Astronomy and Astrophysics – Astrophysics
Scientific paper
2005-03-10
Astronomy and Astrophysics
Astrophysics
29 pages, 11 figures. Submitted to ApJ
Scientific paper
We investigate the variety in quasar UV spectra (1020-1600A) with emphasis on the weak emission lines in the Ly alpha forest region using principal component analysis (PCA). This paper is a continuation of Suzuki et al. (2005, Paper I), but with a different approach. We use 50 smooth continuum fitted quasar spectra (0.14 < z < 1.04) taken by the Hubble Space Telescope (HST) Faint Object Spectrograph. Three weak emission lines in the Ly alpha forest are identified as FeII 1070.95A, FeII+FeIII 1123.17A, and CIII* 1175.88A. Using first two standardized PCS coefficients, we introduce five classifications: Class Zero and Class I-IV. These classifications will guide us in finding the continuum level in the Ly alpha forest, and we discuss the characteristics of each class. We show weak emission lines in the Ly alpha forest become eminent for Class III and IV. By actively using PCS, we can generate artificial quasar spectra which are useful to test the detection of quasars, DLAs, and the continuum calibration. We provide 10,000 artificially generated spectra. We show that the power-law extrapolated continuum is inadequate to perform precise measurements of the mean flux in the Ly alpha forest because of the weak emission lines and the extended tails of Ly alpha and Ly beta/OVI emission lines. We introduce a correction factor dF such that the true mean flux
No associations
LandOfFree
Quasar Spectrum Classification with PCA - II: Introduction of Five Classes, Artificial Quasar Spectrum, the Mean Flux Correction Factor dF,and the Identification of Emission Lines in the Ly alpha Forest does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Quasar Spectrum Classification with PCA - II: Introduction of Five Classes, Artificial Quasar Spectrum, the Mean Flux Correction Factor dF,and the Identification of Emission Lines in the Ly alpha Forest, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Quasar Spectrum Classification with PCA - II: Introduction of Five Classes, Artificial Quasar Spectrum, the Mean Flux Correction Factor dF,and the Identification of Emission Lines in the Ly alpha Forest will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-345707