A key science project for SKA-Low is the interferometer imaging of spatio-temporal fluctuations in the hydrogen ionization fraction and spin temperature as a diagnostic of cosmic dawn (CD) and epoch of reionization (EoR) in the redshift range $6 \lesssim z \lesssim 28$. However, detection of the global CD/EoR signal, which provides the differential HI 21-cm brightness temperature with respect to the background radiation temperature, is outside the current purview of SKA-Low observing in interferometer mode. This global CD/EoR signal can provide the critical zero-spacing measurement vital for establishing the base level of fluctuations measured by SKA-Low interferometers. We present here, a concept to detect the global CD/EoR signal as a supplement to the CD/EoR key science of SKA-Low. This would be enabled by adding a compact array of outrigger antennas interspersed between the core stations of SKA-Low. The autocorrelations of the outrigger antennas would form the measurement set for the global CD/EoR. The visibilities measured between outriggers and SKA stations would be `blind' to the global CD/EoR signal and would provide a Global Sky Model and calibration of the bandpass and mode-coupling in the primary beam of the outriggers. The global signal measurement capabilitywill strengthen the SKA-Low CD/EoR program.
Volume 44, 2023
Continuous Article Publishing mode
Since January 2016, the Journal of Astrophysics and Astronomy has moved to Continuous Article Publishing (CAP) mode. This means that each accepted article is being published immediately online with DOI and article citation ID with starting page number 1. Articles are also visible in Web of Science immediately. All these have helped shorten the publication time and have improved the visibility of the articles.
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