We study a two-dimensional dilaton gravity model related by a conformal transformation of the metric to the Callan-Giddings-Harvey-Strominger model. We find that most of the features and problems of the latter can be simply understood in terms of the class

Of course,the nonvanishing value of the mass is due to the contribution of the dilaton, which cannot be separated from that of the metric.

The temperature at the horizon of the metric(5)can be easily obtained and is inde-pendent of c.Its value is given by

λ

T=

ln(2λr−c).

2λ

Notice that the boundary at r=0is not visible in these coordinates if c>0,since they cover only the region of the black hole spacetime outside the horizon at r=c/2λ.

Once the interpretation of solution(5)as a black hole has been established,at the semiclassical level one would naively expect this black hole to evaporate.The emergence of the Hawking radiation in our simple two-dimensional gravity model is however a point which deserves a careful study.Indeed conformal anomaly arguments have been used to argue that,being the space everywhereflat,there is no Hawking radiation in this model [3].In the following we will demonstrate,using standard quantization techniques,that the semiclassical dynamics of the black holes naturally gives rise to particle creation with

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