Quenched, bulge-dominated, but dynamically cold galaxies in IllustrisTNG and their real-world counterparts

ABSTRACT Galaxy morphologies, kinematics, and stellar populations are thought to be linked each other. However, both simulations observations have pointed out mismatches therein. In this work, we study the nature origin of present-day quenched, bulge-dominated, but dynamically cold galaxies within a mass range $10.3\, \leqslant \, \log M_{\ast }/\mathrm{M_{\odot }}\, 11.2$ in IllustrisTNG-100 Simulation. We compare these with population normal star-forming disc quenched hot elliptical same range. The bulge-dominated (both being hot) used significantly higher star formation rates flatter morphologies at redshift z ? 2. They experienced more frequent larger mass-ratio mergers below 0.7 comparison their counterparts, which is responsible for morphologies. forming quenched) prograde tangential especially 1, contrast ellipticals, had retrograde radial mergers. Such different merging histories can well explain differences on dynamical status among galaxies. point that real-world counterparts fast- slow-rotating early-type galaxies, respectively, as seen hence reveal evolution paths two distinct