Narrow Results

We introduce Probing Radio Intensity at high-Z from Marion (PRI^ZM), a new experiment designed to measure the globally averaged sky brightness, including the expected redshifted 21cm neutral hydrogen absorption feature arising from the formation of the first stars. PRI^ZM consists of two dual-polarization antennas operating at central frequencies of 70 and 100MHz, and the experiment is located on Marion Island in the sub-Antarctic. We describe the initial design and configuration of the PRI^ZM instrument that was installed in 2017, and we present preliminary data that demonstrate that Marion Island offers an exceptionally clean observing environment, with essentially no visible contamination within the FM band.

Measurements of redshifted 21cm emission of neutral hydrogen at $\lesssim 30$MHz have the potential to probe the cosmic “dark ages,” a period of the universe’s history that remains unobserved to date. Observations at these frequencies are exceptionally challenging because of bright Galactic foregrounds, ionospheric contamination, and terrestrial radio-frequency interference. Very few sky maps exist at $\lesssim 30$MHz, and most have modest resolution. We introduce the Array of Long Baseline Antennas for Taking Radio Observations from the Sub-Antarctic (ALBATROS), a new experiment that aims to image low-frequency Galactic emission with an order-of-magnitude improvement in resolution over existing data. The ALBATROS array will consist of antenna stations that operate autonomously, each recording baseband data that will be interferometrically combined offline. The array will be installed on Marion Island and will ultimately comprise 10 stations, with an operating frequency range of 1.2–125MHz and maximum baseline lengths of $\sim 20$km. We present the ALBATROS instrument design and discuss pathfinder observations that were taken from Marion Island during 2018–2019.