On Black Hole Mass Estimation from X-Ray Spectra of Ultraluminous X-Ray Sources
On Black Hole Mass Estimation from X-Ray Spectra of Ultraluminous X-Ray Sources
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DOI：
10.1093/pasj/60.3.653
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发表时间：
2007-12
影响因子：
2.3
通讯作者：
K. Vierdayanti;K. Watarai;S. Mineshige
中科院分区：
文献类型：
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作者：
K. Vierdayanti;K. Watarai;S. Mineshige
我们提出了一种推导超临界吸积流黑洞质量的方法。在这里，我们使用扩展的圆盘黑体(Extended DBB)模型，这是一个有效温度分布服从TJeff/Rp关系的拟合模型，其中r是圆盘半径，p作为拟合参数。我们首先数值计算了给定黑洞质量M和吸积率P M的理论流动结构及其谱。通过扩展的DBB模型对理论谱进行拟合，我们可以估计黑洞质量M_x，其结果是最内盘半径Rin=3rg./M_x/，这里是Schwarzschild半径。然而，我们发现，估计的质量与谱计算中采用的质量有偏差，甚至在低PM-M情况下也是如此。我们还发现，可以通过对最内侧半径引入新的修正来消除偏差。利用这一修正，我们计算了一些FM和PM的超临界区域的质量修正因子M=Mx，结果表明它们的质量修正因子在M=Mx�1.2-1.6之间。PM值越高，质量修正系数越大。由于修正相对较小，我们可以有把握地得出结论，维尔达安蒂等人认为ULX中的黑洞。(2006年，PASJ，58.915)分析，是质量为<；100mˇ的恒星质量的黑洞。
We propose a methodology to derive a black-hole mass for super-critical accretion flow. Here, we use the extended disk blackbody (extended DBB) model, a fitting model in which the effective temperature profile obeys the relationTeff /rp ,w ithr being the disk radius andp being treated as a fitting parameter. We first numerically calcu- late the theoretical flow structure and its spectra for a given black-hole mass, M ,a nd accretion rate, P M.T hr ough fitting to the theoretical spectra by the extended DBB model, we can estimate the black-hole mass, Mx ,a ssuming that the innermost disk radius isrin =3rg./Mx/ ,w hererg is the Schwarzschild radius. We find, however, that the estimated mass deviates from that adopted in the spectral calculations,M ,e ven for low-P M cases. We also find that the deviations can be eliminated by introducing a new correction for the innermost radius. Using this correction, we calculate mass correction factors, M=Mx ,i n the super-critical regimes for some sets ofM and P M ,fi nding that am ass correction factor ranges between M=Mx � 1.2-1.6. The higher is P M ,t he largerdoes the mass correction factor tend to be. Since the correction is relatively small, we can safely conclude that the black holes in ULXs, which Vierdayanti et al. (2006, PASJ, 58, 915) analyzed, are stellar-mass black holes with the mass being<100Mˇ.