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arXiv 1907.02683astro-ph.GAastro-ph.HE
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窄线塞弗特1星系是由低质量黑洞驱动的吗?

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

摘要:

窄线塞弗特1星系(NLS 1)被认为是由物质吸积到螺旋宿主星系中的低质量黑洞(BH)上提供动力的,黑洞质量M_BH为10^6 - 10^8 M_sun。然而,γ射线发射NLS 1 s的宽带谱能量分布被发现是类似于平坦谱射电类星体。这挑战了我们目前关于NLS 1具有低M_BH的概念。为了解决NLS 1 s中低M_BH值的矛盾,我们用标准的Shakura-Sunyaev吸积盘(AD)模型拟合了射电强NLS 1 s(RL-NLS 1 s)、射电静NLS 1 s(RQ-NLS 1 s)和射电静宽线Seyfert 1星系(RQ-BLS 1 s)的观测光谱,每个星系约500个。对于RL-NLS 1,我们发现平均log(M_ADBH/M_sun)为7.98 +/- 0.54。对于RQ-NLS 1和RQ-BLS 1,我们发现平均log(M_ADBH/M_sun)分别为8.00 +/- 0.43和7.90 +/- 0.57。RQ-BLS 1的M_BH值与其维里质量相似,而NLS 1的M_ADBH值比维里估计值大一个数量级。因此,我们的分析表明,NLS 1 s的M_BH类似于RQ-BLS 1 s,并且它们的可用维里M_BH值被低估,这是由于它们观测到的相对较小的发射线宽的影响。考虑到爱丁顿比作为吸积率的估计,利用M_ADBH,我们得到了RQ-NLS 1 s、RL-NLS 1 s和RQ-BLS 1 s的平均吸积率分别为0.06(+0.16,-0.05)、0.05(+0.18,-0.04)和0.05(+0.15,-0.04)。因此,我们的研究结果表明,NLS 1的BH质量和吸积率类似于BLS 1。

英文摘要:

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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