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We report results from a 2007 Suzaku observation of the Seyfert 1 AGN NGC4593. The narrow Fe K alpha emission line has a FWHM width ~4000 km/s,indicating emission from >~ 5000 Rg. There is no evidence for arelativistically broadened Fe K line, consistent with the presence of aradiatively efficient outer disk which is truncated or transitions to aninterior radiatively inefficient flow. The Suzaku observation caught the sourcein a low-flux state; compared to a 2002 XMM observation, the hard X-ray fluxdecreased by 3.6, while the Fe K alpha line intensity and width each roughlyhalved. Two model-dependent explanations for the changes in Fe line profile areexplored. In one, the Fe line width has decreased from ~10000 to ~4000 km/sfrom 2002 to 2007, suggesting that the thin disk truncation/transition radiushas increased from 1000-2000 to >~5000 Rg. However, there are indications fromother compact accreting systems that such truncation radii tend to beassociated only with accretion rates relative to Eddington much lower than thatof NGC 4593. In the second (preferred) model, the line profile in the XMMobservation consists of a time-invariant narrow component plus a broadcomponent originating from the inner part of the truncated disk (~300 Rg) whichhas responded to the drop in continuum flux. The Compton reflection componentstrength R is ~1.1, consistent with the measured Fe K alpha line total EQW withan Fe abundance 1.7 times solar. The modest soft excess has fallen by a factorof ~20 from 2002 to 2007, ruling out emission from a region 5 lt-yr in size.

A Suzaku Observation of NGC 4593: Illuminating the Truncated Disk