Evolution of bar-induced dark gaps in galaxy discs: evidence of strong bar-driven effects already at $z>2$

Abstract

The properties of stellar bars play a crucial role in determining the bar-driven secular evolution in disc galaxies. However, a systematic observational study of the evolution of several bar properties (such as strength and length) across cosmic time is largely missing. In this paper, using a sample of $625$ barred galaxies, taken from SDSS, HST COSMOS, and JWST CEERS surveys, we systematically investigate the evolution of bar properties over redshifts ($0.02\lesssim z<3$) by making a novel usage of dark gap (preferential light deficit along the bar minor axis) properties as a proxy for bar properties. We show that the dark gap strength ($\Delta {\mu }_{\max }$) exhibits a weak evolution, increasing from higher redshifts ($z\sim 2.5$) and slightly declining towards lower redshifts ($z<0.05$). Conversely, the extent of dark gaps ($R_{\mathrm{DG}},R_{\mathrm{dark}}$; normalised by bar length) decreases moderately from $z\ge 1.4$ and remains constant thereafter. Our results suggest that bar formation and the initial rapid growth phase occur before $z\sim 3$, followed by mild growth towards lower redshifts. We also find $R_{\mathrm{dark}}$ to be a better proxy (as compared to $R_{\mathrm{DG}}$) for estimating bar length, supporting earlier theoretical studies. Furthermore, the $\Delta {\mu }_{\max }$ shows a weak but statistically significant correlation with bar-to-total light ratio (Bar/T) and bar ellipticity (${\epsilon }_{\mathrm{bar}}$). Studies of the redshift evolution of bar properties over such an extensive redshift range as done here are instrumental in constraining the bar-driven evolution at early cosmic times.

12 pages, 13 figures (including appendices), accepted for publication in MNRAS