We report an incipient exploration of the Lense-Thirring precession effect in a rotating acoustic analogue black hole spacetime. An exact formula is deduced for the precession frequency of a gyroscope due to inertial frame dragging, close to the ergosphere of a 'Draining Bathtub' acoustic spacetime which has been studied extensively for acoustic Hawking radiation of phonons and also for 'superresonance'. The formula is verified by embedding the two dimensional spatial (acoustic) geometry into a three dimensional one where the similarity with standard Lense-Thirring precession results within a strong gravity framework is well known. Prospects of experimental detection of this new 'fixed-metric' effect in acoustic geometries, are briefly discussed.

Abstract. -We identify a fairly general class of field configurations (of spins 0, 1 2 and 1) which preserve Lorentz invariance in effective field theories of Lorentz violation characterized by a constant timelike vector. These fields concomitantly satisfy the equations of motion yielding cubic dispersion relations similar to those found earlier. They appear to have prospective applications in inflationary scenarios.Introduction. -Invariance under Lorentz transformation is known till date to be a global symmetry of the standard theory of elementary particles when gravitation is ignored. However, questions have been raised regarding the validity of this symmetry at small length scales owing to probable quantum gravity effects . The natural mass scale of quantum gravity is the Planck mass M P l . Departures, suppressed by the Planck mass, from the standard special relativistic dispersion relation of free particles of mass m at large energies have been accepted as a signature of Lorentz invariance violation and has been the principal objet de l'attention of experimental and theoretical probes of Lorentz violation. These hypothesised ad hoc corrections due to Lorentz non-invariance must have their origin in new terms in the action of the system. Myers and Pospelov [38] have studied this issue within the framework of effective field theory involving fields of spins 0, 1/2 and 1, by incorporating into the action dimension five operators containing a constant timelike 4-vector n which ostensibly breaks Lorentz invariance. Choosing a Lorentz frame where n µ = (1, 0), corrections of O(p 3 ) to the dispersion relation of each of the three fields have been obtained in [38] in the limit of relatively high energies E (M P l >> E >> m).

A gravitational wave passing through a pulsar will lead to a variation in the moment of inertia of the pulsar affecting its rotation. This will affect the extremely accurately measured spin rate of the pulsar as well as its pulse profile (due to induced wobbling depending on the source direction). The effect will be most pronounced at resonance and should be detectable by accurate observations of the pulsar signal. The pulsar, in this sense, acts as a remotely stationed Weber detector of gravitational waves whose signal can be monitored on earth. With possible gravitational wave sources spread around in the universe, pulsars in their neighborhoods can provide us a family of remote detectors all of which can be monitored on earth. Even if GW are detected directly by earth based conventional detectors, such pulsar detectors can provide additional information for accurate determination of the source location. This can be of crucial importance for sources which do not emit any other form of radiation such as black hole mergers. For the gravitational wave events already detected by LIGO (and VIRGO), our proposal suggests that one should look for specific pulsars which would have been disturbed by these events, and will transmit this disturbance via their pulse signals in any foreseeable future. If these future pulsar events can be predicted with accuracy then a focused effort can be made to detect any possible changes in the signals of those specific pulsars. Observation of gravitational waves (GW) by LIGO [1]has opened a new window to the universe where even events of black hole mergers can be detected which otherwise leave no signatures in the electromagnetic spectrum. The most recent observation of binary neutron star (BNS) merger via gravitational waves, along with electromagnetic radiation, has provided us the opportunity to probe such events with clear identification of the source [2]. As more and more gravitational wave detectors are set up around the globe, our ability to detect gravitational waves with good localization of the source in the sky will improve tremendously. Future space-based detectors will further complement the search for gravitational wave sources with wide range of wavelengths and strengths. The ultimate limitation on these earth based and space-based detectors will arise from two main factors. Our location is one such factor as most of the powerful sources of gravitational waves are likely to occur very far. Secondly, the ability of our near-earth detectors in triangulating the location of the sources will be limited by the very nature of the detectors. One would wish if a family of detectors could be placed far away in space, and then signals from these far away detectors could be collected with high precision for GW detection and accurate determination of the location of the source (possibly in conjunction with conventional near earth detectors). We propose such a possibility in this paper.Main physics underlying our proposal is based on the fact that with accurate measurements of timings...

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A Lorentz non-invariant higher derivative effective action in flat spacetime, characterised by a constant vector, can be made invariant under infinitesimal Lorentz transformations by restricting the allowed field configurations. These restricted fields are defined as functions of the background vector in such a way that background dependance of the dynamics of the physical system is no longer manifest. We show here that they also provide a field basis for the realisation of Lorentz algebra and allow the construction of a Poincaré invariant symplectic two form on the covariant phase space of the theory. * oindrila@bose.res.in