CGRaBS J2345-1555多波段流量相关性及射电波段多普勒因子估计

Multiwavelength corss-correlation and radio Doppler factor estimation of CGRaBS J2345-1555

收集了Fermi/LAT, Catalina, OVRO发布的CGRa BS J2345-1555长期射电(15 GHz)、伽马、光学V波段的流量和星等数据,用离散相关函数方法评估了多波段间的相关性,结果显示伽马波段和射电波段的相关系数为0.53,时间延迟约为90天,伽马波段比射电波段超前约90天;射电和光学V波段的相关系数为0.84,时间延迟约为–300天,光学V波段比射电波段超前约300天;伽马和光学V波段没得出具体相关性.说明光学波段由同步辐射主导,射电波段与光学波段的时间延迟可以解释为光学波段的辐射区域在上游,射电波段在下游.而伽马波段与射电波段是同源的.用亮温度方法计算了该天体射电波段的多普勒因子,多普勒因子平均值为12.25,并随光变曲线振荡.分析得出喷流具有明显聚束效应.射电波段辐射流量变化来自于喷流.

In this paper,CGRaBS J2345-1555’s long-term radio band,gamma ray flux and optical V-band magnitude data are collected from Fermi/LAT,Catalina,and OVRO dataset.The correlation between multi-bands is evaluated by the discrete correlation function method.The results show that the correlation coefficient between gamma band and radio band is 0.53,and the time delay is about 90 days,a variation of the gamma band is about 90 days ahead of radio band;the correlation coefficient between radio band and optical V-band is 0.84,and the time delay is about–300 days,a variation of the optical V-band is about 300 days ahead of radio band;there is no significant correlation between gamma and optical V-band.These results show that the optical band is dominated by synchrotron radiation,and the time delay between the radio band and the optical band can be explained as the fact that the radiation region of the optical band is upstream,and the radio band is downstream.The gamma band and the radio band are both homologous.The distribution of brightness temperature is used to calculate the Doppler factor of the celestial body’s radio band.The averaged Doppler factor is 12.64,and it oscillates with the light curve.So the jet has obvious bunching effect,and the variation of radiation flux in radio band comes from the jet.