THE SPECTRAL INDEX PROPERTIES OF FERMI BLAZARS

In this paper, a sample of 451 blazars (193 flat spectrum radio quasars (FSRQs), 258 BL Lacertae objects) with corresponding X-ray and Fermi [gamma]-ray data is compiled to investigate the correlation both between the X-ray spectral index and the [gamma]-ray spectral index and between the spectral index and the luminosity, and to compare the spectral indexes [alpha] sub(X), [alpha] sub([gamma]), [alpha] sub(X)[gamma], and [alpha][gamma]X[gamma] for different subclasses. We also investigated the correlation between the X-ray and the [gamma]-ray luminosity. (1) Our analysis indicates that an anti-correlation exists between the X-ray and the [gamma]-ray spectral indexes for the whole sample. However, when we considered the subclasses of blazars (FSRQs, the low-peaked BL Lacertae objects (LBLs) and the high-peaked BL Lacertae objects (HBLs)) separately, there is not a clear relationship for each subclass. The effective spectral index shows that [alpha] sub(X)[gamma]|HBLs sub((= 1.02 + or - 0.12)) > [alpha] sub(X)[gamma]|LBLs sub((= 0.78 + or - 0.09)) ~ [alpha] sub(X)[gamma]|FSRQs(=0.79 + or - 0.09).