Broad-line and Multi-wave Band Emission from Blazars

TL;DR

This study investigates the correlations between broad-line emission and multi-wavelength fluxes in 50 blazars, revealing strong links between jet activity and accretion processes, and differentiating efficiencies between FSRQs and BL Lac objects.

Contribution

It provides the first comprehensive analysis of flux correlations across multiple bands for a large blazar sample, supporting the jet-accretion connection and discussing the unified model.

Findings

Strong correlations between broad-line and X-ray fluxes in FSRQs.

Weak correlations in BL Lac objects, but overall significant links.

FSRQs exhibit high accretion efficiency, BL Lacs show low efficiency.

Abstract

We study the correlations of the flux of the broad-line emission ($F_{BLR}$) with the X-ray emission flux, optical emission flux at 5500 \AA and radio emission flux at 5 GHz, respectively, for a large sample of 50 Blazars (39 flat-spectrum radio quasars (FSRQs) and 11 BL Lac objects). Our main results are as follows. There are very strong correlations between $F_{BLR}$ and $F_{X}$ and between $L_{BLR}$ and $L_{X}$ in both states for 39 FSRQs and the slopes of the linear regression equations are almost equal to 1. There are weak correlations between $F_{BLR}$ and $F_{X}$ and between $L_{BLR}$ and $L_{X}$ for 11 BL Lac objects in both states, and the slopes of the linear regression equations are close to 1. There are significant correlations between $F_{BLR}$ and $F_{X}$ and between $L_{BLR}$ and $L_{X}$ for 50 blazars in both states, the slopes of both the linear regression equations are also close to 1. These results support a close link between relativistic jets and accretion on to the central Kerr black hole. On the other hand, we find that BL Lac objects have low accretion efficiency $\eta$, whereas FSRQs have high accretion efficiency $\eta$. The unified model of FSRQs and BL Lac objects is also discussed.