Sersic properties of disc galaxy mergers

Sersic parameters characterizing the density profiles of remnants formed in collisionless disc galaxy mergers are obtained; no bulge is included in our simulations. The Sersic index range for the luminous matter, n is an element of (1.7, 5.2), is similar to that found in early-type galaxies, for about the same luminous mass range, while the effective radius tends to be higher, R-e is an element of (1.6, 12.3) kpc. A strong correlation of n with the central projected surface density I-0 is found, n proportional to I-0(0.14), which is consistent with observations. No strong positive linear correlation between the size, R-e, and structure, n, of our remnants is found. The derived scaling of the index n with luminous mass, n proportional to M-L(0.20), compares favourably with its observational counterpart, n proportional to L-0.27. The dependence of the effective radius with luminous mass for our remnants, R-e proportional to M-L(0.48), compares well with that determined from early-type galaxies of the Sloan Digital Sky Survey, R-e proportional to M-L(0.56). The photometric plane scaling found for the luminous component, n proportional to (ReI00.13)-I-0.14, assuming a constant stellar mass-to-light ratio, is consistent with that determined for ellipticals in the B band, n proportional to (ReI00.15)-I-0.09, and for K-band remnants, n proportional to (ReI00.14)-I-0.11. We find that the surface defined by Sersic parameters {n, R-e, mu(0)} in log space is not a true plane, but a pseudo-plane with a small curvature at low values of n owed to intrinsic properties of the Sersic model. The dark haloes of our remnants have a mean 3D Sersic index of < n > approximate to 4 +/- 0.5, that is somewhat smaller than the one obtained for dark haloes in Lambda cold dark matter cosmologies, < n > approximate to 6 +/- 1. Also, a tight dark Sersic 'plane' is found to be defined by the parameters of the remnants haloes with n proportional to r(e)(0.10)rho(0.09)(0). We conclude that collisionless merger remnants of pure disc galaxies have Sersic properties and correlations consistent with those of observed in early-type galaxies and local remnants.