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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 sim 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, Gamma_{0.1-2.4 keV}, smaller than 2. We thus postulate that this subclass of NLS1 actually belongs to BLS1.
Black hole mass determination in active galaxies is a key issue in understanding various luminosity states. In the present paper we try to generalise the mass determination method based on the X-ray excess variance, successfully used for typical broa
Values of black hole masses are frequently determined with the help of the reverberation method. This method requires a specific geometrical factor related to the distribution of the orbits of the Broad Line Region clouds. Onken et al. determined the
We discuss two methods to estimate black hole (BH) masses using X-ray data only: from the X-ray variability amplitude and from the photon index Gamma. The first method is based on the anti-correlation between BH mass and X-ray variability amplitude.
Recent studies of active galactic nuclei (AGN) found a statistical inverse linear scaling between the X-ray normalized excess variance $sigma_{rm rms}^2$ (variability amplitude) and the black hole mass spanning over $M_{rm BH}=10^6- 10^9 M_{odot}$. B
Ultra-luminous X-ray sources (ULXs) are off-nuclear X-ray sources in nearby galaxies with X-ray luminosities $geq$ 10$^{39}$ erg s$^{-1}$. The measurement of the black hole (BH) masses of ULXs is a long-standing problem. Here we estimate BH masses in