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In this paper we describe the discontinuous Galerkin time-domain method and apply it to the simulation of ground-penetrating radar (GPR) problems in 3D. The method is first validated with analytical solutions and we show its superior behaviour when compared to the classical finite-difference time-domain method, widely employed in GPR simulation. In the(More)
Thanks to a stellar evolution code able to compute through the C-flash we link the binary population synthesis of single degenerate progenitors of type Ia supernovae (SNe Ia) to their physical condition at the time of ignition. We show that there is a large range of possible ignition densities and we detail how their probability distribution depends on the(More)
The microquasar GRO J1655–40 has a black hole with spin angular momentum apparently misaligned to the orbital plane of its companion star. We analytically model the system with a steady state disc warped by Lense-Thirring precession and find the timescale for the alignment of the black hole with the binary orbit. We make detailed stellar evolution models so(More)
In this work, we present a novel hybrid implicit-explicit algorithm, based on a subgridding boundary condition (SGBC) technique, for the simulation of arbitrarily dispersive thin layers in FDTD. To overcome a reduction of the usual FDTD time step, a Crank-Nicolson scheme is used to model the propagation in a bulk media with equivalent effective parameters.(More)
The physical relationship between low-excitation gas filaments at ∼10 4 K, seen in optical line emission, and diffuse X-ray emitting coronal gas at ∼10 7 K in the centers of many galaxy clusters is not understood. It is unclear whether the ∼10 4 K filaments have cooled and condensed from the ambient hot (∼10 7 K) medium or have some other origin such as the(More)
In the microquasar V4641 Sgr the spin of the black hole is thought to be misaligned with the binary orbital axis. The accretion disc aligns with the black hole spin by the Lense-Thirring effect near to the black hole and further out becomes aligned with the binary orbital axis. The inclination of the radio jets and the FeKα line profile have both been used(More)
We consider the shape of an accretion disc whose outer regions are misaligned with the spin axis of a central black hole and calculate the steady state form of the warped disc in the case where the viscosity and surface densities are power laws in the distance from the central black hole. We discuss the shape of the resulting disc in both the frame of the(More)
Doubly-degenerate binary systems consisting of two white dwarfs both composed of carbon and oxygen and close enough that mass is transferred from the less massive to the more massive are possible progenitors of type Ia supernovae. If the mass transfer rate is slow enough that the accreting white dwarf can reach a mass of 1.38 M ⊙ then it can ignite carbon(More)