Abstract
I reviewed recent X-ray observations of LINERs and low luminosity AGNs (LLAGNs) with the Japanese X-ray satellite ASCA. The main purpose of the ASCA observations was to reveal the X-ray properties of these galaxies, especially nuclear activity. ASCA observed 15 LLAGNs and found nuclear X-ray emission for 13 LLAGNs except NGC 1672 and NGC 4501. On the other hand, compact hard X-ray emission probably associated with nuclear activity was found in seven LINERs, and six LINERs among seven have a broad Hα line. This result suggests that the excitation mechanism of these LINERs is photoionization. Soft X-ray emission from LINERs was found, and the emission can be associated with the starburst phenomenon in LINERs. I characterized the variability time scale using the Fourier timing analysis and deduced the lower limit of central black hole mass. The black hole masses are greater than 10 7 solar mass, which are consistent with those of high luminosity AGNs. However, the X-ray luminosity of LLAGNs and LINERs are only 1 1000 of that of high-luminosity AGNs. This indicates that LLAGNs and LINERs may turn into AGNs if fuel is supplied to the central black hole.
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