The evolution of the bar fraction and bar lengths in the last 12 billion years

Abstract

We investigate the evolution of the bar fraction and length using an extended JWST NIRCam imaging dataset of galaxies at $1\le z\le 4$. We assess the wavelength dependence of the bar fraction and bar length evolution by selecting a nearly mass-complete CEERS disc sample and performing visual classifications on the short (F200W) and long (F356W+F444W) wavelength channels. A similar bar fraction is observed for both samples, and combined, we find a declining bar fraction from $0.16_{-0.03}^{+0.03}$ to $0.07_{-0.01}^{+0.03}$ over the redshift range. No evolution in the F356W+F444W bar length is measured, with a mean of 3.6 kpc. A slight increase of $\sim 1$ kpc towards $z=1$ is measured in the F200W sample, with a mean of 2.9 kpc. We find that the correlation between bar length and galaxy mass, for massive galaxies at $z<1$, is unseen at $z>1$. By incorporating barred galaxies at $z<1$, we show that there is a modest increase in the bar length ($\approx 2$ kpc) towards $z=0$, but bars longer than $\approx 8$ kpc are only found at $z<1$. We show that bars and discs grow in tandem, for the bar length normalised by disc size does not evolve. Not only is a significant population of bars forming beyond $z=1$, but our results also show that some of these bars are as long and strong as the average bar at $z\approx 0$.

18 pages, 12 figures. Accepted in MNRAS