Metallicity Gradient of Barred Galaxies with TYPHOON
First author: Qian-Hui Chen
Bars play an important role in mixing material in the inner regions of
galaxies and stimulating radial migration. Previous observations have found
evidence for the impact of a bar on metallicity gradients but the effect is
still inconclusive. We use the TYPHOON/PrISM survey to investigate the
metallicity gradients along and beyond the bar region across the entire
star-forming disk of five nearby galaxies. Using emission line diagrams to
identify star-forming spaxels, we recover the global metallicity gradients
ranging from -0.0162 to -0.073 dex/kpc with evidence that the galactic bars act
as an agent in affecting in-situ star formation as well as the motions of gas
and stars. We observe cases with a shallow-steep' metallicity radial profile, with evidence of the bar flattening the metallicity gradients inside the bar region (NGC~5068 and NGC~1566) and also note instances where the bar appears to drive a steeper metallicity gradient producing steep-shallow’ metallicity
profiles (NGC~1365 and NGC~1744). For NGC~2835, a `steep-shallow’ metallicity
gradient break occurs at a distance $\sim$ 4 times the bar radius, which is
more likely driven by gas accretion to the outskirt of the galaxy instead of
the bar. The variation of metallicity gradients around the bar region traces
the fluctuations of star formation rate surface density in NGC~1365, NGC~1566
and NGC~1744. A larger sample combined with hydrodynamical simulations is
required to further explore the diversity and the relative importance of
different ISM mixing mechanisms on the gas-phase metallicity gradients in local
galaxies.