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The variability sky survey is a very effective method of searching for quasars. In the paper, we present a novel method to discriminate quasars from variable stars based on their intrinsic variabilities. The power-law model is used to fit the light-curve structure function in five wavebands, but the value of the structure function is normalized. The developed method is applied to 1411 spectroscopically confirmed quasars and 174 stars in SDSS stripe 82. We set a suitable criterion, then obtain a reasonable classified result. The classification accuracies about quasars and stars reach 92.2% and 83.6% respectively. Compared with the structure function only based on one physical parameter, the normalized structure function with amplitude and power-law index has a good efficiency to deal with these data. The method for selecting quasar candidates ensures big sky survey telescope a high survey efficiency and saving valuable astronomical observation time. The results support that the optical variabilities of most of quasars originate from the instabilities of accretion disks.
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Keywords:
- structure function /
- quasars /
- SDSS /
- light curve
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[14] Wu X B, Wang R, Schmidt K B, Bian F Y, Jiang L H, Fan X H 2011 Astron. J. 142 78
[15] Hawkins M R S 1996 Mon. Not. R. Astron. Soc. 278 787
[16] Hawkins M R S 1993 Nature 366 242
[17] Zhang J S 2004 Chin. Phys. 13 1177
[18] Deng J G, Huang R T 2008 Acta Phys. Sin. 57 1285 (in Chinese) [邓家干, 黄仁堂 2008 57 1285]
[19] Meusinger H, Hinze A, Hoon A D 2011 Astron. Astrophys. 525 37
[20] Wilhite B C, Brunner R J, Grier C J 2008 Mon. Not. R. Astron. Soc. 383 1232
[21] Rengstorf A W, Brunner R J, Wilhite B C 2006 Astron. J. 131 1923
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[1] Fan J H, Zhang Y W, Qian B C, Tao J, Liu Y, Hua T X 2009 Astrophys. J. Suppl. Ser. 181 466
[2] Fan J H, Liu Y, Qian B C, Tao J, Shen Z Q, Zhang J S, Huang Y, Wang J 2010 Res. Astron. Astrophys. 10 1100
[3] Tang J, Zhang X 2010 Acta Phys. Sin. 59 7516 (in Chinese) [唐洁, 张雄 2010 59 7516]
[4] Tang J, Wu X B 2011 Acta Phys. Sin. 60 119801 (in Chinese) [唐洁, 吴学兵 2011 60 119801]
[5] Cao X W, Li F 2008 Mon. Not. R. Astron. Soc. 390 561
[6] Li S L, Cao X W 2008 Mon. Not. R. Astron. Soc. 387 41
[7] Cao X W, Bai J M 2008 Astrophys. J. 673 131
[8] Huang K L 2005 Quasars and Active Galactic Nucleus (Beijing: Science Press) p33 (in Chinese) [黄克谅 2005 类星体与活动星系核 (北京: 科学出版社) 第33页]
[9] Crisiani S, Trentini S, la France F 1996 Astron. Asrtophys. 306 395
[10] MacLeod C L, ZIvezić C S, Kochanek S, Koztowski B, Kelly E, Bullock A, Kimball B, Sesar D, Westman K B 2010 Astrophys. J. 721 1014
[11] Schmidt K B, Rix H W, Shields J C, Knecht M, Hogg D W, Maoz D, Bovy J 2012 Astrophys. J. 744 147
[12] Palanque-Delabrouille N, Yeche C, Myers A D, Petitjean P, Nicholas P R, Sheldon E, Aubourg E 2011 Astron. Astrophys. 530 122
[13] Wu X B, Jia Z D 2010 Mon. Not. R. Astron. Soc. 406 1583
[14] Wu X B, Wang R, Schmidt K B, Bian F Y, Jiang L H, Fan X H 2011 Astron. J. 142 78
[15] Hawkins M R S 1996 Mon. Not. R. Astron. Soc. 278 787
[16] Hawkins M R S 1993 Nature 366 242
[17] Zhang J S 2004 Chin. Phys. 13 1177
[18] Deng J G, Huang R T 2008 Acta Phys. Sin. 57 1285 (in Chinese) [邓家干, 黄仁堂 2008 57 1285]
[19] Meusinger H, Hinze A, Hoon A D 2011 Astron. Astrophys. 525 37
[20] Wilhite B C, Brunner R J, Grier C J 2008 Mon. Not. R. Astron. Soc. 383 1232
[21] Rengstorf A W, Brunner R J, Wilhite B C 2006 Astron. J. 131 1923
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