Dear everyone,
A colloquium talk will be held next Monday. Please pay attention to this announcement. Detailed information is as followings:

Title: The Highest Redshift Quasars and the End of Reionization
Speaker: Professor Xiaohui Fan
Affiliation: University of Arizona
Time: 14:00PM, July 21st (Next Monday)
Location: middle conference room, 3rd floor

Abstract：
Luminous quasars at high redshift provide direct probes of the evolution of supermassive black holes (BHs) and the intergalactic medium (IGM) at early cosmic time. Over the last six years, more than 20 quasars have been discovered at z>6 from various wide-field surveys. Two main results emerge from the studies of these quasars. Detections of such objects indicate the existence of billion M_sun BHs merely a few hundred Myrs after the first star formation in the Universe. They are surrounded by metal-enriched gas and young galaxies with intense star formation, providing the strongest constraints on early growth of supermassive BHs and co-evolution with their host galaxies.

Meanwhile, Absorption spectra of the highest redshift quasars reveal complete Gunn-Peterson absorption, indicating a rapid increase in the IGM neutral fraction, marking the end of the reionization epoch at z~6, suggesting a peak of reionization activity and emergence of the earliest galaxies and AGNs at 6<15. These results strongly suggest that crucial changes are happening at z~6-7. A number of ambitious near-IR surveys aiming at finding quasars at z>7 will likely produce the first detection of quasars in this crucial epoch in the next few years.

Please tell each other to participate in.

Welcome to attend! : )