James Webb Space Telescope Feed Post

Harvard ADS: The Abundance and Properties of Barred Galaxies out to z \sim 4 Using \textit{JWST} CEERS Data

Paper abstract: We analyze \textit{JWST} CEERS NIRCam images to present {the first estimate} of the observed fraction and properties of bars out to z ~ 4. We analyze a sample of 1770 galaxies with stellar mass M_* > 10^{10} M_\odot at 0.5 <= z <= 4 and identify barred galaxies via ellipse fits and visual classification of both F200W and F444W images. Our results apply mainly to bars with projected semi-major axis a_{\rm bar} > 1.5 kpc (~ 2 \times PSF 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 when the Universe was ~ 13\% of its present age. At z~ 2-4, compared to our results, TNG50 simulations {predict} a significantly larger bar fraction due to a large population of small bars with a_{\rm bar} < 1.5 kpc {that we cannot robustly detect}. If such a population exists, the true bar fraction may be significantly higher than our results. At z \ge 1.5, many barred galaxies show nearby neighbors, suggesting bars may be tidally triggered. {From z ~ 4 to z ~ 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.