SUBARU HIGH-z EXPLORATION OF LOW-LUMINOSITY QUASARS (SHELLQs). I. DISCOVERY OF 15 QUASARS AND BRIGHT GALAXIES AT 5.7 < z < 6.9
SUBARU HIGH-z EXPLORATION OF LOW-LUMINOSITY QUASARS (SHELLQs). I. DISCOVERY OF 15 QUASARS AND BRIGHT GALAXIES AT 5.7 < z < 6.9
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DOI：
10.3847/0004-637x/828/1/26
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发表时间：
2016-03
期刊：
影响因子：
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通讯作者：
Y. Matsuoka;M. Onoue;N. Kashikawa;K. Iwasawa;M. Strauss;T. Nagao;M. Imanishi;M. Niida;Y. Toba-Y.
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文献类型：
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作者：
Y. Matsuoka;M. Onoue;N. Kashikawa;K. Iwasawa;M. Strauss;T. Nagao;M. Imanishi;M. Niida;Y. Toba-Y.
我们报告了在5.7 < z < 6.9处发现的15个类星体和明亮星系。这是Subaru High-z Exploration of Low-Luminosity Quasars项目的初步结果，该项目利用了Subaru Hyper Suprime-Cam（HSC）战略计划调查产生的精美多波段成像数据。候选人的选择是通过结合几个光度的方法，包括贝叶斯概率算法拒绝恒星和矮星。光谱鉴定是用加那利大望远镜和斯巴鲁望远镜在调查足迹的前80 deg 2进行的。我们的光度选择成功率相当高，在较亮的星等（zAB < 23.5等）下接近100%。我们的选择也恢复了HSC图像上所有已知的高Z类星体。在发现的15个天体中，有6个可能是类星体，而其他6个具有星际吸收线和某些情况下狭窄的发射线的天体可能是明亮的莱曼破裂星系。剩下的三个天体有微弱的连续谱和非常强而窄的Lyα线，可能是由年轻恒星和类星体的紫外线激发的。这些结果表明，与类星体相比，我们开始看到z ≥ 6星系的光度函数在比M1450 <$−22等或zAB <$24等更暗的星等上急剧上升。
We report the discovery of 15 quasars and bright galaxies at 5.7 < z < 6.9. This is the initial result from the Subaru High-z Exploration of Low-Luminosity Quasars project, which exploits the exquisite multiband imaging data produced by the Subaru Hyper Suprime-Cam (HSC) Strategic Program survey. The candidate selection is performed by combining several photometric approaches including a Bayesian probabilistic algorithm to reject stars and dwarfs. The spectroscopic identification was carried out with the Gran Telescopio Canarias and the Subaru Telescope for the first 80 deg2 of the survey footprint. The success rate of our photometric selection is quite high, approaching 100% at the brighter magnitudes (zAB < 23.5 mag). Our selection also recovered all the known high-z quasars on the HSC images. Among the 15 discovered objects, six are likely quasars, while the other six with interstellar absorption lines and in some cases narrow emission lines are likely bright Lyman-break galaxies. The remaining three objects have weak continua and very strong and narrow Lyα lines, which may be excited by ultraviolet light from both young stars and quasars. These results indicate that we are starting to see the steep rise of the luminosity function of z ≥ 6 galaxies, compared with that of quasars, at magnitudes fainter than M1450 ∼ −22 mag or zAB ∼ 24 mag. Follow-up studies of the discovered objects as well as further survey observations are ongoing.