Multi-Frequency Study of Spectral Indices of BL Lacertae Objects and
  Flat Spectrum Radio Quasars
  We present statistical analyses of a large homogenous data sample of
Fermi-detected blazars thoroughly studied in order to reassess the relationship
between flat-spectrum radio quasars (FSRQs) and subclasses of BL Lacertae
objects (BL Lacs) blazar populations. We discovered from the average values of
gamma-ray and X-ray spectral indices that the sequence of distribution is
indicative of the blazar orientation scheme. Analyses of FSRQs and BL Lacs data
show difference in the shape of gamma-ray and X-ray indices: significant
anti-correlation (r~ greater than - 0.79) exists between gamma-ray and X-ray
spectral indices. The spectral energy distributions of the blazar subclasses
show that FSRQs and BL Lacs have similar spectral properties which can be
unified through an evolutionary sequence. Nevertheless, there is a significant
difference between the shapes of X-ray and gamma-ray spectra of blazars
suggesting that different mechanisms are responsible for spectral variations in
the two energy bands. All these results suggest that there is a form of a
unified scheme for all blazars.
