Compaction and quenching of high-z galaxies in cosmological simulations: blue and red nuggets

摘要: We use cosmological simulations to study a characteristic evolution pattern of high-redshift galaxies. Early, stream-fed, highly perturbed, gas-rich discs undergo phases dissipative contraction into compact, star-forming systems (‘blue’ nuggets) at z ∼ 4–2. The peak gas compaction marks the onset central depletion and inside-out quenching compact ellipticals (red by z ∼ 2. These are sometimes surrounded rings or grow extended dry stellar envelopes. occurs roughly constant specific star formation rate (SFR), surface density within inner kpc (Σ 1 ). Massive galaxies quench earlier, faster, higher Σ than lower mass galaxies, which compactify attempt more once. This is consistent with way populate SFR-size–mass space, gradients scatter across main sequence. triggered an intense inflow episode, involving (mostly minor) mergers, counter-rotating streams recycled gas, commonly associated violent disc instability. dissipative, >SFR, maximum anticorrelated initial spin parameter. high SFR stellar/supernova feedback (maybe also active galactic nucleus feedback) due density, while weakens as vanishes. Suppression fresh supply hot halo allows long-term maintenance once above threshold mass, inducing downsizing.