The 128-tile MWA is able to detect the Epoch of Reionisation
The Murchison Widefield Array (MWA) is the low-frequency SKA precursor being built at the radio-quiet Murchison Radio-astronomy Observatory (MRO) in Western Australia and will be sensitive enough to pick up faint radio signals from the very early Universe. This era shortly after the Big Bang when cool atomic hydrogen gas was heated and ionised by the first light-emitting objects in the Universe, called the Epoch of Reionisation (EoR), is still poorly understood and as such is one of the MWA’s main science goals. A central core of 112 tiles (covering an area of approximately 1.5 square kilometres) yields an impressive field of view of approximately 40°, with short baselines and good conditions for calibrating and adjusting the instrument to overcome contaminating foreground signals from our own galaxy and distant galaxies.
A new publication by the MWA consortium, with lead author Adam Beardsley, a PhD student from the University of Washington, and a number of CAASTRO co-authors (“The EoR Sensitivity of the 128 Antenna Murchison Widefield Array”, accepted for publication in Monthly Notices of the Royal Astronomical Society - Letters), presents an estimate of the sensitivity of the MWA to the faint signals from the EoR. The researchers based their calculations on a neutral intergalactic medium and the standard model of cosmology (λ Cold Dark Matter), assuming an isotropic (i.e. uniform in all directions) distribution of matter in the Universe.
Taking a couple of restrictions on the MWA measurements into account, the team can characterise the “EoR window” in the power spectrum sensitivity. Depending on the amount of observation time obtained with the MWA (and assuming that the instrument stability is sufficiently good), the MWA is expected to be able to detect the EoR signal at a Signal-to-Noise level of up to 14.
A. P. Beardsley, B. J. Hazelton, M. F. Morales, W. Arcus, D. Barnes, G. Bernardi, J. D. Bowman, F. H. Briggs, J. D. Bunton, R. J. Cappallo, B. E. Corey, A. Deshpande, L. deSouza, D. Emrich, B. M. Gaensler, R. Goeke, L. J. Greenhill, D. Herne, J. N. Hewitt, M. Johnston-Hollitt, D. L. Kaplan, J. C. Kasper, B. B. Kincaid, R. Koenig, E. Kratzenberg, C. J. Lonsdale, M. J. Lynch, S. R. McWhirter, D. A. Mitchell, E. Morgan, D. Oberoi, S. M. Ord, J. Pathikulangara, T. Prabu, R. A. Remillard, A. E. E. Rogers, A. Roshi, J. E. Salah, R. J. Sault, N. Udaya Shankar, K. S. Srivani, J. Stevens, R. Subrahmanyan, S. J. Tingay, R. B. Wayth, M. Waterson, R. L. Webster, A. R. Whitney, A. Williams, C. L. Williams, J. S. B. Wyithe in MNRAS Letters 2012