arXiv 1001.21682010-01-13astro-ph.CO

SDSS-maxBCG星系团的红外特性

Infrared properties of the SDSS-maxBCG galaxy clusters

M. Roncarelli, E. Pointecouteau, M. Giard, L. Montier, R. Pello

备注：: 12 pages, 6 figures, 2 tables. Accepted for publication in A&A
DOI：: 10.1051/0004-6361/200912726

摘要：

星系团的物理学已被证明受到与其银河组成部分有关的几个过程的影响，这些过程使ICM受到金属、恒星和尘埃的污染。然而，目前还不清楚弥漫尘埃的存在是否可以在集群物理中发挥作用，因为星系团的红外特性的表征尚未完全实现。Giard等人（2008）对数千个星系团的IRAS数据进行了叠加分析，给出了星系团红外光度和红移演化的统计特征。我们模拟了SDSS-maxBCG星系团（0.1<z<0.3）星系群的红外特性，以检查它是否解释了整个观测到的信号，并限制其他成分的可能存在，如ICM中的尘埃。从星系成员的光学性质出发，我们估计它们的发射在60和100微米的IRAS波段利用不同的光谱类型（E/S 0，Sa，Sb，Sc和星爆）建模的SED。我们还考虑了星系人口/光度随红移的演化。我们的结果表明，银河系的发射，这是占主导地位的恒星形成星系的贡献，是与观测到的信号。事实上，我们的模型稍微高估了观测到的通量，多余的通量集中在低红移星系团（z <~ 0.17）。这表明，如果存在的话，来自星团内尘埃的红外辐射一定非常小。我们得到了ICM中尘气质量比的上限值Z_d <~ 5 × 10^-5。在低红移下获得的光度过剩表明，星团环境正在推动其星系成员中恒星形成的淬灭过程。

英文摘要：

The physics of galaxy clusters has proven to be influenced by several processes connected with their galactic component which pollutes the ICM with metals, stars and dust. However, it is not clear whether the presence of diffuse dust can play a role in clusters physics since a characterisation of the IR properties of galaxy clusters is yet to be completely achieved. We focus on the recent work of Giard et al. (2008) who performed a stacking analysis of the IRAS data in the direction of several thousands of galaxy clusters, providing a statistical characterisation of their IR luminosity and redshift evolution. We model the IR properties of the galactic population of the SDSS-maxBCG clusters (0.1<z<0.3) in order to check if it accounts for the entire observed signal and to constrain the possible presence of other components, like dust in the ICM. Starting from the optical properties of the galaxy members, we estimate their emission in the 60 and 100 micron IRAS bands making use of modeled SEDs of different spectral types (E/S0, Sa, Sb, Sc and starburst). We also consider the evolution of the galactic population/luminosity with redshift. Our results indicate that the galactic emission, which is dominated by the contribution of star-forming galaxies, is consistent with the observed signal. In fact, our model slightly overestimates the observed fluxes, with the excess being concentrated in low-redshift clusters (z <~ 0.17). This indicates that, if present, the IR emission from intracluster dust must be very small. We obtain an upper limit on the dust-to-gas mass ratio in the ICM of Z_d <~ 5 10^-5. The excess in luminosity obtained at low redshift constitutes an indication that the cluster environment is driving a process of star-formation quenching in its galaxy members.

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