Isolating broad-band radio technosignatures (BRaTs): a framework for detecting planetary-scale leakage

Monthly Notices of the Royal Astronomical Society, vol. 549

Abstract

ABSTRACT The search for extraterrestrial intelligence (SETI) has traditionally focused on the detection of narrowband electromagnetic beacons. However, terrestrial technology is increasingly evolving towards distributed, low-power, wideband digital infrastructure. The strict adherence to narrowband filtering that characterizes most SETI surveys, therefore, risks discarding the aggregate leakage signatures of advanced civilizations by systematically misclassifying them as unstructured noise. We investigate the feasibility of detecting such planetary-scale broad-band radio technosignatures using a hierarchical observational framework. In this tiered approach, wide-field radio surveys conducted by next-generation arrays (such as the Square Kilometre Array and its precursors) perform the initial deep-field observations, with targeted Very Long Baseline Interferometry providing the definitive, high-resolution follow-up. Because broad-band continuum emission is largely insensitive to Doppler drift, long-duration ‘SETI Deep Fields’ are observationally viable, extending the accessible detection volume for Kardashev Type I leakage to ${\sim} 100$ pc. To distinguish these signals from other astrophysical confounders, a multiparameter diagnostic framework is proposed. Candidate technosignatures are identified through a convergence of high brightness temperatures, negligible circular polarization, spectral non-uniformity, interstellar scintillation, and sub-milliarcsecond astrometric co-motion with nearby Galactic stars/exoplanets.

Authors 1

1. Michael A Garrett corresponding Aachen Leiden Observatory

   Leiden University · University of Manchester · Leiden Observatory · University of Malta

   Affiliation as printed

   Institute of Space Sciences and Astronomy, University of Malta , Msida MSD2080 ,

   Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, Alan Turing Building, University of Manchester , Oxford Road, Manchester, M13 9PL ,

   Leiden Observatory, Leiden University , P.O. Box 9513, NL-2300 RA Leiden ,