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首页> 外文期刊>The Astrophysical journal >Abundance Profiles In Cooling-core Clusters: A Fossil Record Of Past Agn-driven Convection?
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Abundance Profiles In Cooling-core Clusters: A Fossil Record Of Past Agn-driven Convection?

机译:冷却核群中的丰度分布:过去Agn驱动的对流的化石记录?

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Central peaks in the iron abundance of intracluster plasma are a common feature of cooling-core galaxy clusters. Although they are centrally localized, these abundance peaks have a broader profile than the stars of the brightest cluster galaxy (BCG) that produce the excess iron, indicating that metal-enriched plasma is transported out of the BCG by some process such as turbulent diffusion. The AGN-driven convection model of Chandran & Rasera predicts the turbulent velocity profile in a steady state cluster in which radiative cooling is balanced by heating from AGN-driven convection and thermal conduction. We use the velocity profiles from this model as input into an advection/diffusion model for the transport of metals in the intracluster medium. We compare the results of our model to XMM-Newton and Chandra observations of eight clusters. Assuming a constant turbulence level over a cluster's lifetime equal to the present value, the turbulent velocities in the model can explain the observed abundance profiles in only five of the eight clusters. However, we go on to develop an analytic fit of the turbulent velocity profile as a function of the AGN power. We then deduce for each cluster the average AGN power (during the past~10 Gyr) required to match the abundance profiles. The required average values are between 10~(43) and 2 × 10~(44) erg s~(-1), while the present AGN powers span a much larger range. Our results suggest that AGN-driven convection can account for the observed abundance profiles if the AGN power varies in time with average values in the above-quoted range.
机译:团簇内血浆铁丰度的中心峰是冷却核心星系团的共同特征。尽管这些丰度峰位于中心位置,但它们的轮廓要比产生过量铁的最亮星系星系(BCG)的恒星宽,这表明富含金属的等离子体是通过湍流扩散等过程从BCG运出的。 Chandran&Rasera的AGN驱动的对流模型预测了稳态簇中的湍流速度分布,在稳态簇中,辐射冷却通过AGN驱动的对流和热传导的热量得到平衡。我们使用该模型的速度剖面作为对流/扩散模型的输入,以在簇内介质中传输金属。我们将模型的结果与XMM-Newton和Chandra对八个聚类的观察结果进行比较。假设整个星团的整个生命周期中的湍流水平等于当前值,则模型中的湍流速度可以解释八个星团中只有五个的观测到的丰度分布。但是,我们继续根据AGN功率开发出湍流速度分布的解析拟合。然后,我们为每个聚类推导匹配丰度分布图所需的平均AGN功率(过去10 Gyr内)。所需的平均值在10〜(43)和2×10〜(44)erg s〜(-1)之间,而当前的AGN功率跨度更大。我们的结果表明,如果AGN功率随时间在上述范围内变化,则AGN驱动的对流可以解释观测到的丰度分布。

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