Radio light curves during the passage of cloud G2 near Sgr A*

Abstract

We calculate radio light curves produced by the bow shock that is likely to form in front of the G2 cloud when it penetrates the accretion disk of Sgr A∗ . The shock acceleration of the radioemitting electrons is captured self-consistently by means of first-principles particle-in-cell simulations. We show that the radio luminosity is expected to reach maximum in early 2013, roughly a month after the bow shock crosses the orbit pericenter. We estimate the peak radio flux at 1.4 GHz to be 1.4 − 22 Jy depending on the assumed orbit orientation and parameters. We show that the most promising frequencies for radio observations are in the 0.1 < ν < 1 GHz range, for which the bow shock emission will be much stronger than the intrinsic radio flux for all the models considered.