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A multiwavelength continuum characterization of high-redshift broad absorption line quasars

Abstract: We present the results of a multiwavelength study of a sample of high-redshift radio-loud (RL) broad absorption line (BAL) quasars. This way, we extend to higher redshift previous studies on the radio properties and broad-band optical colours of these objects. We have selected a sample of 22 RL BAL quasars with 3.6 ? z ? 4.8 cross-correlating the FIRST radio survey with the Sloan Digital Sky Survey (SDSS). Flux densities between 1.25 and 9.5 GHz have been collected with the Jansky Very Large Array and Effelsberg-100 m telescopes for 15 BAL and 14 non-BAL quasars used as a comparison sample. We determine the synchrotron peak frequency, constraining their age. A large number of gigahertz peaked spectrum and high-frequency peakers sources have been found in both samples (80 per cent for BAL and 71 per cent for non-BAL quasars), not suggesting a younger age for BAL quasars. The spectral index distribution provides information about the orientation of these sources, and we find statistically similar distributions for the BAL and non-BAL quasars in contrast to work done on lower redshift samples. Our sample may be too small to convincingly find the same effect, or might represent a real evolutionary effect based on the large fraction of young sources. We also study the properties of broad-band colours in both optical (SDSS) and near- and mid-infrared (UK Infrared Telescope Deep Sky Survey and Wide-field Infrared Survey Explorer ?WISE) bands, finding that also at high-redshift BAL quasars tend to be optically redder than non-BAL quasars. However, these differences are no more evident at longer wavelength, when comparing colours of the two samples by mean of the WISE survey.

 Authorship: Tuccillo D., Bruni G., DiPompeo M., Brotherton M., Pasetto A., Kraus A., González-Serrano J., Mack K.,

 Fuente: MNRAS 467, 4763?4776 (2017)

 Publisher: Oxford University Press

 Publication date: 01/06/2017

 No. of pages: 14

 Publication type: Article

 DOI: 10.1093/mnras/stx333

 ISSN: 0035-8711,1365-2966

 Spanish project: AYA2011-29517-C03-02 ; AYA2014-58861-C3-2-P

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