12 research outputs found
Ultra-stable performance of an underground-based laser interferometer observatory for gravitational waves
In order to detect the rare astrophysical events that generate gravitational
wave (GW) radiation, sufficient stability is required for GW antennas to allow
long-term observation. In practice, seismic excitation is one of the most
common disturbances effecting stable operation of suspended-mirror laser
interferometers. A straightforward means to allow more stable operation is
therefore to locate the antenna, the ``observatory'', at a ``quiet'' site. A
laser interferometer gravitational wave antenna with a baseline length of 20m
(LISM) was developed at a site 1000m underground, near Kamioka, Japan. This
project was a unique demonstration of a prototype laser interferometer for
gravitational wave observation located underground. The extremely stable
environment is the prime motivation for going underground. In this paper, the
demonstrated ultra-stable operation of the interferometer and a well-maintained
antenna sensitivity are reported.Comment: 8 pages, to appear on PR
Coincidence analysis to search for inspiraling compact binaries using TAMA300 and LISM data
Japanese laser interferometric gravitational wave detectors, TAMA300 and
LISM, performed a coincident observation during 2001. We perform a coincidence
analysis to search for inspiraling compact binaries. The length of data used
for the coincidence analysis is 275 hours when both TAMA300 and LISM detectors
are operated simultaneously. TAMA300 and LISM data are analyzed by matched
filtering, and candidates for gravitational wave events are obtained. If there
is a true gravitational wave signal, it should appear in both data of detectors
with consistent waveforms characterized by masses of stars, amplitude of the
signal, the coalescence time and so on. We introduce a set of coincidence
conditions of the parameters, and search for coincident events. This procedure
reduces the number of fake events considerably, by a factor
compared with the number of fake events in single detector analysis. We find
that the number of events after imposing the coincidence conditions is
consistent with the number of accidental coincidences produced purely by noise.
We thus find no evidence of gravitational wave signals. We obtain an upper
limit of 0.046 /hours (CL ) to the Galactic event rate within 1kpc from
the Earth. The method used in this paper can be applied straightforwardly to
the case of coincidence observations with more than two detectors with
arbitrary arm directions.Comment: 28 pages, 17 figures, Replaced with the version to be published in
Physical Review