Isolating Broadband Radio Technosignatures (BRaTs): A Framework for Detecting Planetary-Scale Leakage

TL;DR

This paper proposes a hierarchical framework for detecting broadband radio technosignatures (BRaTs) from extraterrestrial civilizations, leveraging next-generation radio arrays and multi-parameter diagnostics to identify planetary-scale leakage signals.

Contribution

It introduces a novel tiered observational approach combining wide-field surveys and high-resolution follow-up to detect broadband leakage signals from distant civilizations.

Findings

Long-duration SETI Deep Fields can detect leakage up to 100 parsecs.

Multi-parameter diagnostics can distinguish technosignatures from astrophysical sources.

The framework enhances the detection volume for Kardashev Type I civilizations.

Abstract

The search for extraterrestrial intelligence (SETI) has traditionally focused on the detection of narrowband electromagnetic beacons. However, terrestrial technology is increasingly evolving toward distributed, low-power, wideband digital infrastructure. The strict adherence to narrowband filtering that characterises most SETI surveys, therefore, risks discarding the aggregate leakage signatures of advanced civilisations by systematically misclassifying them as unstructured noise. We investigate the feasibility of detecting such planetary-scale broadband radio technosignatures (BRaTs) using a hierarchical observational framework. In this tiered approach, wide-field radio surveys conducted by next-generation arrays (such as the SKA and its precursors) perform the initial deep-field observations, with targeted Very Long Baseline Interferometry (VLBI) providing the definitive, high-resolution follow-up. Because broadband 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 100 pc. To distinguish these signals from other astrophysical confounders, a multi-parameter diagnostic framework is proposed. Candidate technosignatures are identified through a convergence of high brightness temperatures, negligible circular polarisation, spectral non-uniformity, interstellar scintillation, and sub-milliarcsecond astrometric co-motion with nearby Galactic stars/exoplanets.