A Pilot Radio Search for Magnetic Activity in Directly Imaged Exoplanets

TL;DR

This study conducted the first systematic GHz radio search for directly imaged exoplanets using VLA, setting upper limits on their radio emission, and emphasizing the need for more sensitive future observations.

Contribution

It provides the first systematic radio emission upper limits for directly imaged exoplanets, demonstrating the feasibility and challenges of such observations.

Findings

No radio emission detected from the five exoplanet systems.

Luminosity upper limits are comparable to ultracool dwarfs.

Highlights the need for more sensitive GHz radio observations.

Abstract

We present the first systematic search for GHz frequency radio emission from directly imaged exoplanets using Very Large Array (VLA) observations of sufficient angular resolution to separate the planets from their host stars. We obtained results for five systems and eight exoplanets located at $\lesssim 50$ pc, through new observations (Ross 458, GU Psc, and 51 Eri) and archival data (GJ 504 and HR 8799). We do not detect radio emission from any of the exoplanets, with $3\sigma$ luminosity upper limits of $(0.9-23)\times10^{21}$ erg s$^{-1}$. These limits are comparable to the level of radio emission detected in several ultracool dwarfs, including T dwarfs, whose masses are only a factor of two times higher than those of the directly-imaged exoplanets. Despite the lack of detections in this pilot study, we highlight the need for continued GHz frequency radio observations of nearby exoplanets at $\mu$Jy-level sensitivity.