Absorption cross section and Hawking radiation in two-dimensional AdS black hole

We calculate the absorption coefficient of scalar field on the background of the two-dimensional AdS black hole, which is of relevance to Hawking radiation. For the massless scalar field, we find that there does not exist any massless radiation. electronic address:[email protected] electronic address:[email protected] electronic address:[email protected] 1 There has been much attention to the lower-dimensional black holes to study the final state of black holes at the end of evaporation [1,2] without encountering some complexities of realistic four-dimensional gravity. The evaporation of the black hole is essentially based on Hawking radiation [3]. The Hawking radiation of Callan-Giddings-HarveyStrominger(CGHS) model is given by the vacuum expectation value of energy-momentum tensors, which means that the black hole is no more black, instead, grey hole after quantization. Therefore the absorption coefficient [4,5] is less than one and the reflection coefficient should be nontrivial. On the other hand, two-dimensional anti-de Seitter(AdS2) geometry which has a constant curvature scalar appears in the CGHS model with the help of quantum back reaction of the geometry on a constant dilaton background [6,7], where the AdS2 black hole geometry is given by ds = − (