Soft X-ray spectral observations of low-luminosity active galaxies

The X-ray spectra of a sample of 12 low-luminosity AGNs observed using the solid state spectrometer on the HEAO 2 satellite are investigated. The AGNs discussed here have X-ray luminosities below about 10 to the 44th erg/s, and thus form a sample complementary to the higher luminosity sample discussed by Petre et al. (1984). The spectra are well described by a simple model consisting of a power law, with photon spectral index about 1.7, plus absorption by cold gas. The objects in the sample can be separated into three groups: (1) those whose spectra show no significant absorption; (2) those for which the X-ray source is totally covered by a spatially uniform absorbing medium; and (3) those for which partial covering by patchy absorbers is indicated. Column densities and covered fractions do not correlate systematically with X-ray luminosity. Implications regarding physical conditions in AGNs are discussed. 56 references