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tokens: assumption that BBHs trace the location of their parent star particles. The prospects for detecting BHs without stellar companions remain limited. Still, with a refined model of the star formation history in the MW, non-detections with X-ray, radio and microlensing surveys will put constraints on binary evolution models. Conversely, a much higher number of detected systems will be equally constraining, and may inform us of additional BBH formation channels (Rodriguez et al. 2015 ; Marchant et al. 2016 ). Our understanding of massive binary evolution is still very uncertain, especially the modelling of stellar mass-loss through different evolutionary phases, the properties of common-envelope mass transfer, and supernova kicks. Specifically, we have assumed that common envelope interactions during the Hertzprung gap result in stellar mergers, which may underestimate the BBH production rate. Conversely, we assume the BH natal kicks are reduced with respect to NS natal kicks, which may overestimate the number of systems surviving both supernova explosions. As our work highlights the importance of improved galactic models, we do not explore the wide parameter space of current binary models. The different BBH merger rates predicted by Mapelli et al. ( 2017 ) show how different binary evolution models will eventually be ruled in or out by observational data, provided appropriate models are used for the star formation. Based on our assumptions for binary evolution, we predict that LISA will detect about 25 BBHs within the MW halo. The frequency of these systems will not vary over the duration of the LISA mission, which means that the measured chirp mass will be degenerate with the distance of the system (see equation 4 ) and discerning it from a closer NS binary may not be possible. While certain aspects of binary evolution are likely to be revised, we emphasize that the BBH predictions of our model are somewhat on the high end (see a discussion in Lamberts et al. 2016 ) and that fine-tunning it in order to produce more galactic BBHs may overproduce the observed BH merger rate (Abbott et al. 2017c ). Unless a mechanism allows for the formation of BBHs at close to solar metallicity, BBHs are strongly biased towards the galactic halo, which strongly reduces their GW signal on Earth relative to disc populations. Even a single detection with accurate localization will provide information on the binary evolution mechanism and the conditions of its formation. We find that less than a million BBHs have merged in the MW by the present day. Focusing on the mergers within the last 2 Gyr, we find a merger rate of ≃10 −5 yr −1 . Our model, which assumes a binary fraction of unity, is on the higher end of the measured rate. We find the mean mass of the systems to be 29, which is in line with the announced detections (Abbott et al. 2016a ; 2017a , b , c ). We find that sources with represent 8 per cent of the merged systems, meaning there could be roughly 40 000