On the Formation of Elliptical Galaxies via Mergers in Galaxy Groups

Elliptical galaxies comprise the majority of luminous galaxies in our universe. Ellipticals have long been thought to form through gas-rich "major" mergers of two roughly equal-mass spiral galaxies. We propose instead that ellipticals form through gas-poor, mainly minor mergers of spirals in groups. This hypothesis is tested using a novel sample of hundreds of numerical simulations of mergers in groups of three to twenty-five spiral galaxies. These simulations are accompanied by mock observations of the central remnants in each group, comparing to data on ellipticals from galaxy surveys. The simulated merger remnants have similar surface brightness profiles to observed ellipticals - if the spirals begin with concentrated bulges. The remnants follow tight size-luminosity and velocity dispersion-luminosity relations (Ph.D