Robin Stebbins, JILA/University of Colorado
The First International LISA Symposium was held at the Rutherford Appleton Laboratory in Chilton, 9-12 July 1996. The symposium highlighted the scientific opportunities of gravitational wave detection in space. The symposium was further enriched by poster sessions, technology demonstrations, a full-scale mockup of a LISA spacecraft, laboratory tours and a delightful dinner cruise on the Thames with live jazz! The main oral sessions are summarized below. Selected papers from the symposium are scheduled to appear in the March 1997 issue of Classical and Quantum Gravity. Mike Sandford, the scientific and local organizing committees, and the RAL staff are to be commended for putting together such a stimulating and pleasant symposium.
In the overview session, Rudiger Reinhard (ESA) described the status of LISA in ESA's Horizons 2000 Plus Programme, and Karsten Danzmann (Hannover), Bill Folkner (JPL) and Koos Cornelisse (ESTEC) described the current baseline LISA mission. Kip Thorne (Caltech) described a menagerie of dark, extremely relativistic objects in the Universe which might be discovered with a low-frequency gravitational wave detector in space, and the insight into gravitation theories to be gained from them. Martin Rees (Cambridge) surveyed the available information on massive black holes and gave a very positive assessment of the likelihood of detection of signals from various scenarios.
The sources session focused on astrophysical systems which could produce low-frequency gravitational waves likely to be detected by LISA. Frank Verbunt (Utrecht) reviewed the state of observational knowledge about binaries systems consisting of main sequence stars and/or compact objects which could give rise to detectable signals. Steinn Sigurdsson (Cambridge) described the capture of low-mass black holes by massive black holes in galactic cusps. Alberto Vecchio (MPI/Potsdam) reported on signals from coalescing massive black holes. Curt Cutler (Penn State) showed that LISA could only identify the source of signals from coalescing massive black holes if there was some supplementary optical indication. Pete Bender (JILA) described a revised estimation of the confusions limit from galactic and extragalactic binaries. I. Pinto (Salerno) described the spectrum of signals from insular clusters.
The session on gravitational theories and numerical relativity began with a talk by Richard Matzner (Texas) on the computation of waveforms from the coalescence of black hole binary systems. Leonid Grishchuk (Cardiff) offered an explanation of cosmic background anisotropies based on relic gravitational waves, and noted existing observational support. Ewald Muller (MPI/Garching) described the gravitational wave generation in the inner core and the outer convective region of a type II supernova. Gerhard Shafer (MPI/Jena) discussed how alternate theories of gravitation might be checked with LISA.
Updates were given by on the VIRGO Project by Francesco Fidecaro (Pisa), on GEO 600 by Harald Luck (MPI/Hannover), on LIGO by David Shoemaker (MIT), on the TAMA Project by Keita Kawabe (Tokyo) experiments. Construction is proceeding well on all of these ground-based interferometers. Bruno Bertotti (Pavia) reviewed past attempts to detect gravitational waves by spacecraft tracking and previewed plans for the Cassini mission. Guido Pizzella (Rome) summarized the current and expected performance of resonant detectors. Stefano Vitale (Trento) analyzed the sensitivity of two resonant detectors, and two resonant detectors and an interferometer, to an isotropic, stochastic background. M. Cerdonio (Padova) reported performance of AURIGA when cooled to 140 mK.
The next session delved into gravitational wave signal extraction and data analysis. Robin Stebbins (JILA) outlined the challenges of extracting astrophysical information from the many and varied gravitational wave signals likely to be in LISA data. Michael Peterseim (Hannover) examined the angular resolution obtainable with various signal parameters. Roland Schilling (MPI/Garching) analyzed the response function of LISA above 10 mHz where the wavelength is shorter than the armlength. Giacomo Giampieri (QMC) discussed the anisotropy of the stochastic background caused by galactic binaries, as seen by LISA. Oliver Jennrich (Hannover) reported on the polarization resolution which LISA could obtain. Bill Folkner (JPL) described the onboard signal processing planned for in the LISA mission. L. Milano (INFN) simulated the application of matched filters to search for binary signals in VIRGO data.
The final session of the conference addressed enabling technologies for gravitational wave detection. Sheila Rowan (Glasgow) reported on the performance of prototype monolithic fused quartz suspensions for ground-based interferometers. Paul McNamara (Glasgow) described a laboratory demonstration of weak light phase-locking, a requirement for LISA. Dan DeBra (Stanford) reviewed drag-free satellite technology, both flown and future. M. Rodrigues (ONERA) explained the LISA accelerometer design. Clive Speake (Birmingham) analyzed two designs for capacitive sensing circuits for the dominant noise source, and showed that LISA goals can be achieved with either design. Yusuf Jafry (ESA) reported on a simulation of cosmic ray charging of the LISA proof mass done with the GEANT code. And P. Rottengatter (LZH) reported on the successful intensity and amplitude stabilization of Nd:YAG lasers for use in LISA. Dave Robertson (Glasgow) described the LISA optics and limiting noise sources in the optical measurement. Walter Winkler (MPI/Garching) gave an analysis of the far-field effects of LISA transmitting a truncated Gaussian beam. Wei-Tou Ni (Taiwan) described the ASTROD mission for performing several relativistic tests in solar orbit, and technology development activities to support fundamental physics missions. Dan DeBra read a paper submitted by S. Marcuccio (Centrospacio) reporting on recent tests and development of the Field Emission Electric Propulsion (FEEP) thrusters planned for LISA.