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arXiv · 1907.02683

Are Narrow Line Seyfert 1 Galaxies powered by low mass black holes?

Gayathri Viswanath·C S Stalin·Suvendu Rakshit·Kshama S. Kurian·Ujjwal Krishnan·Shivappa B. Gudennavar·Sreeja S. Kartha
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Abstract

Narrow line Seyfert 1 galaxies (NLS1s) are believed to be powered by accretion of matter onto low mass black holes (BHs) in spiral host galaxies with BH masses M_BH of 10^6 - 10^8 M_sun . However, the broad band spectral energy distribution of the gamma-ray emitting NLS1s are found to be similar to flat spectrum radio quasars. This challenges our current notion of NLS1s having low M_BH . To resolve this tension of low M_BH values in NLS1s, we fitted the observed optical spectrum of a sample of radio-loud NLS1s (RL-NLS1s), radio-quiet NLS1s (RQ-NLS1s) and radio-quiet broad line Seyfert 1 galaxies (RQ-BLS1s) of about 500 each with the standard Shakura-Sunyaev accretion disk (AD) model. For RL-NLS1s we found a mean log(M_ADBH/M_sun) of 7.98 +/- 0.54. For RQ-NLS1s and RQ-BLS1s we found mean log(M_ADBH/M_sun) of 8.00 +/- 0.43 and 7.90 +/- 0.57, respectively. While the derived M_BH values of RQ-BLS1s are similar to their virial masses, for NLS1s the derived M_ADBH values are about an order of magnitude larger than their virial estimates. Our analysis thus indicates that NLS1s have M_BH similar to RQ-BLS1s and their available virial M_BH values are underestimated influenced by their observed relatively small emission line widths. Considering Eddington ratio as an estimation of the accretion rate and using M_ADBH, we found the mean accretion rate of our RQ-NLS1s, RL-NLS1s and RQ-BLS1s as 0.06 (+0.16, -0.05), 0.05 (+0.18, -0.04) and 0.05 (+0.15, -0.04) respectively. Our results therefore suggest that NLS1s have BH masses and accretion rates similar to BLS1s.

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Gayathri Viswanath, C S Stalin, Suvendu Rakshit, Kshama S. Kurian, Ujjwal Krishnan, Shivappa B. Gudennavar, Sreeja S. Kartha. 2019-07-05. Are Narrow Line Seyfert 1 Galaxies powered by low mass black holes?. https://doi.org/10.3847/2041-8213/ab365e

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