[1] Univ Portsmouth, Inst Cosmol & Gravitat, Portsmouth PO1 3FX, Hants, England
[2] Univ Vienna, Dept Astrophys, Tuerkenschanzstr 17, A-1180 Vienna, Austria
[3] Heidelberg Univ, Inst Theoret Astrophys, Albert Ueberle Str 2, D-69120 Heidelberg, Germany
[4] Uppsala Univ, Dept Phys & Astron, Observat Astrophys, Box 516, SE-75120 Uppsala, Sweden
[5] Harvard Univ, Black Hole Initiat, Cambridge, MA 02138 USA
[6] Ctr Astrophys Harvard & Smithsonian, Cambridge, MA 02138 USA
[7] Univ Copenhagen, Niels Bohr Inst, DARK, Lyngbyvej 2, DK-2100 Copenhagen, Denmark