The Murchison Widefield Array – Epoch of Reionisation Project

Inyarrimanha Ilgari Bundara, CSIRO’s Murchison Radio-astronomy Observatory, hosts a low frequency radio telescope in the Western Australian desert. Operating between 80 and 300 MHz, the Murchison Widefield Array (MWA) explores many scientific questions. The MWA will search for signals from neutral hydrogen that resides between galaxies in the first billion years of the Universe. During this crucial evolutionary period, entitled the Epoch of Reionisation (EoR), the first stars and galaxies in our Universe were born, completing our understanding of the full history of the Universe.

The hydrogen signal encodes key information about the spatial location and evolution of these first astrophysical objects, but its detection remains elusive due to the weakness of the signal compared with the foreground radio sky, and the complexity of the instrumental measurement.

The ASTRO 3D EoR program, led by CIs Cathryn Trott and Rachel Webster, will provide new measurements of this period of the Universe. Utilising the upgraded MWA, in which additional receiving stations have been added to enhance EoR science, and building on our growing knowledge of our instrument and foreground sky, we will firstly re-process the existing four years of MWA data, building a quality database to triage the cleanest data from the most contaminated.

Telescope Upgrade

To achieve an EoR signal detection, the team has further refined our understanding of the MWA telescope. They have improved their knowledge of its response to the sky and its behaviour over different observing frequencies. In tandem with this, we have developed new tools to understand how to treat the data, including improving their ability to calibrate the telescope and remove the foreground sky, taking advantage of the new receiving stations optimised for EoR science.

In addition, the extra sensitivity and capabilities of the upgraded MWA have afforded improved models for the bright extended radio galaxies that contaminate their data. These advances have led to improvements in the limits that can be placed on the magnitude of the signal.

Improving data

During 2018, the team processed all of the highest-quality data observed over four years to create a database of data quality metrics. Utilising this database, they were able to choose the cleanest data with which to pursue this weak cosmological signal.

MWA-EOR PROJECT leadership

Cathryn Trott
Cathryn TrottChief Investigator
Rachel Webster
Rachel WebsterChief Investigator

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