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arXiv 2009.04838astro-ph.GA
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ALMA透镜星系团巡天：一个ALMA星系标志着一个MUSE星系群位于“El Gordo”后面z=4.3

ALMA Lensing Cluster Survey: an ALMA galaxy signposting a MUSE galaxy group at z=4.3 behind 'El Gordo'

K. I. Caputi, G. B. Caminha, S. Fujimoto, K. Kohno, F. Sun, E. Egami, S. Deshmukh, F. Tang, Y. Ao, L. Bradley, D. Coe, D. Espada, C. Grillo, B. Hatsukade, K. K.… 展开作者

K. I. Caputi, G. B. Caminha, S. Fujimoto, K. Kohno, F. Sun, E. Egami, S. Deshmukh, F. Tang, Y. Ao, L. Bradley, D. Coe, D. Espada, C. Grillo, B. Hatsukade, K. K. Knudsen, M. M. Lee, G. E. Magdis, K. Morokuma-Matsui, P. Oesch, M. Ouchi, P. Rosati, H. Umehata, F. Valentino, E. Vanzella, W. -H. Wang, J. F. Wu, A. Zitrin

备注：
13 pages including 7 figures and 1 table. Accepted for publication at the ApJ. Minor changes with respect to version 1. Figure 6 has been expanded to broaden comparison with the literature
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摘要：

我们报告了一个多单元光谱探测器（MUSE）星系群的发现，该星系群被z=0.87的大质量星系团ACT-CL J 0102 -4915（又名El Gordo）透镜，与一个1.2 mm的源有关，该源距离该星系群中的一个星系的投影距离为2.07+/-0.88 kpc。整个系统的三个图像出现在图像平面中。在阿塔卡马大型毫米/亚毫米阵列（ALMA）透镜集群调查（ALCS）中检测到了1.2毫米源。由于这个ALMA源在波长λ < 2微米时未被探测到，因此它的红移不能独立地确定，然而，三个透镜分量表明它属于z=4.32的同一星系群。MUSE星系群的四个成员具有低到中等的恒星质量（~ 10^7-10^{10} Msun）和0.4-24 Msun/年的恒星形成率（SFR），导致其中两个星系的高比SFR（sSFR），这表明这些星系正在快速增长（恒星质量倍增时间仅为~ 2x10^7年）。星暴星系的高发生率可能是星系群内部相互作用的结果，星系群是紧凑的，具有高速分散。根据放大率校正的亚毫米连续通量密度和估计的恒星质量，我们推断ALMA源被归类为一个普通的超亮红外星系（与相关的尘埃遮蔽的SFR~200-300 Msun/yr），并位于恒星形成的主序列。这个ALMA/MUSE星系团关联的案例表明，一些可能孤立的ALMA源实际上是高红移时更丰富的恒星形成环境的路标。

英文摘要：

We report the discovery of a Multi Unit Spectroscopic Explorer (MUSE) galaxy group at z=4.32 lensed by the massive galaxy cluster ACT-CL J0102-4915 (aka El Gordo) at z=0.87, associated with a 1.2 mm source which is at a 2.07+/-0.88 kpc projected distance from one of the group galaxies. Three images of the whole system appear in the image plane. The 1.2 mm source has been detected within the Atacama Large Millimetre/submillimetre Array (ALMA) Lensing Cluster Survey (ALCS). As this ALMA source is undetected at wavelengths lambda < 2 microns, its redshift cannot be independently determined, however, the three lensing components indicate that it belongs to the same galaxy group at z=4.32. The four members of the MUSE galaxy group have low to intermediate stellar masses (~ 10^7-10^{10} Msun) and star formation rates (SFRs) of 0.4-24 Msun/yr, resulting in high specific SFRs (sSFRs) for two of them, which suggest that these galaxies are growing fast (with stellar-mass doubling times of only ~ 2x10^7 years). This high incidence of starburst galaxies is likely a consequence of interactions within the galaxy group, which is compact and has high velocity dispersion. Based on the magnification-corrected sub-/millimetre continuum flux density and estimated stellar mass, we infer that the ALMA source is classified as an ordinary ultra-luminous infrared galaxy (with associated dust-obscured SFR~200-300 Msun/yr) and lies on the star-formation main sequence. This reported case of an ALMA/MUSE group association suggests that some presumably isolated ALMA sources are in fact signposts of richer star-forming environments at high redshifts.

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