Michelle Cluver (Caltech)

The Nature and Nurture of a Starburst Supermassive HI Galaxy: HIZOA J0836-43 - Michelle Cluver Colloquium

ATNF Marsfield Lecture Theatre

Abstract

HIZOA J0836-43 is a remarkable and enigmatic spiral galaxy hidden behind the Vela region of the Milky Way. Discovered as part of a
systematic HI survey of the southern Zone of Avoidance, the enormous
HI (7.5 x 10^10 M_odot) and dynamical mass in its extended disk revealed it to be one of the most massive HI galaxies ever found, but unlike other Malin 1-type galaxies is not low surface brightness.

In an effort to probe the origin and nature of this intriguing galaxy,
we have undertaken a mid-infrared study of the galaxy and its environment using the Spitzer Space Telescope. High resolution spatial
imaging and spectroscopy have revealed a luminous infrared galaxy (LIRG) suggesting a recent burst that is triggered by gas funneling down into the nuclear region. The galaxy has a star formation rate of 21 M_odot/yr, but exhibits unusual properties compared to other starforming galaxies.

The PAH emission of HIZOA J0836-43, compared to its stellar light distribution, suggests extended star formation in the disk. Compared to local galaxies, the galaxy appears to be a "scaled-up" spiral
undergoing inside-out galaxy formation, possibly resembling stellar disk building processes at intermediate redshifts. We shall also discuss the relevance of recent MOPRA observations in understanding the star formation mechanism taking place in HIZOA J0836-43.