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"Low ionization nuclear emission-line regions (LINERs): Nature and Watermarks"

Dr. Omaira Gonzalez-Martin
Physics department, University of Crete, Greece
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When: Wednesday, 4th of November of 2009 at 3:15 pm
Where: 2nd Floor Seminar Room

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Abstract:  

AGN emit over the entire electromagnetic spectrum and are widely believed to be 
powered by the accretion of matter onto a supermassive black hole (Rees 1984). 
Several families within the AGN category have been established from the observational 
point of view. Although their classification is sometimes misleading, it is
widely believed that a unified model can explain them all under a single scenario 
(Antonucci 1993). However, this scheme needs to be further confirmed since there 
are several sub-classes of object that cannot be easily fitted into this scenario. 

One of the most intriguing cases are Low Ionization Nuclear Emission line Regions 
(LINERs). A long debate can be found in the literature proposing different physical 
processes as the main emission mechanism. This question become even more important 
since, according to their luminosity, they might be the link between active and 
normal galaxies. 

X-ray studies are one of the most powerful tools to unveil the true nature of LINERs. 
We have performed a careful  study of the X-ray nuclear properties of a sample of 82 
of these LINERs (Gonzalez-Martin et al. 2006; 2009a; 2009b). 
Around 90% of our sample shows evidences of AGN adding to this other indicators (radio 
flatness, UV variability and the presence of a broad Ha line).

Therefore, we concluded that the vast majority of LINERs host an AGN as the main source 
of energy realized. However, the most important question is still open: Why are they 
different to other AGN families? I will describe two of the main differencies found 
between LINERs and their parent population of AGN, type 2 Seyfert: strong thermal 
emission and peculiar obscuration of the central source. Finally I would like to give 
you the main open outlines of this work and working progress on the field. 
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