Using cosmological simulations, we address the interplay between structure and star formation in high-redshift galaxies via the evolution of surface density profiles. Our sample consists of 26 galaxies evolving in the redshift range z = 7 - 1, spanning the stellar mass range (0.2- 6.4) × 1010M⊙ at z = 2.We recover the main trends by stacking the profiles in accordance to their evolution phases. Following a wet compaction event that typically occurs when the stellar mass is ~109.5M⊙ at z ~ 2-4, the gas develops a cusp inside the effective radius, associated with a peak in star formation rate (SFR). The SFR peak and the associated feedback, in the absence of further gas inflow to the centre, marks the onset of gas depletion from the central 1 kpc, leading to quenching of the central SFR. An extended, star-forming ring that forms by fresh gas during the central quenching process shows as a rising specific SFR (sSFR) profile, which is interpreted as inside-out quenching. Before quenching, the stellar density profile grows self-similarly, maintaining its log-log shape because the sSFR is similar at all radii. During the quenching process, the stellar density saturates to a constant value, especially in the inner 1 kpc. The stellar mass and SFR profiles deduced from observations show very similar shapes, consistent with the scenario of wet compaction leading to inside-out quenching and the subsequent saturation of a dense stellar core. We predict a cuspy gas profile during the blue nugget phase, and a gas-depleted core, sometimes surrounded by a ring, in the post-blue nugget phase.
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The authors are thankful to the anonymous referee for her/his useful comments which improved our original manuscript. We acknowledge stimulating discussions with Guillermo Barro, Andi Burkert, Sandy Faber, John Forbes, Reinhard Genzel, David Koo, Mark Krumholz, Simon Lilly, Benny Trakhtenbrot, Joanna Woo and Adi Zolotov. Development and most of the analysis have been performed in the astro cluster at the Hebrew University. The simulations were performed at the National Energy Research Scientific Computing Center (NERSC), Lawrence Berkeley National Laboratory, and at NASA Advanced Supercomputing (NAS) at NASA Ames Reserach Center. This work was supported byMINECO grant AYA2012- 32295, by ISF grant 24/12, by the I-CORE Program of the PBC, by ISF grant 1829/12, and by NSF grants AST-1010033 and AST- 1405962. We acknowledge support by the Swiss National Science Foundation.
© 2016 The Authors.
- Galaxies: evolution
- Galaxies: formation
- Galaxies: fundamental parameters
- Galaxies: high-redshift
- Galaxies: structure