Quasar Photometric Redshifts and Candidate Selection: A New Algorithm Based on Optical and Mid-infrared Photometric Data

doi:10.3847/1538-3881/aa943c

CORC > 上海天文台 > 中国科学院上海天文台

	Quasar Photometric Redshifts and Candidate Selection: A New Algorithm Based on Optical and Mid-infrared Photometric Data
	Yang, Qian 2,3,4; Wu, Xue-Bing 2,3; Fan, Xiaohui 3,4; Jiang, Linhua 3; McGreer, Ian 4; Green, Richard 4; Yang, Jinyi 2,3; Schindler, Jan-Torge 4; Wang, Feige 2,3; Zuo, Wenwen 1
刊名	ASTRONOMICAL JOURNAL
	2017-12-01
卷号	154 期号:6
关键词	Catalogs Cosmology: Observations Galaxies: Distances And Redshifts Methods: Statistical Quasars: General
ISSN号	0004-6256
DOI	10.3847/1538-3881/aa943c
英文摘要	We present a new algorithm to estimate quasar photometric redshifts (photo-zs), by considering the asymmetries in the relative flux distributions of quasars. The relative flux models are built with multivariate Skew-t distributions in the multidimensional space of relative fluxes as a function of redshift and magnitude. For 151,392 quasars in the SDSS, we achieve a photo-z accuracy, defined as the fraction of quasars with the difference between the photo-z z(p) and the spectroscopic redshift z(s), vertical bar Delta z vertical bar=vertical bar z(s)-z(p)vertical bar/(1 + z(s)) within 0.1, of 74%. Combining the WISE W1 and W2 infrared data with the SDSS data, the photo-z accuracy is enhanced to 87%. Using the Pan-STARRS1 or DECaLS photometry with WISE W1 and W2 data, the photo-z accuracies are 79% and 72%, respectively. The prior probabilities as a function of magnitude for quasars, stars, and galaxies are calculated, respectively, based on (1) the quasar luminosity function, (2) the Milky Way synthetic simulation with the Besancon model, and (3) the Bayesian Galaxy Photometric Redshift estimation. The relative fluxes of stars are obtained with the Padova isochrones, and the relative fluxes of galaxies are modeled through galaxy templates. We test our classification method to select quasars using the DECaLS g, r, z, and WISE W1 and W2 photometry. The quasar selection completeness is higher than 70% for a wide redshift range 0.5 < z < 4.5, and a wide magnitude range 18 < r < 21.5 mag. Our photo-z regression and classification method has the potential to extend to future surveys. The photo-z code will be publicly available.
WOS研究方向	Astronomy & Astrophysics
语种	英语
出版者	IOP PUBLISHING LTD
WOS记录号	WOS:000425427500001
内容类型	期刊论文
源URL	[http://119.78.226.72/handle/331011/32485]
专题	中国科学院上海天文台
通讯作者	Yang, Qian
作者单位	1.Chinese Acad Sci, Shanghai Astron Observ, Shanghai 200030, Peoples R China 2.Peking Univ, Sch Phys, Dept Astron, Beijing 100871, Peoples R China 3.Peking Univ, Kavli Inst Astron & Astrophys, Beijing 100871, Peoples R China 4.Univ Arizona, Steward Observ, 933 North Cherry Ave, Tucson, AZ 85721 USA
推荐引用方式 GB/T 7714	Yang, Qian,Wu, Xue-Bing,Fan, Xiaohui,et al. Quasar Photometric Redshifts and Candidate Selection: A New Algorithm Based on Optical and Mid-infrared Photometric Data[J]. ASTRONOMICAL JOURNAL,2017,154(6).
APA	Yang, Qian.,Wu, Xue-Bing.,Fan, Xiaohui.,Jiang, Linhua.,McGreer, Ian.,...&Fu, Yuming.(2017).Quasar Photometric Redshifts and Candidate Selection: A New Algorithm Based on Optical and Mid-infrared Photometric Data.ASTRONOMICAL JOURNAL,154(6).
MLA	Yang, Qian,et al."Quasar Photometric Redshifts and Candidate Selection: A New Algorithm Based on Optical and Mid-infrared Photometric Data".ASTRONOMICAL JOURNAL 154.6(2017).