Speaker
Description
Maps of the gas-phase metallicity are presented for four nearby Seyfert galaxies selected from the optical S7 IFU survey, including the (obscured) narrow-line Seyfert 1 galaxy Mrk 573. We also measure the ionisation parameter, the hardness of the ionising continuum "E_peak", and the pressure across the large-scale extended narrow-line regions (ENLRs). These three parameters were constrained simultaneously with the metallicity using the new code NebulaBayes and a grid of photoionisation models. We observe metallicity gradients in a double ionisation cone, an inverse metallicity gradient, and in Mrk 573 we find a uniformly high metallicity. The near-constant ionisation parameters but steeply radially-declining pressures together imply that radiation pressure regulates the ISM density structure on large scales in all of the ENLRs in our sample. The peak of the ionising continuum, E_peak, is determined by the nuclear spectrum and the absorbing column between the nucleus and the observed nebula. Our measurements of E_peak cannot differentiate between variation in this intrinsic E_peak and spectral contamination by shock or HII-region emission. Nevertheless the E_peak measurements give insight into the excitation of the ENLRs, and the measurements could potentially be used to diagnose spectral contamination.
Motivation
I am a final-year PhD student. To attend the meeting I need to travel from Canberra, Australia, and the very large distance will result in expensive airfares. For these reasons the financial assistance of the grant would be very welcome.
| Grant | yes |
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