Science with a lunar low-frequency array: from the dark ages of the Universe to nearby exoplanets

TL;DR

Lunar low-frequency radio arrays offer unique opportunities to study the universe's dark ages, exoplanets, and cosmic rays by overcoming Earth's ionospheric limitations, with detailed analysis of scientific potential, constraints, and feasibility.

Contribution

This paper reviews the scientific potential, constraints, and feasibility of lunar low-frequency radio arrays for groundbreaking astronomical observations.

Findings

Calculated resolution, sensitivity, and confusion limits for lunar arrays.

Identified scientific drivers like dark ages, reionization, and exoplanets.

Discussed constraints from interstellar medium and array design considerations.

Abstract

Low-frequency radio astronomy is limited by severe ionospheric distortions below 50 MHz and complete reflection of radio waves below 10-30 MHz. Shielding of man-made interference from long-range radio broadcasts, strong natural radio emission from the Earth's aurora, and the need for setting up a large distributed antenna array make the lunar far side a supreme location for a low-frequency radio array. A number of new scientific drivers for such an array, such as the study of the dark ages and epoch of reionization, exoplanets, and ultra-high energy cosmic rays, have emerged and need to be studied in greater detail. Here we review the scientific potential and requirements of these and other new scientific drivers and discuss the constraints for various lunar surface arrays. In particular we describe observability constraints imposed by the interstellar and interplanetary medium, calculate the achievable resolution, sensitivity, and confusion limit of a dipole array using general scaling laws, and apply them to various scientific questions. Whichever science is deemed most important, pathfinder arrays are needed to test the feasibility of these experiments in the not too distant future. Lunar low-frequency arrays are thus a timely option to consider, offering the potential for significant new insights into a wide range of today's crucial scientific topics. This would open up one of the last unexplored frequency domains in the electromagnetic spectrum.