报告题目：Measurements of Quasar Ages 

　　报 告 人：郑玮教授 (The Johns Hopkins University)

　　摘    要：What is the lifespan of these supermassive black holes? I will start with a general introduction of the existing methods of quasar-age estimations, then present our recent results on the proximity profiles in the spectra of z ≈ 3 quasars, where fluxes extend blueward of the He ii Ly wavelength 304(1+z) A. Based on the HST spectra of He II quasars collected over two decades, we find a large difference in the proximity-zone sizes up to 20 Mpc in the source’s rest frame. With further modeling, we should in principle be able to estimate the quasar ages from their proximity sizes. Several special interesting cases will be discussed.

　　时间及地点：4月29日（周三）上午10点，天文楼402会议室 

欢迎各位老师、同学参加！

　　                                  南京大学天文与空间科学学院