Black hole spin and radio loudness in a Λ cold dark matter universe

摘要: We use a combination of cosmological N-body simulation the concordance A cold dark matter paradigm and semi-analytic model galaxy formation to investigate spin development central supermassive black holes (BHs) its relation BH host properties. In order compute spins, we Shakura & Sunyaev consider King et al. warped disc alignment criterion. The orientation accretion is inferred from angular momentum source accreted material, which bears close relationship large-scale structure in simulation. find that final depends almost exclusively on history only weakly alignment. main mechanisms spin-up are found be gas cooling processes instabilities, result partially compatible with Monte Carlo models where major mergers instabilities; latter results reproduced when implementing randomly oriented discs our model. Regarding population, more massive BHs, hosted by ellipticals, have higher values than less spiral galaxies. analyse whether rates spins can used as tracers radio loudness active galactic nuclei (AGN). current observational indications an increasing trend radio-loud AGN fractions stellar mass easily obtained placing lower limits spin, minimum influence rates; random orientations unable reproduce this trend. Our favour scenario key parameter separate radio-quiet populations.