Detecting stars at the galactic centre via synchrotron emission

Abstract

Stars orbiting within 1 arcsec of the supermassive black hole in the Galactic Centre, Sgr A∗, are notoriously difficult to detect due to obscuration by gas and dust. We show that some stars orbiting this region may be detectable via synchrotron emission. In such instances, a bow shock forms around the star and accelerates the electrons. We calculate that around the 10 GHz band (radio) and at 1014 Hz (infrared) the luminosity of a star orbiting the black hole is comparable to the luminosity of Sgr A∗. The strength of the synchrotron emission depends on a number of factors including the star's orbital velocity. Thus, the ideal time to observe the synchrotron flux is when the star is at pericentre. The star S2 will be ∼0.015 arcsec from Sgr A∗ in 2018, and is an excellent target to test our predictions.