The formation of bars in disk galaxies is a tracer of the dynamical maturity of thepopulation. Previous studies have found that the incidence of bars in disks decreasesfrom the local Universe to z ∼ 1, and by z > 1 simulations predict that bar featuresin dynamically mature disks should be extremely rare. Here we report the discoveryof strong barred structures in massive disk galaxies at z ∼ 1.5 in deep rest-frameoptical images from CANDELS. From within a sample of 876 disk galaxies identifiedby visual classification in Galaxy Zoo, we identify 123 barred galaxies. Selecting a sub-sample within the same region of the evolving galaxy luminosity function (brighterthan L), we find that the bar fraction across the redshift range 0.5 ≤ z ≤ 2 (fbar =10.7+6.3−3.5% after correcting for incompleteness) does not significantly evolve.We discussthe implications of this discovery in the context of existing simulations and our currentunderstanding of the way disk galaxies have evolved over the last 11 billion years.
- ST/J500665/1 and ST/K502236/1 and ST/I001204/1