Type 2 counterparts of narrow-line Seyfert 1 galaxies

Abstract

Unified models of Seyfert galaxies, based on viewing angles, successfully explain the observed differences between type 1 and 2 Seyferts. The existence of a range in accretion rates relative to the Eddington rate (from broad-line Seyfert 1s to narrow-line Seyfert 1s or NLS1s) and the unification of Seyfert galaxies imply that there must be type 2 counterparts of NLS1 galaxies i.e., Seyfert 2s with high accretion rate or small black hole mass. One such Seyfert 2, NGC5506, has already been unmasked based on near infra-red spectroscopy. Here we confirm the above result, and present evidence for two additional type 2 counterparts of NLS1s based on XMM-Newton observations. The three AGNs NGC7314, NGC7582 and NGC5506, with a type 1.9/2 optical spectrum, show extremely rapid variability by factors >2.4, 1.3, and 1.7 in 200s, 350s and 300s, respectively, and steep 2-12 keV spectrum in their intrinsic X-ray emission, characteristic of NLS1 galaxies. These observations establish the obscured NLS1 galaxies as a subclass of Seyfert 2 galaxies.

4 pages, To appear in ApJ Letters

References in corpus (2)

• Fe XXV and Fe XXVI Diagnostics of the Black Hole and Accretion Disk in Active Galaxies: Chandra Time-Resolved Spectroscopy of NGC 7314
• The recent X-ray history of NGC 5506

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