论文标题

Meerkat对子弹群的观点1E 0657-55.8

MeerKAT's View of the Bullet Cluster 1E 0657-55.8

论文作者

Sikhosana, S. P., Knowles, K., Hilton, M., Moodley, K., Murgia, M.

论文摘要

子弹群(1E 0657-55.8)是RedShift $ z $ = 0.296的大规模合并系统,已知可以举办强大的无线电光环和遗物。在这里,我们提供了对子弹群的高保真度MEERKAT L波段(0.9-1.7 GHz)的观察结果,与以前的研究相比,我们追踪了更大程度的无线电晕和遗物。回收的无线电光环的大小为1.6 MPC $ \ times $ 1.3 MPC,遗物的最大线性大小为〜988 kpc。我们在光晕发射的南部郊区发现了一个新的减少特征,与周围环境相比,一个区域似乎具有较低的表面亮度。光环郊区的较大延伸是微弱的,这表明较低的相对论电子密度或较弱的磁场。无线电光环的带中光谱指数图揭示了朝向弥散源边缘的径向陡峭的迹象,这可能是由于同步基因电子衰老所致。无线电光环的集成光谱指数为1.1 $ \ pm $ 0.2。我们执行无线电X射线表面亮度点对点分析,该分析揭示了无线电光环的线性相关性。这表明无线电光环发射是由主要的重新加速机制产生的。最后,我们为Relic Shock区域的M_R = 4.6 $ \ PM $ 0.9得出了无线电马赫数,该射击位数高于基于X射线数据的早期分析推断的马赫数。对于多个系统,已经观察到无线电和X射线马赫数之间的差异,研究表明这是由于各种因素,包括遗物方向。

The Bullet cluster (1E 0657-55.8) is a massive merging system at redshift $z$=0.296, known to host a powerful radio halo and a relic. Here we present high fidelity MeerKAT L-band (0.9-1.7 GHz) observations of the Bullet cluster, in which we trace a larger extent of both the radio halo and relic in comparison to previous studies. The size of the recovered radio halo is 1.6 Mpc $\times$ 1.3 Mpc and the largest linear size of the relic is ~988 kpc. We detect a new decrement feature on the southern outskirts of the halo emission, where a region appears to have a lower surface brightness in comparison to its surroundings. The larger extension on the outskirts of the halo is faint, which suggests lower relativistic electron density or a weaker magnetic field. An in-band spectral index map of the radio halo reveals a hint of radial steepening towards the edges of the diffuse source, likely due to synchrotron electron ageing. The integrated spectral index of the radio halo is 1.1$\pm$0.2. We perform a radio-X-ray surface brightness point-to-point analysis, which reveals a linear correlation for the radio halo. This indicates that the radio halo emission is produced by primary re-acceleration mechanisms. Finally, we derive a radio Mach number of M_R= 4.6$\pm$0.9 for the relic shock region, which is higher than the Mach number inferred by earlier analyses based on X-ray data. Discrepancies between radio and X-ray Mach numbers have been observed for multiple systems, with studies suggesting that this is due to various factors, including relic orientation.

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