Radio jets from stellar tidal disruptions

Abstract

A star that passes too close to a massive black hole will be torn apart by tidal forces. The flare of photons emitted during the accretion of the stellar debris is predicted to be observable and candidates of such events have been observed at optical to X-ray frequencies. If a fraction of the accreted material is fed into a jet, tidal flares should be detectable at radio frequencies too, thus comprising a new class of rare radio transients. Using the well-established scaling between accretion power and jet luminosity and basic synchrotron theory, we construct an empirically-rooted model to predict the jet luminosity for a time-dependent accretion rate. We apply this model to stellar tidal disruptions and predict the snapshot rate of these events. For a small angle between the observer and the jet, our model reproduces the observed radio flux of the tidal flare candidate GRB 110328A. We find that future radio surveys will be able to test whether the majority of tidal disruptions are accompanied by a jet.Comment: Accepted for publication in MNRAS letter