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arXiv 1703.04535astro-ph.GAastro-ph.CO
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大型毫米望远镜的早期科学:在由前沿场星系团透镜的$z>4$正常星系的多幅图像中探测尘埃发射

Early Science with the Large Millimeter Telescope: Detection of dust emission in multiple images of a normal galaxy at $z>4$ lensed by a Frontier Fields cluster

Alexandra Pope, Alfredo Montana, Andrew Battisti, Marceau Limousin, Danilo Marchesini, Grant W. Wilson, Stacey Alberts, Itziar Aretxaga, Vladimir Avila-Reese, J… 展开作者

Alexandra Pope, Alfredo Montana, Andrew Battisti, Marceau Limousin, Danilo Marchesini, Grant W. Wilson, Stacey Alberts, Itziar Aretxaga, Vladimir Avila-Reese, Jose Ramon Bermejo-Climent, Gabriel Brammer, Hector Bravo-Alfaro, Daniela Calzetti, Ranga-Ram Chary, Ryan Cybulski, Mauro Giavalisco, David Hughes, Erin Kado-Fong, Erica Keller, Allison Kirkpatrick, Ivo Labbe, Daniel Lange-Vagle, James Lowenthal, Eric Murphy, Pascal Oesch, Daniel Rosa Gonzalez, David Sanchez-Arguelles, Heath Shipley, Mauro Stefanon, Olga Vega, Katherine Whitaker, Christina C. Williams, Min Yun, Jorge A. Zavala, Milagros Zeballos

摘要:

我们直接检测尘埃排放在光学检测,多重成像星系透镜的前沿领域集群MACSJ0717.5+3745。我们用大毫米望远镜上的AzTEC相机在1.1毫米处探测到同一星系的两幅图像,在对应的识别中没有任何模糊。这个星系,MACS 071_Az9,在z>4和强透镜模型(mu=7.5)允许我们计算的内在红外光度为9.7e10 Lsun和一个模糊的恒星形成率为14.6 +/- 4.5 Msun/年。紫外线的未遮蔽恒星形成率仅为4.1 +/- 0.3 Msun/yr,这意味着总的恒星形成率(18.7 +/- 4.5 Msun/yr)由遮蔽部分主导(75-80%)。MACS 0717_Az9的恒星质量只有6.9e9Msun,是少数几个z>4的星系之一。这个星系位于估计的恒星形成序列在这个时代。然而,它并不依赖于本地星暴星系的尘埃遮蔽关系(IRX-beta),而是与小麦哲伦云(SMC)衰减定律相一致。这个显著的低质量星系显示出低金属含量和高尘埃含量的迹象,可能会挑战我们对早期宇宙尘埃产生的看法。

英文摘要:

We directly detect dust emission in an optically-detected, multiply-imaged galaxy lensed by the Frontier Fields cluster MACSJ0717.5+3745. We detect two images of the same galaxy at 1.1mm with the AzTEC camera on the Large Millimeter Telescope leaving no ambiguity in the counterpart identification. This galaxy, MACS071_Az9, is at z>4 and the strong lensing model (mu=7.5) allows us to calculate an intrinsic IR luminosity of 9.7e10 Lsun and an obscured star formation rate of 14.6 +/- 4.5 Msun/yr. The unobscured star formation rate from the UV is only 4.1 +/- 0.3 Msun/yr which means the total star formation rate (18.7 +/- 4.5 Msun/yr) is dominated (75-80%) by the obscured component. With an intrinsic stellar mass of only 6.9e9Msun, MACS0717_Az9 is one of only a handful of z>4 galaxies at these lower masses that is detected in dust emission. This galaxy lies close to the estimated star formation sequence at this epoch. However, it does not lie on the dust obscuration relation (IRX-beta) for local starburst galaxies and is instead consistent with the Small Magellanic Cloud (SMC) attenuation law. This remarkable lower mass galaxy showing signs of both low metallicity and high dust content may challenge our picture of dust production in the early Universe.

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