Published online by Cambridge University Press: 25 May 2016
There have long been two competing views on the formation history of the ellipticals galaxies we see today. One is that most of the stars in present-day galactic bulges and ellipticals were produced during a relatively short, early phase of intense star formation at high redshift. The second view is that elliptical galaxies are relative latecomers, having been produced as the result of the merging of disk galaxies drawn together by gravity as their surrounding dark matter halos coalesced.