofcouplings [38].Interferometric Transducer — The Advanced LIGO

detector uses a modified Michelson laser interferometer totranslate strain into an optical phase shift [3]. Similar toan electromagnetic receiver, the optimal antenna lengthfor a gravitational-wave detector is a quarter wavelength.For a gravitational wave at 100 Hz this is 750 km. TheAdvanced LIGO interferometer arms are 4 km long andemploy an optical resonator between the input and endtest masses that multiplies the physical length by the ef-fective number of round-trips of the light. However, thephysical length cannot be arbitrarily short, because testmass displacement noises are multiplied by the same fac-tor.

The output port of the Michelson interferometer isheld at an offset from a dark fringe, resulting in a smallamount of light leaving the output port [39]. A differen-tial optical phase shift will then decrease or increase theamount of light, depending which interferometer arm ismomentarily stretched or squeezed by a passing gravita-tional wave. This light signal is measured by a photode-tector, digitized and calibrated [40], before being sent tothe analysis pipelines [41, 42].

The calibration factor that converts detected laser lightpower to mirror displacement is measured by applyinga known force to a test mass [43]. An auxiliary 1047-nm wavelength laser is reflected off the end test massand modulated in intensity to generate a varying force.The response of the optical transducer is measured bysweeping the modulation frequency through the entiredetection band. It is also tracked by a set of fixed fre-quency lines. This way, the calibrated strain readout is

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FIG. 3. The displacement sensitivity of the Advanced LIGOdetector in Hanford during the first observation run O1; theLivingston detector has a similar sensitivity, as shown in Fig-ure 1. The sum of all known noise sources accounts for mostof the observed noise with the exception of the frequency bandbetween 20 Hz and 100 Hz. This will be the focus of futurecommissioning to full sensitivity. The quantum noise includesboth shot noise and radiation pressure noise. Thermal noiseincludes terms due to the suspensions, the test masses andthe coatings. Seismic noise is the ground displacement atten-uated through the seismic isolation system and the suspen-sions. Cross couplings from the auto-alignment system andfrom the auxiliary lengths are combined into the trace labelled“other DOF” (degrees-of-freedom). Newtonian gravitationalnoise is estimated from density perturbations due to surfaceground motion. The strong line features are due to the violinmodes of the suspension wires, the roll and bounce modes ofthe suspensions, the AC power line and its harmonics, andthe calibration lines. Not shown are numerous noise sourcesthat don’t contribute significantly—such as laser frequency,intensity and beam jitter noise, sensor and actuation noise,and Rayleigh scattering by the residual gas [34].

computed in real-time with less than 10% uncertainty inamplitude. The overall variability of the detector’s sen-sitivity was about ±10%.

The main light source is a pre-stabilized 1064-nm wave-length Nd:YAG laser. It is followed by a high power am-plifier stage, capable of generating a maximum outputpower of 180 W [44]. During the first observation run,only 20 W were injected into the interferometer. A tri-angular optical resonator of 32.9 m round-trip length isplaced between the laser source and the interferometer toreject higher order transverse optical modes and to stabi-lize the laser frequency further [45]. At the output port,a bow-tie optical resonator of 1.3 m round-trip length isused to reject unwanted frequency components on thelight. Optical curvature mismatch of the interferometermirrors is caused by manufacturing imperfections and bythermal lensing due to heating from the main laser beam.A thermal compensation system provides active correc-tion by means of ring heaters arranged around the testmasses and a set of CO2 lasers for central heating [46].

The Advanced LIGO detector uses coupled optical res-onators to maximize the sensitivity of the interferometrictransducer. These optical resonators enhance the lightpower circulating in each arm while simultaneously opti-mizing the effective antenna length and the gravitational-wave signal bandwidth [47–51]. As the interferometer isheld near a dark fringe, most of the light is reflectedback to the laser source. Adding a partially transmissivemirror at the interferometer input forms an optical res-onator, leading to a power gain of 35 to 40 at the beam-splitter. The optical resonator in the interferometer armsenhances the circulating power by another factor of 300.Thus, 20 W of laser power entering the interferometerresults in nearly 100 kW circulating in each arm. A par-tially reflective mirror is also placed at the output port toenhance the signal extraction and to increase the detec-tor bandwidth. The resulting differential pole frequencyor detector bandwidth is ' 335 Hz (H1) and ' 390 Hz(L1) [34].

All of these coupled optical resonators require servocontrols to be brought and held on resonance [52]. Thelengths of the optical resonators in the interferometerarms are stabilized to less than 100 fm, whereas thelengths of the other coupled resonators are kept within1 to 10 pm [34]. Similarly, the interferometer test massesare aligned within tens of nanoradians relative to the op-tical axis for optimal performance. The noise arising fromsensing and control of these extra degrees-of-freedom arecombined together in the curve labeled “other DOF”in Figure 3. The Pound-Drever-Hall reflection lock-ing technique is used to sense the auxiliary longitudi-nal degrees-of-freedom [53, 54], while an interferometricwavefront sensing scheme is deployed for the alignmentsystem [55, 56]. Digital servo systems are used to feedcontrol signals back to actuators which steer the rela-tive longitudinal positions and orientations of the inter-ferometer mirrors. To prevent reintroducing ground mo-tion onto the test masses, electrostatic actuators [57] aremounted to a second quadruple pendulum known as thereaction chain. Only test masses use reaction chains; allother interferometer mirrors use coil actuators mountedon a rigid structure surrounding the suspensions.

