observations of LINER-2 galaxies

¹ Institute of Astronomy & Astrophysics, National Observatory of Athens, Palaia Penteli, 15236, Athens, Greece
² Dipartimento di Astronomia, Universita di Bologna, via Ranzani 1, 40127, Bologna, Italy
³ Istituto Technologie e Studio delle Radiazioni Extraterrestri/CNR, via Gobetti 101, 40129, Bologna, Italy
⁴ Physics Department, University of Athens, Panepistimiopolis, Zografos, 15783, Athens, Greece
⁵ Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USA
⁶ Osservatorio Astronomico di Bologna, via Ranzani 1, 40127, Bologna, Italy

Corresponding author: I. Georgantopoulos, ig@astro.noa.gr

Received: 14 September 2001
Accepted: 15 January 2002

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. ([CITE]) spectroscopic sample of nearby galaxies. All objects are detected in the 2–10 keV band, having luminosities in the range  . 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 while there is evidence neither for a significant absorption above the Galactic nor for an FeK_α 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.