Dissecting and modelling galaxy assembly bias

Understanding the galaxy-halo connection is fundamental for contemporary models of galaxy clustering. The extent to which haloes' assembly history and environment impact clustering (a.k.a. bias; GAB), remains a complex challenging problem. Using semi-analytic formation model, we study individual contributions different secondary halo properties GAB signal. These are obtained by comparing stellar-mass selected samples that shuffled where galaxies randomly reassigned haloes fixed mass specified property. We explore large range internal environmental measures. find commonly used like age or concentration amount only 20-30 per cent signal, while smoothed matter density tidal anisotropy can account full level (though care should be given specific definition). For "successful" measures, examine occupancy variations associated changes in occupation function parameters. create mock catalogues reproduce GAB. Finally, propose practical modification standard distribution tuned any bias. Fitting parameters our demonstrate corresponding catalogue recovers target as well variations. Our results enable producing realistic directly inform theoretical modelling bias attempts detect it Universe.