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Astron. Astrophys. 342, L41-L44 (1999)

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1. Introduction

Active Galactic Nuclei (AGN) classified as Narrow Emission Line Galaxies (NELG) were first discovered in X-rays because of their intense 2-10 keV emission. Like Seyfert 2 galaxies, their optical spectra are dominated by narrow emission lines. This fact, together with the presence of a broad H[FORMULA] feature in the spectrum of a few of them (Shuder 1980), has led to the suggestion that NELG can form a transition class between Seyfert 1 and Seyfert 2 galaxies (e.g. Lawrence and Elvis 1982). The NELG NGC 2110 (z=0.0076) was first observed in X-rays with SAS-3 (Bradt et al. 1978), and then by HEAO 1 (Mushotzky 1982), and by EXOSAT (Turner & Pounds 1989). The 2-10 keV ASCA data revealed a moderately flat ([FORMULA]) absorbed power law plus FeK[FORMULA] line spectrum attenuated by partial covering material, while GINGA did not measure a significant reflection component (Hayashi et al. 1996). The scenario described by the data available prior to the present work indicates (Smith & Done 1996) the possibility that the 2-10 keV spectrum of NGC 2110 is intrinsically flatter than the [FORMULA] slope observed for Seyfert 1 galaxies by GINGA (Nandra & Pounds 1994). This situation, if confirmed, would clearly pose questions to the unified models (Antonucci 1993). In the following, we present BeppoSAX observation of NGC 2110 which highlights the key role played by the measurement of the spectrum above 20 keV in disentangling the intrinsic nuclear emission.

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© European Southern Observatory (ESO) 1999

Online publication: February 23, 1999