Correlation Analysis for Gamma-ray (radio) and Broad Line Emissions of Fermi Blazars.

In this work, we compiled a sample of 202 Fermi/LAT blazars with available broad line emissions. Out of the 202 sources, 66 have known Doppler factors. The correlation between ($\gamma$-ray) and broad-line emission, and that between radio and broad-line emission are investigated by removing the effects of redshift and beaming boosting for the whole sample and the subclasses, flat spectrum radio quasars (FSRQs) and BL Lacertae objects (BL Lacs) respectively. We obtained a strong positive correlation between ($\gamma$-ray) and broad-line emission and between radio and broad-line emission for the 202 blazars; It is worth noting that the correlation still exists after removing redshift effect. For the 66 sources with Doppler factors, there is also a positive correlation between ($\gamma$-ray) and broad-line emission after removing the Doppler factors, as well as that between radio and broad-line emission. Our analysis suggest that 1. There are strong correlations between the ($\gamma$-ray) and the broad line emission for the whole blazar sample and their subclasses. The correlations exist when the redshift effect is removed for the whole sample and their subclasses, confirming the results by Ghisellini et al. (2014) and Chen (2018). 2. For the 66 blazars with available Doppler factors, a strong correlation between the broad line emission and the Doppler factor is found. The correlation between the ($\gamma$-ray) and the broad line emission exists after the Doppler factor effect is removed. Similar results for 1 and 2 also obtained between radio and broad-line emission. 3. Our analysis suggests a robust connection between the accretion process and the jet.