arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0909.1803astro-ph.CO
收藏

超深WFC3/IR观测发现HUDF中z~8星系

Discovery of z~8 Galaxies in the HUDF from ultra-deep WFC3/IR Observations

R. J. Bouwens, G. D. Illingworth, P. A. Oesch, M. Stiavelli, P. van Dokkum, M. Trenti, D. Magee, I. Labbe, M. Franx, M. Carollo, V. Gonzalez

备注：
5 pages, 5 figures, 2 tables, accepted for publication in the Astrophysical Journal Letters, updated to match accepted version
阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

我们利用新获得的，超深的WFC 3/红外观测HUDF搜索恒星形成星系在z~8-8.5，只有6亿年的重组，使用Y_{105} -dropout选择。新的4.7 arcmin**2 WFC 3/IR观测值在Y_{105} J_{125} H_{160}波段达到~28.8 AB等（5 σ）。这些显著的数据达到~1.5 AB MAG比以前的数据超过HUDF，现在是一个很好的匹配HUDF光学ACS数据。对于我们的搜索标准，我们使用双色Lyman-Break选择技术来识别z~8-8.5 Y_{105} -脱落。我们发现5个可能的z~8-8.5候选者。这些源的H_{160}波段星等约为28.3 AB等，紫外连续谱斜率非常蓝，估计β值中值<-2.5（其中f_λ \propto λ^β）。这表明z~8星系不仅基本上没有尘埃，而且可能具有非常年轻的年龄或低金属丰度。观察到的Y_{105} -脱落候选者的数量小于假设没有从z~6演变的预期20+/-6个来源，但与Bouwens等人2008年LF结果外推到z~8的预期5个来源一致。这些结果提供了证据，从z~7到z~3看到的LF中的演化继续到z~8。WFC 3/IR灵敏度的显著提高使HST能够跨越一个阈值，揭示z~8-9的恒星形成星系。

英文摘要：

We utilize the newly-acquired, ultra-deep WFC3/IR observations over the HUDF to search for star-forming galaxies at z~8-8.5, only 600 million years from recombination, using a Y_{105}-dropout selection. The new 4.7 arcmin**2 WFC3/IR observations reach to ~28.8 AB mag (5 sigma) in the Y_{105}J_{125}H_{160} bands. These remarkable data reach ~1.5 AB mag deeper than the previous data over the HUDF, and now are an excellent match to the HUDF optical ACS data. For our search criteria, we use a two-color Lyman-Break selection technique to identify z~8-8.5 Y_{105}-dropouts. We find 5 likely z~8-8.5 candidates. The sources have H_{160}-band magnitudes of ~28.3 AB mag and very blue UV-continuum slopes, with a median estimated beta of <~-2.5 (where f_λ\propto λ^β). This suggests that z~8 galaxies are not only essentially dust free but also may have very young ages or low metallicities. The observed number of Y_{105}-dropout candidates is smaller than the 20+/-6 sources expected assuming no evolution from z~6, but is consistent with the 5 expected extrapolating the Bouwens et al. 2008 LF results to z~8. These results provide evidence that the evolution in the LF seen from z~7 to z~3 continues to z~8. The remarkable improvement in the sensitivity of WFC3/IR has enabled HST to cross a threshold, revealing star-forming galaxies at z~8-9.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

↑