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arXiv 1111.5162astro-ph.CO
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用朱雀XIS观测Abell 3667的团簇内介质性质

Properties of the intracluster medium of Abell 3667 observed with Suzaku XIS

H. Akamatsu, J. de Plaa, J. Kaastra, Y. Ishisaki, T. Ohashi, M. Kawaharada, K. Nakazawa

摘要:

我们用朱雀XIS观测了A3667星系团的西北区。的温度和表面亮度的簇内介质进行了测量维里半径(r200-2.3 Mpc)。径向温度分布比其他星团的平均温度分布平坦,直到半径达到西北射电遗迹。在西北射电遗迹区,温度从5 keV急剧下降到2keV左右。温度的急剧变化可以解释为马赫数约为2.5的激波。熵的斜率在外围区域变平缓,在射电遗迹区域附近为负值。在这个区域中,电子-离子库仑碰撞的弛豫时间尺度比冲击加热后经过的时间长,等离子体可能失去平衡。利用差分辐射测量(DEM)模型,我们还确认了多温度结构周围的无线电遗迹区,其特征在于在1 keV和4 keV的两个峰值。这些特征表明,气体被从中心向外区传播的激波加热。

英文摘要:

We observed the northwest region of the cluster of galaxies A3667 with the Suzaku XIS instrument. The temperature and surface brightness of the intracluster medium were measured up to the virial radius (r200-2.3 Mpc). The radial temperature profile is flatter than the average profile for other clusters until the radius reaches the northwest radio relic. The temperature drops sharply from 5 keV to about 2 keV at the northwest radio relic region. The sharp changes of the temperature can be interpreted as a shock with a Mach number of about 2.5. The entropy slope becomes flatter in the outer region and negative around the radio relic region. In this region, the relaxation timescale of electron-ion Coulomb collisions is longer than the time elapsed after the shock heating and the plasma may be out of equilibrium. Using differential emission measure (DEM) models, we also confirm the multi-temperature structure around the radio relic region, characterized by two peaks at 1 keV and 4 keV. These features suggest that the gas is heated by a shock propagating from the center to outer region.

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