Tuccillo, D.D.TuccilloBruni, GabrieleGabrieleBruniDiPompeo, M. A.M. A.DiPompeoBrotherton, M. S.M. S.BrothertonPasetto, A.A.PasettoKraus, A.A.KrausGonzález-Serrano, J. I.J. I.González-SerranoMack, K. -H.K. -H.Mack2020-09-092020-09-0920170035-8711http://hdl.handle.net/20.500.12386/27258We 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.STAMPAenArticle10.1093/mnras/stx3332-s2.0-85061511511000398421100073https://academic.oup.com/mnras/article/467/4/4763/29780442017MNRAS.467.4763TFIS/05 - ASTRONOMIA E ASTROFISICA