Campanelli-Lousto and veiled spacetimes

Abstract

The Campanelli-Lousto solutions of Brans-Dicke theory, usually reported as black holes, are reconsidered and shown to describe, according to the values of a parameter, wormholes or naked singularities. The veiled Schwarzschild metric recently used as an example to discuss conformal frames and their equivalence corresponds to a special case of the Campanelli-Lousto metric. The conformal cousins of these solutions, and of the Riegert black hole solution of conformally invariant Weyl theory, are analyzed, leading to a word of caution when physically interpreting spacetimes generated via conformal transformations from known seed solutions.

Interpreting the conformal cousin of the Husain-Martinez-Nuñez spacetime

“…, a ' 0:1547, and  ¼ À 4 3 ' À1:1547 < À1) the Campanelli-Lousto spacetime contains a wormhole throat coinciding with an apparent horizon and located at r 0 ¼ 2Cð 1À 2 Þ > 2C [25]. This is consistent with Eq.…”

“…For a < 0 (which is reproduced by the choice ¼ À ffiffiffi 3 p =2 and gives a ' À2:1547 and  ' 1:1547 > 0) there are no apparent horizons and the spacetime contains a naked singularity [25]. This is consistent with the fact that Eq.…”

“…Indeed, there are comments in the literature about the fact that conformally related solutions of Brans-Dicke theory and of the Einstein equations do not share the same properties [32]. A similar situation occurs with the Campanelli-Lousto solutions of Brans-Dicke theory [24], which relate to Fisher-JanisNewman-Winicour solutions of the Einstein equations in the Einstein frame [25], and with the veiled black holes of Refs. [29][30][31] (see Ref.…”

“…[29][30][31] (see Ref. [25] for a detailed discussion). To conclude, the physical nature of the Clifton-Mota-Barrow class of solutions is now clear and they do not cause problems for the interpretation of conformal frames.…”

“…The nature of the Campanelli-Lousto spacetime depends on the sign of the parameter a [25] which, in our case, corresponds to the choice ¼ ffiffiffi…”