Hydrodynamical response of a circumbinary gas disc to black hole recoil and mass loss Gas disc response to black hole merger Corrales, Lia R. Haiman, Zoltán MacFadyen, Andrew Finding electromagnetic (EM) counterparts of future gravitational wave (GW) sources would bring rich scientific benefits. A promising possibility, in the case of the coalescence of a supermassive black hole binary (SMBHB), is that the prompt emission from merger-induced disturbances in a supersonic circumbinary disc may be detectable. We follow the post-merger evolution of a thin, zero-viscosity circumbinary gas disc with two-dimensional simulations, using the hydrodynamic code flash. We analyse perturbations arising from the 530 km s−1 recoil of a 106 M⊙ binary, oriented in the plane of the disc, assuming either a non-radiative gamma-law or a pseudo-isothermal equation of state for the gas. We find that a single-armed spiral shock wave forms and propagates outwards, sweeping up ∼40 per cent of the mass of the disc. The morphology and evolution of the perturbations agrees well with those of caustics predicted to occur in a collisionless disc. Assuming that the disc radiates nearly instantaneously to maintain a constant temperature, we estimate the amount of dissipation and corresponding post-merger light curve. The luminosity rises steadily on the time-scale of months, and reaches few ×1043 erg s−1, corresponding to ≈10 per cent of the Eddington luminosity of the central SMBHB. We also analyse the case in which gravitational wave emission results in a 5 per cent mass loss in the merger remnant. The mass loss reduces the shock overdensities and the overall luminosity of the disc by ≈15–20 per cent, without any other major effects on the spiral shock pattern. Oxford University Press 2010 info:eu-repo/semantics/article doc-type:Article Article http://purl.org/coar/resource_type/c_2df8fbb1 https://research-explorer.ista.ac.at/record/17665 Corrales LR, Haiman Z, MacFadyen A. Hydrodynamical response of a circumbinary gas disc to black hole recoil and mass loss. <i>Monthly Notices of the Royal Astronomical Society</i>. 2010;404(2):947-962. doi:<a href="https://doi.org/10.1111/j.1365-2966.2010.16324.x">10.1111/j.1365-2966.2010.16324.x</a> eng info:eu-repo/semantics/altIdentifier/doi/10.1111/j.1365-2966.2010.16324.x info:eu-repo/semantics/altIdentifier/issn/0035-8711 info:eu-repo/semantics/altIdentifier/issn/1365-2966 info:eu-repo/semantics/openAccess