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Black hole masses in NLS1 galaxies from the X-ray excess variance method

M. Nikolajuk, P. Gurynowicz, B. Czerny

astro-pharXiv:astro-ph/0612376

Abstract

We estimate black hole masses in Narrow Line Seyfert 1 (NLS1) galaxies at the basis of their X-ray excess variance. We apply the standard approach appropriate for Broad Line Seyfert 1 (BLS1) galaxies. In general, we find that the obtained masses are by a factor 20 too small to agree with values obtained from other methods (reverberation, stellar dispersion). However, a small subset of our NLS1 objects does not require that multiplication, or the correction factor is less than 4. We find that this subset have a soft X-ray photon index, Γ0.1-2.4 keV, smaller than 2. We thus postulate that this subclass of NLS1 actually belongs to BLS1.

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