A Caltech Library Service

The contribution of narrow-line Seyfert 1 galaxies to the soft X-ray background

Hasinger, G. and Lehmann, I. and Schmidt, M. and Gunn, J. E. and Schneider, D. P. and Giacconi, R. and Trümper, J. and Zamorani, G. (2000) The contribution of narrow-line Seyfert 1 galaxies to the soft X-ray background. New Astronomy Reviews, 44 (7-9). pp. 497-501. ISSN 1387-6473.

[img] PDF - Submitted Version
See Usage Policy.


Use this Persistent URL to link to this item:


The ROSAT Ultradeep HRI survey in the Lockman Hole contains a complete sample of 91 X-ray sources with fluxes in the 0.5–2 keV band larger than 1.2×10^(−15) erg cm^(−2) s^(−1), where over 75% of the sources are quasars or Seyfert galaxies. During the course of our optical identification work, we have obtained optical spectra of 67 narrow emission line galaxies (NELG), which are physically not associated with the X-ray sources. We have derived the equivalent width (EW) and the full width at half maximum (FWHM) for the most prominent emission lines of 41 quasars and Seyfert galaxies taken from the ROSAT Deep Survey (RDS), which has a flux limit of 5.5×10^(−15) erg cm^(−2) s^(−1) in the 0.5–2.0 keV band. Furthermore, we have obtained the EW and FWHM values of the field NELGs. Here, we present the spectroscopic discrimination between RDS Seyfert galaxies and field galaxies (NELG). The analysis of the emission lines has revealed that a single object out of 69 spectroscopically identified AGN fits the optical criteria of narrow-line Seyfert 1 galaxies (NLS1). This may indicate that NLS1 contribute only marginally to the soft X-ray background, but we can not exclude a possible larger contribution.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Hasinger, G.0000-0002-0797-0646
Additional Information:© 2000 Elsevier. Available online 25 September 2000.
Subject Keywords:Galaxies: active; Quasars: general; Quasars: absorption lines; X-rays: galaxies
Issue or Number:7-9
Record Number:CaltechAUTHORS:20170408-160319034
Persistent URL:
Official Citation:G Hasinger, I Lehmann, M Schmidt, J.E Gunn, D.P Schneider, R Giacconi, J Trümper, G Zamorani, The contribution of narrow-line Seyfert 1 galaxies to the soft X-ray background, New Astronomy Reviews, Volume 44, Issues 7–9, September 2000, Pages 497-501, ISSN 1387-6473, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:76118
Deposited By: 1Science Import
Deposited On:15 Jun 2017 21:26
Last Modified:24 Feb 2020 21:53

Repository Staff Only: item control page