Servo controls are also necessary for damping theplethora of normal modes of the pendular suspensionsand for stabilizing the seismic isolation system to an in-ertial reference frame. Moreover, at high laser power,optical springs introduce angular instabilities due to pho-ton radiation pressure-induced torques acting on the mir-rors [58, 59], while the mirror acoustic modes introduceparametric instabilities [60, 61]. At the current laserpower only one acoustic mode is unstable which can betuned away by the ring heaters. Together with thermalheating, angular optical springs and multiple paramet-ric instabilities are the main challenges that need to beovercome to increase the circulating laser power; bothwill require active damping for stable operations.

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Overall, more than 300 digital control loops with band-widths spanning from sub-Hz to hundreds of kHz areemployed to keep each Advanced LIGO interferometeroperating optimally during observation. The digital con-trols computers also serve as the data acquisition systemthat continuously writes on the order of 105 channels oftime series data to disk, at a rate of ' 12 MB/s. It issynchronized to GPS to better than 10µs [40]. A state-based automation controller provides hands-free runningduring operations.

Outlook — The global gravitational-wave network willbe significantly enhanced in the upcoming years. In2016 Advanced LIGO will be joined by Advanced Virgo,the 3 km detector located near Pisa, Italy [62]. TheJapanese KAGRA interferometer [63] and a possiblethird LIGO detector in India [64] will provide a globalnetwork that allows for improved parameter estimationand sky localization [65]. Achieving design sensitivitywith the network of current detectors will define earth-bound gravitational-wave astrophysics in the near future.Looking further ahead, we can envision current technolo-gies leading to a factor of two improvement over theAdvanced LIGO design sensitivity [11], so that eventssuch as GW150914 could be detected with SNRs up to200. More dramatic improvements will require significanttechnology development and new facilities.

Acknowledgement — The authors gratefully acknowl-edge the support of the United States National ScienceFoundation (NSF) for the construction and operation ofthe LIGO Laboratory and Advanced LIGO as well asthe Science and Technology Facilities Council (STFC)of the United Kingdom, the Max-Planck-Society (MPS),and the State of Niedersachsen/Germany for support ofthe construction of Advanced LIGO and constructionand operation of the GEO600 detector. Additional sup-port for Advanced LIGO was provided by the AustralianResearch Council. The authors gratefully acknowledgethe Italian Istituto Nazionale di Fisica Nucleare (INFN),the French Centre National de la Recherche Scientifique(CNRS) and the Foundation for Fundamental Researchon Matter supported by the Netherlands Organisationfor Scientific Research, for the construction and opera-tion of the Virgo detector and the creation and supportof the EGO consortium. The authors also gratefully ac-knowledge research support from these agencies as wellas by the Council of Scientific and Industrial Researchof India, Department of Science and Technology, India,Science & Engineering Research Board (SERB), India,Ministry of Human Resource Development, India, theSpanish Ministerio de Economıa y Competitividad, theConselleria d’Economia i Competitivitat and Conselleriad’Educacio, Cultura i Universitats of the Govern de lesIlles Balears, the National Science Centre of Poland, theEuropean Commission, the Royal Society, the ScottishFunding Council, the Scottish Universities Physics Al-liance, the Hungarian Scientific Research Fund (OTKA),

the Lyon Institute of Origins (LIO), the National Re-search Foundation of Korea, Industry Canada and theProvince of Ontario through the Ministry of EconomicDevelopment and Innovation, the Natural Science andEngineering Research Council Canada, Canadian Insti-tute for Advanced Research, the Brazilian Ministry ofScience, Technology, and Innovation, Russian Founda-tion for Basic Research, the Leverhulme Trust, the Re-search Corporation, Ministry of Science and Technology(MOST), Taiwan and the Kavli Foundation. The au-thors gratefully acknowledge the support of the NSF,STFC, MPS, INFN, CNRS and the State of Niedersach-sen/Germany for provision of computational resources.

This document has been assigned the LIGO Labora-tory document number LIGO-P1500237.

