Research Byte
Published in the RSAA Lunations
Vol1 Issue25 1–28 February 2022
Neutral hydrogen (HI) permeates the interstellar medium (ISM), making it a powerful tracer of galaxy kinematics, total gas content, and energy injection from feedback mechanisms that operate over a range of length scales. For example, expanding super shells seen in HI data reveal the influence that supernovae have on shaping the anatomy of the surrounding ISM on several hundred parsec scales.
The HI component of the Galactic ASKAP (GASKAP-HI) survey recently produced the most detailed and sensitive image of the HI associated with the Small Magellanic Cloud (SMC) ever achieved using the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope, a 36-element interferometer located at the Murchison Radio-astronomy Observatory in Western Australia. ASKAP possesses new phased array feed receivers, which expand the instantaneous field-of-view to a mammoth 30 square degrees by forming 36 simultaneous radio beams on the sky, making it the ideal instrument to efficiently map this key ingredient of the ISM across the entire southern sky.
But with new technology comes new data processing challenges. The GASKAP-HI team, led by Professor Naomi McClure-Griffiths and Dr. Nickolas Pingel, developed a unique processing pipeline that utilizes software originally developed for use on other world-class radio telescopes, such as the Low Frequency Array (LOFAR) in Europe and MeerKAT in South Africa, to successfully recover the HI emission that extend beyond the boundaries of multiple ASKAP beams. This pipeline was successfully deployed on RSAA’s own AVATAR cluster to produce this spectacular image of one of the Milky Way’s nearest neighboring galaxies.
This new image of the SMC enables us to connect the properties of HI over a continuous range of scales from 30 kpc down to 10 pc. The unprecedented angular and spectral resolution of these GASKAP-HI data provides an unequivocal view of the nearby HI associated with the detailed structures observed in the dust and molecular gas. For the first time, these data allow us to truly characterize the multi-phase make up of the ISM and facilitate the study of how HI contributes to the conditions necessary for star formation.
Nick Pingel
