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 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:
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FileName Lrecl Records Explanations
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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
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Byte-by-byte Description of file: xi.dat
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Bytes Format Units Label Explanations
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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
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Byte-by-byte Description of file: zeta.dat
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Bytes Format Units Label Explanations
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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
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Byte-by-byte Description of file: proj.dat
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Bytes Format Units Label Explanations
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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
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Acknowledgements:
Isabelle Paris, paris(at)iap.fr
(End) Isabelle Paris [IAP], Patricia Vannier [CDS] 15-Apr-2011