Chandra discovery of an X-ray jet and lobes in 3C 15
Chandra discovery of an X-ray jet and lobes in 3C 15
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DOI：
10.1051/0004-6361:20031343
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发表时间：
2003-08
影响因子：
6.5
通讯作者：
Jun Kataoka;J. Leahy;P. G. Edwards;M. Kino;M. Kino;Fumio Takahara;Y. Serino;N. Kawai;
中科院分区：
文献类型：
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作者：
Jun Kataoka;J. Leahy;P. G. Edwards;M. Kino;M. Kino;Fumio Takahara;Y. Serino;N. Kawai;
我们报告了 3C 15 中 X 射线射流的钱德拉探测。射流中 X 射线发射的峰值距原子核 4.1 英寸（5.1 kpc 的投影距离），与先前在无线电和光学射流中识别的成分一致。我们构建了该组件（光学结 C）的光谱能量分布 (SED)，并发现 X 射线通量远低于无线电到光学连续谱的外推。我们研究了 X 射线射流发射的四种模型：(I) 等分弱同步加速器冷却，(II) 等分中度同步加速器冷却，(III) 弱同步加速器加同步加速器自康普顿 (SSC) 冷却，以及 (IV) 中度同步加速器加 SSC 冷却。鉴于 X 射线光谱中凹特征的证据微弱，我们认为情况 (II) 可以最合理地解释结 C 的总体发射。情况 (III) 也是可能的，但需要与均分有很大的偏离，并且喷射功率必须与最亮类星体的功率相当。在所有模型 (I)-(IV) 中，电子必须加速到 $\gamma_{\rm max} \ga 10^7$，这表明在 3C 15 射流的结 C 中需要重新加速。还检测到了漫射 X 射线发射，广泛分布在射电波瓣的整个范围（63 kpc $\times$ 25 kpc）。漫射发射的 X 射线光谱由双分量模型描述，由来自主星系晕的软热等离子体发射和硬非热幂律分量组成。硬成分可以归因于射电波瓣中同步加速器发射电子对宇宙微波背景（CMB）光子的逆康普顿化。我们将波瓣中包含的总能量与根据结 C 估计的射流功率进行比较，并讨论射流和波瓣之间的能量联系。我们认为，对于情况 (II)，加燃料时间 ( t Fuel ) 和源年龄 ( t src ) 是可比的，而对于情况 (III)，t Fuel ≪ t src 可能是这样。后者可能意味着射流的填充系数非常小，~10 -3 。我们考虑射电瓣中热星系晕和非热相对论电子之间的压力平衡。最后，我们表明，来自原子核的 X 射线发射不能通过简单的吸收幂律模型充分拟合，而是需要源固有的具有重吸收的附加幂律 ($N_{\rm H} \simeq 10^{22-23}$ cm -2 )。如此高的柱密度与遮蔽类星体核的致密、尘埃环面的存在相一致。
We report the Chandra detection of an X-ray jet in 3C 15. The peak of the X-ray emission in the jet is 4.1 '' (a projected distance of 5.1 kpc) from the nucleus, and coincident with a component previously identified in the radio and optical jets. We construct the spectral energy distribution (SED) for this component, optical knot C, and find that X-ray flux is well below the extrapolation of the radio-to-optical continuum. We examine four models for the X-ray jet emission: (I) weak synchrotron cooling in equipartition, (II) moderate synchrotron cooling in equipartition, (III) weak synchrotron plus synchrotron self-Compton (SSC) cooling, and (IV) moderate synchrotron plus SSC cooling. Given weak evidence for a concave feature in the X-ray spectrum, we argue that case (II) can most reasonably explain the overall emission from knot C. Case (III) is also possible, but requires a large departure from equipartition and for the jet power to be comparable to that of the brightest quasars. In all models, (I)-(IV), electrons must be accelerated up to $\gamma_{\rm max} \ga 10^7$, suggesting that re-acceleration is necessary in knot C of the 3C 15 jet. Diffuse X-ray emission has also been detected, distributed widely over the full extent (63 kpc $\times$ 25 kpc) of the radio lobes. The X-ray spectrum of the diffuse emission is described by a two-component model, consisting of soft thermal plasma emission from the host galaxy halo and a hard nonthermal power-law component. The hard component can be ascribed to the inverse Comptonization of cosmic microwave background (CMB) photons by the synchrotron emitting electrons in the radio lobes. We compare the total energy contained in the lobes with the jet power estimated from knot C, and discuss the energetic link between the jet and the lobes. We argue that the fueling time ( t fuel ) and the source age ( t src ) are comparable for case (II), whereas t fuel ≪ t src is likely for case (III). The latter may imply that the jet has a very small filling factor, ~10 -3 . We consider the pressure balance between the thermal galaxy halo and non-thermal relativistic electrons in the radio lobes. Finally, we show that the X-ray emission from the nucleus is not adequately fitted by a simple absorbed power-law model, but needs an additional power-law with heavy absorption ($N_{\rm H} \simeq 10^{22-23}$ cm -2 ) intrinsic to the source. Such a high column density is consistent with the presence of a dense, dusty torus which obscures the quasar nucleus.