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For refcode 1988MNRAS.233..801O:
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NED Abstract

Copyright by Royal Astronomical Society. 1988MNRAS.233..801O The ultraviolet continuum of quasars - I. The shape of the continuum, continuum reddening and intervening absorption P. T. O'Brien, P. M. Gondhalekar and R. Wilson Deparment of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX Accepted 1988 February 11. Received 1988 January 11; in original form 1987 September 21 Summary. We present ultraviolet data for a sample of 81 quasars covering a wide redshift and luminosity range. After allowing for the effect of absorption due to intervening clouds, the intrinsic optical and ultraviolet continuum for quasars is found to steepen towards shorter wavelengths from ~ 1 micron to ~800 A by ~1 in spectral index. The mean ratio of the predicted flux at 2 keV, calculated by extrapolating the continuum shortward of Ly{alpha} to that observed = 5+/-3. The mean shape of the ultraviolet continuum is very similar for the radio and non-radio selected quasars. The ultraviolet continuum above Ly{alpha} is found to get slightly harder with increasing redshift, suggesting possible evolution. No conclusive evidence is found for any intrinsic continuum reddening in the majority of known quasars. The increase with increasing redshift of the observed continuum depression between the Ly{alpha} and Ly{beta}/OVI emission lines relative to the continuum above Ly{alpha} implies evolution in the comoving number density of the intervening absorbing clouds.
Retrieve 103 NED objects in this reference.
Please click here for ADS abstract

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