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Paper: The Millennium Simulation Compared to Observations of z ≈ 2 Galaxies
Volume: 419, Galaxy Evolution: Emerging Insights and Future Challenges
Page: 223
Authors: Genel, S.
Abstract: Recent observations of UV-/optically selected, massive star forming galaxies at z ≈ 2 indicate that their mass assembly and star formation history is dominated by continuous rapid gas accretion and internal secular evolution, rather than by major mergers. We use the Millennium Simulation to gain insights on these observations. We find that even for halos not undergoing major mergers the mass accretion rates are plausibly sufficient to account for the high star formation rates observed in z ≈ 2 disks. At the same time, the fraction of major mergers in the Millennium Simulation is sufficient to account for the submillimeter galaxies (SMGs), in support of observational evidence that these are major mergers. Following these populations in the simulation to z = 0, we find that subsequent mergers are not frequent enough to convert all z ≈ 2 turbulent disks into late-type galaxies. Therefore, internal evolution must play an important role in the evolution of a significant fraction of z ≈ 2 galaxies to z = 0.
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