Foreground effects in the search for the Epoch of Reionisation

(originally published by Curtin Institute of Radio Astronomy)

Associate Professor Cathryn Trott showcases how the search for the Epoch of Reionisation (EoR) is affected by the presence of the Milky Way and other galaxies within an observation.

The EoR project is hunting for a weak signal from the early Universe. To detect this signal, parts of the sky that are free from emission from our own Galaxy and other nearby galaxies are observed.

The effect the Milky Way and other galaxies have on the power spectrum observations can be seen in the video below.

Video: Left: The power spectrum image, which breaks the radio observation into its component scale-structures. Right: The visible sky above the telescope for each observation, overlayed with the telescope’s beam pattern. 

The power spectrum is the generated diagram on the left of the video, showing the amount of signal power on different size scales on the sky.

When the observation passes over bright parts of the sky (e.g., the Galactic Anti-Center at RA = 8 hours – towards the end of the video), we can see the signal power increase.

These increases in power destroy an EoR observation, as they obscure the same scale-frequencies the EoR signal is expected occupy.

This information helps to define the observing fields for the EoR experiment and bring its detection closer.