Detection of Increasingγ-Ray Emissions from 4FGL J1718.5+4237 with Fermi-LAT  

作　　者：Jiao Zheng Pengfei Zhang Li Zhang 

机构地区：[1]Department of Astronomy,School of Physics and Astronomy,Key Laboratory of Astroparticle Physics of Yunnan Province,Yunnan University,Kunming 650091,China [2]School of Physics and Engineering Technology,Xingyi Normal University for Nationalities,Xingyi 562400,China

出　　处：《Research in Astronomy and Astrophysics》2024年第8期169-174,共6页天文和天体物理学研究（英文版）

基　　金：supported in part by the National Natural Science Foundation of China(NSFC,grant Nos.12233006 and 12163006);the Basic Research Program of Yunnan Province No.202201AT070137;the joint foundation of Department of Science and Technology of Yunnan Province and Yunnan University No.202201BF070001-020;support by the Xingdian Talent Support Plan—Youth Project。

摘　　要：We report a gradual brighteningγ-ray source,4FGL J1718.5+4237,in 0.1-500.0 GeV,which may be associated with a blazar NVSS J171822+423948 with a redshift of~2.7.We analyzed 15.25 yr ofγ-ray data recorded by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope and detected significantγ-ray emissions in the direction of the blazar with a test statistic(TS)of~135.Based on timing analysis using a 1 yr time bin,we have observed a gradual brightening inγ-ray emissions from the target.In our analysis,we categorize them into two states:Quiet(TS~0)and Loud(TS~226)states,with the distinction occurring in 2016 August(MJD57602.69).From the Quiet state to the brightest period(the last data point),theγ-ray flux in 0.1-500.0 GeV increased by more than 12-fold from<0.2×10^(-8)photons cm^(-1)s^(-1)to 2.6×10^(-8)photons cm^(-1)s^(-1).Additionally,we studied the spectral properties in detail for the Loud state and the overall data.While no significant variation was detected,both exhibited a spectral indexΓof~2.6.The origin of the brighteningγ-ray emissions from the target is not yet clear.Future long-term multi-wavelength observations and studies will provide insight into the astrophysical mechanisms of the target.

关 键 词：GALAXIES active-blazars individual(4FGL J1718.5+4237) 

分 类 号：P172.3[天文地球—天文学]