In Search of New Physics in the Dark Ages using Low Radio Frequency Arrays on the Moon’s Far Side

Recently, the Astro2020 Decadal Survey of Astronomy and Astrophysics released by the National Academy of Sciences declared “mapping of the Dark Ages and reionization era as both the discovery area for the next decade and as the likely future technique for measuring the initial conditions of the Universe.” The redshifted 21-cm line of neutral hydrogen offers the only known observational probe of the Dark Ages. It is the ideal epoch to test our fundamental models of physics and cosmology without the complicated astrophysics produced by stars and galaxies. However, this technique requires observations at VHF frequencies free from Earth’s ionospheric and anthropogenic contamination, necessitating a mission in space. Low radio frequency arrays of dipole antennas, operating below 50 MHz (z>27) from the radio-quiet far side of the Moon, can uniquely probe for new physics in this unexplored epoch to potentially unveil the nature of dark matter, dark energy, and inflation. Such arrays can measure the first structures in the Universe using the 21-cm 3D power spectra telling us, for example, about the characteristics of dark matter: Is it cold or warm? Does it decay or self-annihilate? Does it heat or cool the hydrogen in the Dark Ages? In this talk, we will describe design work on two radio arrays to investigate new physics in the Dark Ages. FARSIDE, identified as a candidate Probe mission in Astro2020, consists of 256 dipole antennas deployed by four single-axle rovers from a mid-sized lander currently under development for later this decade. A second lunar far side array called FarView has a design study underway funded by NASA’s Innovative Advanced Concepts (NIAC) program; it consists of 100,000 dipole elements that will be manufactured from lunar regolith on the Moon using molten regolith electrolysis and a vapor deposition manufacturing technology that could be deployed in the 2030s.