The connection between black hole mass and Doppler boosted emission in BL Lacertae type objects

TL;DR

This study explores the link between black hole mass and Doppler-boosted emission in BL Lac objects, revealing correlations with luminosity and jet properties, and suggesting more massive black holes host faster jets.

Contribution

It introduces a method to estimate black hole masses in BL Lacs and demonstrates their relation to jet emission and SED shapes, which was previously unclear.

Findings

Black hole masses are consistent across HBL and LBL types.

Significant correlation between MBH and radio, optical, X-ray luminosities.

Evidence that more massive black holes are associated with faster jets.

Abstract

We investigate the relationship between black hole mass (MBH) and Doppler boosted emission for BL Lacertae type objects (BL Lacs) detected in the SDSS and FIRST surveys. The synthesis of stellar population and bidimensional decomposition methods allows us to disentangle the components of the host galaxy from that of the nuclear black hole in their optical spectra and images, respectively. We derive estimates of black hole masses via stellar velocity dispersion and bulge luminosity. We find that masses delivered by both methods are consistent within errors. There is no difference between the black hole mass ranges for high-synchrotron peaked BL Lacs (HBL) and low-synchrotron peaked BL Lacs (LBL). A correlation between the black-hole mass and radio, optical and X-ray luminosity has been found at a high significance level. The optical-continuum emission correlates with the jet luminosity as well. Besides, X-ray and radio emission are correlated when HBLs and LBLs are considered separately. Results presented in this work: (i) show that the black hole mass does not decide the SED shapes of BL Lacs, (ii) confirm that X-ray and optical emission is associated to the relativistic jet, and (iii) present evidence of a relation between MBH and Doppler boosted emission, which among BL Lacs may be understood as a close relation between faster jets and more massive black holes.