In the past years several authors studied the abundance of satellites around galaxies in order to better estimate , for example , the halo masses of the host galaxies .
To investigate this connection , we analyze a sample of galaxies with stellar masses M _ { \mathrm { star } } \geq 10 ^ { 10 } M _ { \odot } , taken from the hydrodynamical cosmological simulation suit Magneticum .
We find that the satellite fraction of centrals is independent of their morphology .
With the exception of very massive galaxies at low redshift , our results do not support the assumption that the dark matter haloes of spheroidal galaxies are significantly more massive than those of disc galaxies at fixed stellar mass .
We show that the density-morphology-relation , i.e .
the correlation between the quiescent fraction of satellites and the environmental density , starts to build up at z \sim 2 and is independent of the star formation properties of the central galaxies .
We conclude that environmental quenching is more important for satellite galaxies than for centrals .
Our simulations also indicate that conformity is already in place at z = 2 , where formation redshift and current star formation rate ( SFR ) of central and satellite galaxies already clearly correlate .
Centrals with low SFRs tend to have formed earlier ( at fixed stellar mass ) while centrals with high SFR formed later , with a typical formation redshift well in agreement with current observations .
However , we confirm the recent observations that the apparent number of satellites of spheroidal galaxies is significantly larger than for disc galaxies .
This difference completely originates from the inclusion of companion galaxies , i.e .
galaxies that do not sit in the potential minimum of a massive dark matter halo .
Thus , due to the density-morphological-relation the number of satellites is not a good tracer for the halo mass , unless samples are restricted to the central galaxies of dark matter haloes only .