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Authors

B. P. Abbott,1 R. Abbott,1 T. D. Abbott,2 M. R. Abernathy,1 F. Acernese,3,4 K. Ackley,5 C. Adams,6 T. Adams,7

P. Addesso,3 R. X. Adhikari,1 V. B. Adya,8 C. Affeldt,8 M. Agathos,9 K. Agatsuma,9 N. Aggarwal,10

O. D. Aguiar,11 L. Aiello,12,13 A. Ain,14 P. Ajith,15 B. Allen,8,16,17 A. Allocca,18,19 P. A. Altin,20 S. B. Anderson,1

W. G. Anderson,16 K. Arai,1 M. C. Araya,1 C. C. Arceneaux,21 J. S. Areeda,22 N. Arnaud,23 K. G. Arun,24

S. Ascenzi,25,13 G. Ashton,26 M. Ast,27 S. M. Aston,6 P. Astone,28 P. Aufmuth,8 C. Aulbert,8 S. Babak,29

P. Bacon,30 M. K. M. Bader,9 P. T. Baker,31 F. Baldaccini,32,33 G. Ballardin,34 S. W. Ballmer,35 J. C. Barayoga,1

S. E. Barclay,36 B. C. Barish,1 D. Barker,37 F. Barone,3,4 B. Barr,36 L. Barsotti,10 M. Barsuglia,30 D. Barta,38

J. Bartlett,37 I. Bartos,39 R. Bassiri,40 A. Basti,18,19 J. C. Batch,37 C. Baune,8 V. Bavigadda,34 M. Bazzan,41,42

B. Behnke,29 M. Bejger,43 C. Belczynski,44 A. S. Bell,36 C. J. Bell,36 B. K. Berger,1 J. Bergman,37 G. Bergmann,8

C. P. L. Berry,45 D. Bersanetti,46,47 A. Bertolini,9 J. Betzwieser,6 S. Bhagwat,35 R. Bhandare,48 I. A. Bilenko,49

G. Billingsley,1 J. Birch,6 R. Birney,50 S. Biscans,10 A. Bisht,8,17 M. Bitossi,34 C. Biwer,35 M. A. Bizouard,23

J. K. Blackburn,1 C. D. Blair,51 D. G. Blair,51 R. M. Blair,37 S. Bloemen,52 O. Bock,8 T. P. Bodiya,10 M. Boer,53

G. Bogaert,53 C. Bogan,8 A. Bohe,29 P. Bojtos,54 C. Bond,45 F. Bondu,55 R. Bonnand,7 B. A. Boom,9 R. Bork,1

V. Boschi,18,19 S. Bose,56,14 Y. Bouffanais,30 A. Bozzi,34 C. Bradaschia,19 P. R. Brady,16 V. B. Braginsky,49

M. Branchesi,57,58 J. E. Brau,59 T. Briant,60 A. Brillet,53 M. Brinkmann,8 V. Brisson,23 P. Brockill,16

A. F. Brooks,1 D. A. Brown,35 D. D. Brown,45 N. M. Brown,10 C. C. Buchanan,2 A. Buikema,10 T. Bulik,44

H. J. Bulten,61,9 A. Buonanno,29,62 D. Buskulic,7 C. Buy,30 R. L. Byer,40 L. Cadonati,63 G. Cagnoli,64,65

C. Cahillane,1 J. Calderon Bustillo,66,63 T. Callister,1 E. Calloni,67,4 J. B. Camp,68 K. C. Cannon,69 J. Cao,70

C. D. Capano,8 E. Capocasa,30 F. Carbognani,34 S. Caride,71 J. Casanueva Diaz,23 C. Casentini,25,13 S. Caudill,16

M. Cavaglia,21 F. Cavalier,23 R. Cavalieri,34 G. Cella,19 C. B. Cepeda,1 L. Cerboni Baiardi,57,58 G. Cerretani,18,19

E. Cesarini,25,13 R. Chakraborty,1 T. Chalermsongsak,1 S. J. Chamberlin,72 M. Chan,36 S. Chao,73 P. Charlton,74

E. Chassande-Mottin,30 H. Y. Chen,75 Y. Chen,76 C. Cheng,73 A. Chincarini,47 A. Chiummo,34 H. S. Cho,77

M. Cho,62 J. H. Chow,20 N. Christensen,78 Q. Chu,51 S. Chua,60 S. Chung,51 G. Ciani,5 F. Clara,37 J. A. Clark,63

F. Cleva,53 E. Coccia,25,12,13 P.-F. Cohadon,60 A. Colla,79,28 C. G. Collette,80 L. Cominsky,81 M. Constancio Jr.,11

A. Conte,79,28 L. Conti,42 D. Cook,37 T. R. Corbitt,2 N. Cornish,31 A. Corsi,71 S. Cortese,34 C. A. Costa,11

M. W. Coughlin,78 S. B. Coughlin,82 J.-P. Coulon,53 S. T. Countryman,39 P. Couvares,1 E. E. Cowan,63

D. M. Coward,51 M. J. Cowart,6 D. C. Coyne,1 R. Coyne,71 K. Craig,36 J. D. E. Creighton,16 J. Cripe,2

