Seminar: Interaction Signatures in Quantified HI Morphology of Galaxies

Interaction Signatures in Quantified HI Morphology of Galaxies

Presented by Benne Holwerda of the University of Cape Town

The upcoming new perspective of the high redshift Universe in the 21 cm line of atomic hydrogen opens possibilities to explore topics of spiral disk evolution, hitherto reserved for other wavelengths: the interaction fraction and rate of galaxies over cosmic times.

Morphology of disks is quantified over Cosmic time using star-formation dominated wavelengths. In studies of deep Hubble Space Telescope fields, the rest-frame optical or UV morphology of high-redshift objects have been characterised using a few quantities: concentration (C), asymmetry (A), smoothness (S), second-order-moment (M20), the GINI coefficient (G), and Ellipticity (E).

I will present these parameters for the The HI Nearby Galaxy Survey (THINGS) and the Westerborg HI Spiral Project (WHISP). We used the multi-wavelength data to compare the morphology of star-formation to that of HI. I will discuss the suitability of HI morphology to detect interaction and mergers. The future goal is to determine a merger rate in the local Universe with ASKAP, the distant Universe with MeerKAT and ultimately SKA.