Vol 24, No 1

H i in High Gas-phase Metallicity Dwarf Galaxy WISEA J230615.06+143927.9

Yan Guo, C. Sengupta, T. C. Scott, P. Lagos and Y. Luo


We present resolved Giant Metrewave Radio Telescope H i observations of the high gas-phase metallicity dwarf galaxy WISEA J230615.06+143927.9 (z = 0.005) (hereafter J2306) and investigate whether it could be a Tidal Dwarf Galaxy (TDG) candidate. TDGs are observed to have higher metallicities than normal dwarfs. J2306 has an unusual combination of a blue g − r color of 0.23 mag, irregular optical morphology and high-metallicity (12 + log(O/H) = 8.68 ± 0.14), making it an interesting galaxy to study in more detail. We find J2306 to be an H i rich galaxy with a large extended, unperturbed rotating H i disk. Using our H i data we estimated its dynamical mass and found the galaxy to be dark matter (DM) dominated within its H i radius. The quantity of DM, inferred from its dynamical mass, appears to rule out J2306 as an evolved TDG. A wide area environment search reveals J2306 to be isolated from any larger galaxies which could have been the source of its high gas metallicity. Additionally, the H i morphology and kinematics of the galaxy show no indication of a recent merger to explain the high-metallicity. Further detailed optical spectroscopic observations of J2306 might provide an answer to how a seemingly ordinary irregular dwarf galaxy achieved such a high level of metal enrichment.


Key words: galaxies: abundances – galaxies: dwarf – galaxies: irregular – radio lines: galaxies – radio lines: ISM

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