Low-luminosity X-ray Active Nuclei in S0 galaxies NGC 3065 and NGC 4203

Abstract

We present ASCA X-ray results on two S0 galaxies, NGC 3065 and NGC 4203. In both galaxies, we detected hard X-ray emission from a point-like source at the nucleus. Single power law model having a photon index of 1.8 well described the spectra of these sources, while thin thermal emission which is common in S0 galaxies was not detected. The 2-10 keV luminosities of these nuclear sources, 2.2 times 10^{41} erg s^{-1} and 1.5 times 10^{40} erg s^{-1}, are 1-2 orders of magnitude higher than those expected as an assembly of low-mass X-ray binaries in these galaxies. Our results strongly suggest that NGC 3065 and NGC 4203 host low-luminosity active galactic nuclei (LLAGNs).

7 pages, 5 figures, to be published in the Astrophysical Journal