A novel reverberation mapping method for blazars

Abstract

Reverberation mapping (RM) is the most promising method to measure the masses of supermassive black holes in the center of active galaxy nuclei (AGNs). However, the dominant jet component hinders the application of RM method for blazars. In this work, we present a new algorithm to disentangle the contribution of the accretion disk from that of the relativistic jet in blazars by analyzing the spectral break of the optical spectroscopic data. We applied this method to two flat-spectrum radio quasars (FSRQs), PKS 1510-089 and PKS 0736+017. In PKS 1510-089, the variability of the H$\gamma$ line is delayed with respect to the disk emission by approximately 94 days, while the H$\beta$ line shows a lag of about 111 days relative to the disk. In PKS 0736+017, the H$\gamma$ variability is delayed with respect to the disk by roughly 66 days, and the H$\beta$ line exhibits a lag of about 67 days. Based on these measured time lags, we estimate black hole masses of $\sim1.4\times10^{8}\,M_{\odot}$ for PKS 1510-089 and $\sim8.1\times10^{7}\,M_{\odot}$ for PKS 0736+017. This method paves the way to apply the RM method for blazars, and improves the understanding of disk and jet activities.