Can a satellite galaxy merger explain the active past of the galactic centre?

Abstract

Observations of the Galactic Centre (GC) have accumulated a multitude of 'forensic' evidence indicating that several million years ago the centre of the MilkyWay galaxy was teeming with star formation and accretion-powered activity - this paints a rather different picture from the GC as we understand it today. We examine a possibility that this epoch of activity could have been triggered by the infall of a satellite galaxy into the MilkyWay which began at the redshift of z = 8 and ended a few million years ago with a merger of the Galactic supermassive black hole with an intermediate-mass black hole brought in by the inspiralling satellite. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.