Formation of galactic bulges from the cold gas filaments in high-redshift dark matter haloes

ABSTRACT Formation process(es) of galactic bulges are not yet clarified, although several mechanisms have been proposed. In a previous study, we suggested one possibility that formed from the cold gas inflowing through surrounding hot halo in massive dark matter haloes at high redshifts. It was shown this scenario leads to bulge-to-total stellar mass ratio increasing with galaxy mass, agreement well-known observed trend. We here indicate it also reproduces recent observational results mean age bulge increases while gradient across decreases. infer formation path applies mainly high-mass galaxies and lower different origins such as secular disc material.