Spectral principal component analysis of the Hβ region of low-redshift SDSS quasars

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	Spectral principal component analysis of the Hβ region of low-redshift SDSS quasars
	Bin Ma1 ; Zhaohui Shang 1; Michael SBrotherton 4
	2019
Source Publication	天文和天体物理学研究:英文版
ISSN	1674-4527
Volume	19.0 Issue:012 Pages:169
Abstract	Studying the relationships among quasar spectral features is essential to unveil the origins of the emission lines and the quasars’ physical processes. Principal component analysis(PCA) is a powerful tool to investigate correlations between variables. Here, we present the results of PCA on the spectra of low-redshift SDSS quasars. The rest-frame wavelength range studied is 4000 – 5500 ?, involving some typical features of quasar spectra, such as Hβ, O Ⅲ and Fe Ⅱ emission lines. The first principal component is the anti-correlation between O Ⅲ and Fe Ⅱ, the well-known eigenvector one(EV1). The next six principal components also show clear(anti-)correlations between line strengths and/or velocity widths of various features, which agree well with measured spectral properties. By comparing the weights of these principal components with other quasar properties, we can identify their underlying drivers. We find that the second principal component represents spectral slope, and can quantify quasar host fraction, intrinsic slope and reddening well. The third component exhibits the velocity width variation of Hβ, and may be a proxy for orientation. In addition, we calculate the fractional-contribution spectra to investigate which components dominate the variance at individual wavelength ranges. Our results also indicate that the optical Fe Ⅱ emission may have distinct origins.
Keyword	quasars:emission lines quasars:general
Language	英语
Document Type	期刊论文
Identifier	http://ir.bao.ac.cn/handle/114a11/56622
Collection	中国科学院国家天文台
Affiliation	1.中国科学院国家天文台 2.中国科学院 3.Tianjin Astrophysics Center,Tianjin Normal University 4.Department of Physics and Astronomy,University of Wyoming,Laramie
First Author Affilication	National Astronomical Observatories, Chinese Academy of Sciences
Recommended Citation GB/T 7714	Bin Ma,Zhaohui Shang,Michael SBrotherton. Spectral principal component analysis of the Hβ region of low-redshift SDSS quasars[J]. 天文和天体物理学研究:英文版,2019,19.0(012):169.
APA	Bin Ma,Zhaohui Shang,&Michael SBrotherton.(2019).Spectral principal component analysis of the Hβ region of low-redshift SDSS quasars.天文和天体物理学研究:英文版,19.0(012),169.
MLA	Bin Ma,et al."Spectral principal component analysis of the Hβ region of low-redshift SDSS quasars".天文和天体物理学研究:英文版 19.0.012(2019):169.

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