Barbado, L. C.Barceló, CarlosGaray Elizondo, Luis Javier2023-06-202023-06-202012-04-120264-938110.1088/0264-9381/29/7/075013https://hdl.handle.net/20.500.14352/44511©IOP Publishing Ltd. The authors want to thank an anonymous referee for some useful comments and suggestions. Financial support was provided by the Spanish MICINN through the projects FIS2008-06078-C03-01, FIS2008-06078-C03-03, FIS2011-30145-C03-01 and FIS2011-30145-C03-02 (with FEDER contribution), and by the Junta de Andalucía through the project FQM219.Given a field vacuum state in a black hole spacetime, this state can be analysed in terms of how it is perceived (in terms of particle content) by different observers. This can be done by means of the effective-temperature function introduced by Barcelo et al (2011 Phys. Rev. D 83 041501). In Barbado et al (2011 Class. Quantum Grav. 28 125021), this function was analysed in a case-by-case basis for a number of interesting situations. In this work, we find a general analytic expression for the effective-temperature function which, apart from the vacuum state choice, depends on the position, the local velocity and the acceleration of the specific observer. We give a clear physical interpretation of the quantities appearing in the expression, and illustrate its potentiality with a few examples.spajournal articlehttp://iopscience.iop.org/0264-9381/http://arxiv.org/pdf/1201.3820v2.pdfopen access51-73Astronomy & astrophysicsPhysicsmultidisciplinaryparticles & fieldsFísica-Modelos matemáticosFísica matemática