The intrinsic anisotropy \delta and flattening \epsilon of simulated merger remnants is compared with elliptical galaxies that have been observed by the SAURON collaboration , and that were analysed using axisymmetric Schwarzschild models .
Collisionless binary mergers of stellar disks and disk mergers with an additional isothermal gas component , neglecting star formation can not reproduce the observed trend \delta = 0.55 \epsilon ( SAURON relationship ) .
An excellent fit of the SAURON relationship for flattened ellipticals with \epsilon \geq 0.25 is however found for merger simulations of disks with gas fractions \geq 20 \% , including star formation and stellar energy feedback .
Massive black hole feedback does not strongly affect this result .
Subsequent dry merging of merger remnants however does not generate the slowly-rotating SAURON ellipticals which are characterized by low ellipticities \epsilon < 0.25 and low anisotropies .
This indicates that at least some ellipticals on the red galaxy sequence did not form by binary mergers of disks or early-type galaxies .
We show that stellar spheroids resulting from multiple , hierarchical mergers of star-bursting subunits in a cosmological context are in excellent agreement with the low ellipticities and anisotropies of the slowly rotating SAURON ellipticals and their observed trend of \delta with \epsilon .
The numerical simulations indicate that the SAURON relation might be a result of strong violent relaxation and phase mixing of multiple , kinematically cold stellar subunits with the angular momentum of the system determining its location on the relation .