On the Temperature Profile of Radiatively Efficient Geometrically Thin Disks in Black Hole Binaries with the ASCA GIS
On the Temperature Profile of Radiatively Efficient Geometrically Thin Disks in Black Hole Binaries with the ASCA GIS
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DOI：
10.1086/432900
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发表时间：
2005-05
期刊：
影响因子：
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通讯作者：
A. Kubota;K. Ebisawa;K. Makishima;K. Nakazawa
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文献类型：
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作者：
A. Kubota;K. Ebisawa;K. Makishima;K. Nakazawa
利用ASCA地理信息系统数据和部分RXTE PCA数据，对标准高软态黑洞双星的X射线光谱进行了综合研究。将数学盘模型应用于几个黑洞双星，以考察观测到的吸积盘温度分布是否与标准吸积盘模型所预期的一致。这个模型被称为无p盘，它假定光谱由多温度黑体发射组成，其中半径r处的局域温度T(R)由T(R)∝r-p给出，其中p是正的自由参数。在标准盘中，吸积物质的引力能以黑体辐射的形式有效地释放，大致需要p≈3/4，而根据内边界条件、一般相对论效应和盘的垂直结构，预计会有小的偏差。我们的样本对象包括LMC X-1、LMC X-3、XTE J2012+381和Gro J1655-40。在ASCA观测期间，这些黑洞双星表现出标准的高/软态特征。在高态黑洞双星的标准模拟下，源显示盘内部温度为0.76-1.17keV，盘在0.7-10keV总通量中的比例为54%-98%，吸收柱为(0.7-12)×1021 cm-2。P的最佳拟合值范围为0.6-0.8，标准值p=3/4适用于所有来源。利用所谓的Grad模型，将得到的p与Schwarzschild度规中标准吸积盘的期望值进行了比较。观测到的p值确实与Schwarzschild度规中标准吸积盘的预期值一致。
X-ray spectra of black hole binaries in the standard high/soft state were studied comprehensively using ASCA GIS data and, partially, RXTE PCA data. A mathematical disk model was applied to several black hole binaries to see whether the observed accretion disk temperature profile was consistent with that expected from the standard accretion disk model. This model is called a p-free disk and assumes that the spectrum is composed of multitemperature blackbody emission, where the local temperature T(r) at radius r is given by T(r) ∝ r-p, with p being a positive free parameter. The standard disk, where the gravitational energy of the accreted matter is effectively released as blackbody radiation, roughly requires p ≈ 3/4, while a small deviation is expected depending on the inner boundary conditions, general relativistic effects, and disk vertical structures. Our sample objects included LMC X-1, LMC X-3, XTE J2012+381, and GRO J1655-40. During the ASCA observations, these black hole binaries showed characteristics of the standard high/soft state. Under the standard modeling of high-state black hole binaries, the sources show disk inner temperatures of 0.76-1.17 keV, a disk fraction of the total 0.7-10 keV flux of 54%-98%, and absorption columns of (0.7-12) × 1021 cm-2. The best-fit values of p were found in the range 0.6-0.8, and the standard value of p = 3/4 was accepted for all the sources. The obtained values of p are also compared with those expected for the standard accretion disk in the Schwarzschild metric using the so-called GRAD model. The observed p-values were indeed found to be consistent with those expected from the standard accretion disk in the Schwarzschild metric.