The gamma-ray Doppler factor determinations for a Fermi blazar sample

Observations suggest that gamma-ray loud blazars are strongly beamed. The Fermi mission has detected many of blazars, which provide us with a good opportunity to investigate the emission mechanism and the beaming effect in the gamma-ray region. We compiled the X-ray observations for 138 Fermi blazars (54 flat spectrum radio quasars, 36 low-peaked BL Lacertae objects, and 48 high-peaked BL Lacertae objects) and calculated their Doppler factors, delta(gamma) . It is interesting that the calculated Doppler factors, delta(gamma), are strongly correlated with the gamma-ray luminosity.