S. G. Crowder,83 A. Cumming,36 L. Cunningham,36 E. Cuoco,34 T. Dal Canton,8 S. L. Danilishin,36 S. D’Antonio,13

K. Danzmann,17,8 N. S. Darman,84 V. Dattilo,34 I. Dave,48 H. P. Daveloza,85 M. Davier,23 G. S. Davies,36

E. J. Daw,86 R. Day,34 D. DeBra,40 G. Debreczeni,38 J. Degallaix,65 M. De Laurentis,67,4 S. Deleglise,60

W. Del Pozzo,45 T. Denker,8,17 T. Dent,8 H. Dereli,53 V. Dergachev,1 R. T. DeRosa,6 R. De Rosa,67,4 R. DeSalvo,87

S. Dhurandhar,14 M. C. Dıaz,85 L. Di Fiore,4 M. Di Giovanni,79,28 A. Di Lieto,18,19 S. Di Pace,79,28 I. Di Palma,29,8

A. Di Virgilio,19 G. Dojcinoski,88 V. Dolique,65 F. Donovan,10 K. L. Dooley,21 S. Doravari,6,8 R. Douglas,36

T. P. Downes,16 M. Drago,8,89,90 R. W. P. Drever,1 J. C. Driggers,37 Z. Du,70 M. Ducrot,7 S. E. Dwyer,37

T. B. Edo,86 M. C. Edwards,78 A. Effler,6 H.-B. Eggenstein,8 P. Ehrens,1 J. Eichholz,5 S. S. Eikenberry,5

W. Engels,76 R. C. Essick,10 T. Etzel,1 M. Evans,10 T. M. Evans,6 R. Everett,72 M. Factourovich,39

V. Fafone,25,13,12 H. Fair,35 S. Fairhurst,91 X. Fan,70 Q. Fang,51 S. Farinon,47 B. Farr,75 W. M. Farr,45 M. Favata,88

M. Fays,91 H. Fehrmann,8 M. M. Fejer,40 I. Ferrante,18,19 E. C. Ferreira,11 F. Ferrini,34 F. Fidecaro,18,19 I. Fiori,34

D. Fiorucci,30 R. P. Fisher,35 R. Flaminio,65,92 M. Fletcher,36 J.-D. Fournier,53 S. Franco,23 S. Frasca,79,28

F. Frasconi,19 Z. Frei,54 A. Freise,45 R. Frey,59 V. Frey,23 T. T. Fricke,8 P. Fritschel,10 V. V. Frolov,6 P. Fulda,5

M. Fyffe,6 H. A. G. Gabbard,21 J. R. Gair,93 L. Gammaitoni,32,33 S. G. Gaonkar,14 F. Garufi,67,4 A. Gatto,30

G. Gaur,94,95 N. Gehrels,68 G. Gemme,47 B. Gendre,53 E. Genin,34 A. Gennai,19 J. George,48 L. Gergely,96

V. Germain,7 Archisman Ghosh,15 S. Ghosh,52,9 J. A. Giaime,2,6 K. D. Giardina,6 A. Giazotto,19 K. Gill,97

A. Glaefke,36 E. Goetz,98 R. Goetz,5 L. Gondan,54 G. Gonzalez,2 J. M. Gonzalez Castro,18,19 A. Gopakumar,99

N. A. Gordon,36 M. L. Gorodetsky,49 S. E. Gossan,1 M. Gosselin,34 R. Gouaty,7 C. Graef,36 P. B. Graff,62

M. Granata,65 A. Grant,36 S. Gras,10 C. Gray,37 G. Greco,57,58 A. C. Green,45 P. Groot,52 H. Grote,8

S. Grunewald,29 G. M. Guidi,57,58 X. Guo,70 A. Gupta,14 M. K. Gupta,95 K. E. Gushwa,1 E. K. Gustafson,1

R. Gustafson,98 J. J. Hacker,22 B. R. Hall,56 E. D. Hall,1 G. Hammond,36 M. Haney,99 M. M. Hanke,8 J. Hanks,37

C. Hanna,72 M. D. Hannam,91 J. Hanson,6 T. Hardwick,2 J. Harms,57,58 G. M. Harry,100 I. W. Harry,29

M. J. Hart,36 M. T. Hartman,5 C.-J. Haster,45 K. Haughian,36 A. Heidmann,60 M. C. Heintze,5,6 H. Heitmann,53

9

P. Hello,23 G. Hemming,34 M. Hendry,36 I. S. Heng,36 J. Hennig,36 A. W. Heptonstall,1 M. Heurs,8,17 S. Hild,36

D. Hoak,101 K. A. Hodge,1 D. Hofman,65 S. E. Hollitt,102 K. Holt,6 D. E. Holz,75 P. Hopkins,91 D. J. Hosken,102

J. Hough,36 E. A. Houston,36 E. J. Howell,51 Y. M. Hu,36 S. Huang,73 E. A. Huerta,103,82 D. Huet,23 B. Hughey,97

S. Husa,66 S. H. Huttner,36 T. Huynh-Dinh,6 A. Idrisy,72 N. Indik,8 D. R. Ingram,37 R. Inta,71 H. N. Isa,36

J.-M. Isac,60 M. Isi,1 G. Islas,22 T. Isogai,10 B. R. Iyer,15 K. Izumi,37 T. Jacqmin,60 H. Jang,77 K. Jani,63

