One stage to go before Australia’s ASKAP begins full survey science

The ASKAP radio telescope delivered new insights into our Universe even while it was being developed. A final phase of pilot surveys will provide a thorough test of all operations involved in this 36-antenna, multi-beam SKA precursor to ensure many more intergalactic discoveries are made.

Nine survey science teams, consisting of 739 astronomers from 208 institutions around the world, have been exploring the cosmos while assessing the telescope’s capabilities. The test data, processed at the Pawsey Supercomputing Research Centre in Perth, Western Australia, has been incredibly informative. ASKAP, owned and operated by Australia’s national science agency, CSIRO, has already localised fast radio bursts, revealed odd radio circles and discovered one million new galaxies.

More highly anticipated results from the initial phase of pilot surveys are currently being released.

The Evolutionary Map of the Universe (EMU) team conducted the largest ever radio survey at the high sensitivities ASKAP enables. Their next surveys will exceed that record and the full survey is predicted to generate a catalogue of 70 million galaxies. In their survey, EMU discovered many peculiar radio sources, including one nicknamed ‘dancing ghosts’. Among the flowing forms are two radio galaxies whose weird shapes are not easily explained by existing models.

A new paper from the ASKAP Variables and Slow Transients (VAST) survey team reports the discovery of a highly polarised, highly-variable, steep spectrum radio source near the centre of our galaxy. Having also demonstrated ASKAP’s capabilities in detecting variable objects like pulsars and galactic nuclei, they will use this next stage to become even more efficient in crunching the data. Speed can be important, so that when massive flares are detected from nearby stars, other telescopes can be swung into position as soon as possible, to get a better look at the phenomena.

By pushing boundaries and uncovering challenges in the first pilot surveys, these final surveys provide a chance to overcome them. The WALLABY (Widefield ASKAP L-band Legacy Allsky Blind surveY) team, amongst their other surveys, has selected regions of the sky that are traditionally difficult to analyse. Bright radio quasars – though useful in other surveys – can result in imaging artefacts that inhibit the detection of fainter sources. The team will explore how best to deal with such sources in their data. ASKAP’s last pilot stage will help stream-line observations in preparation for the start of the full surveys early next year. And who knows what more will be discovered in the process?

by Rachel Rayner (CSIRO)

Dancing Ghosts - two radio galaxies detected in the EMU pilot survey

CREDIT: Jayanne English & Ray Norris,EMU/Dark Energy Survey