Possible Evidence for a Truncated Thin Disk in Seyfert 1 Galaxy NGC4593

Abstract

We compile the multi-band spectral energy distribution (SED) of Seyfert 1 galaxy NGC4593, and investigate its optical-to-ultraviolet (OUV) continuum and iron K\alpha line profile. No strong ``big blue bump'' is found in OUV band. The iron K\alpha line profile is not as broad as expected from a disk which extends down to the last stable orbit. Both of them can be modeled by a truncated thin disk, and support the existence of a truncated thin disk in the system. It is of much interest that NGC4593 may be a typical object with an accretion rate \dot{m}=\dot{M}/M_{Edd} \sim 0.01-0.1 and harbors a two component accretion flow: an outer thin disk and an inner hot flow--possibly ADAF, analogous to the low and intermediate state of low mass X-ray binaries (LMXB).