A transition mass for black holes to show broad emission lines
A transition mass for black holes to show broad emission lines
复制标题
黑洞的过渡质量显示宽发射线
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
G. Ferland
中科院分区：
文献类型：
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作者：
S. Chakravorty;M. Elvis;G. Ferland
虽然超大质量黑洞（AGN）和恒星质量黑洞（BHB）有许多共同的性质，但宽发射线（BEL）是活动星系核（AGN）的唯一特征。根据斯隆数字巡天（SDSS）数据库对这些谱线的探测，似乎不存在质量为MBH 10 5 M�的活动星系核。在本文中，我们调查了这种低质量黑洞是否真的不存在，或者它们是否因为其中的BELs没有有效地产生而未被检测到。利用从黑洞X射线双星（BHB）到活动星系核（AGN）的宽质量范围（10-10 9 M Ω）的电离光谱能量分布，计算了Lyα 1216 A，Hβ 4861 A，C IV 1549 A和Mg II 2798 A的紫外线和光学线的等效宽度（EW）.计算中采用了局部最佳发射云模式（BELR）来描述宽发射线区。我们发现，硬化的SED形状与减少质量不减少BEL电子战。然而，有限的尺寸的BELR，作为衡量的线宽，这是由黑洞的质量控制，调节这些发射线的生产。对于典型的活动星系核黑洞，其发射线的电子波在1010 - 8 M-1处似乎有一个峰值，低于该峰值，发射线变得本质上较暗，并在1010 - 6 M-1以下急剧下降。这可能是导致
Although the supermassive (AGN) and stellar mass (BHBs) black holes have many properties in common, the broad emission lines (BELs) are exclusively signatures of the active galactic nuclei (AGN). Based on the detection of these lines from Sloan Digital Sky Survey (SDSS) data bases, there seems to be no AGN with mass MBH 10 5 M� . In this paper, we investigate if such low-mass black holes are really non-existent or they are undetected because the BELs in them are not produced efficiently. Using the ionizing spectral energy distribution for a wide range of black hole mass, 10–10 9 M� , spanning black hole X-ray binaries (BHBs) to AGN, we calculate the equivalent widths (EWs) of ultraviolet and optical lines Lyα 1216 A, Hβ 4861 A, C IV 1549 A and Mg II 2798 A. The LOC (locally optimally emitting cloud) model has been used to describe the broad emission-line region (BELR) for the calculations. We find that the hardening of the SED shape with decreasing mass do not decrease the BEL EWs. However, finite size of the BELR, as measured by the line widths, which is controlled by the mass of the black hole, regulates the production of these emission lines. There seems to be a peak in the EWs of the emission lines for typical AGN black holes of ∼10 8 M� , below which the lines become intrinsically fainter with a sharp fall-off below ∼10 6 M� . This may be the cause of