The X-ray spectral properties for gamma-ray loud blazars

We selected a sample of bright gamma-ray (E>100 MeV) blazars whose X-rays in 0.1-10.0 keV band are observed by ROSAT and other Xray satellites, and make a detailed spectral analysis between the soft (0.1-2.0 keV) and hard band (2.0-10.0keV) as well as between X-ray and gamma-ray properties using both un-weighted and weighted analysis methods. Our results indicate: (i) there are significant anti-correlations of the spectral indices between soft X-rays and gamma-rays, and between hard X-ray and gamma-ray of flat-spectrum radio quasars (FSRQs) and BL Lac objects; (ii) in the X-ray band, the correlation is confusing, there is positive correlation of the spectral indices between soft and hard X-ray band using weighted correlation analysis, but this correlation is negative using un-weighted correlation analysis.