XMM-Newton Detection of a Compton-thick AGN in the 1-Jy ULIRG/LINER F04103-2838

We report on the detection of Fe Kalpha emission in F04103$-$2838, an ultraluminous infrared galaxy (ULIRG; log[L${}_{\mathrm{I}\mathrm{R}}$/L${}_{\odot }$] $\ge$ 12) that is optically classified as a LINER. Previous {\it Chandra} observations suggested the presence of both a starburst and an AGN in this source. A deeper ($\sim$20 ksec) {\it XMM-Newton} spectrum reveals an Fe Kalpha line at rest frame energy $\sim$6.4 keV, consistent with cold neutral iron. The best-fit spectral model indicates the Fe Kalpha line has an equivalent width of $\sim$1.6 keV. The hard X-ray emission is dominated by a Compton-thick AGN with intrinsic 0.2–10 keV luminosity $\sim {10}^{44}$ ergs s${}^{-1}$, while the soft X-ray emission is from $\sim$0.1 keV gas attributed to the starburst. The X-ray spectrum of this source bears a striking resemblance to that of the archetypal luminous infrared galaxy NGC 6240 despite differences in merger state and infrared properties.