Detection of an Iron K Emission Line from the LINER NGC 4579

We present the results of an ASCA observation of the LINER NGC 4579. A pointlike X-ray source is detected at the nucleus with a 2-10 keV luminosity of 1.5 × 10 41 ergs s -1 assuming a distance of 16.8 Mpc. The X-ray spectrum is represented by a combination of a power law with a photon index of ~1.7 and a soft thermal component with kT ~ 0.9 keV. An iron K emission line is detected at 6.73 ± 0.13 keV (rest-frame) with an equivalent width of 490 −190 +180 eV, and it is statistically significant at greater than 99.9% confidence. The line center energy is consistent with helium-like iron and is significantly higher than 6.4 keV, which is expected from fluorescence by "cold" (or a lower ionization state of) iron. The iron line profile shows no significant red tail in contrast to Seyfert 1 galaxies, although the statistics are limited. The line center energy, the equivalent width, and the profile are consistent with an origin in an ionized accretion disk. However, the large mass accretion rate necessary to ionize the accretion disk is not consistent with the observed luminosity and the normal accretion models.