3D-HST GRISM SPECTROSCOPY OF A GRAVITATIONALLY LENSED, LOW-METALLICITY STARBURST GALAXY AT z = 1.847
3D-HST GRISM SPECTROSCOPY OF A GRAVITATIONALLY LENSED, LOW-METALLICITY STARBURST GALAXY AT z = 1.847
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DOI：
10.1088/2041-8205/758/1/l17
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发表时间：
2012-07
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通讯作者：
G. Brammer;R. Sánchez-Janssen;I. Labbé;E. da Cunha;D. Erb;M. Franx;M. Fumagalli;B. Lundgren
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作者：
G. Brammer;R. Sánchez-Janssen;I. Labbé;E. da Cunha;D. Erb;M. Franx;M. Fumagalli;B. Lundgren
我们展示了引力透镜 SL2SJ02176-0513 的哈勃太空望远镜 (HST) 成像和光谱，即 z = 1.847 处的尖点弧。透镜星系的紫外连续谱非常蓝，这似乎与其较红的光学颜色不一致。透镜的 3D-HST WFC3/G141 近红外光谱揭示了这种差异的根源是极强的 [O iii] λ5007 和 Hβ 发射线，其静止框架等效宽度分别为 2000 ± 100 和 520 ± 40 Å。源的恒星质量为∼108 M☉，sSFR ∼ 100 Gyr−1，检测到[O iii] λ4363 得到的金属丰度为12 + log (O/H) = 7.5 ± 0.2。我们确定了与 SL2SJ02176-0513 类似的本地蓝致密矮星，它们是斯隆数字巡天中金属最贫乏的星系之一。局部类似物在许多方面类似于透镜星系，包括紫外/光学光谱能量分布、空间形态以及发射线等效宽度和比率。 SL2SJ02176-0513 及其本地同类产品的共同点是中红外波长的上升，可能是由星暴加热的热尘埃引起的。由于透镜和 HST 的高空间分辨率的结合，SL2SJ02176-0513 的发射线具有空间分辨率。透镜星系由两个团块组成，总尺寸约为 300 pc，我们解决了它们之间紫外颜色和发射线等效宽度的显着差异。尽管它偶尔具有活跃星系核的特征，但我们得出结论，SL2SJ02176-0513 是一个低金属丰度的星爆矮星系。在完整的 3D-HST 棱面巡天中将会发现大量此类星系。
We present Hubble Space Telescope (HST) imaging and spectroscopy of the gravitational lens SL2SJ02176-0513, a cusp arc at z = 1.847. The UV continuum of the lensed galaxy is very blue, which is seemingly at odds with its redder optical colors. The 3D-HST WFC3/G141 near-infrared spectrum of the lens reveals the source of this discrepancy to be extremely strong [O iii] λ5007 and Hβ emission lines with rest-frame equivalent widths of 2000 ± 100 and 520 ± 40 Å, respectively. The source has a stellar mass ∼108 M☉, sSFR ∼ 100 Gyr−1, and detection of [O iii] λ4363 yields a metallicity of 12 + log (O/H) = 7.5 ± 0.2. We identify local blue compact dwarf analogs to SL2SJ02176-0513, which are among the most metal-poor galaxies in the Sloan Digital Sky Survey. The local analogs resemble the lensed galaxy in many ways, including UV/optical spectral energy distribution, spatial morphology, and emission line equivalent widths and ratios. Common to SL2SJ02176-0513 and its local counterparts is an upturn at mid-IR wavelengths likely arising from hot dust heated by starbursts. The emission lines of SL2SJ02176-0513 are spatially resolved owing to the combination of the lens and the high spatial resolution of HST. The lensed galaxy is composed of two clumps with combined size re ∼300 pc, and we resolve significant differences in UV color and emission line equivalent width between them. Though it has characteristics occasionally attributed to active galactic nuclei, we conclude that SL2SJ02176-0513 is a low-metallicity star-bursting dwarf galaxy. Such galaxies will be found in significant numbers in the full 3D-HST grism survey.