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THE LIFETIME AND POWERS OF FR IIs IN GALAXY CLUSTERS

机译:银河团簇中FR II的寿命和能力

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We have identified and studied a sample of 151 FR?IIs found in brightest cluster galaxies (BCGs) in the MaxBCG cluster catalog with data from FIRST and NVSS. We have compared the radio luminosities and projected lengths of these FR?IIs to the projected length distribution of a range of mock catalogs generated by an FR?II model and estimate the FR?II lifetime to be 1.9 × 108?yr. The uncertainty in the lifetime calculation is a factor of two, primarily due to uncertainties in the intracluster medium (ICM) density and the FR?II axial ratio. We furthermore measure the jet power distribution of FR?IIs in BCGs and find that it is well described by a log-normal distribution with a median power of 1.1 × 1037?W and a coefficient of variation of 2.2. These jet powers are nearly linearly related to the observed luminosities, and this relation is steeper than many other estimates, although it is dependent on the jet model. We investigate correlations between FR?II and cluster properties and find that galaxy luminosity is correlated with jet power. This implies that jet power is also correlated with black hole mass, as the stellar luminosity of a BCG should be a good proxy for its spheroid mass and therefore the black hole mass. Jet power, however, is not correlated with cluster richness, nor is FR?II lifetime strongly correlated with any cluster properties. We calculate the enthalpy of the lobes to examine the impact of the FR?IIs on the ICM and find that heating due to adiabatic expansion is too small to offset radiative cooling by a factor of at least six. In contrast, the jet power is approximately an order of magnitude larger than required to counteract cooling. We conclude that if feedback from FR?IIs offsets cooling of the ICM, then heating must be primarily due to another mechanism associated with FR?II expansion.
机译:我们已经从FIRST和NVSS的数据中识别并研究了MaxBCG群集目录中最亮的群集星系(BCG)中发现的151个FR?II样本。我们已将这些FR?II的辐射发光度和预计长度与FR?II模型生成的一系列模拟目录的预计长度分布进行了比较,并估计FR?II的寿命为1.9×108?yr。寿命计算中的不确定性是两个因素,主要是由于簇内介质(ICM)密度和FR?II轴向比的不确定性。我们还测量了BCG中FRIIs的射流功率分布,发现它很好地用对数正态分布描述,中值功率为1.1×1037ΩW,变异系数为2.2。这些射流功率与观测到的光度几乎呈线性关系,尽管依赖于射流模型,但这种关系比许多其他估计要陡峭。我们研究了FRII和星团性质之间的相关性,发现星系的光度与射流功率有关。这意味着喷射功率也与黑洞质量有关,因为BCG的恒星发光度应该很好地替代其球状质量,因此也可以代替黑洞质量。但是,射流功率与簇的富集度没有关系,FR?II的寿命也与簇的任何性质都没有强相关。我们计算了叶片的焓,以检查FRIIs对ICM的影响,发现绝热膨胀所产生的热量太小而不能抵消辐射冷却至少六倍。相反,喷射功率比抵消冷却所需的功率大大约一个数量级。我们得出的结论是,如果来自FRII的反馈抵消了ICM的冷却,则加热必须主要归因于与FRII膨胀相关的另一种机理。

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