arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1003.0827astro-ph.CO
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子弹星系团背后的亚毫米星系(1E 0657 - 56)

Submillimeter galaxies behind the Bullet Cluster (1E 0657-56)

Daniel Johansson, Cathy Horellou, Martin W. Sommer, Kaustuv Basu, Frank Bertoldi, Mark Birkinshaw, Katy Lancaster, Omar Lopez-Cruz, Hernan Quintana

摘要:

星系团是有效的引力透镜,能够放大背景星系,使探测星系群中较暗的部分成为可能。亚毫米星系是典型红移为2~3的恒星形成星系,是星系团扩展的Sunyaev-Zeldovich(SZ)信号的主要污染物。对于一个适当的量化的SZ信号的亚毫米星系的贡献需要量化。这项研究的目的是确定子弹星系团(1E 0657 - 56),z~0.3的大质量星系团领域的亚毫米源,测量它们在870微米的通量密度,并寻找其他波长的对应物,以限制它们的属性。我们使用阿塔卡马探路者实验(APEX)望远镜上的大型APEX BOlometer CAmera(LABOCA)对870微米的亚毫米连续辐射进行了深入观测。几种数值技术被用来量化数据的噪声特性和提取源。总共发现了17个源,其中13个位于地图的中心10弧分,其像素灵敏度为每22弧秒束1.2 mJy。经过通量提升和引力透镜的校正后,计数结果与发表的亚毫米级测量结果一致。其中九个来源在斯皮策地图上有红外对应物。最强的submm探测与以前报道的其他波长的源相吻合,估计红移z~2.7。如果像模型所建议的那样,一个星系的两张图像放大了75倍,那么亚毫米级的流量就产生了,它的内禀流量大约是0.6 mJy,这与内禀光度低于10^12 L_sun是一致的。

英文摘要:

Clusters of galaxies are effective gravitational lenses able to magnify background galaxies and making it possible to probe the fainter part of the galaxy population. Submillimeter galaxies, which are believed to be star-forming galaxies at typical redshifts of 2 to 3, are a major contaminant to the extended Sunyaev-Zeldovich (SZ) signal of galaxy clusters. For a proper quantification of the SZ signal the contribution of submillimeter galaxies needs to be quantified. The aims of this study are to identify submillimeter sources in the field of the Bullet Cluster (1E 0657-56), a massive cluster of galaxies at z~0.3, measure their flux densities at 870 micron, and search for counterparts at other wavelengths to constrain their properties. We carried out deep observations of the submillimeter continuum emission at 870 micron using the Large APEX BOlometer CAmera (LABOCA) on the Atacama Pathfinder EXperiment (APEX) telescope. Several numerical techniques were used to quantify the noise properties of the data and extract sources. In total, seventeen sources were found. Thirteen of them lie in the central 10 arcminutes of the map, which has a pixel sensitivity of 1.2 mJy per 22 arcsec beam. After correction for flux boosting and gravitational lensing, the number counts are consistent with published submm measurements. Nine of the sources have infrared counterparts in Spitzer maps. The strongest submm detection coincides with a source previously reported at other wavelengths, at an estimated redshift z~2.7. If the submm flux arises from two images of a galaxy magnified by a total factor of 75, as models have suggested, its intrinsic flux would be around 0.6 mJy, consistent with an intrinsic luminosity below 10^12 L_sun.

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