Color-redshift Relations and Photometric Redshift Estimations of Quasars in Large Sky Surveys

Abstract

With a recently constructed composite quasar spectrum and the χ^2 minimization technique, we demonstrated a general method to estimate the photometric redshifts of a large sample of quasars by deriving the theoretical color-redshift relations and comparing the theoretical colors with the observed ones. We estimated the photometric redshifts from the 5-band SDSS photometric data of 18678 quasars in the first major data release of SDSS and compare them with the spectroscopic redshifts. The redshift difference is smaller than 0.1 for 47% of quasars and 0.2 for 68 % of them. Based on the calculation of the theoretical color-color diagrams of stars, galaxies and quasars in both the SDSS and BATC photometric systems, we expected that with the BATC system of 15 intermediate filters we would be able to select candidates of high redshift quasars more efficiently than in the SDSS, provided the BATC survey could detect objects with magnitude fainter than 21.

12 pages, 8 figures, accepted for publication in Chinese Journal of Atronomy & Astrophysics

References in corpus (11)

• Composite Quasar Spectra From the Sloan Digital Sky Survey
• Spectroscopic Target Selection in the Sloan Digital Sky Survey: The Quasar Sample
• The First Data Release of the Sloan Digital Sky Survey
• Evidence for Reionization at z ~ 6: Detection of a Gunn-Peterson Trough in a z=6.28 Quasar
• Evolution of the Ionizing Background and the Epoch of Reionization from the Spectra of z~6 Quasars
• Red and Reddened Quasars in the Sloan Digital Sky Survey
• Photometric Redshifts of Quasars
• Photometric redshifts from reconstructed QSO templates
• 15 colour photometry of Landolt SA95 standard star field
• Photometric Redshift Determination with the BATC Multicolor System
• Multicolor photometry of the galaxies in the central region of Abell 2634

Cited by in corpus (14)

• Data Mining and Machine Learning in Astronomy
• Discovery of 21 New Changing-look AGNs in Northern Sky
• SDSS quasars in the WISE preliminary data release and quasar candidate selection with optical/infrared colors
• Robust Machine Learning Applied to Astronomical Datasets III: Probabilistic Photometric Redshifts for Galaxies and Quasars in the SDSS and GALEX
• ImpZ: a new photometric redshift code for galaxies and quasars
• Quasar candidate selection and photometric redshift estimation based on SDSS and UKIDSS data
• Finding Quasars behind the Galactic Plane. I. Candidate Selections with Transfer Learning
• Quasar Photometric Redshifts and Candidate Selection: A New Algorithm Based on Optical and Mid-Infrared Photometric Data
• Estimating Photometric Redshifts of Quasars via K-nearest Neighbor Approach Based on Large Survey Databases
• Photometric Redshift Estimation for Quasars by Integration of KNN and SVM
• GeneticKNN: A Weighted KNN Approach Supported by Genetic Algorithm for Photometric Redshift Estimation of Quasars
• Discovering bright quasars at intermediate redshifts based on the optical/near-IR colors
• Discovery of six high-redshift quasars with the Lijiang 2.4m telescope and the Multiple Mirror Telescope
• Machine learning techniques for astrophysical modelling and photometric redshift estimation of quasars in optical sky surveys