2024A&A...685A..40S

Stellar population synthesis (SPS) is essential for understanding galaxy formation and evolution. However, the recent discovery of rotation-driven phenomena in star clusters warrants a review of uncertainties in SPS models caused by overlooked factors, including stellar rotation. In this study, we investigated the impact of rotation on SPS specifically using the PARSEC V2.0 rotation model and its implications for high-redshift galaxies with the JWST. Rotation enhances the ultraviolet (UV) flux for up to ∼400 Myr after the starburst, with the slope of UV increasing as the population becomes faster rotating and metal-poorer. Using the Prospector tool, we constructed simulated galaxies and deduce their properties associated with dust and star formation. Our results suggest that rapid rotation models result in a gradual UV slope up to 0.1 dex higher and an approximately 50% increase in dust attenuation for identical wide-band spectral energy distributions. Furthermore, we investigated biases if the stellar population was characterized by rapid rotation and demonstrate that accurate estimation can be achieved for rotation rates up to ω_i = 0.6. Accounting for the bias in the case of rapid rotation aligns specific star formation rates more closely with predictions from theoretical models. Notably, this also implies a slightly higher level of dust attenuation than previously anticipated, while still allowing for a “dust-free” interpretation of the galaxy. The impact of rapid rotation SPS models on the rest-UV luminosity function is found to be minimal. Overall, our findings have potentially important implications for comprehending dust attenuation and mass assembly history in the high-redshift Universe.