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arXiv 1003.3718astro-ph.CO
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星系团中的磁场和Sunyaev-Zel'dovich效应

Magnetic fields and Sunyaev-Zel'dovich effect in galaxy clusters

Rajesh Gopal, Suparna Roychowdhury

摘要:

在这项工作中,我们研究了磁场对团内介质中Sunyaev Zeldovich(SZ)效应的贡献。特别地,我们计算了SZ角功率谱和中心温度衰减。通过将洛伦兹力分为两项,一项是由于向外作用的磁压力引起的力,另一项是向内作用的磁张力,将磁场的影响包括在流体静力平衡方程中。采用微扰法求解弱磁场(< 4 μ G})下的气体密度分布。这导致在近径向磁场配置的中心区域的气体密度的增强。以前的作品已经考虑了由于单独的磁压力,这是一组特殊的字段配置的情况下,由于力。然而,我们看到存在ICM磁场的可能配置集,其中由于磁张力而产生的力将占主导地位。随后,这种效果外推为典型的场强(~ 10微G)和缩放参数被用来估计由于二次各向异性在集群规模的角功率。特别地,我们发现,对于典型的星系团磁场,在l > 2000时,用σ_8 ~ 0.8(WMAP 5年数据)来解释CMB实验(如CBI,BIMA,ACBAR)所报道的过剩功率是可能的。此外,我们还看到,磁场对SZ温度下降的影响是更明显的低质量团簇(<T>~ 2 keV)。未来的SZ探测低质量集群在几个弧秒的分辨率将能够探测这种效果更精确。因此,这将是有益的,以探讨这一模式的影响,在未来的工作更详细。

英文摘要:

In this work we study the contribution of magnetic fields to the Sunyaev Zeldovich (SZ) effect in the intracluster medium. In particular we calculate the SZ angular power spectrum and the central temperature decrement. The effect of magnetic fields is included in the hydrostatic equilibrium equation by splitting the Lorentz force into two terms one being the force due to magnetic pressure which acts outwards and the other being magnetic tension which acts inwards. A perturbative approach is adopted to solve for the gas density profile for weak magnetic fields (< 4 micro G}). This leads to an enhancement of the gas density in the central regions for nearly radial magnetic field configurations. Previous works had considered the force due to magnetic pressure alone which is the case only for a special set of field configurations. However, we see that there exists possible sets of configurations of ICM magnetic fields where the force due to magnetic tension will dominate. Subsequently, this effect is extrapolated for typical field strengths (~ 10 micro G) and scaling arguments are used to estimate the angular power due to secondary anisotropies at cluster scales. In particular we find that it is possible to explain the excess power reported by CMB experiments like CBI, BIMA, ACBAR at l > 2000 with sigma_8 ~ 0.8 (WMAP 5 year data) for typical cluster magnetic fields. In addition we also see that the magnetic field effect on the SZ temperature decrement is more pronounced for low mass clusters (<T> ~ 2 keV). Future SZ detections of low mass clusters at few arc second resolution will be able to probe this effect more precisely. Thus, it will be instructive to explore the implications of this model in greater detail in future works.

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。

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