Mergers in Galaxy Groups - I. Structure and Properties of Elliptical
  Remnants
  We present collisionless simulations of dry mergers in groups of three to
twenty-five galaxies to test the hypothesis that elliptical galaxies form at
the centers of such groups. Mock observations of the central remnants confirm
their similarity to ellipticals, despite having no dissipational component. We
vary the profile of the original spiral's bulge and find that ellipticals
formed from spirals with exponential bulges have too low Sersic indices.
Mergers of spirals with de Vaucouleurs (classical) bulges produce remnants with
larger Sersic indices correlated with luminosity, as with SDSS ellipticals.
Exponential bulge mergers are better fits to faint ellipticals, whereas
classical bulge mergers better match luminous ellipticals. Similarly, luminous
ellipticals are better reproduced by remnants undergoing many (>5) mergers, and
fainter ellipticals by those with fewer mergers.
  The remnants follow tight size-luminosity and velocity dispersion-luminosity
(Faber-Jackson) relations (<0.12 dex scatter), demonstrating that stochastic
merging can produce tight scaling relations if the merging galaxies also follow
tight scaling relations. The slopes of the size-luminosity and Faber-Jackson
relations are close to observations but slightly shallower in the former case.
Both relations' intercepts are offset - remnants are too large but have too low
dispersions at fixed luminosity. Some remnants show substantial (v/\sigma >
0.1) rotational support, although most are slow rotators and few are very fast
rotators (v/\sigma > 0.5).
  These findings contrast with previous studies concluding that dissipation
necessary to produce ellipticals from binary mergers of spirals. Multiple,
mostly minor and dry mergers can produce bright ellipticals, whereas
significant dissipation could be required to produce faint, rapidly-rotating
ellipticals.
