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 MUV vs M∗ plane of galaxies at redshifts z>5. We find that the simplest model that fits the data has a quiescence period between bursts Δt∼100~Myrs and the stellar mass in each galaxy grows linearly as a function of time from z=12 to z=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/dM∗∝M∗α with slope α∼−2. At z>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 M∗∼1010~M⊙), roughly represent the distribution of masses formed in one burst.
@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