X-RAY EVIDENCE FOR SEYFERT ACTIVITY BURIED IN THE INFRARED GALAXY NGC-4945

We have observed the infrared galaxy NGC 4945 using the Japanese X-ray astronomy satellite, Ginga. The X-ray spectrum is found to be compose d of three components: hard X-ray emission which is heavily absorbed b y cold material with column density of about 10(24.7) cm-2; a soft X-r ay component seen in the 2-10 keV band; and an iron emission line, The hard component exhibits a power-law spectrum with photon index of abo ut 1.7. The mean X-ray luminosity in the 2-20 keV band, after correcti on for absorption is 3 x 10(42) ergs s-1 with significant intensity va riation on a time scale of several hours. These results are thought to be evidence for an AGN (active galactic nucleus) in the galaxy. The X -ray spectrum of the soft component can be fitted with a power-law mod el having nearly the same photon index, but the luminosity is only 3% that of the hard component. The soft component shows no time variabili ty. The energy of the iron line is found to be 6.5 +/- 0.1 keV, and th e equivalent width is 1.5 +/- 0.3 keV. The X-ray spectrum is interpret ed to be composed of the X-ray emission from a hidden Seyfert nucleus behind an obscuring torus, the scattered continuum radiation, and a fl uorescence line emission from ionized iron in the scattering medium. T hus NGC 4945 is the first example of an active galaxy which exhibits b oth the obscuring and scattering picture of the type 2 AGN.