丝路天文讲坛第十八讲 The most distant radio quasars - with t

报告题目：The most distant radio quasars - with the highest resolution

报告人：Sándor Frey Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, Budapest

报告摘要: I will start with a brief introduction of Konkoly Observatory, the largest astronomical research institution in Hungary. Then I review our current knowledge and summarize our most interesting recent results about radio-emitting active galactic nuclei (AGN) at the highest redshifts, observed with radio interferometry. Jetted AGN powered by accretion onto supermassive black holes (SMBHs) are rare and interesting objects by themselves, but are even more so at very high redshifts (z>4). They are associated with the youngest SMBHs formed in the early Universe. The most distant ones known to date are found above redshift 6 when the Universe was less than 1 billion years old. Radio-loud AGN at extremely high redshifts provide a unique insight into the AGN phenomena, the evolution of this class of objects on a cosmological time scale, and can even be used as probes of cosmological models. The technique of very long baseline interferometry (VLBI) offers the sharpest view of the innermost parts of the radio jets. Among the most interesting individual cases to be highlighted, I will mention the quasar J1026+2542 (z=5.27) whose jet proper motion could be measured, J1427+3312 (z=6.12) with a ~100-pc scale double structure reminiscent of very young compact symmetric objects, and a couple of puzzling sources which were initially thought to be blazars with relativistic jets pointing nearly to our line of sight, but recently turned out to be something completely different when imaged with high resolution.

报告人简介：

Sandor Frey graduated as an astronomer in 1991 and obtained his PhD degree in 2001, both at the Eotvos University in Budapest, Hungary. His main research fields are radio interferometry, VLBI studies of high-redshift quasars, dual active galactic nuclei, astrometry. For more than 25 years, he worked at the Satellite Geodetic Observatory of the former Institute of Geodesy, Cartography and Remote Sensing, where he was also involved in space geodesy projects. Since 2016, he is a senior research fellow at the Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences. Earlier he spent longer periods in Germany at the European Space Operations Centre, and in the Netherlands at the Joint Institute for VLBI in Europe. He has been giving radio astronomy lectures at the Eotvos University since 2003, and supervised more than 20 students. He is also active in science popularization and serves as a vice-president of the Hungarian Astronautical Society. From 2014 to 2017, he was a member of the European VLBI Network Program Committee.