Gravitational waves: Sources, detectors and searches

Abstract

Gravitational wave science should transform in this decade from a study of what has not been seen to a full-fledged field of astronomy in which detected signals reveal the nature of cataclysmic events and exotic objects. The LIGO Scientific Collaboration and Virgo Collaboration have recently completed joint data runs of unprecedented sensitivities to gravitational waves. So far, no gravitational radiation has been seen (although data mining continues). It seems likely that the first detection will come from 2nd-generation LIGO and Virgo interferometers now being installed. These new detectors are expected to detect ∼40 coalescences of neutron star binary systems per year at full sensitivity. At the same time, research and development continues on 3rd-generation underground interferometers and on space-based interferometers. In parallel there is a vigorous effort in the radio pulsar community to detect ∼several-nHz gravitational waves via the timing residuals from an array of pulsars at different locations in the sky. As the dawn of gravitational wave astronomy nears, this review, intended primarily for interested particle and nuclear physicists, describes what we have learned to date and the prospects for direct discovery of gravitational waves.

Cross-correlation search for continuous gravitational waves from a compact object in SNR 1987A in LIGO Science run 5

“…Several birth scenarios for the pulsar in SNR 1987A were considered byÖgelman and Alpar [49] in this context, who concluded that the maximum magnetic dipole moment is 1.1 × 10 26 G cm 3 , 2.5 × 10 28 G cm 3 , and 2.5 × 10 30 G cm 3 for birth periods of 2 ms, 30 ms, and 0.3 s respectively. The dynamo model also accommodates a magnetar in SNR 1987A, with magnetic dipole moment exceeding 2.4 × 10 34 G cm 3 , regardless of the initial spin period [49].…”

“…2 Iνν (where I is the stellar moment of inertia) goes into gravitational radiation [3,19]. However, by a similar energy conservation argument, one can place an upper limit on h 0 in terms of the object's age, T age [3,8,20], viz.…”

“…First, searches for periodic gravitational waves from younger neutron stars can more easily reach or probe below the indirect upper limits inferred from the spin-down rateν (wherė ν is measured) or the age (whereν is unknown). Indirect wave strain upper limits are proportional toν or inversely proportional to the age and hence are larger for younger neutron stars [1][2][3]; see also Eq. (1) in Section II B.…”

“…A prohibitively large set of matched filters is needed for a coherent search, if a radio ephemeris is unavailable [8]. Hence less sensitive semi-coherent search strategies are favoured [3,[9][10][11][12][13].…”

Upper limit on the amplitude of gravitational waves around 0.1Hz from the Global Positioning System

“…2 Hz [9,10]. However, seismic oscillations interfere ground-based observations of gravitational waves at lower frequencies as f 10 Hz (see [11]).…”