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arXiv 1202.4490astro-ph.CO
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高红移射电星系附近24 μ m源的超密度

Overdensities of 24um Sources in the Vicinities of High-Redshift Radio Galaxies

Jack H. Mayo, Joel Vernet, Carlos De Breuck, Audrey Galametz, Nick Seymour, Daniel Stern

摘要:

本文利用斯皮策空间望远镜MIPS 24 μ m波段的观测数据,对63个红移在1<z<5.2之间的高红移射电星系(HzRGs)的环境进行了统计研究。使用计数在细胞分析,一个统计上显着的源过密被发现在1.75弧分半径的圆形细胞中心的HzRGs相比,参考字段。在f_(24)μ m = 0.3mJ_y的通量密度切割下,平均过密度δ(= {N}_{targets} / {N}_{reference})= 2.2 +/- 1.2。这一结果意味着HzRGs可能位于高红移的活动星系和恒星形成星系的原星系团中。超过95%的目标HzRG位于高于平均密度的区域。此外,我们选择的字段中有20个(32%)被发现是过度密集的,至少有3西格玛的意义,其中9个是新确定的原簇候选人。我们观察到的红移和24 μ m,源密度之间的弱相关性,并讨论了人口被探测在不同的红移。在我们的均匀选择的样品中,它被设计成在整个z=1-4覆盖两个数量级的射电光度,我们发现,24 μ m的源密度不依赖于射电光度。我们还比较了这一结果与最近的工作描述IRAC源overdensities周围相同的HzRGs,并找到结果之间的相关性。

英文摘要:

We present a statistical study of the environments of 63 high-redshift radio galaxies (HzRGs) between redshifts 1<z<5.2, using the 24um, waveband of the MIPS instrument aboard the Spitzer Space Telescope. Using a counts-in-cell analysis, a statistically significant source overdensity is found in 1.75arcmin radius circular cells centred on the HzRGs when compared to reference fields. We report an average overdensity of delta (= {N}_{targets} / {N}_{reference}) = 2.2 +/- 1.2 at a flux density cut of f24um=0.3mJy. This result implies that HzRGs are likely to lie in protoclusters of active and star-forming galaxies at high redshift. Over 95% of our targeted HzRGs lie in higher than average density fields. Further, 20 (32%) of our selected fields are found to be overdense to at least a 3sigma significance, of which 9 are newly identified protocluster candidates. We observe a weak correlation between redshift and 24um, source density, and discuss the populations being probed at different redshifts. In our uniformly selected sample, which was designed to cover two orders of magnitude in radio luminosity throughout z=1-4, we find that the 24um, source density does not depend on radio luminosity. We also compare this result with recent work describing IRAC source overdensities around the same HzRGs and find correlations between the results.

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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