耀变体PKS 0537–441的光学谱特性

Optical spectral behaviour of the blazar PKS 0537–44

利用耶鲁大学SMARTS数据库提供观测数据,得到了耀变体PKS 0537–441从2011年1月到2015年5月的光学B和R波段光变曲线,并计算了两波段对应的谱指数.使用离散相关函数法等方法对流量、谱指数及二者的相关性进行研究,结果表明:(1)PKS 0537-441光变剧烈,在长时标,中等时标爆发上升期和衰退期均表现出BWB(Bluer-When-Brighter)的光学谱特性,该特性可由喷流内的激波模型作出解释;(2)B和R波段流量变化有强相关性,且B波段流量变化领先R波段(35.62±8.63)d;(3)R波段可能具有(53.06±6.62)d和(273.88±20.69)d的准周期性光变.

We present the long-term light curves of the blazar PKS 0537-441 in the optical B and R bands during the period from January 2011 to May 2015 on the basis of the photometric data provided by the SMARTS Consortium, and calculate the corresponding colour indices. The linear regression and discrete correlation function methods have been performed on the light curves and the colour indices curve. The results can be summarized as follows： （1） the light curves in the B and R bands show large variabilities on various timescales, while the colour indices curve reveals significant fluctuations which indicates the variation of spectra. A general BWB （bluer-when-brighter） trend is confirmed in long-term timescales and in the ascent and descent states during flares; （2） the linear regression shows that the light curves in the B and R bands are well correlated. The results obtained by the discrete correlation function method which reveals that the flux variation in the B band led that in the R band by （35.62 ± 8.63） d; （3） the analysis of periodicity suggests that （53.06 ± 6.62） d and （273.88 ± 20.69） d are the possible periods in the R-band light curve.