Volume 18 No 12 (2020)
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Feedback from Ionized Outflows Traced Across the Nearly Edge-on Disk of the Nearby Seyfert 2 Galaxy NGC 4945*
Hasanein A. Hamza, Ameerah Ab. Al-Sadooni, Jacco Th. Van Loon
Abstract
The aim of this work is to understand the impact of ionized outflows from H II regions in the nearby Seyfert 2 galaxy NGC4945. The study is based on long-slit optical spectra obtained at the Southern African large Telescope (SALT). The analysis focussed on recombination lines (Hα and Hβ) and forbidden lines ([N II]λλ6549,6583, [S II]λλ 6717,6731 and [O III] λλ4959,5007). The physical properties of 26 emission-line objects were determined from a diagnostic diagram. They are found to represent different physical environments normally encountered in supernova remnants, planetary nebulae (PNe) and classical HII regions, with electron densities varying between 16–3000 cm-3. Apart from tracing the galactic rotation, in some cases the line profiles show broadening or even line splitting – we take this as evidence that these regions will have an impact (feedback) onto the surrounding interstellar medium. The presentday chemical abundances were determined using the strong lines method (O3N2 and N2 indices). The oxygen abundances are constant between galactocentric distances of ~ 1–5 kpc, while the nitrogen abundance increases outwards.
Keywords
Galaxy: Formation, Evolution, Abundances, HII, Disc.
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