your ID: 0213 
First Name: Isabel 
Last Name: Marquez 
Affiliation: Instituto de Astrofisica de Andalucia 
Title: X-ray nature of LINER nuclei 
Authors: I. Marquez, O. Gonzalez-Martin, J. Masegosa 
Topic: 1 
Session: oral 
Abstract: We report the results from an homogeneous analysis of the 
X-ray (Chandra-ACIS) data available for a sample of 51 LINER galaxies 
selected from the catalogue by Carrillo et al. (1999) and representative 
of the population of bright LINER sources. The nuclear X-ray morphology
 has been classified attending to their nuclear compactness in the hard 
band (4.5-8.0 keV) into 2 categories: Active Galactic Nuclei (AGN) 
candidates (with a clearly identified unresolved nuclear source) and 
Starburst (SB) candidates (without a clear nuclear source). 60% of 
the total sample are classified as AGNs, with a median luminosity 
of LX(2-10 keV)=2.5 x 10^(40)erg/s, which is an order of magnitude 
higher than that for SB-like nuclei. The spectral fitting allows to conclude 
that most of the objects need a non-negligible power-law contribution. 
When no spectral fitting can be performed (data with low signal-to-noise ratio), 
the Color-Color diagrams allow us to roughly estimate physical parameters 
such as column density, temperature of the thermal model or spectral index 
for a power-law and therefore to better constrain the origin of the X-ray emission.
 All together the X-ray morphology, the spectra and the Color-Color diagrams 
allow us to conclude that a high percentage of LINER galaxies, at least ~60%, 
could host AGN nuclei, although contributions from High Mass X-ray Binaries 
or Ultra-luminous X-ray sources cannot be ruled out for some galaxies.