The SAMI Galaxy Survey: The discovery of a luminous, low-metallicity HII complex in the dwarf galaxy GAMAJ141103.98-003242.3


S. N. Richards, A. L. Schaefer, A. R. Lopez-Sanchez, S. M. Croom, J. J. Bryant, S. M. Sweet, I. S. Konstantopoulos, J. T. Allen, J. Bland-Hawthorn, J. V. Bloom, S. Brough, L. M. R. Fogarty, M. Goodwin, A. W. Green, I.-T. Ho, L. J. Kewley, B. S. Koribalski, J. S. Lawrence, M. S. Owers, E. M. Sadler, R. Sharp


We present the discovery of a luminous unresolved H II complex on the edge of dwarf galaxy GAMA J141103.98-003242.3 using data from the Sydney-AAO Multi-object Integral field spectrograph (SAMI) Galaxy Survey. This dwarf galaxy is situated at a distance of ~100 Mpc and contains an unresolved region of H II emission that contributes ~70 per cent of the galaxy's $\mathrm{H}\alpha$ luminosity, located at the top end of established H II region luminosity functions. For the H II complex, we measure a star-formation rate of $0.147\pm0.041 \mathrm{M}_\odot\,\mathrm{yr}^{-1}$ and a metallicity of $12+log(O/H) = 8.01\pm0.05$ that is lower than the rest of the galaxy by $\sim 0.2$ dex. Data from the H I Parkes All-Sky Survey (HIPASS) indicate the likely presence of neutral hydrogen in the galaxy to potentially fuel ongoing and future star-forming events. We discuss various triggering mechanisms for the intense star-formation activity of this H II complex, where the kinematics of the ionised gas are well described by a rotating disc and do not show any features indicative of interactions. We show that SAMI is an ideal instrument to identify similar systems to GAMA J141103.98-003242.3, and the SAMI Galaxy Survey is likely to find many more of these systems to aid in the understanding of their formation and evolution.

This paper has been accepted by MNRAS on 08/10/2014. The MNRAS manuscript can be found below and the weblink is here:

Publication Date: 
October 2014