On the emission lines in active galactic nuclei with relativistic jets

作     者：Luigi Foschini 

作者机构：INAF-Osservatorio Astronomico di Brera Via E. Bianchi 46 23807 Merate (LC) Italy 

出 版 物：《Research in Astronomy and Astrophysics》 (天文和天体物理学研究（英文版）)

年 卷 期：2012年第12卷第4期

页      面：359-368页

核心收录：

学科分类：0709[理学-地质学] 07[理学] 0708[理学-地球物理学] 070401[理学-天体物理] 0825[工学-航空宇航科学与技术] 0704[理学-天文学] 

主　　题：line: profiles—galaxies: jets—BL Lacertae Objects: general—galaxies: Seyfert 

摘      要：The effect of the observed continuum emitted from a relativistic jet on the measurement of the full width at half maximum （FWHM） of an emission line is analyzed. If the jet contribution is not properly subtracted, the FWHM of the line could seem narrower than it should. The cases of an emission line detected in BL Lac objects and γ-ray Narrow-Line Seyfert 1 galaxies （γ-NLS1s） are addressed. It is shown that the smallness of the observed FWHM of the Lyα lines detected in three well-known BL Lacs is an effect due to the combined action of both the relativistic jet and a weak accretion disk. Once the Doppler boosting effect of the jet continuum is removed, the intrinsic FWHM values of the lines are found to be in the usual range. By contrast, the narrow permitted lines in γ-NLS1s are really narrow, since the disk and the lines are much more powerful. This also confirms that γ-NLS1 is really a new class of γ-ray emitting AGN, different from blazars and radio galaxies.