The ASCA images are generally consistent with emission from point-sources at energies above ~ 3 keV. We use archival ROSAT data to examine each field at high spatial resolution and check for the presence of sources which would contaminate the ASCA data.
Of the five sources bright enough for 128 s temporal analysis, three are variable at > 99% confidence, with characteristics consistent with those observed in Seyfert 1 galaxies. Analysis on a timescale of 5760 s reveals six sources variable at > 99% confidence and comparison with previous X-ray results shows most of the sample to be variable in hard X-ray flux on timescales of years.
Simple continuum models are fit to the sample spectra to characterize the variety of spectral forms and hence determine the fundamental nature of the X-ray spectrum of each source. No single spectral model provides an adequate fit to all the sample sources. 36% of the sample cannot be adequately fit by any of our test models (all rejected at > 95% confidence). Approximately half of the sample have an iron Kalpha line with an equivalent width consistent with an origin in the line-of-sight absorber, the remaining lines must be produced in material out of the line-of-sight. Absorbing columns up to 10^24 atom cm^-2 are detected and even larger columns are inferred for some sources. The mean underlying hard X-ray power-law index is gamma ~ 2.
Many X-ray emission lines were detected at high levels of confidence. The iron K-shell regime is dominated by emission from `neutral' material. Many datasets also show evidence for complexity in the iron Kalpha profile, which may be interpreted as evidence for broad line profiles, including flux both red-ward and blue-ward of the line peak, and/or for the existence of hydrogen-like and helium-like iron K lines.
Hydrogen-like and helium-like lines are detected from Fe, Ne, Si, S and Ar in addition to Mg lines. While almost half of the sample have an estimated starburst contribution of > 30% in the 0.5-4.5 keV bandpass, the soft X-ray emission lines are not solely associated with a strong starburst component.