Adrian C. Ottewill

Detection of anisotropies in the gravitational-wave stochastic background

By correlating the signals from a pair of gravitational-wave detectors, one can undertake sensitive searches for a stochastic background of gravitational radiation. If the stochastic background is anisotropic, then this correlated signal varies harmonically with Earth’s rotation. We calculate how the harmonics of this varying signal are related to the multipole moments which characterize the anisotropy, and give a formula for the signal-to-noise ratio of a given harmonic. The specific case of the two LIGO ~Laser Interferometric Gravitational Observatory! detectors, which will begin operation around the year 2000, is analyzed in detail. We consider two possible examples of anisotropy. If the gravitational-wave stochastic background contains a dipole intensity anisotropy whose origin ~like that of the cosmic background radiation! is the motion of our local system, then that anisotropy will be observable by the advanced LIGO detector ~with 90% confidence in one year of observation! if V GW.5.3310 28 h1002 . We also study the signal produced by stochastic sources distributed in the same way as the luminous matter in the galactic disk, and in the same way as the galactic halo. The anisotropy due to sources distributed as the galactic disk or as the galactic halo will be observable by the advanced LIGO detector ~with 90% confidence in one year of observation! if V GW.1.8310 210 h1002 or

TreeP: A Tree Based P2P Network Architecture

In this paper we proposed a hierarchical P2P network based on a dynamic partitioning on a 1-D space. This hierarchy is created and maintained dynamically and provides a grid middleware (like DGET) a P2P basic functionality for resource discovery and load-balancing. This network architecture is called TreeP (Tree based P2P network architecture) and is based on a tessellation of a 1-D space. We show that this topology exploits in an efficient way the heterogeneity feature of the network while limiting the overhead introduced by the overlay maintenance. Experimental results show that this topology is highly resilient to a large number of network failures

Renormalized stress tensor in Kerr space-time: General results

We derive constraints on the form of the renormalized stress tensor for states on Kerr space-time based on general physical principles: symmetry, the conservation equations, the trace anomaly and regularity on (sections of) the event horizon. This is then applied to the physical vacua of interest. We introduce the concept of past and future Boulware vacua and discuss the non-existence of a state empty at both

Long-range effects of cosmic string structure

{\mathfrak{I}}^{\ensuremath{-}}

Tidal invariants for compact binaries on quasicircular orbits

and

Analytical high-order post-Newtonian expansions for extreme mass ratio binaries

{\mathfrak{I}}^{+}.

Quantum vacuum instability near rotating stars.

By calculating the stress tensor for the Unruh vacuum at the event horizon and at infinity, we are able to check our earlier conditions. We also discuss the difficulties of defining a state equivalent to the Hartle-Hawking vacuum and comment on the properties of two candidates for this state.

Direct‐view microscopy: optical sectioning strength for finite‐sized, multiple‐pinhole arrays

We combine and further develop ideas and techniques of Allen & Ottewill, Phys. Rev. D, 42, 2669 (1990) and Kay & Studer Commun. Math. Phys., 139, 103 (1991) for calculating the long range effects of cosmic string cores on classical and quantum field quantities far from an (infinitely long, straight) cosmic string. We find analytical approximations for (a) the gravity-induced ground state renormalized expectation values of ˆ ϕ 2 and ˆ Tµ � for a non-minimally coupled quantum scalar field far from a cosmic string (b) the classical electrostatic self force on a test charge far from a superconducting cosmic string. Surprisingly – even at cosmologically large distances – all these quantities would be very badly approximated by idealizing the string as having zero thickness and imposing regular boundary conditions; instead they are well approximated by suitably fitted strengths of logarithmic divergence at the string core. Our formula for h ˆ ϕ 2 i reproduces (with much less effort and much more generality) the earlier numerical results of Allen & Ottewill. Both h ˆ

High frequency asymptotics for the spin-weighted spheroidal equation

we dene and calculate at O( ) (conservative) shifts in the eigenvalues of the electric- and magnetic-type tidal tensors, and a (dissipative) shift in a scalar product between their eigenbases. This approach yields four gauge-invariant functions, from which one may construct other tidal quantities such as the curvature scalars and the speciality index. First, we analyze the general case of a geodesic in a regular perturbed vacuum spacetime admitting a helical Killing vector and a reection symmetry. Next, we specialize to focus on circular orbits in the equatorial plane of Kerr spacetime at O( ). We present accurate numerical results for the Schwarzschild case for orbital radii up to the light-ring, calculated via independent implementations in Lorenz and Regge-Wheeler gauges. We show that our results are consistent with leading-order post-Newtonian expansions, and demonstrate the existence of additional structure in the strong-eld regime. We anticipate that our strong-eld results will inform (e.g.) eective

Analytic results for the gravitational radiation from a class of cosmic string loops

We present analytic computations of gauge invariant quantities for a point mass in a circular orbit around a Schwarzschild black hole, giving results up to 15.5 post-Newtonian order in this paper and up to 21.5 post-Newtonian order in an online repository. Our calculation is based on the functional series method of Mano, Suzuki and Takasugi (MST) and a recent series of results by Bini and Damour. We develop an optimised method for generating post-Newtonian expansions of the MST series, enabling significantly faster computations. We also clarify the structure of the expansions for large values of