A figure of merit for blazar-like source identification in the gamma-ray energy band

The microwave to gamma†ray slope αμγ can be used as a viable figure of merit for blazar†like source identification in gamma†rays. Taking into account the constraints from the observed extragalactic gamma†ray background, one can estimate the maximum duty cycle allowed for a selected sample of low energy peaked (LBL) blazars, in order to be detectable for the nominal sensitivity values of AGILE and GLAST gamma†ray experiments. This work is based on the results of a recently derived blazar radio LogN†LogS obtained by combining several multi†frequency surveys. We present our estimates of duty cycle constraints applied on a sample composed by 146 high latitude and 74 medium latitude LBL blazars from the new WMAP3 yr catalog. Our results can be used as an indicator to identify good gamma†ray blazar candidates: sources with high values of duty cycle can in principle be detectable also in a “steady†state by AGILE and GLAST without over†predicting the extragalactic background.