论文标题
27 Fermi Blazars的光谱特征
The optical spectral features of 27 Fermi blazars
论文作者
论文摘要
伴随通量变异性的光谱变化是通常观察到的现象。为了进一步研究Blazars的光谱特征，我们收集了27个Blazars（14 BL LAC和13 FSRQ）的长期光学V和R带数据，并计算了其光谱指数。结果表明，光谱指数因所有这些大麻的亮度而有所不同。通常，当亮度增加时，光谱逐渐变平（或陡峭）。但是，频谱变化越来越慢，直到它趋于稳定为止。换句话说，源变成蓝色（或红色），然后在变亮时逐渐稳定，当亮点（BSWB）和红色稳定时，当它被简短地命名为蓝色稳定的稳定性时，分别将其命名为blue-stable-stable-stable-stable-stable-ner-brighter（RSWB）行为。 14个BL LAC中有13个显示了BSWB的行为，但AO 0235+164。相反，大多数FSRQ（13分中的10个）都表现出RSWB趋势。可以证实，Blazars遵循两种通用光谱行为，即BSWB和RSWB。两个恒定 - 光谱索引组件的模型可以很好地解释光谱特征。结果表明，光发射主要由两个稳定的颜色组件组成，即变量较小的热发射和高可变同步子辐射。在大多数情况下，BL LAC的热成分比同步加速器辐射的热成分是红色的，而FSRQ则相反。
A spectral variation accompanied with flux variability is a commonly-observed phenomenon for blazars. In order to further investigate the optical spectral feature of blazars, we have collected the long-term optical V and R band data of 27 blazars (14 BL Lacs and 13 FSRQs), and calculated their optical spectral indices. The results show that the spectral indices vary with respect to the brightness for all of these blazars. In general, the optical spectrum progressively becomes flatter (or steeper), when the brightness increases. However the spectrum changes more and more slowly, until it tends to be stable. In other words, the source becomes bluer (or redder) and then gradually stabilizes when it brightens, which are briefly named the bluer-stable-when-brighter (BSWB) and redder-stable-when-brighter (RSWB) behaviors, respectively. Thirteen of the 14 BL Lacs show the BSWB behavior, with an exception of AO 0235+164. On the contrary, most of FSRQs (10 out of 13) exhibit the RSWB trend. It is confirmed that blazars follow the two universal optical spectral behaviors, namely, BSWB and RSWB. The model of two constant-spectral-index components can well explain the optical spectral features qualitatively and quantitatively. The results illustrate that the optical emission are mainly composed of two stable-color components, i.e., less variable thermal emission and high variable synchrotron radiation. And in most cases, the thermal component of BL Lacs is redder than that of synchrotron radiation, whereas FSRQs are the opposite.
