A soft X-ray study of Type I AGN observed with Chandra HETGS
A soft X-ray study of Type I AGN observed with Chandra HETGS
复制标题
使用 Chandra HETGS 观察到的 I 型 AGN 的软 X 射线研究
DOI：
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发表时间：
2007
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通讯作者：
Tahir Yaqoob Chris Reynolds
中科院分区：
文献类型：
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作者：
B. McKernan;Tahir Yaqoob Chris Reynolds
本文给出了用Chandra星载高分辨率X射线光栅观测到的15个I型活动星系核的软X射线谱的统一分析结果。我们发现15个活动星系核中有10个表现出内禀电离吸收体的特征。吸收体被光致电离并向外流出，速度范围为10 - 10 km/s。温吸收气体的柱密度为10 cm ~ 3。十个活动星系核中有九个表现出暖吸收，最适合由多个电离分量，十个活动星系核中有三个需要多个运动分量。在我们的活动星系核样本中，温暖的吸收气体具有广泛的电离参数，总共跨越大约4个数量级（约10尔格·厘米·秒），并且通常在同一气体中跨越3个数量级。热吸收体成分的电离参数λ < 10产生一个未解决的过渡阵列，由于铁在10个活动星系核表现出温暖的吸收七。这些低电离态的吸收体也可能带走活动星系核最大的质量外流。质量流出率主要取决于气体的体积填充因子，这还不能直接测量。然而，对于单位填充因子的质量流出率的上限可能远远大于预期的中心超大质量黑洞的吸积率，并且填充因子小到1%可以给出与吸积率相当的流出率。在我们的样本中，流出速度似乎在10300 - 500 km s之间存在一个差距，其来源尚不清楚。速度低于该间隙的流出分量倾向于与比速度高于差距的流出分量更低的柱密度相关联。
We present the results of a uniform analysis of the soft X-ray spectra of fifteen type I AGN observed with the high resolution X-ray gratings on board Chandra. We found that ten of the fifteen AGN exhibit signatures of an intrinsic ionized absorber. The absorbers are photoionized and outflowing, with velocities in the range ∼ 10−10 km s. The column density of the warm absorbing gas is ∼ 10cm. Nine of the ten AGN exhibiting warm absorption are best–fit by multiple ionization components and three of the ten AGN require multiple kinematic components. The warm absorbing gas in our AGN sample has a wide range of ionization parameter, spanning roughly four orders of magnitude (ξ ∼ 10 ergs cm s) in total, and often spanning three orders of magnitude in the same gas. Warm absorber components with ionization parameter ξ < 10 generate an unresolved transition array due to Fe in seven of the ten AGN exhibiting warm absorption. These low ionization state absorbers may also carry away the largest mass outflows from the AGN. The mass outflow rate depends critically on the volume filling factor of the gas, which cannot yet be directly measured. However, upper limits on the mass outflow rates for filling factors of unity can be much greater than the expected accretion rate onto the central supermassive black hole and filling factors as small as 1% can give outflow rates comparable to the accretion rate. There appears to be a gap in the outflow velocities in our sample between ∼ 300 − 500 km s, the origin of which is not clear. The outflow components with velocities below this gap tend to be associated with lower column densities than those with with velocities above the gap.