3FGL J1959.8-4725:蝎虎天体候选体
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摘要
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.
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.
引文
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[15]MASSARO F,CRESPO N A,D′ABRUSCO R,et al.The gamma-ray blazar quest:new optical spectra,state of art and future perspectives[J].Astrophysics&Space Science,2016,361(10):337.
[2]STOCKE J T,MORRIS S L,GIOIA I M,et al.The Einstein Observatory Extended Medium-Sensitivity Survey.IIThe optical identifications[J].Astrophysical Journal Supplement,1991,76(3):813-874.
[3]STICKEL M,PADOVANI P,URRY C M,et al.The complete sample of 1Jansky BL Lacertae objects.I-Summary properties[J].Astrophysical Journal,1991,374(2):431-439.
[4]ABDO A A,ACKERMANN M,AJELLO M,et al.The Spectral Energy Distribution of Fermi bright blazars[J].Astrophysical Journal,2010,716(1):30-70.
[5]ACERO F,ACKERMANN M,AJELLO M,et al.Fermi Large Area Telescope Third Source Catalog[J].Astrophysical Journal Supplement,2015,218(2):23.
[6]ACKERMANN M,AJELLO M,ATWOOD W,et al.The Third Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope[J].Astrophysical Journal,2015,810(1):14.
[7]王雪品,王兴华,丁楠,等.费米选耀变体序列研究[J].云南师范大学学报:自然科学版,2016,36(1):1-6.
[8]李斯,王艳芳,龙光波,等.费米耀变体多波段辐射流量相关性研究[J].云南师范大学学报:自然科学版,2015,35(6):1-7.
[9]徐云冰,刘文广,易庭丰.Fermi耀变体红移和gamma射线谱指数特性研究[J].云南师范大学学报:自然科学版,2015,35(4):1-4.
[10]徐云冰,易庭丰.两类BL Lac天体和FSRQs之间的关系[J].云南师范大学学报:自然科学版,2014,34(6):30-34.
[11]ABDO A A,ACKERMANN M,AJELLO M,et al.FERMI LARGE AREA TELESCOPE FIRST SOURCE CATALOG[J].Astrophysical Journal Supplement,2010,188(2):405-436.
[12]NOLAN P L,ABDO A A,ACKERMANN M,et al.Fermi Large Area Telescope Second Source Catalog[J].Astrophysical Journal Supplement,2012,199(2):31.
[13]YI T F,ZHANG J,LU R J,et al.Evaluating Optical Classification for Fermi Blazar Candidates with a Statistical method using Broadband Spectral Indices[J].Astrophysical Journal,2017,838(1):34.
[14]LEFAUCHEUR J,PITA S.Research and characterisation of blazar candidates among the Fermi/LAT 3FGL catalogue using multivariate classifications[J].Astronomy&Astrophysics,2016,602:86.
[15]MASSARO F,CRESPO N A,D′ABRUSCO R,et al.The gamma-ray blazar quest:new optical spectra,state of art and future perspectives[J].Astrophysics&Space Science,2016,361(10):337.