The detectability of radio emission from exoplanets

TL;DR

This study estimates radio emission potential from known exoplanets, especially Hot Jupiters around young stars, and reports new observational limits using MWA and GMRT, advancing the search for detectable exoplanet radio signals.

Contribution

It provides updated predictions for exoplanet radio fluxes and frequencies, and presents the first low-frequency radio emission limits for V830 Tau b, a Hot Jupiter around a pre-main sequence star.

Findings

Hot Jupiters around young stars are most likely to produce observable radio emission.

New observational limits set at 200 MHz with MWA and GMRT.

First low-frequency radio emission limit reported for V830 Tau b.

Abstract

Like the magnetised planets in our Solar System, magnetised exoplanets should emit strongly at radio wavelengths. Radio emission directly traces the planetary magnetic fields and radio detections can place constraints on the physical parameters of these features. Large comparative studies of predicted radio emission characteristics for the known population of exoplanets help to identify what physical parameters could be key for producing bright, observable radio emission. Since the last comparative study, many thousands of exoplanets have been discovered. We report new estimates for the radio flux densities and maximum emission frequencies for the current population of known exoplanets orbiting pre-main sequence and main-sequence stars with spectral types F-M. The set of exoplanets predicted to produce observable radio emission are Hot Jupiters orbiting young stars. The youth of these system predicts strong stellar magnetic fields and/or dense winds, which are key for producing bright, observable radio emission. We use a new all-sky circular polarisation Murchison Widefield Array survey to place sensitive limits on 200 MHz emission from exoplanets, with $3\sigma$ values ranging from 4.0 - 45.0 mJy. Using a targeted Giant Metre Wave Radio Telescope observing campaign, we also report a $3\sigma$ upper limit of 4.5 mJy on the radio emission from V830 Tau b, the first Hot Jupiter to be discovered orbiting a pre-main sequence star. Our limit is the first to be reported for the low-frequency radio emission from this source.