A JWST investigation of the evolution of the bar fraction at 1<z<3

Disc galaxies are thought to undergo two essential evolutionary phases: firstly, an unstable merging period, followed by internal secular evolution, thought to commence at z ≈ 1 and driven by the redistribution of angular momentum by a stellar bar. Therefore, the observed fraction of barred galaxies as a function of redshift provides crucial information on the onset and importance of secular evolution. However, it is well known that the fraction of bars in disc galaxies is underestimated by rest-frame optical and UV images because these wavelengths trace the younger stellar population. In contrast, stellar bars typically contain older stellar populations, which are more favourably imaged in the rest-frame near-infrared. The launch of JWST has provided us with the unique opportunity to study massive disc galaxies at higher redshifts with improved sensitivity and spatial resolution and at longer wavelengths than with HST. We will present a study of the bar fraction in the redshift range of 1 < z < 3 with imaging data from both JWST and HST. Stellar bars are significantly more apparent in the redder JWST NIRCam images than in the HST WFC3 images. Our results show that stellar bars exist already at z ≈ 2.5, which suggests that the secondary evolution phase could have begun only ≈ 2 Gyr after the Big Bang. Therefore, this calls for a review of our theories about when internal secular evolution began