The formation and evolution of massive galaxies

The discovery of massive galaxies at high redshifts, especially the passive ones, poses a big challenge for the current standard galaxy formation models. Here we use the semi-analytic galaxy formation model developed by Henriques et al. to explore the formation and evolution of massive galaxies (MGs, stellar-mass M-* > 10(11) M-circle dot). Different from previous works, we focus on the ones just formed (e.g. just reach similar or equal to 10(11) M-circle dot). We find that most of the MGs are formed around z = 0.6, with the earliest formation at z > 4. Interestingly, although most of the MGs in the local Universe are passive, we find that only 13% of the MGs are quenched at the formation time. Most of the quenched MGs at formation already host a very massive supermassive black hole (SMBH) which could power the very effective AGN feedback. For the star-forming MGs, the ones with more massive SMBH prefer to quench in shorter timescales; in particular, those with M-SMBH > 10(7.5) M-circle dot have a quenching timescale of similar to 0.5 Gyr and the characteristic M-SMBH depends on the chosen stellar mass threshold in the definition of MGs as a result of their co-evolution. We also find that the "in-situ" star formation dominates the stellar mass growth of MGs until they are formed. Over the whole redshift range, we find the quiescent MGs prefer to stay in more massive dark matter halos, and have more massive SMBH and less cold gas masses. Our results provide a new angle on the whole life of the growth of MGs in the Universe.