P. Jaranowski,104 S. Jawahar,105 F. Jimenez-Forteza,66 W. W. Johnson,2 D. I. Jones,26 R. Jones,36 R. J. G. Jonker,9

L. Ju,51 Haris K,106 C. V. Kalaghatgi,24,91 V. Kalogera,82 S. Kandhasamy,21 G. Kang,77 J. B. Kanner,1 S. Karki,59

M. Kasprzack,2,23,34 E. Katsavounidis,10 W. Katzman,6 S. Kaufer,17 T. Kaur,51 K. Kawabe,37 F. Kawazoe,8,17

F. Kefelian,53 M. S. Kehl,69 D. Keitel,8,66 D. B. Kelley,35 W. Kells,1 R. Kennedy,86 J. S. Key,85 A. Khalaidovski,8

F. Y. Khalili,49 I. Khan,12 S. Khan,91 Z. Khan,95 E. A. Khazanov,107 N. Kijbunchoo,37 C. Kim,77 J. Kim,108

K. Kim,109 Nam-Gyu Kim,77 Namjun Kim,40 Y.-M. Kim,108 E. J. King,102 P. J. King,37 D. L. Kinzel,6

J. S. Kissel,37 L. Kleybolte,27 S. Klimenko,5 S. M. Koehlenbeck,8 K. Kokeyama,2 S. Koley,9 V. Kondrashov,1

A. Kontos,10 M. Korobko,27 W. Z. Korth,1 I. Kowalska,44 D. B. Kozak,1 V. Kringel,8 A. Krolak,110,111

C. Krueger,17 G. Kuehn,8 P. Kumar,69 L. Kuo,73 A. Kutynia,110 B. D. Lackey,35 M. Landry,37 J. Lange,112

B. Lantz,40 P. D. Lasky,113 A. Lazzarini,1 C. Lazzaro,63,42 P. Leaci,29,79,28 S. Leavey,36 E. O. Lebigot,30,70

C. H. Lee,108 H. K. Lee,109 H. M. Lee,114 K. Lee,36 A. Lenon,35 M. Leonardi,89,90 J. R. Leong,8 N. Leroy,23

N. Letendre,7 Y. Levin,113 B. M. Levine,37 T. G. F. Li,1 A. Libson,10 T. B. Littenberg,115 N. A. Lockerbie,105

J. Logue,36 A. L. Lombardi,101 J. E. Lord,35 M. Lorenzini,12,13 V. Loriette,116 M. Lormand,6 G. Losurdo,58

J. D. Lough,8,17 H. Luck,17,8 A. P. Lundgren,8 J. Luo,78 R. Lynch,10 Y. Ma,51 T. MacDonald,40 B. Machenschalk,8

M. MacInnis,10 D. M. Macleod,2 F. Magana-Sandoval,35 R. M. Magee,56 M. Mageswaran,1 E. Majorana,28

I. Maksimovic,116 V. Malvezzi,25,13 N. Man,53 I. Mandel,45 V. Mandic,83 V. Mangano,36 G. L. Mansell,20

M. Manske,16 M. Mantovani,34 F. Marchesoni,117,33 F. Marion,7 S. Marka,39 Z. Marka,39 A. S. Markosyan,40

E. Maros,1 F. Martelli,57,58 L. Martellini,53 I. W. Martin,36 R. M. Martin,5 D. V. Martynov,1 J. N. Marx,1

K. Mason,10 A. Masserot,7 T. J. Massinger,35 M. Masso-Reid,36 F. Matichard,10 L. Matone,39 N. Mavalvala,10

N. Mazumder,56 G. Mazzolo,8 R. McCarthy,37 D. E. McClelland,20 S. McCormick,6 S. C. McGuire,118 G. McIntyre,1

J. McIver,1 D. J. McManus,20 S. T. McWilliams,103 D. Meacher,72 G. D. Meadors,29,8 J. Meidam,9 A. Melatos,84

G. Mendell,37 D. Mendoza-Gandara,8 R. A. Mercer,16 E. Merilh,37 M. Merzougui,53 S. Meshkov,1 C. Messenger,36

C. Messick,72 P. M. Meyers,83 F. Mezzani,28,79 H. Miao,45 C. Michel,65 H. Middleton,45 E. E. Mikhailov,119

L. Milano,67,4 J. Miller,10 M. Millhouse,31 Y. Minenkov,13 J. Ming,29,8 S. Mirshekari,120 C. Mishra,15 S. Mitra,14

V. P. Mitrofanov,49 G. Mitselmakher,5 R. Mittleman,10 A. Moggi,19 M. Mohan,34 S. R. P. Mohapatra,10

M. Montani,57,58 B. C. Moore,88 C. J. Moore,121 D. Moraru,37 G. Moreno,37 S. R. Morriss,85 K. Mossavi,8

B. Mours,7 C. M. Mow-Lowry,45 C. L. Mueller,5 G. Mueller,5 A. W. Muir,91 Arunava Mukherjee,15 D. Mukherjee,16

S. Mukherjee,85 N. Mukund,14 A. Mullavey,6 J. Munch,102 D. J. Murphy,39 P. G. Murray,36 A. Mytidis,5

I. Nardecchia,25,13 L. Naticchioni,79,28 R. K. Nayak,122 V. Necula,5 K. Nedkova,101 G. Nelemans,52,9 M. Neri,46,47

A. Neunzert,98 G. Newton,36 T. T. Nguyen,20 A. B. Nielsen,8 S. Nissanke,52,9 A. Nitz,8 F. Nocera,34 D. Nolting,6

M. E. Normandin,85 L. K. Nuttall,35 J. Oberling,37 E. Ochsner,16 J. O’Dell,123 E. Oelker,10 G. H. Ogin,124

J. J. Oh,125 S. H. Oh,125 F. Ohme,91 M. Oliver,66 P. Oppermann,8 Richard J. Oram,6 B. O’Reilly,6

R. O’Shaughnessy,112 C. D. Ott,76 D. J. Ottaway,102 R. S. Ottens,5 H. Overmier,6 B. J. Owen,71 A. Pai,106

S. A. Pai,48 J. R. Palamos,59 O. Palashov,107 C. Palomba,28 A. Pal-Singh,27 H. Pan,73 C. Pankow,82 F. Pannarale,91

B. C. Pant,48 F. Paoletti,34,19 A. Paoli,34 M. A. Papa,29,16,8 H. R. Paris,40 W. Parker,6 D. Pascucci,36

A. Pasqualetti,34 R. Passaquieti,18,19 D. Passuello,19 B. Patricelli,18,19 Z. Patrick,40 B. L. Pearlstone,36 M. Pedraza,1

