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BEGIN:VEVENT
DTSTART;TZID=Atlantic/Canary:20140708T123000
DTEND;TZID=Atlantic/Canary:20140708T133000
UID:iactalks-654
X-WR-CALNAME: IAC Talks: Open Astronomy Seminars
X-ORIGINAL-URL: /iactalks/Talks/view/654
CREATED:2014-07-08T12:30:00+01:00
X-WR-CALDESC: IAC Talks upcomming talks
SUMMARY:Active galactic nuclei synapses: X-ray versus optical classificatio
 ns using artificial neural networks 
DESCRIPTION:Active galactic nuclei synapses: X-ray versus optical classific
 ations using artificial neural networks \nDr. Omaira Gonzalez Martin\n\nTh
 e active galactic nuclei is conformed by a number of  classes. Optically t
 hey are defined using diagnostics based on optical  emission lines. At X-r
 ays they are classified by the power of the AGN  continuum and the shape o
 f the X-ray spectra. Therefore, optical and  X-ray classes are independent
  classifications. However, optical and  X-ray classes show many discrepanc
 ies not fully understood yet. Some AGN  at X-rays do not show any AGN sign
 ature at optical wavelengths (called  optical elusive). Classical obscured
  AGN are ’sometimes’ not obscured at  X-rays.\nWe have studied
  the ‘synapses’ between them using  artificial neural networks
  (Gonzalez-Martin+14). To do so, we used  flux-calibrated X-ray spectra of
  a sample of 90 emission line nuclei  (ELN) observed with XMM-Newton. It i
 ncludes starbursts (SB), transition  objects (T2), LINERs (L1.8 and L2), a
 nd Seyferts (S1, S1.8, and S2).\nThe ELN can be classified into six classe
 s, based on  the shape of their X-ray spectra. These classes are associate
 d with most  of the optical classes. The key parameters to explain them at
  X-rays  are three. The first parameter is an AGN-like component, which is
   present in all of them (even non-AGN at optical wavelengths!). The  seco
 nd one is obscuration, which almost certainly drives the  Type-1/Type-2 di
 chotomy, but may also explain why L1.8 are more similar  to S1s while L2/T
 2 are more similar to S1.8s. The third component is  star-forming activity
  happening at the host galaxy and contributing at  X-rays. The AGN strengt
 h, relative to the host-galaxy component,  determines the average X-ray sp
 ectrum for these classes as follows: S1  -> S1.8 -> L1.8/S2 -> L2
 /T2/ -> SB.
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