Does black hole spin play a key role in the FSRQ/BL Lac dichotomy?. (arXiv:1302.3442v1 [astro-ph.HE])

Does black hole spin play a key role in the FSRQ/BL Lac dichotomy?. (arXiv:1302.3442v1 [astro-ph.HE]):
It is believed that jets emerging from blazars (Flat Spectrum Radio Quasars
(FSRQs) and BL Lacs) are almost aligned to the line-of-sight. BL Lacs usually
exhibit lower luminosity and harder power law spectra at gamma-ray energies
than FSRQs. It was argued previously that the difference in accretion rates is
mainly responsible for the large observed luminosity mismatch between them.
However, when intrinsic luminosities are derived by correcting for beaming
effects, this mismatch is significantly reduced. We show that spin plays an
important role to reveal the dichotomy of luminosity distributions between BL
Lacs and FSRQs, suggesting BL Lacs to be low luminous and slow rotators
compared to FSRQs.