R. Pedurand,65 L. Pekowsky,35 A. Pele,6 S. Penn,126 A. Perreca,1 M. Phelps,36 O. Piccinni,79,28 M. Pichot,53

F. Piergiovanni,57,58 V. Pierro,87 G. Pillant,34 L. Pinard,65 I. M. Pinto,87 M. Pitkin,36 R. Poggiani,18,19

P. Popolizio,34 A. Post,8 J. Powell,36 J. Prasad,14 V. Predoi,91 S. S. Premachandra,113 T. Prestegard,83 L. R. Price,1

M. Prijatelj,34 M. Principe,87 S. Privitera,29 G. A. Prodi,89,90 L. Prokhorov,49 O. Puncken,8 M. Punturo,33

P. Puppo,28 M. Purrer,29 H. Qi,16 J. Qin,51 V. Quetschke,85 E. A. Quintero,1 R. Quitzow-James,59 F. J. Raab,37

D. S. Rabeling,20 H. Radkins,37 P. Raffai,54 S. Raja,48 M. Rakhmanov,85 P. Rapagnani,79,28 V. Raymond,29

M. Razzano,18,19 V. Re,25 J. Read,22 C. M. Reed,37 T. Regimbau,53 L. Rei,47 S. Reid,50 D. H. Reitze,1,5 H. Rew,119

S. D. Reyes,35 F. Ricci,79,28 K. Riles,98 N. A. Robertson,1,36 R. Robie,36 F. Robinet,23 A. Rocchi,13 L. Rolland,7

J. G. Rollins,1 V. J. Roma,59 R. Romano,3,4 G. Romanov,119 J. H. Romie,6 D. Rosinska,127,43 S. Rowan,36

A. Rudiger,8 P. Ruggi,34 K. Ryan,37 S. Sachdev,1 T. Sadecki,37 L. Sadeghian,16 L. Salconi,34 M. Saleem,106

10

F. Salemi,8 A. Samajdar,122 L. Sammut,84,113 E. J. Sanchez,1 V. Sandberg,37 B. Sandeen,82 J. R. Sanders,98,35

B. Sassolas,65 B. S. Sathyaprakash,91 P. R. Saulson,35 O. Sauter,98 R. L. Savage,37 A. Sawadsky,17 P. Schale,59

R. Schilling†,8 J. Schmidt,8 P. Schmidt,1,76 R. Schnabel,27 R. M. S. Schofield,59 A. Schonbeck,27 E. Schreiber,8

D. Schuette,8,17 B. F. Schutz,91,29 J. Scott,36 S. M. Scott,20 D. Sellers,6 A. S. Sengupta,94 D. Sentenac,34

V. Sequino,25,13 A. Sergeev,107 G. Serna,22 Y. Setyawati,52,9 A. Sevigny,37 D. A. Shaddock,20 S. Shah,52,9

M. S. Shahriar,82 M. Shaltev,8 Z. Shao,1 B. Shapiro,40 P. Shawhan,62 A. Sheperd,16 D. H. Shoemaker,10

D. M. Shoemaker,63 K. Siellez,53,63 X. Siemens,16 D. Sigg,37 A. D. Silva,11 D. Simakov,8 A. Singer,1

L. P. Singer,68 A. Singh,29,8 R. Singh,2 A. Singhal,12 A. M. Sintes,66 B. J. J. Slagmolen,20 J. R. Smith,22

N. D. Smith,1 R. J. E. Smith,1 E. J. Son,125 B. Sorazu,36 F. Sorrentino,47 T. Souradeep,14 A. K. Srivastava,95

A. Staley,39 M. Steinke,8 J. Steinlechner,36 S. Steinlechner,36 D. Steinmeyer,8,17 B. C. Stephens,16 R. Stone,85

K. A. Strain,36 N. Straniero,65 G. Stratta,57,58 N. A. Strauss,78 S. Strigin,49 R. Sturani,120 A. L. Stuver,6

T. Z. Summerscales,128 L. Sun,84 P. J. Sutton,91 B. L. Swinkels,34 M. J. Szczepanczyk,97 M. Tacca,30

D. Talukder,59 D. B. Tanner,5 M. Tapai,96 S. P. Tarabrin,8 A. Taracchini,29 R. Taylor,1 T. Theeg,8

M. P. Thirugnanasambandam,1 E. G. Thomas,45 M. Thomas,6 P. Thomas,37 K. A. Thorne,6 K. S. Thorne,76

E. Thrane,113 S. Tiwari,12 V. Tiwari,91 K. V. Tokmakov,105 C. Tomlinson,86 M. Tonelli,18,19 C. V. Torres‡,85

C. I. Torrie,1 D. Toyra,45 F. Travasso,32,33 G. Traylor,6 D. Trifiro,21 M. C. Tringali,89,90 L. Trozzo,129,19

M. Tse,10 M. Turconi,53 D. Tuyenbayev,85 D. Ugolini,130 C. S. Unnikrishnan,99 A. L. Urban,16 S. A. Usman,35

H. Vahlbruch,17 G. Vajente,1 G. Valdes,85 N. van Bakel,9 M. van Beuzekom,9 J. F. J. van den Brand,61,9

C. Van Den Broeck,9 D. C. Vander-Hyde,35,22 L. van der Schaaf,9 J. V. van Heijningen,9 A. A. van Veggel,36

M. Vardaro,41,42 S. Vass,1 M. Vasuth,38 R. Vaulin,10 A. Vecchio,45 G. Vedovato,42 J. Veitch,45 P. J. Veitch,102

K. Venkateswara,131 D. Verkindt,7 F. Vetrano,57,58 A. Vicere,57,58 S. Vinciguerra,45 D. J. Vine,50 J.-Y. Vinet,53

S. Vitale,10 T. Vo,35 H. Vocca,32,33 C. Vorvick,37 D. Voss,5 W. D. Vousden,45 S. P. Vyatchanin,49

A. R. Wade,20 L. E. Wade,132 M. Wade,132 M. Walker,2 L. Wallace,1 S. Walsh,16,8,29 G. Wang,12 H. Wang,45

M. Wang,45 X. Wang,70 Y. Wang,51 R. L. Ward,20 J. Warner,37 M. Was,7 B. Weaver,37 L.-W. Wei,53

M. Weinert,8 A. J. Weinstein,1 R. Weiss,10 T. Welborn,6 L. Wen,51 P. Weßels,8 T. Westphal,8 K. Wette,8

J. T. Whelan,112,8 S. E. Whitcomb,1 D. J. White,86 B. F. Whiting,5 R. D. Williams,1 A. R. Williamson,91

J. L. Willis,133 B. Willke,17,8 M. H. Wimmer,8,17 W. Winkler,8 C. C. Wipf,1 H. Wittel,8,17 G. Woan,36 J. Worden,37

J. L. Wright,36 G. Wu,6 J. Yablon,82 W. Yam,10 H. Yamamoto,1 C. C. Yancey,62 M. J. Yap,20 H. Yu,10 M. Yvert,7

A. Zadrozny,110 L. Zangrando,42 M. Zanolin,97 J.-P. Zendri,42 M. Zevin,82 F. Zhang,10 L. Zhang,1 M. Zhang,119

Y. Zhang,112 C. Zhao,51 M. Zhou,82 Z. Zhou,82 X. J. Zhu,51 M. E. Zucker,1,10 S. E. Zuraw,101 and J. Zweizig1

(LIGO Scientific Collaboration and Virgo Collaboration)

