The Lyman break analogue Haro 11: spatially resolved chemodynamics with VLT FLAMES

James, B. L.; Tsamis, Y.G.; Walsh, J. R.; Barlow, M. J. and Westmoquette, M. S. (2013). The Lyman break analogue Haro 11: spatially resolved chemodynamics with VLT FLAMES. Monthly Notices of the Royal Astronomical Society, 430(3) pp. 2097–2112.

DOI: https://doi.org/10.1093/mnras/stt034

Abstract

Using VLT/Fibre Large Array Multi Element Spectrograph (FLAMES) optical integral field unit observations, we present the first spatially resolved spectroscopic study of the well-known blue compact galaxy Haro 11, thought to be a local analogue to high-redshift Lyman break galaxies. Haro 11 displays complex emission line profiles, consisting of narrow (full width at half-maximum, FWHM ≲ 200 km s-1) and broad (FWHM ∼ 200–300 km s-1) components. We identify three distinct emission knots kinematically connected to one another. A chemodynamical analysis is presented, revealing that spatially resolved ionic and elemental abundances do not agree with those derived from integrated spectra across the galaxy. We conclude that this is almost certainly due to the surface brightness weighting of electron temperature in integrated spectra, leading to higher derived abundances. We find that the eastern knot has a low gas density, but a higher temperature (by ∼4000 K) and consequently an oxygen abundance ∼0.4 dex lower than the neighbouring regions. A region of enhanced N/O is found specifically in Knot C, confirming previous studies that found anomalously high N/O ratios in this system. Maps of the Wolf–Rayet (WR) feature at 4686 Å reveal large WR populations (∼900–1500 stars) in Knots A and B. The lack of WR stars in Knot C combined with an age of ∼7.4 Myr suggests that a recently completed WR phase may be responsible for the observed N/O excess. Conversely, the absence of N-enriched gas and strong WR emission in Knots A and B suggests that we are observing these regions at an epoch where stellar ejecta has yet to cool and mix with the interstellar medium.

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