BeppoSAX observations of Mkn 3: Piercing through the torus of a Seyfert 2 galaxy

A new BeppoSAX broad-band (0.6-150 keV) spectrum of the Seyfert 2 galaxy Mk n 3 is presented. The spectrum provides a direct measurement of a large, ne utral column of gas with N-H similar to 10(24) cm(-2) in the source directi on. The source, as bright as 3C 273 above 10 keV, has a steep (Gamma simila r to 1.8) spectrum without any evidence of a high-energy cutoff up to at le ast 150 keV. At lower energies, the data are best modeled with the addition of an unabsorbed reflection component. Combining these data with previous Ginga and ASCA observations, the Fe K-alpha and reflection continuum indica te that the reprocessed emission is responding slower than the intrinsic co ntinuum variations suggesting a size of the reprocessor greater than or sim ilar to 2 pc. Identifying such a reprocessor with a (close to edge-on) obsc uring torus, the overall result fits well into unified models since, presum ably, one can interpret the strong absorption as due to transmission throug h the rim of the torus and the unabsorbed (directly viewed) reflection comp onent as due to reprocessing from the torus inner surface.