†Deceased, May 2015. ‡Deceased, March 2015.1LIGO, California Institute of Technology, Pasadena, CA 91125, USA

2Louisiana State University, Baton Rouge, LA 70803, USA3Universita di Salerno, Fisciano, I-84084 Salerno, Italy

4INFN, Sezione di Napoli, Complesso Universitario di Monte S.Angelo, I-80126 Napoli, Italy5University of Florida, Gainesville, FL 32611, USA

6LIGO Livingston Observatory, Livingston, LA 70754, USA7Laboratoire d’Annecy-le-Vieux de Physique des Particules (LAPP),

Universite Savoie Mont Blanc, CNRS/IN2P3, F-74941 Annecy-le-Vieux, France8Albert-Einstein-Institut, Max-Planck-Institut fur Gravitationsphysik, D-30167 Hannover, Germany

9Nikhef, Science Park, 1098 XG Amsterdam, Netherlands10LIGO, Massachusetts Institute of Technology, Cambridge, MA 02139, USA

11Instituto Nacional de Pesquisas Espaciais, 12227-010 Sao Jose dos Campos, Sao Paulo, Brazil12INFN, Gran Sasso Science Institute, I-67100 L’Aquila, Italy13INFN, Sezione di Roma Tor Vergata, I-00133 Roma, Italy

14Inter-University Centre for Astronomy and Astrophysics, Pune 411007, India15International Centre for Theoretical Sciences, Tata Institute of Fundamental Research, Bangalore 560012, India

16University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA17Leibniz Universitat Hannover, D-30167 Hannover, Germany

18Universita di Pisa, I-56127 Pisa, Italy19INFN, Sezione di Pisa, I-56127 Pisa, Italy

20Australian National University, Canberra, Australian Capital Territory 0200, Australia21The University of Mississippi, University, MS 38677, USA

22California State University Fullerton, Fullerton, CA 92831, USA

11

23LAL, Universite Paris-Sud, CNRS/IN2P3, Universite Paris-Saclay, 91400 Orsay, France24Chennai Mathematical Institute, Chennai 603103, India25Universita di Roma Tor Vergata, I-00133 Roma, Italy

26University of Southampton, Southampton SO17 1BJ, United Kingdom27Universitat Hamburg, D-22761 Hamburg, Germany

28INFN, Sezione di Roma, I-00185 Roma, Italy29Albert-Einstein-Institut, Max-Planck-Institut fur Gravitationsphysik, D-14476 Potsdam-Golm, Germany

30APC, AstroParticule et Cosmologie, Universite Paris Diderot,CNRS/IN2P3, CEA/Irfu, Observatoire de Paris,

Sorbonne Paris Cite, F-75205 Paris Cedex 13, France31Montana State University, Bozeman, MT 59717, USA

32Universita di Perugia, I-06123 Perugia, Italy33INFN, Sezione di Perugia, I-06123 Perugia, Italy

34European Gravitational Observatory (EGO), I-56021 Cascina, Pisa, Italy35Syracuse University, Syracuse, NY 13244, USA

36SUPA, University of Glasgow, Glasgow G12 8QQ, United Kingdom37LIGO Hanford Observatory, Richland, WA 99352, USA

38Wigner RCP, RMKI, H-1121 Budapest, Konkoly Thege Miklos ut 29-33, Hungary39Columbia University, New York, NY 10027, USA40Stanford University, Stanford, CA 94305, USA

41Universita di Padova, Dipartimento di Fisica e Astronomia, I-35131 Padova, Italy42INFN, Sezione di Padova, I-35131 Padova, Italy

43CAMK-PAN, 00-716 Warsaw, Poland44Astronomical Observatory Warsaw University, 00-478 Warsaw, Poland

45University of Birmingham, Birmingham B15 2TT, United Kingdom46Universita degli Studi di Genova, I-16146 Genova, Italy

47INFN, Sezione di Genova, I-16146 Genova, Italy48RRCAT, Indore MP 452013, India

49Faculty of Physics, Lomonosov Moscow State University, Moscow 119991, Russia50SUPA, University of the West of Scotland, Paisley PA1 2BE, United Kingdom51University of Western Australia, Crawley, Western Australia 6009, Australia

52Department of Astrophysics/IMAPP, Radboud University Nijmegen,P.O. Box 9010, 6500 GL Nijmegen, Netherlands

53Artemis, Universite Cote d’Azur, CNRS, Observatoire Cote d’Azur, CS 34229, Nice cedex 4, France54MTA Eotvos University, “Lendulet” Astrophysics Research Group, Budapest 1117, Hungary55Institut de Physique de Rennes, CNRS, Universite de Rennes 1, F-35042 Rennes, France

56Washington State University, Pullman, WA 99164, USA57Universita degli Studi di Urbino “Carlo Bo,” I-61029 Urbino, Italy58INFN, Sezione di Firenze, I-50019 Sesto Fiorentino, Firenze, Italy

