Soft X-ray properties of the Seyfert 1.8 galaxy NGC 3786

Abstract

An analysis of survey and pointed ROSAT PSPC observations of the Seyfert 1.8 galaxy NGC 3786 has revealed interesting spectral and temporal behaviour. The spectrum is found to show clear signs of excess absorption, and there is evidence that part (or all) of it is caused by the presence of a warm absorber. The soft X-ray spectral properties are discussed in the context of the Sy 1.8 classification of NGC 3786, and are combined with published optical data in an effort to discriminate between several possible absorption models. The one involving a warm absorber with internal dust, located between BLR and NLR, is favoured and shown to account successfully for the high observed broad line reddening as well as for the strong X-ray variability (a factor $\sim$ 10) we detect between the 1990 and 1992 observation.