BeppoSAX observations of LINER-2 galaxies

Abstract

We present BeppoSAX observations of 6 "type-2" LINER and "transition" galaxies (NGC 3379, NGC 3627, NGC 4125, NGC 4374, NGC 5195 and NGC 5879) from the Ho et al. (1997) spectroscopic sample of nearby galaxies. All objects are detected in the 2-10 kev band, having luminosities in the range L2-10keV ∼ 1 × 1039-1 × 1040 erg s-1. The PDS upper limits above 10 keV place Constraints on the presence of a heavily obscured AGN in the case of NGC 3379 and NGC 4125. No significant variability is detected in any of the objects. The spectra are described in most cases by a simple power-law model with a spectral slope of Γ ∼ 1.7-2.5 while there is evidence neither for a significant absorption above the Galactic nor for an FeKα emission line. Therefore, based on the spectral properties alone, it is difficult to differentiate between a low-luminosity AGN or a star-forming galaxy scenario. However, imaging observations of NGC 3627 and NGC 5195 with Chandra ACIS-S reveal very weak nuclear sources while most of the X-ray flux originates either in off-nuclear point sources or in diffuse emission. The above clearly argue in favour of a star-forming origin for the bulk of the X-ray emission, at least in the above two sources.