出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：The Micro-Arcsecond Scintillation-Induced Variability (MASIV) 5 GHz VLA Survey provided a large sample of radio sources showing interstellar scintillation with which to investigate the highest brightness temperature components of AGN. One of the most intriguing findings of MASIV is that compact radio AGN at redshifts above z 2:5 show significantly reduced interstellar scintillation (ISS) compared with their lower redshift counterparts. As ISS is strongly dependent on source angular size, this implies that on average, the high redshift MASIV sources appear much less compact to the ionized interstellar medium (ISM) than the lower redshift sources. We discuss the current status of ongoing investigations to determine the cause of the observed effect.
