SIMBAD references

We present the first estimate of the observed fraction and properties of bars out to z ∼ 4 using JWST CEERS NIRCam images. We analyze 1770 galaxies with M_⋆ > 10¹⁰M_⊙ at 0.5 ≤ z ≤ 4 and identify barred galaxies from 839 moderately inclined disk galaxies via ellipse fits and visual classification of both F200W and F444W images. Our results apply mainly to bars with projected semimajor axis a_bar > 1.5 kpc (∼2× point-spread function in F200W images) that can be robustly traced by ellipse fits. For such bars, the observed bar fraction at z ∼ 2-4 is low (≲10%), and they appear to be emerging at least as early as z ∼ 4. Our observed bar fraction at z ∼ 0.5-4 is consistent with the bar fraction predicted by TNG50 simulations for large bars with a_bar > 1.5 kpc at z ∼ 0.5-4 and with the bar fraction from Auriga simulations out to z ∼ 1.5. However, TNG50 simulations predict a large population of smaller bars that our data cannot robustly detect. If such bars exist, the true bar fraction at z ∼ 2-4 may be significantly higher than our results. At z ≥ 1.5, many barred galaxies show nearby neighbors, suggesting bars may be tidally triggered. From z ∼ 4 to 0.5, the observed bar fraction, average projected bar length, and projected bar strength rise. Our results highlight the early emergence and evolution of barred galaxies and the rising importance of bar-driven secular evolution from z ∼ 4 to today.