The optical variability of steep-spectrum radio quasars in the SDSS stripe 82 region

	The optical variability of steep-spectrum radio quasars in the SDSS stripe 82 region
	Gu, MF 1; Ai YL(艾艳丽)2,3
刊名	ASTRONOMY & ASTROPHYSICS
	2011-10
卷号	534
关键词	galaxies: photometry quasars: general galaxies: active
ISSN号	0004-6361
通讯作者	Gu, MF (reprint author), Chinese Acad Sci, Key Lab Res Galaxies & Cosmol, Shanghai Astron Observ, 80 Nandan Rd, Shanghai 200030, Peoples R China.
产权排序	第二完成单位
英文摘要	Context. There have been many investigations of the optical variability of flat-spectrum radio quasars (FSRQs), but the optical variability of steep-spectrum radio quasars (SSRQs) has been poorly studied. Aims. We investigate the optical variability of SSRQs, comparing this with the optical variability of FSRQs. Methods. We measure the optical variability of 18 SSRQs and 15 FSRQs in the SDSS Stripe 82 region using SDSS DR7 released multi-epoch data covering about nine years. We determine the spectral index by fitting a power law to SDSS ugriz photometric data, and explore the relationship between this spectral index and source brightness. Results. For all SSRQs studied, we detect variations in r band flux of overall amplitude between 0.22 mag and 0.92 mag in different sources. Eight of 18 SSRQs display a bluer-when-brighter (BWB) trend. In contrast, the variability amplitude of 15 FSRQs in r band ranges from 0.18 to 0.97 mag, and 11 of 15 sources follow a BWB trend. For all SSRQs studied, we found an anti-correlation between the Eddington ratio and the variability amplitude in r band, which is similar to that in radio-quiet AGNs. This implies that the thermal emission from the accretion disk may be responsible for the variability in SSRQs, although the jet nonthermal emission cannot be excluded. In contrast, there is no correlation found for FSRQs, which implies that the mechanisms of variability in FSRQs may be different from that in SSRQs. The optical continuum variability of radio-loud broad absorption-line quasars (BALQs) are investigated for the first time here for two sources with steep radio spectra. Both radio-loud BALQs display variations with amplitudes of about 0.3 mag at r band. Their spectral variability all follow a BWB trend. In our previous analysis of a combined sample of 18 SSRQs and 44 FSRQs, we found that the line width of the broad Mg II emission line is broader for steeper radio spectral indices. It implies a disk-like broad line region (BLR) geometry may present in these quasars. In these 62 quasars, we found a similar to 57% source percentage showing BWB trend in FSRQs, whereas it is similar to 44% in SSRQs.
学科主题	Astronomy & Astrophysics
WOS标题词	Science & Technology ; Physical Sciences
类目[WOS]	Astronomy & Astrophysics
研究领域[WOS]	Astronomy & Astrophysics
关键词[WOS]	ABSORPTION-LINE QUASARS ; DIGITAL SKY SURVEY ; ACTIVE GALACTIC NUCLEI ; LACERTAE OBJECT S5-0716+714 ; BLACK-HOLE MASSES ; 7TH DATA RELEASE ; NRAO PMN SURVEYS ; BL-LACERTAE ; MULTIYEAR TIMESCALES ; SLOPE VARIABILITY
收录类别	SCI ; EI
原文出处	http://www.aanda.org/articles/aa/abs/2011/10/aa17467-11/aa17467-11.html
语种	英语
WOS记录号	WOS:000296554800107
内容类型	期刊论文
源URL	[http://ir.ynao.ac.cn/handle/114a53/5006]
专题	云南天文台_高能天体物理研究组云南天文台_中国科学院天体结构与演化重点实验室
作者单位	1.Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, PR China 2.National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, PO Box 110, 650011 Kunming, Yunnan, PR China 3.Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, PO Box 110, 650011 Kunming, Yunnan, PR China
推荐引用方式 GB/T 7714	Gu, MF,Ai YL. The optical variability of steep-spectrum radio quasars in the SDSS stripe 82 region[J]. ASTRONOMY & ASTROPHYSICS,2011,534.
APA	Gu, MF,&Ai YL.(2011).The optical variability of steep-spectrum radio quasars in the SDSS stripe 82 region.ASTRONOMY & ASTROPHYSICS,534.
MLA	Gu, MF,et al."The optical variability of steep-spectrum radio quasars in the SDSS stripe 82 region".ASTRONOMY & ASTROPHYSICS 534(2011).