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We study the effect of angular momentum on the surface density profiles ofdisc galaxies, using high resolution simulations of major mergers whoseremnants have downbending radial density profiles (type II). As described inthe previous papers of this series, in this scenario, most of the disc mass isacquired after the collision via accretion from a hot gaseous halo. We findthat the inner and outer disc scalelengths, as well as the break radius,correlate with the total angular momentum of the initial merging system, andare larger for high angular momentum systems. We follow the angular momentumredistribution in our simulated galaxies, and find that, like the mass, thedisc angular momentum is acquired via accretion, i.e. to the detriment of thegaseous halo. Furthermore, high angular momentum systems give more angularmomentum to their discs, which affects directly their radial density profile.Adding simulations of isolated galaxies to our sample, we find that thecorrelations are valid also for disc galaxies evolved in isolation. We showthat the outer part of the disc at the end of the simulation is populatedmainly by inside-out stellar migration, and that in galaxies with higherangular momentum, stars travel radially further out. This, however, does notmean that outer disc stars (in type II discs) were mostly born in the innerdisc. Indeed, generally the break radius increases over time, and not takingthis into account leads to overestimating the number of stars born in the innerdisc.

Forming disc galaxies in major mergers: III. The effect of angular momentum on the radial density profiles of disc galaxies