A Search for Narrowband Technosignatures from LTT 3780 with the Allen Telescope Array and the Karl G. Jansky Very Large Array

Journal article

The LTT 3780 system hosts two known exoplanets—LTT 3780 b, a rocky super-Earth, and LTT 3780 c, a temperate sub-Neptune—orbiting a nearby M dwarf on opposite sides of the radius valley. LTT 3780 c has been proposed as a candidate Hycean world, making the system an important target for astrobiological investigation, particularly in light of recent JWST atmospheric observations. Although biosignature and technosignature searches both seek evidence of life beyond Earth, these approaches have historically been pursued independently. Well-characterized exoplanet systems provide an opportunity to combine these complementary search strategies. In this work, we conducted radio technosignature observations of the LTT 3780 system using both the Allen Telescope Array and the Karl G. Jansky Very Large Array (VLA). The two facilities provide complementary observational capabilities, with the ATA optimized for wide-band multibeam postprocessing analyses and the VLA enabling high-sensitivity real-time interferometric searches. Across ∼30 hr of total observing time, we searched for narrowband Doppler-drifting signals in the frequency range ∼1–10 GHz. After applying comprehensive radio-frequency interference mitigation and multibeam consistency tests, no candidate signals consistent with astrophysical or technosignature origins were identified. We place minimum detectable effective isotropic radiated power limits of 4.7 × 1012–3.6 × 1013 W across the observed bands and facilities. Although no technosignatures were detected, this work demonstrates how complementary observation and analysis strategies can be applied to exoplanets of astrobiological interest and serves as a pathfinder for future combined biosignature and technosignature investigations.

Authors: Tremblay, CD; Sheikh, SZ; Gajjar, V; Madhusudhan, N; Gerrard, I

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Astronomical Society
• Journal: The Astrophysical Journal Letters
• Volume: 1006
• Issue: 2
• Pages: L56-L56
• Publication date: 2026-07-28
• DOI: 10.3847/2041-8213/ae86f0
• EISSN: 2041-8213
• ISSN: 2041-8205
• Language: English
• Keywords: Microsaccade; Exoplanet; Pathfinder; Range (aeronautics); Jansky; Telescope; Narrowband