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

TL;DR

This study uses VLT FLAMES to spatially resolve the chemodynamics of Haro 11, revealing complex emission profiles, distinct knots, and variations in chemical abundances, providing insights into local analogues of high-redshift galaxies.

Contribution

First spatially resolved spectroscopic analysis of Haro 11, showing detailed chemodynamical properties and highlighting differences from integrated spectra, advancing understanding of local Lyman Break Galaxy analogues.

Findings

Spatially resolved abundances differ from integrated spectra.

Eastern knot has lower oxygen abundance and higher temperature.

Knots A and B host large Wolf-Rayet populations.

Abstract

Using VLT/FLAMES optical integral field unit observations, we present the first spatially resolved spectroscopic study of the well known blue compact galaxy Haro11, thought to be a local analogue to high redshift Lyman Break Galaxies. Haro11 displays complex emission line profiles, consisting of narrow (FWHM<200 km/s) and broad (FWHM 200-300 km/s) 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 ~4,000 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 feature at 4686A 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 suggest 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 we are observing these regions at an epoch where stellar ejecta has yet to cool and mix with the ISM.