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

TL;DR

This paper models the radio emission from the bow shock formed by the G2 cloud near Sgr A* using particle-in-cell simulations, predicting a peak in radio luminosity in early 2013 and identifying optimal observation frequencies.

Contribution

It provides the first self-consistent simulation-based prediction of radio light curves from the G2 cloud's bow shock near Sgr A*.

Findings

Radio luminosity peaks in early 2013, about a month after pericenter crossing.

Peak flux at 1.4 GHz ranges from 1.4 to 22 Jy depending on parameters.

Optimal observation frequencies are between 0.1 and 1 GHz, where emission exceeds intrinsic flux.

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 radio-emitting 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<nu<1 GHz range, for which the bow shock emission will be much stronger than the intrinsic radio flux for all the models considered.