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J/A+A/530/A50    Principal Component Analysis of QSO UV spectra   (Paris+, 2011)

A Principal Component Analysis of quasar UV spectra at z∼3. Paris I., Petitjean P., Rollinde E., Aubourg E., Busca N., Charlassier R., Delubac T., Hamilton J.-C., Le Goff J.-M., Palanque-Delabrouille N., Peirani S., Pichon C., Rich J., Vargas-Magana M., Yeche C. <Astron. Astrophys. 530, A50 (2011)> =2011A&A...530A..50P
ADC_Keywords: Models ; Spectra, ultraviolet ; QSOs Keywords: methods: numerical - intergalactic medium - quasars: absorption lines - quasars: emission lines Abstract: From a principal component analysis (PCA) of 78 z∼3 high-quality quasar spectra in the SDSS-DR7 we derive the principal components that characterize the QSO continuum over the full available wavelength range. The shape of the mean continuum is similar to that measured at low-z (z∼1), but the equivalent width of the emission lines is larger at low redshift. We calculate the correlation between fluxes at different wavelengths and find that the emission line fluxes in the red part of the spectrum are correlated with those in the blue part. We construct a projection matrix to predict the continuum in the Lymanα forest from the red part of the spectrum. Description: The first 10 Principal Components derived from a sub-sample of SDSS-DR7 QSO spectra are presented over the 1020-2000A wavelength range (in the restframe, xi.dat) and redwards to the Ly-alpha emission (1216-2000A in the restframe, zeta.dat). A projection matrix is also provided (proj.dat), allowing to fit a quasar continuum. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file xi.dat 106 1962 Principal Components over the full wavelength zeta.dat 106 1569 Principal Components redwards to Ly-alpha emission proj.dat 89 10 Projection matrix
Byte-by-byte Description of file: xi.dat
Bytes Format Units Label Explanations
1- 7 F7.2 0.1nm lambda Restframe wavelength in Angstroms 10- 16 F7.5 --- Flux Mean Continuum normalized near 1280Å 18- 25 F8.5 --- xi1 1st Principal Component ξ1 27- 34 F8.5 --- xi2 2nd Principal Component ξ2 36- 43 F8.5 --- xi3 3rd Principal Component ξ3 45- 52 F8.5 --- xi4 4th Principal Component ξ4 54- 61 F8.5 --- xi5 5th Principal Component ξ5 63- 70 F8.5 --- xi6 6th Principal Component ξ6 72- 79 F8.5 --- xi7 7th Principal Component ξ7 81- 88 F8.5 --- xi8 8th Principal Component ξ8 90- 97 F8.5 --- xi9 9th Principal Component ξ9 99-106 F8.5 --- xi10 10th Principal Component ξ10
Byte-by-byte Description of file: zeta.dat
Bytes Format Units Label Explanations
1- 7 F7.2 0.1nm Wave Restframe wavelength in Angstroms 10- 16 F7.5 --- Flux Mean Continuum normalized near 1280Å 18- 25 F8.5 --- zeta1 1st Principal Component ζ1 27- 34 F8.5 --- zeta2 2nd Principal Component ζ2 36- 43 F8.5 --- zeta3 3rd Principal Component ζ3 45- 52 F8.5 --- zeta4 4th Principal Component ζ4 54- 61 F8.5 --- zeta5 5th Principal Component ζ5 63- 70 F8.5 --- zeta6 6th Principal Component ζ6 72- 79 F8.5 --- zeta7 7th Principal Component ζ7 81- 88 F8.5 --- zeta8 8th Principal Component ζ8 90- 97 F8.5 --- zeta9 9th Principal Component ζ9 99-106 F8.5 --- zeta10 10th Principal Component ζ10
Byte-by-byte Description of file: proj.dat
Bytes Format Units Label Explanations
1- 8 F8.5 --- Xi1 1st column of projection matrix 10- 17 F8.5 --- Xi2 2nd column of projection matrix 19- 26 F8.5 --- Xi3 3rd column of projection matrix 28- 35 F8.5 --- Xi4 4th column of projection matrix 37- 44 F8.5 --- Xi5 5th column of projection matrix 46- 53 F8.5 --- Xi6 6th column of projection matrix 55- 62 F8.5 --- Xi7 7th column of projection matrix 64- 71 F8.5 --- Xi8 8th column of projection matrix 73- 80 F8.5 --- Xi9 9th column of projection matrix 82- 89 F8.5 --- Xi10 10th column of projection matrix
Acknowledgements: Isabelle Paris, paris(at)
(End) Isabelle Paris [IAP], Patricia Vannier [CDS] 15-Apr-2011
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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