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Date and Time of the Query: 2019-06-26 T07:14:29 PDT
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For refcode 2000MNRAS.317.1023S:
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Copyright by Royal Astronomical Society. 2000MNRAS.317.1023S Infrared photometry of z ~ 1 3C quasars Chris Simpson and Steve Rawlings Accepted 2000 June 5. Received 2000 June 1; in original form 1999 November 2 ABSTRACT We present JHKL' photometry of a complete sample of steep-spectrum radio- loud quasars from the revised 3CR catalogue in the redshift range 0.65z<1.20. After correcting for contributions from emission lines and the host galaxies, we investigate their spectral energy distributions (SEDs) around 1 mm. About 75 per cent of the quasars are tightly grouped in the plane of optical spectral index, {alpha}_opt_, versus near-infrared spectral index, a_IR_, with the median value of a_opt_ close to the canonical value, and the median a_IR_ slightly flatter. We conclude that the fraction of moderately obscured, red quasars decreases with increasing radio power, in accordance with the receding torus model which can also explain the relatively flat median near-infrared spectra of the 3CR quasars. Two of the red quasars have inverted infrared spectral indices, and we suggest that their unusual SEDs might result from a combination of dust-scattered and transmitted quasar light. Keywords: galaxies: active - galaxies: photometry - quasars: general - infrared: galaxies
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