标题： 类星体3C 279的紫外各向同性辐射 显示英文标题

标题： Ultraviolet Isotropic Emission from the Blazar 3C 279

摘要： 档案中的IUE SWP和HST FOS光谱显示，在耀变体3C 279的紫外光谱连续谱上存在一个相对较强且宽的莱曼阿尔法发射线。 与八年期间连续谱通量约50倍的变化相反，该发射线没有表现出显著的强度变化。 在低发射状态下，3C 279的同时IUE SWP和LWP光谱可以用指数为alpha_nu ~1（f_nu ~ nu^{-α_nu}）的幂律进行拟合，明显比在较高状态下的测量结果更平坦。 我们的观测表明，莱曼阿尔法线不是由产生观测到的连续谱的定向、各向异性的同步辐射所驱动的，而是由一个非定向成分所产生的，该成分具有较慢和较低振幅的变化。 后者可能解释了1993年1月非常低状态下的紫外连续谱。 显示英文摘要

摘要： Archival IUE SWP and HST FOS spectra show the presence of a relatively strong, broad Lyman alpha emission line superposed onto the UV spectral continuum of the blazar 3C 279. As opposed to a factor ~50 variation of the continuum flux during eight years, the emission line did not exhibit significant intensity changes. Simultaneous IUE SWP and LWP spectra of 3C 279 in low emission state are fitted by power-laws of index alpha_nu ~1 (f_nu ~ nu^{-alpha_nu}), significantly flatter than measured during higher states. Our observations suggest that the Lyman alpha line is not powered by the beamed, anisotropic synchrotron radiation which produces the observed continuum in 3C 279, but rather by an unbeamed component characterized by slower and lower amplitude variability. The latter may account for the UV continuum observed during the very low state of January 1993.