Seminarium Fizyki Wielkich Energii

The redshifted 21cm line of neutral hydrogen (HI), which can potentially be observed at low radio frequencies (~ 50-200 MHz), is a powerful probe of the physical conditions of the inter-galactic medium during Cosmic Dawn and the Epoch of Reionisation (EoR). The sky-averaged HI signal (global EoR) is expected to be extremely weak (of the order of 100 mK) in comparison to the foregrounds of up to 10000 K at the lowest frequencies. Moreover, the tiny signature of the EoR has to be identified amongst instrumental, ionospheric and other effects.BIGHORNS (Broadband Instrument for Global HydrOgen ReioNisation Signal) is a total power radiometer designed and build at Curtin University (Perth, Western Australia). In October 2014, the system with a conical log spiral antenna was permanently deployed at the Murchison Radio-astronomy Observatory (MRO), where it also monitors RFI at the future site of the low-frequency component of the Square Kilometre Array (SKA). I will present the BIGHORNS instrument and address the main challenges of the global EoR measurements. I will also present results of 2014/2015 data analysis, which suggest that ionospheric effects and fluctuations are not fundamental impediments preventing ground-based instruments from integrating down to the precision required by global EoR experiments. Finally, I will give a brief overview of other SKA-low activities in Western Australia.