59University of Oregon, Eugene, OR 97403, USA60Laboratoire Kastler Brossel, UPMC-Sorbonne Universites, CNRS,

ENS-PSL Research University, College de France, F-75005 Paris, France61VU University Amsterdam, 1081 HV Amsterdam, Netherlands

62University of Maryland, College Park, MD 20742, USA63Center for Relativistic Astrophysics and School of Physics,

Georgia Institute of Technology, Atlanta, GA 30332, USA64Institut Lumiere Matiere, Universite de Lyon, Universite ClaudeBernard Lyon 1, UMR CNRS 5306, 69622 Villeurbanne, France

65Laboratoire des Materiaux Avances (LMA), IN2P3/CNRS,Universite de Lyon, F-69622 Villeurbanne, Lyon, France

66Universitat de les Illes Balears, IAC3—IEEC, E-07122 Palma de Mallorca, Spain67Universita di Napoli “Federico II,” Complesso Universitario di Monte S.Angelo, I-80126 Napoli, Italy

68NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA69Canadian Institute for Theoretical Astrophysics,

University of Toronto, Toronto, Ontario M5S 3H8, Canada70Tsinghua University, Beijing 100084, China

71Texas Tech University, Lubbock, TX 79409, USA72The Pennsylvania State University, University Park, PA 16802, USA

73National Tsing Hua University, Hsinchu City, 30013 Taiwan, Republic of China74Charles Sturt University, Wagga Wagga, New South Wales 2678, Australia

75University of Chicago, Chicago, IL 60637, USA76Caltech CaRT, Pasadena, CA 91125, USA

77Korea Institute of Science and Technology Information, Daejeon 305-806, Korea78Carleton College, Northfield, MN 55057, USA

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79Universita di Roma “La Sapienza,” I-00185 Roma, Italy80University of Brussels, Brussels 1050, Belgium

81Sonoma State University, Rohnert Park, CA 94928, USA82Northwestern University, Evanston, IL 60208, USA

83University of Minnesota, Minneapolis, MN 55455, USA84The University of Melbourne, Parkville, Victoria 3010, Australia

85The University of Texas Rio Grande Valley, Brownsville, TX 78520, USA86The University of Sheffield, Sheffield S10 2TN, United Kingdom

87University of Sannio at Benevento, I-82100 Benevento,Italy and INFN, Sezione di Napoli, I-80100 Napoli, Italy88Montclair State University, Montclair, NJ 07043, USA

89Universita di Trento, Dipartimento di Fisica, I-38123 Povo, Trento, Italy90INFN, Trento Institute for Fundamental Physics and Applications, I-38123 Povo, Trento, Italy

91Cardiff University, Cardiff CF24 3AA, United Kingdom92National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan

93School of Mathematics, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom94Indian Institute of Technology, Gandhinagar Ahmedabad Gujarat 382424, India

95Institute for Plasma Research, Bhat, Gandhinagar 382428, India96University of Szeged, Dom ter 9, Szeged 6720, Hungary

97Embry-Riddle Aeronautical University, Prescott, AZ 86301, USA98University of Michigan, Ann Arbor, MI 48109, USA

99Tata Institute of Fundamental Research, Mumbai 400005, India100American University, Washington, D.C. 20016, USA

101University of Massachusetts-Amherst, Amherst, MA 01003, USA102University of Adelaide, Adelaide, South Australia 5005, Australia

103West Virginia University, Morgantown, WV 26506, USA104University of Bia lystok, 15-424 Bia lystok, Poland

105SUPA, University of Strathclyde, Glasgow G1 1XQ, United Kingdom106IISER-TVM, CET Campus, Trivandrum Kerala 695016, India107Institute of Applied Physics, Nizhny Novgorod, 603950, Russia

108Pusan National University, Busan 609-735, Korea109Hanyang University, Seoul 133-791, Korea

110NCBJ, 05-400 Swierk-Otwock, Poland111IM-PAN, 00-956 Warsaw, Poland

112Rochester Institute of Technology, Rochester, NY 14623, USA113Monash University, Victoria 3800, Australia

114Seoul National University, Seoul 151-742, Korea115University of Alabama in Huntsville, Huntsville, AL 35899, USA

116ESPCI, CNRS, F-75005 Paris, France117Universita di Camerino, Dipartimento di Fisica, I-62032 Camerino, Italy118Southern University and A&M College, Baton Rouge, LA 70813, USA

119College of William and Mary, Williamsburg, VA 23187, USA120Instituto de Fısica Teorica, University Estadual Paulista/ICTP South

American Institute for Fundamental Research, Sao Paulo SP 01140-070, Brazil121University of Cambridge, Cambridge CB2 1TN, United Kingdom

122IISER-Kolkata, Mohanpur, West Bengal 741252, India123Rutherford Appleton Laboratory, HSIC, Chilton, Didcot, Oxon OX11 0QX, United Kingdom

124Whitman College, 345 Boyer Avenue, Walla Walla, WA 99362 USA125National Institute for Mathematical Sciences, Daejeon 305-390, Korea

126Hobart and William Smith Colleges, Geneva, NY 14456, USA127Janusz Gil Institute of Astronomy, University of Zielona Gora, 65-265 Zielona Gora, Poland

128Andrews University, Berrien Springs, MI 49104, USA129Universita di Siena, I-53100 Siena, Italy

130Trinity University, San Antonio, TX 78212, USA131University of Washington, Seattle, WA 98195, USA

132Kenyon College, Gambier, OH 43022, USA133Abilene Christian University, Abilene, TX 79699, USA

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