Discovery of an extremely bright submillimeter galaxy at z=3.93
Discovery of an extremely bright submillimeter galaxy at z=3.93
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发现 z=3.93 处极其明亮的亚毫米星系
DOI：
10.1051/0004-6361/201015673
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
Nicola Schneider
中科院分区：
文献类型：
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作者：
J. Lestrade;F. Combes;P. Salomé;A. Omont;F. Bertoldi;Philippe André;Nicola Schneider
我们偶然发现了一个罕见的，明亮的亚毫米星系（SMG），在λ =1.2mm时，它的通量密度为30 +/- 2 mJy，使用了IRAM 30米毫米望远镜的MAMBO2。虽然没有已知的MM18423+5938的光学对应，但我们能够通过使用IRAM 8混频器接收器（EMIR）检测CO线来测量红移z=3.92960 +/- 0.00013。此外，通过收集所有可用的远红外和射电光度数据来限制其光谱能量分布，我们得出其尘埃的FIR光度为4.8 10^14/m Lsol，质量为6.0 10^9/m Msol，允许可能的引力透镜引起的放大因子m。相应的恒星形成速率为8.3 10^4/m Msol/yr。通过对CO旋转阶梯的三条线的检测，以及第四条CO线的显著上限，我们可以估计H2的质量在1.9 10^11/m Msol和1.1 10^12/m Msol之间。两系CI（3p1-3p0）和CI（3p2-3p1）的丰度在1.4 - 10^-5和8.0 - 10^-5之间。给出了观测到的HCN、HCO^+、HNC、H_2O等分子的发射谱线的上限。CO谱线的适度激发表明是一次扩展的星暴，并且排除了AGN在加热这个高红移的SMG中的主导作用。
Serendipitously we have discovered a rare, bright submillimeter galaxy (SMG) with a flux density of 30 +/- 2 mJy at lambda=1.2mm, using MAMBO2 at the IRAM 30-meter millimeter telescope. Although no optical counterpart is known for MM18423+5938, we were able to measure the redshift z=3.92960 +/- 0.00013 from the detection of CO lines using the IRAM Eight MIxer Receiver (EMIR). In addition, by collecting all available photometric data in the far-infrared and radio to constrain its spectral energy distribution, we derive the FIR luminosity 4.8 10^14/m Lsol and mass 6.0 10^9/m Msol for its dust, allowing for a magnification factor m caused by a probable gravitational lens. The corresponding star-formation rate is 8.3 10^4/m Msol/yr. The detection of three lines of the CO rotational ladder, and a significant upper limit for a fourth CO line, allow us to estimate an H2 mass of between 1.9 10^11/m Msol and 1.1 10^12/m Msol. The two lines CI(3p1-3p0) and CI(3p2-3p1) were clearly detected and yield a [CI]/[H2] number abundance between 1.4 10^-5 and 8.0 10^-5. Upper limits are presented for emission lines of HCN, HCO^+, HNC, H_2O and other molecules observed. The moderate excitation of the CO lines is indicative of an extended starburst, and excludes the dominance of an AGN in heating this high-redshift SMG.