Jet interactions with a giant molecular cloud in the Galactic centre and ejection of hypervelocity stars

¹ Institut d’Astrophysique de Paris, CNRS, 98bis bd Arago, 75014 Paris, France
² Department of Physics and Astronomy, The Johns Hopkins University Homewood Campus, Baltimore, MD 21218, USA
³ BIPAC, Department of Physics, University of Oxford, Oxford OX1 3RH, UK
e-mail: silk@astro.ox.ac.uk
⁴ INAF – Osservatorio Astrofisico di Catania, via S. Sofia 78, Catania, & Scuola Superiore di Catania, via Valdisavoia 9, 95123 Catania, Italy
⁵ Universität Heidelberg, Zentrum für Astronomie, Institut für Theoretische Astrophysik, Albert-Ueberle-Str. 2, 69120 Heidelberg, Germany
⁶ STScI, 3700 San Martin Drive, Baltimore, MD 21218, USA
⁷ Max-Planck Institut für extraterrestrische Physik, PO Box 1312, 85478 Garching, Germany
⁸ Excellence Cluster Universe, Technische Universität München, Boltzmannstrasse 2, 85748 Garching, Germany
⁹ Geneva Observatory, University of Geneva, 51 Chemin des Maillettes, 1290 Versoix, Switzerland

Received: 18 July 2012
Accepted: 29 August 2012

Abstract

The hypervelocity OB stars in the Milky Way Galaxy were ejected from the central regions some 10–100 million years ago. We argue that these stars, as well as many more abundant bound OB stars in the innermost few parsecs, were generated by the interactions of an AGN jet from the central black hole with a dense molecular cloud. Considerations of the associated energy and momentum injection have broader implications for the possible origin of the Fermi bubbles and for the enrichment of the intergalactic medium.