分类： 天文学 >> 天文学 提交时间： 2023-02-19
Hongliang Yan
Haining Li
Song Wang
Weikai Zong
Haibo Yuan
Maosheng Xiang
Yang Huang
Jiwei Xie
Subo Dong
Hailong Yuan
Shaolan Bi
Yaoquan Chu
Xiangqun Cui
Licai Deng
Jianning Fu
Zhanwen Han
Jinliang Hou
Guoping Li
Chao Liu
Jifeng Liu
摘要： The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST), also known as the Guoshoujing Telescope, is a major national scientific facility for astronomical research located in Xinglong, China. Beginning with a pilot survey in 2011, LAMOST has been surveying the night sky for more than 10 years. The LAMOST survey covers various objects in the Universe, from normal stars to peculiar ones, from the Milky Way to other galaxies, and from stellar black holes and their companions to quasars that ignite ancient galaxies. Until the latest data release 8, the LAMOST survey has released spectra for more than 10 million stars, ~220,000 galaxies, and ~71,000 quasars. With this largest celestial spectra database ever constructed, LAMOST has helped astronomers to deepen their understanding of the Universe, especially for our Milky Way galaxy and the millions of stars within it. In this article, we briefly review the characteristics, observations, and scientific achievements of LAMOST. In particular, we show how astrophysical knowledge about the Milky Way has been improved by LAMOST data.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Yuanqi Liu
Ran Wang
Emmanuel Momjian
Jeff Wagg
Xiaolong Yang
Tao An
Yali Shao
Chris L. Carilli
Xuebing Wu
Xiaohui Fan
Fabian Walter
Linhua Jiang
Qiong Li
Jianan Li
Qinyue Fei
Fuxiang Xu
摘要： We report deep Karl G. Jansky Very Large Array (VLA) observations of the optically ultraluminous and radio-quiet quasar SDSS J010013.02 + 280225.8 (hereafter J0100+2802) at redshift $z=$6.3. We detected the radio continuum emission at 1.5 GHz, 6 GHz, and 10 GHz. This leads to a radio power-law spectral index of $\alpha = -0.52\pm0.18$ ($S \propto \nu^{\alpha}$). The radio source is unresolved in all VLA bands with an upper limit to the size of $0.2^{\prime \prime}$ (i.e., $\sim$ 1.1 kpc) at 10 GHz. We find variability in the flux density (increase by $\sim 33\%$) and the spectral index (steepened) between observations in 2016 and 2017. We also find that the VLA 1.5 GHz flux density observed in the same year is 1.5 times that detected with the Very Long Baseline Array (VLBA) in 2016 at the same frequency. This difference suggests that half of the radio emission from J0100+2802 comes from a compact core within 40 pc, and the rest comes from the surrounding few kpc area which is diffuse and resolved out in the VLBA observations. The diffuse emission is four times brighter than that would be expected if driven by star formation. We conclude that the central active galactic nucleus is the dominant power engine of the radio emission in J0100+2802.
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