English

How Bursty is Star Formation at z>5?

Astrophysics of Galaxies 2026-02-19 v1

Abstract

Motivated by observational evidence from JWST and theoretical results from cosmological simulations, we use a simple parametric, phenomenological model to test to what extent bursty star formation with standard Initial Mass Function, no continuous star formation, no mergers, \mr{and no dust} can account for the observed properties in the MUVM_{UV} vs MM_* plane of galaxies at redshifts z>5z>5. We find that the simplest model that fits the data has a quiescence period between bursts Δt100\Delta t \sim 100~Myrs and the stellar mass in each galaxy grows linearly as a function of time from z=12z=12 to z=5z=5 (i.e., repeated bursts in each galaxy produce approximately equal mass in stars). The distribution of burst masses across different galaxies follows a power-law dN/dMMαdN/dM_* \propto M_*^\alpha with slope α2\alpha \sim -2. At z>910z>9-10 the observed galaxy population typically had only one or two bursts of stars formation, hence the observed stellar masses at these redshifts (reaching M1010M_* \sim 10^{10}~M_\odot), roughly represent the distribution of masses formed in one burst.

Keywords

Cite

@article{arxiv.2602.16706,
  title  = {How Bursty is Star Formation at z>5?},
  author = {Massimo Stiavelli and Massimo Ricotti},
  journal= {arXiv preprint arXiv:2602.16706},
  year   = {2026}
}

Comments

7 pages, 4 figures, one table. Accepted for publication by ApJ