Evolution of density profiles in high-z galaxies: Compaction and quenching inside-out

Sandro Tacchella*, Avishai Dekel, C. Marcella Carollo, Daniel Ceverino, Colin DeGraf, Sharon Lapiner, Nir Mandelker, Joel R. Primack

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

192 Scopus citations


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.

Original languageAmerican English
Pages (from-to)242-263
Number of pages22
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - 22 Feb 2016

Bibliographical note

Publisher Copyright:
© 2016 The Authors.


  • Galaxies: evolution
  • Galaxies: formation
  • Galaxies: fundamental parameters
  • Galaxies: high-redshift
  • Galaxies: structure


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