Revision 1

Accepted · first revision · record

Title: When and how did galactic bars first form?
Plain: The James Webb Space Telescope has found bars in galaxies only two to three billion years after the Big Bang. It is not known whether bars form on their own in cooled-down disks or are triggered by collisions with other galaxies.
Precise: Determine the barred fraction of disk galaxies versus redshift up to $z \sim 3$ and the trigger of bar formation (internal disk instability once the disk is dynamically cold and dominant, or tidal interactions), including the dependence on the disk-to-halo mass ratio.
Settled by: A mass-complete JWST census of bars to $z \sim 3$ compared with cosmological simulations that resolve bar instability.
Kind: phenomenon
Answer type: mechanism
References: (empty)
Literature status: open
Status note: (empty)
Posed since: (empty)