Suzaku Observations of the Type 2 QSO in the Central Galaxy of the Phoenix Cluster
Suzaku Observations of the Type 2 QSO in the Central Galaxy of the Phoenix Cluster
复制标题
凤凰星团中央星系 2 型 QSO 的朱雀观测
DOI：
10.1088/0004-637x/778/1/33
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发表时间：
2013
影响因子：
4.9
通讯作者：
Hiroshi Tsunemi
中科院分区：
文献类型：
--
作者：
Shutaro Ueda;Kiyoshi Hayashida;Naohisa Anabuki;Hiroshi Nakajima;Katsuji Koyama;Hiroshi Tsunemi
我们报道了红移z=0.596的凤凰团的X-射线光谱的Suzaku/Xis，HXD和Chandra/ACIS-I的结果。低温等离子体(∼3.0keV和∼0.76太阳)和高温等离子体(∼11keV和∼0.33太阳)的发射能很好地再现星系团内介质的光谱，前者位于星系团核心，而后者分布在整个星系团上。除了这些ICM辐射外，还发现了一个强吸收的幂定律分量，这是由于星系团中心的活动星系核(AGN)所致。活动星系核的吸收柱密度为∼3 2×10 2 3 cm−2，非遮蔽光度为∼4 7×10 4 5 erg S−1(2-10keV)。此外，首次发现了一条中性铁(Fe I)K壳线，其在静止标架上的宽度相当于∼15 0 eV。对于如此高亮度的活动星系核，FeI线的列密度和EW都非常大，因此该活动星系核被归类为第二类恒星天体(QSO)。我们推测，ICM冷却气体的很大一部分将被用来维持环面和激活第二类星体。凤凰星系团在中央星系有一次大规模的恒星爆发，这表明冷却气流的抑制效果较差。这可能是因为最新的AGN反馈是最近开始的，尚未奏效。或者，活动星系核的反馈主要是辐射模式，而不是动力学模式，环状结构可以起到屏蔽的作用，以减少其影响。
We report the Suzaku/XIS and HXD and Chandra/ACIS-I results on the X-ray spectra of the Phoenix cluster at the redshift z= 0.596. The spectrum of the intracluster medium (ICM) is well reproduced with the emissions from low-temperature (∼ 3.0 keV and∼ 0.76 solar) and high-temperature (∼ 11 keV and∼ 0.33 solar) plasmas; the former is localized at the cluster core, while the latter distributes over the cluster. In addition to these ICM emissions, a strongly absorbed power-law component is found, which is due to an active galactic nucleus (AGN) in the cluster center. The absorption column density and unobscured luminosity of the AGN are∼ 3.2× 10 23 cm− 2 and∼ 4.7× 10 45 erg s− 1 (2–10 keV), respectively. Furthermore, a neutral iron (Fe i) K-shell line is discovered for the first time with the equivalent width (EW) of∼ 150 eV at the rest frame. The column density and the EW of the Fe i line are exceptionally large for such a high-luminosity AGN, and hence the AGN is classified as a type 2 quasi-stellar object (QSO). We speculate that a significant fraction of the ICM cooled gas would be consumed to maintain the torus and to activate the type 2 QSO. The Phoenix cluster has a massive starburst in the central galaxy, indicating that suppression in the cooling flow is less effective. This may be because the onset of the latest AGN feedback has occurred recently and has not yet been effective. Alternatively, the AGN feedback is predominantly in radiative mode, not in kinetic mode, and the torus may work as a shield to reduce its effect.