J/A+A/585/A87 Quasar composite made from bright QSOs (Selsing+, 2016)
An X-shooter composite of bright 1 < z < 2 quasars from UV to infrared.
Selsing J., Fynbo J. P. U, Christensen L., Krogager J.-K.
<Astron. Astrophys. 585, A87 (2016)>
=2016A&A...585A..87S 2016A&A...585A..87S (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Spectra, ultraviolet ; Spectra, infrared
Keywords: quasars: general - galaxies: ISM - methods: data analysis -
techniques: spectroscopic
Abstract:
Quasi-stellar object (QSO) spectral templates are important both to
QSO physics and for investigations that use QSOs as probes of
intervening gas and dust. However, combinations of various QSO samples
obtained at different times and with different instruments so as to
expand a composite and to cover a wider rest frame wavelength region
may create systematic effects, and the contribution from QSO hosts may
contaminate the composite. We have constructed a composite spectrum
from luminous blue QSOs at 1<z<2.1 selected from the Sloan Digital
Sky Survey (SDSS). The observations with X-shooter simultaneously
cover ultraviolet (UV) to near-infrared (NIR) light, which ensures
that the composite spectrum covers the full rest-frame range from
Lyβ to 11350Å without any significant host contamination.
Assuming a power-law continuum for the composite we find a spectral
slope of αλ=1.70±0.01, which is steeper than
previously found in the literature. We attribute the differences to
our broader spectral wavelength coverage, which allows us to
effectively avoid fitting any regions that are affected either by
strong QSO emissions lines (e.g., Balmer lines and complex [FeII]
blends) or by intrinsic host galaxy emission. Finally, we demonstrate
the application of the QSO composite spectrum for evaluating the
reddening in other QSOs.
Description:
Quasar composite made from bright QSOs, as described in the paper. The
composite consists of wavelength with corresponding arbitrarily
normalized flux and error.
The source code and composite is also made available at
https://github.com/jselsing/QuasarComposite
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
spectrum.dat 22 25875 Quasar composite spectrum
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Byte-by-byte Description of file: spectrum.dat
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Bytes Format Units Label Explanations
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1- 7 F7.1 0.1nm lambda Wavelength array for the composite
9- 15 F7.4 --- S Normalized flux density,
normalized to unity at 6800Å (1)
17- 22 F6.4 --- e_S Error relative to the normalized flux density
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Note (1): Constituent spectra are corrected for galactic extinction using their
coordinates and the extinctions map from
http://irsa.ipac.caltech.edu/applications/DUST/
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Acknowledgements:
Jonatan Selsing, jselsing(at)dark-cosmology.dk
(End) Jonatan Selsing [DARK, NBI], Patricia Vannier [CDS] 26-Oct-2015