What We Talk about When We Talk about Blazars

[摘要] After the discovery of powerful relativistic jets from Narrow-Line Seyfert 1 Galaxies, and the understanding of their similarity with those of blazars, a problem of terminology was born. The word blazar is today associated to BL Lac Objects and Flat-Spectrum Radio Quasars, which are somehow different from Narrow-Line Seyfert 1 Galaxies. Using the same word for all the three classes of AGN could drive either toward some misunderstanding, or to the oversight of some important characteristics. I review the main characteristics of these sources, and finally I propose a new scheme of classification.

[学科分类] 空间科学

[关键词] relativistic jet;Blazar;quasar;BL Lac object;Narrow-Line Seyfert 1 Galaxy;black hole;neutron star