3FGL J1959.8-4725:蝎虎天体候选体

3FGL J1959.8-4725:a Candidate BL Lacertae Object

依据费米大面积巡天望远镜的第三期活动星系核数据,收集了1 419个耀变体的4个参量:光子谱指数Γph,光变指数VI,射电流量FR和同步峰峰值频率νspeak.耀变体的γ射线谱通常呈现为单一幂律(PL),而在第三期活动星系核样本中,有部分源的γ射线谱呈现为对数正态(称为对数抛物线,LP)形状.通过对LP和PL型γ射线谱的blazars分布的统计分析,我们发现所有的LP型γ射线谱的平谱射电类星体(FSRQ)具有:光子谱指数Γph>1.8,光变指数logVI>1.8,射电流量log FR>1.8,同步峰峰值频率logνspeak<15.然而,一个未知其光学分类的blazars:3FGL J1959.8-4725,具有Γph=1.524、logVI=1.695、log FR=1.377、logνspeak=15.355,与LP型FSRQ的分布不同,因此3FGL J1959.8-4725很可能是一个候选蝎虎天体.

In this letter,based on the third catalog of active galactic nuclei detected by the FermiLAT（3 LAC）Clean Sample,we collect 1 419 Fermi blazars with 4 parameters：photon spectral indexΓph,variability index VI,radio flux FRand synchrotron peak frequencyνspeak.Where theγ-ray spectra of these blazars are normally shown either a single power-law（PL）or a log-normal（call Logarithmic Parabola,LP）shape.We study the possible distributions of the LP and PL blazars based on the simple statistical analyses on the 4 parameters.We find that all the LP flat spectrum radio quasars（FSRQs）show the photon spectral index,Γph 〉1.8,variability index,Γph 1.8,radio flux,log FR 〉1.8 and synchrotron peak frequency,logνspeak 〈15.However,one Fermi source：3 FGL J1959.8-4725,a LP blazar candidate of uncertain type withΓph =1.524、logVI =1.695、log FR =1.377、logνspeak=15.355,did not match the distribution of the LP FSRQs.Moreover,we suggest that 3 FGL J1959.8-4725 is likely to be a candidate BL Lacertae object.