X-Ray Emission of the gamma-ray-loud Young Radio Galaxy NGC 3894

The radio source 1146+596 is hosted by the elliptical/S0 galaxy NGC 3894, with a low-luminosity active nucleus. The radio structure is compact, suggesting a very young age for the jets in the system. Recently, the source has been confirmed as a high-energy (HE; >0.1 GeV) gamma-ray emitter in the most recent accumulation of Fermi Large Area Telescope data. Here we report on the analysis of the archival Chandra X-ray Observatory data for the central part of the galaxy, consisting of a single 40 ks long exposure. We have found that the core spectrum is best fitted by a combination of an ionized thermal plasma with a temperature of similar or equal to 0.8 keV, and a moderately absorbed power-law component (photon index Gamma = 1.4 +/- 0.4, hydrogen column density N-H/10(22) cm(-2) = 2.4 +/- 0.7). We have also detected the iron K alpha line at 6.5 +/- 0.1 keV, with a large equivalent width of 1.0(-0.5)(+0.9) keV. Based on the simulations of Chandra's point-spread function, we have concluded that while the soft thermal component is extended on the scale of the galaxy host, the hard X-ray emission within the narrow photon energy range 6.0-7.0 keV originates within the unresolved core (effectively the central kiloparsec radius). The line is therefore indicative of the X-ray reflection from a cold neutral gas in the central regions of NGC 3894. We discuss the implications of our findings in the context of the X-ray Baldwin effect. NGC 3894 is the first young radio galaxy detected in HE gamma-rays with the iron K alpha line.