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大幅度、快速光变是BL Lac天体的重要特征之一,光变研究对探索BL Lac天体内部的物理过程和机理具有特殊的意义.从大量文献中收集了BL Lac天体S5 0716+714光学V,R,I 3个波段从1994年到2008年的有效观测数据,并将这些数据30天平均后进行自回归模型(AR)的双谱估计. 双谱的等高线图和对角切片图表明,双谱估计能消除噪声的干扰来提取有用信息,抑制了噪声、提高了信噪比,有很高的分辨率,避免了伪峰的出现,能准确地认证BL Lac天体的光变周期值.由V,R,I 3个波段的双谱等高线图和对
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关键词:
- S5 0716+714 /
- 光变周期 /
- 自回归 /
- 双谱估计
Large and rapid variability is one of the defining properties of BL Lac objects. Variability in BL Lac objects has always served as a powerful and important tool for inquring into the physics of these unusual objects. From an extensive seach in the literature we have collected a total of data points of effective observations of BL Lac object S5 0716+714 in V, R and I bands from 1994 to 2008. Then these data are processed on 30 days baseline by autoregressive bispectrum model. In order to eliminate noise interference to extract useful information in the background of Gaussian noise, we propose a method of signal analysis and processing,which analyzes the additive Gaussion noise signal based on autoregressive bispectrum model. Bispectrum is not sensitive to Gaussian noise, it not only suppresses the Gaussion noise in the signal and greatly improves the signal to noise ratio, but also can identify the periodical variations of BL Lac objects. Our results show that the long term periods of variation are 3.33 years and 3.47 years. The conclusion is consistent with 3.3 years period which was found by Raiteri et al. The brightness peak was observed in 2007, so we expect the next burst in 2011—2012.-
Keywords:
- S5 0716+714 /
- period /
- autoregressive /
- bispectrum estimation
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[28] Quirrenbach A 1991 Astrophys. J. 372 L71
[29] Asantha C, Michael K 2003 New Astron. 8 231
[30] Xie Z H, Xu L P, Ni G R 2008 Acta Phys. Sin. 57 6683 (in Chinese) [谢振华、许录平、倪广仁 2008 57 6683]
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[1] Stein W A, ODell S L, Strittmatter P A 1976 Ann. Rev. Astron. Astrophys. 14 173
[2] Begelman M C, Blandford R D, Rees M J 1980 Nature 287 307
[3] Tang J, Zhang X, Wu L 2008 Acta Astron. Sin. 48 488 (in Chinese) [唐 洁、张 雄、伍 林 2007 天文学报 48 488]
[4] Tang J, Zhang X, Wu L 2008 Chin. Astron. Astrophys. 32 151
[5] Tang J, Zhang X J, Pang Q, Zhang H J, Zheng Y G, Zhang X 2009 Acta Astron. Sin. 50 364 (in Chinese) [唐 洁、张晓娟、庞 桥、张皓晶、郑永刚、张 雄 2009 天文学报 50 364]
[6] Zhang X D 1996 Time-Series Analysis-Higher-Order Statistics Method (Beijing: Tsinghua University Press) pp36—102 [张贤达 1996 时间序列分析—— 高阶统计量方法(北京:清华大学出版社)第36—102页]
[7] Hakala P, Ramsay G, Wheatley P 2004 Astron. Astrophys. 420 273
[8] Raiteri C M, Villata M, Tosti G 2003 Aston. Astrophys. 402 151
[9] Zhang H J, Zhang X 2007 Acta Phys. Sin. 56 4305 (in Chinese) [张皓晶、张 雄 2007 56 4305]
[10] Zhang H J, Zhang X, Dong F T 2009 Acta Astron. Sin. 50 141 (in Chinese) [张皓晶、张 雄、董富通 2009 天文学报 50 141]
[11] Qian B C, Tao J, Fan J H 2002 Astron. J. 123 678
[12] Gadzow J A 1982 Proc. IEEE 70 707
[13] Biermann P, Duerbeck H, Eckart A 1981 Astrophys. J. 247 L53
[14] Ghisellini G, Villata M, Raiteri C M 1997 Aston. Astrophys. 327 61
[15] Impey C D, Bychkov V, Tapia S 2000 Astron. J. 119 1542
[16] Qian B C, Tao J, Fan J H 2000 Pub. Astron. Soc. Pacif. 52 Q1075
[17] Nesci R, Massaro E, Rossi C 2005 Astron. J. 130 1466
[18] Bai J M, Xie G Z, Li K H 1999 Astron. Astrophys. Suppl. Ser. 136 455
[19] Poon H, Fan J H, Fu J N 2009 Astrophys. J. Suppl. Ser. 185 511P
[20] Heidt J, Wagner S J 1996 Aston. Astrophys. 305 42
[21] Wu J H, Peng B, Zhou X 2005 Astron. J. 129 1818
[22] Sagar R, Gopal-Krishna 1999 Astron. Astrophys. Suppl. 134 453
[23] Katajainen S, Takalo L O, Sillanp A 2000 Astron. Astrophys. Suppl. 143 357
[24] Dai B Z, Zhang B K, Zhang L 2006 New Astron. 11 471
[25] Gupta A C, Cha S M, Lee S 2008 Astron. J. 136 2359
[26] Gupta A C, Fan J H, Bai J M, Wagner S J 2008 Astron. J. 135 1384
[27] Gupta A C, Srivastava A K, Wiita P J 2009 Astrophys. J. 690 216
[28] Quirrenbach A 1991 Astrophys. J. 372 L71
[29] Asantha C, Michael K 2003 New Astron. 8 231
[30] Xie Z H, Xu L P, Ni G R 2008 Acta Phys. Sin. 57 6683 (in Chinese) [谢振华、许录平、倪广仁 2008 57 6683]
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