Abstract The Star-Forming Main Sequence (SFMS) serves as a critical framework for understanding galaxy evolution, highlighting the relationship between star formation rates (SFR) and stellar masses M* across cosmic time, for star forming galaxies. Despite its significance, the origin of the 0. 3-0. 4 dex dispersion in the SFMS remains a topic of debate. Uncovering the origin of dispersion is crucial for understanding the evolution of galaxies. Using a large sample of approximately 500, 000 galaxies, we reveal a set of clear and systematic symmetries in the distribution of key structural properties-effective radius (Re), stellar surface density (M_*/R ₄²), and morphology-on the SFMS. This symmetry implies that galaxies with high (above SFMS) and low (below SFMS) SFRs share similar fundamental parameters. Moreover, galaxies with smaller Re or higher M_/R ₄² exhibit greater dispersion in SFR. This dispersion reflects the response to fluctuations in cosmic accretion flows, while the SFR itself represents the time-averaged effect over the gas consumption timescale. Shorter gas consumption timescales, associated with higher M_/R ₄², lead to greater SFR dispersion. Our results reveal that the variation of SFR originates from the oscillation of accretion flow and is regulated by the stellar surface density.
He et al. (Wed,) studied this question.