Vol 19, No 6 (2019) / Chen

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The morphology, kinematics and metallicity of blue-core galaxies

Yong-Yun Chen, Yan-Mei Chen, Qiu-Sheng Gu, Yong Shi, Long-Ji Bing, Xiao-Ling Yu

Abstract

We select 107 blue-core galaxies from the MaNGA survey, studying their morphology, kinematics as well as the gas-phase metallicity. Our results are as follows: (i) In our sample, 26% of blue-core galaxies have decoupled gas-star kinematics, indicating external gas accretion; 15% have bar-like structure and 8% show post-merger features, such as tidal tails and irregular gas/star velocity field. All these processes/features, such as accreting external misaligned gas, interaction and bar, can trigger gas inflow. Thus the central star-forming activities lead to bluer colors in their centers (blue-core galaxies). (ii) By comparing with the SDSS DR7 star-forming galaxy sample, we find that the blue-core galaxies have higher central gas-phase metallicity than what is predicted by the local mass-metallicity relation. We explore the origin of the higher metallicity, finding that not only the blue-core galaxies, but also the flat-gradient and red-core galaxies all have higher metallicity. This can be explained by the combined effect of redshift and galaxy color.

Keywords


galaxies: abundances — galaxies: formation — galaxies: structure

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DOI: https://doi.org/10.1088/1674–4527/19/6/81

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