Logo Logo
Switch Language to German
Teklu, Adelheid F.; Remus, Rhea-Silvia; Dolag, Klaus; Burkert, Andreas (2017): The morphology-density relation: impact on the satellite fraction. In: Monthly Notices of the Royal Astronomical Society, Vol. 472, No. 4: pp. 4769-4785
Full text not available from 'Open Access LMU'.


In the past years several authors studied the abundance of satellites around galaxies in order to better estimate the halo masses of host galaxies. To investigate this connection, we analyse galaxies with M-star >= 10(10) M-circle dot from the hydrodynamical cosmological simulation 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 (DM) haloes of spheroidal galaxies are significantly more massive than those of disc galaxies at fixed M-star. We show that the density-morphology relation starts to build up at z similar to 2 and is independent of the star-formation properties of central galaxies. We conclude that environmental quenching is more important for satellites than for centrals. Our simulations indicate that conformity is already in place at z = 2, where formation redshift and current star formation rate (SFR) of central and satellite galaxies correlate. Centrals with low SFRs have formed earlier (at fixed M-star), while centrals with high SFR formed later, with typical formation redshifts well in agreement with 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 DM 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 DM haloes.