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On the Definition of Narrow-Line Seyfert 1 Galaxies: A Catalog from the Final Data Release of SDSS-II
  • Aycha Tammour
Aycha Tammour
University of Western Ontario

Corresponding Author:[email protected]

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Abstract

We present a catalog of 936 Narrow-Line Seyfert 1 (NLS1) candidates extracted from the 7\({}^{\rm th}\) data release of the Sloan Digital Sky Survey. The sample is selected from the QSO database based on the FWHM of the Balmer lines (H\(\alpha\) and H\(\beta\)) and detection by ROSAT. We examine the correlations among the emission lines H\(\beta\), [O III] and Fe II and the continuum. We particularly focus on the correlations associated with the eigenvector 1 (EV1) of the \citet{borosongreen92} study. We find Fe II to be inversely correlated with [O III] regardless of the metric used to measure line strength. In addition, the \(L/L_{\rm Edd}\) ratio is correlated with both [[O III]] and Fe II in our sample. The width of H\(\beta\) is also strongly correlated with the various measures of line and continuum luminosities. We investigate the change of properties (or lack thereof) with H\(\beta\) FWHM, which is used as the main defining criterion of NLS1s, by comparing a subsample containing objects with FWHM(H\(\beta\)) \(<2000\) \({\rm km~{}s^{-1}}\) (NLS1s) with another containing objects with 2000 \({\rm km~{}s^{-1}}\) \(<\) FWHM(H\(\beta\)) \(<\) 4000 \({\rm km~{}s^{-1}}\) (Broad-Line Seyfert 1, BLS1). Except for the [O III] EW, none of the quantities that we tested showed any significant change between the NLS1 and BLS1 populations. We conclude that NLS1s (defined solely by their H\(\beta\) width) form a continuous distribution with their broad-line counterparts. Other parameters (such as the [O III] strength and accretion rates) need to be used in combination with the width of the broad-lines to better isolate this class from the general AGN population.