Two-component model of the X-ray emissions for Fermi-LAT selected blazars

In a two-component model, the total observed emissions are the sum of two contributions, namely a beamed one and an unbeamed one. The observed beamed emissions from a relativistic jet are strongly boosted due to the beaming effect while the observed unbeamed emissions are the same as that in the co-moving frame. In the X-ay band, it is hard to separate the beamed and the unbeamed emissions from observations. However, it is interesting to investigate the X-ray emissions applying the two-component model as in Kembhavi (Mon. Not. R. Astron. Soc. 264:683, 1993). In this work, a sample of 397 blazars with available X-ray data and radio core-dominance parameters are compiled and the method proposed by Kembhavi et al is adopted to separate the two components in the X-ray emissions, then we also discuss the difference between BL Lac objects and FSRQs. Our results show that: (1) The beamed emissions dominate the X-ray emissions. (2) The averaged X-ray core-dominance parameter in BL Lacertae objects is greater than that in FSRQs. (3) A correlation between X-ray spectral index and X-ray core-dominance parameter is obtained, which supports the unified scheme of BL Lac objects, FR type I galaxies and FR type II with galaxy morphology, FSRQs unified with FR type two quasars.