arXiv 0905.09662009-05-07astro-ph.CO

Abell 754的射电散射

Diffuse Radio Emission in Abell 754

Ruta Kale, K. S. Dwarakanath

备注：: 13 pages inclusive of 5 figures and 3 tables. Accepted for publication in Astrophysical Journal
发表信息：: Astrophys.J.699:1883-1890,2009
DOI：: 10.1088/0004-637X/699/2/1883

摘要：

本文对星系团A754的弥散射电辐射进行了低频研究。本文介绍了用巨米波射电望远镜（GMRT）拍摄的星系团A754的150 MHz新图像，并讨论了4个漫射特征的探测。我们比较了150 MHz的图像在74，330和1363 MHz的图像，一个新的扩散功能检测。在330和1363兆赫的通量密度上限意味着同步加速器光谱指数，$α> 2$，（$S\propto ν^{-α}$）的新功能。在74 MHz（Kassim等人，2001年）检测到的“西遗迹”在150 MHz时未检测到，因此与在1363 MHz（Bacchi等人，2003年）和330 MHz（Kassim等人，2001年）时未检测到的情况一致。综合光谱的所有扩散功能。第四个扩散特征位于A754中沿着拟议的合并轴（Zabluquet al 1995），距离X射线发射峰值0.7 Mpc。我们利用绝热压缩模型（Ensslin & Gopal-Krishna 2001）的框架来获得光谱。我们表明，第四个弥漫功能的频谱是一致的，一个茧的射电星系潜伏约$9\times10^{7}$年，没有冲击压缩是必需的。其他三个漫发射的光谱比1.5陡，可能是潜伏时间较长的茧。我们讨论了其他的可能性，如冲击和湍流再加速是负责在A754的漫发射。

英文摘要：

We present a low frequency study of the diffuse radio emission in the galaxy cluster A754. We present new 150 MHz image of the galaxy cluster A754 made with the Giant Metrewave Radio Telescope (GMRT) and discuss the detection of 4 diffuse features. We compare the 150 MHz image with the images at 74, 330 and 1363 MHz; one new diffuse feature is detected. The flux density upperlimits at 330 and 1363 MHz imply a synchrotron spectral index, $α> 2$, ($S\propto ν^{-α}$) for the new feature. The 'west relic' detected at 74 MHz (Kassim et al 2001) is not detected at 150 MHz and is thus consistent with its non-detection at 1363 MHz (Bacchi et al 2003) and 330 MHz(Kassim et al 2001). Integrated spectra of all the diffuse features are presented. The fourth diffuse feature is located along the proposed merger axis (Zabludoff et al 1995) in A754 and 0.7 Mpc away from the peak of X-ray emission. We have made use of the framework of adiabatic compression model (Ensslin & Gopal-Krishna 2001) to obtain spectra. We show that the spectrum of the fourth diffuse feature is consistent with that of a cocoon of a radio galaxy lurking for about $9\times10^{7}$ yr; no shock compression is required. The other three diffuse emission have spectra steeper than 1.5 and could be cocoons lurking for longer time. We discuss other possibilities such as shocks and turbulent reacceleration being responsible for the diffuse emission in A754.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

摘要：

英文摘要：

相关论文