Blue quasars and blazar unification schemes

Blue quasars (BQs) are sources with strong broad emission lines and flat ha rd X-ray spectra-properties that resemble classical flat-spectrum radio qua sars (FSRQs)-and high peak frequencies and steep soft X-ray spectra-propert ies that resemble intermediate or high peak frequency BL Lacertae objects. BQs challenge our understanding of blazar properties in terms of a luminosi ty sequence, which makes their incorporation into current blazar unificatio n schemes problematic. In this work we show that this situation can be reme died if, in addition to the intrinsic luminosity, the orientation of the bl azar jet is explicitly considered. We show, using published data, that the recently studied BQs are relatively misaligned blazars, and we examine the predicted aligned population. We examine both possible cases, sources with pure synchrotron spectra and sources with an optical to UV thermal contribu tion, for both constant velocity and accelerating jets. We show that the al igned sources are similar to FSRQs, and we suggest ways to distinguish betw een constant velocity and accelerating flows. We point out that intermediat e-frequency BL Lac objects are more aligned and less powerful than BQs, and we address the very different emission-line properties of these sources th at display similar spectral energy distributions.