X-ray observations of high-z radio loud/quiet quasars |
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| Institution: | 1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;2. Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China;3. State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China;4. College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China;5. State Key Lab of Clean Energy Utilization, State Environmental Protection Engineering Center for Coal-Fired Air Pollution Control, Zhejiang University, Hangzhou 310027, China;6. Key Laboratory of Ecological Metallurgy of Multi-metal Intergrown Ores of Ministry of Education, School of Metallurgy, Northeastern University, Shenyang 110819, China;7. School of Resource and Environmental Engineering, Wuhan University of Science and Technology, Wuhan 430081, China |
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| Abstract: | It is widely recognized that a knowledge of the X-ray properties of high-z radio loud/quiet quasars (RLQs/RQQs) would have important consequences for probing the conditions of the early Universe, studying the evolution of quasars, and assessing quasar contributions to the CXB. In distant active galactic nuclei (AGN) we can detect only the quasars having high luminosities or collimated beams with current X-ray astronomy satellites. We have also detected more than ten RLQs above z=2 with ASCA. We have observed 8 high z RQQs above z=2, but have not detected the higher z RQQs, above z=2.5. A considerable fraction of the high z RLQs show excess absorption over Galactic column densities, while most high z RQQs do not indicate excess absorption, although the samples are small. The X-ray photon index of RLQs is smaller than that of RQQs. The two RLQs above z=4 are very flat, suggesting that they are blazar-like AGN. A long term observation of RQQ, H1400#10 (z=2.078) did not indicate an Fe Kα emission line, giving a weaker upper limit than a typical line intensity of Seyfert 1 galaxies. |
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