A PHOTOMETRIC REDSHIFT OF z ∼ 9.4 FOR GRB 090429B
A PHOTOMETRIC REDSHIFT OF z ∼ 9.4 FOR GRB 090429B
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DOI：
10.1088/0004-637x/736/1/7
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发表时间：
2011-05
期刊：
影响因子：
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通讯作者：
A. Cucchiara;A. Cucchiara;A. Cucchiara;A. Levan;D. Fox;N. Tanvir;T. Ukwatta;T. Ukwatta;E. Berger
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文献类型：
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作者：
A. Cucchiara;A. Cucchiara;A. Cucchiara;A. Levan;D. Fox;N. Tanvir;T. Ukwatta;T. Ukwatta;E. Berger
伽马射线暴（GRBs）是研究早期宇宙的有力探针，其明亮的余辉揭示了处于最高红移处的恒星形成星系的位置和物理性质，并有可能确定第一代（星族III）恒星的位置。由于伽马射线暴余辉本质上具有非常简单的光谱，它们可以从低信噪比的光谱学或光度测量中得出可靠的红移值。在此，我们基于使用双子座北座望远镜、甚大望远镜以及伽马射线暴光学和近红外探测器所进行的深度观测，给出了Swift探测到的伽马射线暴090429B的一个光度红移值约为9.4。假设遵循小麦哲伦星云的尘埃定律（这在大多数伽马射线暴视线方向中都已被发现），红移的90%置信区间为9.06 < z < 9.7。在我们使用哈勃太空望远镜进行的后期光学和红外观测中，对宿主星系未探测到极深极限（Y（AB）约为28，这大致相当于在z = 1处的0.001L*），这有力地支持了伽马射线暴090429B来自极高红移的起源，因为我们本应能探测到任何低红移星系，即使它尘埃含量很高。最后，伽马射线暴090429B的能量学特征与其他伽马射线暴相当，这表明它的前身星与低红移爆发的前身星并没有太大差异。
Gamma-ray bursts (GRBs) serve as powerful probes of the early universe, with their luminous afterglows revealing the locations and physical properties of star-forming galaxies at the highest redshifts, and potentially locating first-generation (Population III) stars. Since GRB afterglows have intrinsically very simple spectra, they allow robust redshifts from low signal-to-noise spectroscopy, or photometry. Here we present a photometric redshift of z ∼ 9.4 for the Swift detected GRB 090429B based on deep observations with Gemini-North, the Very Large Telescope, and the GRB Optical and Near-infrared Detector. Assuming a Small Magellanic Cloud dust law (which has been found in a majority of GRB sight lines), the 90% likelihood range for the redshift is 9.06 7. The non-detection of the host galaxy to deep limits (Y(AB) ∼ 28, which would correspond roughly to 0.001L* at z = 1) in our late-time optical and infrared observations with the Hubble Space Telescope strongly supports the extreme-redshift origin of GRB 090429B, since we would expect to have detected any low-z galaxy, even if it were highly dusty. Finally, the energetics of GRB 090429B are comparable to those of other GRBs and suggest that its progenitor is not greatly different from those of lower redshift bursts.