The animations show mass transfer from a He white dwarf (MWD=0.15M⊙) or O-Ne white dwarf (MWD=1.0M⊙) onto a 1.4M⊙ point-like neutron star. We use an improved version of Oil-on-Water technique to artificially separate the stellar body of the white dwarf (1·105 particles) and the atmosphere (3·105 particles). This allows us to model arbitrarily low mass transfer rates. The simulations are used to measure the amount of angular momentum lost during mass transfer.
The animations to demonstrate the stability of the code. First animation: A CO white dwarf (MWD=0.6M⊙) is orbiting a neutron star on an eccentric orbit which is wide enough so that no mass transfer occurs. Second animation: The same CO white dwarf is set on a tighter orbit so that very few particles get transferred per orbit. Third animation: An example of a system with a He donor from the main set of runs at wider separations (shorter stripe in Figure 7 in Bobrick et al, 2017). Even though less particles are transferred per orbit, the amount of specific angular momentum lost remains unchanged.
Mass transfer in white dwarf-black hole binaries, visualisations for Church et al. (2017)
These animations have been made with our latest Oil-on-Water code to support the conclusions of Church et al. 2017. First animation: 16.8 M⊙ black hole in a circular binary with a 0.6 M⊙ white dwarf, SPH resolution is 400 000 particles. Second animation: The same binary in x'-z plane in a corotating reference frame. The angular momentum loss efficiency measured in these simulations is consistent with the one based on the model from Bobrick et al. 2017.