LoFreq-SETI: A Low-Frequency Technosignature Search Pipeline for the LWA Swarm

Abstract

The search for extraterrestrial intelligence (SETI) is conducted across the electromagnetic spectrum to understand the prevalence and distribution of intelligent life in the universe. At radio frequencies, this effort focuses on searching for "technosignatures", observable indicators of technological activity consistent with our understanding of an advanced civilization. Historically, the microwave regime from 1-10 GHz has been the primary frequency range searched for these technosignatures, but recent SETI experiments utilizing low-frequency radio telescopes, such as the Low Frequency Array (LOFAR), Murchison Widefield Array, and MeerKAT radio telescope have explored the insufficiently studied frequency range below 1 GHz. However, the lowest radio frequencies ($<$100 MHz) have been even less explored for technosignatures, despite significant human communication signals occupying this band. The Long Wavelength Array (LWA) is a low-frequency (3-88 MHz) interferometer array telescope collaboration comprised of dipole 'stations' distributed across the Southwestern United States, and the LWA Swarm is the aperture synthesis telescope consisting of interconnected LWA stations operating as a long baseline interferometer. Here we present a narrowband technosignature pipeline using the Breakthrough Listen Interesting Signal Search algorithm for raw beamformed single-station LWA data and outline its planned extension to correlated visibilities from the LWA Swarm. We demonstrate the pipeline on a limited selection of fast radio burst observations to evaluate the data processing and spatial coincidence filtering for a future observing campaign of exoplanet systems.