X-ray properties of LINERs

We present an investigation of the X-ray properties of 13 LINERs based on ROSAT all-sky survey and pointed PSPC and HRI observations. Several sources are studied for the first time in X-rays. The X-ray spectra are best described by a powerlaw with photon index Gamma(X) approximate to -2.0 or thermal emission from gas with very subsolar abundances. The luminosities range between log L(x) = 37.7 (NGC404) and 40.8 (NGC4450). No X-ray variability on the timescale of hours/days is detected. This is in line with the suggestion that LINERs may accrete in the advection-dominated mode. On a longer term, one of the objects, NGC 2768, turns out to be slightly variable. Some sources appear to be extended at weak emission levels whereas the bulk of the X-ray emission is consistent with arising from a point source within the PSPC instrumental resolution. L(X)/L(B) ratios are derived and emission mechanisms that potentially contribute to the observed X-ray luminosities are discussed. We also examine the presence of second X-ray sources near the target sources both in terms of instrumental effects and in terms of 'real' sources within the LINER galaxies.