New black hole solutions in Brans-Dicke theory of gravity

An existence check of nontrivial, stationary axisymmetric black hole solutions in the Brans-Dicke theory of gravity in different directions from those of Penrose, Thorne and Dykla, and Hawking is performed. Namely, working directly with the known explicit spacetime solutions in Brans-Dicke theory, it is found that nontrivial Kerr-Newman-type black hole solutions different from general relativistic solutions could occur for the generic Brans-Dicke parameter values -5/2<~ω<-3/2. Finally, issues such as whether these new black holes carry scalar hair and can really arise in nature, and if they can, what the associated physical implications would be, are discussed carefully.