Comments on Accretion of Phantom Fields by Black Holes and the Generalized Second Law

Abstract

The thermodynamic properties of a phantom fluid and accretion by a black hole were recently revisited by Pereira (2008) and Lima et al. (2008). In order to keep positive both the entropy and the temperature, those authors assumed that the phantom fluid has a non null chemical potential. In this short not we will show that there is a flaw in their derivation of the thermodynamic state functions which invalidates their analysis and their conclusions concerning the accretion of a phantom fluid by a black hole.