%0 Generic
%A Khochfar, Sadegh
%D 2003
%F heidok:3621
%K Galaxienentwicklung , elliptische GalaxienGalaxy Evolution , Elliptical Galaxies
%R 10.11588/heidok.00003621
%T Origin and Properties of Elliptical Galaxies in a Hierarchical Universe
%U https://archiv.ub.uni-heidelberg.de/volltextserver/3621/
%X The formation of elliptical galaxies by merging galaxies has been investigated adopting three different paths. First, we confirm that  the frequency of major merger events predicted by hierarchical models is in fair agreement with  observations. Second, the generally assumed initial conditions used in  numerical   simulations of merging galaxies were tested. Orbital  parameters of the  merging galaxies are derived self-consistently from large scale N-body  simulations, showing that the commonly used parameters are in agreement, but   resemble just a small fraction of the possible parameter space.  Most of the  mergers are taking place on parabolic orbits with pericenter distances larger  than generally assumed in simulations. Using semi-analytical modeling  techniques, the morphology of progenitors is found  to be dependent on the luminosity of the present-day elliptical.  One can distinguish three different regions:  ellipticals with M_B < -21 are mainly formed by a merger of two  bulge-dominated  galaxies, while ellipticals with roughly M_B = -20 are  mainly the result  of a disk-dominated galaxy merging with a bulge-dominated  galaxy. Only low luminous ellipticals with  M_B > -18 are   the product of disk galaxies merging, as usually assumed in merger simulations. The third path is to implement results of detailed numerical simulations into a semi-analytic models of  galaxy formation model and to compare global predictions for ellipticals with observations. The dependence of the isophotal shape of an elliptical  on the mass ratio of the last major merger, as suggested by dissipationless simulations, fails in reproducing the observed  correlation between isophotal shape and mass of an elliptical. Only the  assumption that all major mergers between  elliptical galaxies lead to boxy ellipticals allows to recover the observed trend. Including the effects of binary black hole merging in the centers of the remnants,  it is possible to recover the observed core mass deficit-black hole  mass relation.