The Central Engines of Fermi Blazars

TL;DR

This paper provides a catalog of black hole masses and accretion properties for 1077 Fermi-detected blazars, revealing correlations between accretion rate, Compton dominance, and blazar classification, and proposing a new classification scheme based on Compton dominance.

Contribution

It introduces a comprehensive catalog of central engine parameters for a large blazar sample and proposes a novel classification scheme based on Compton dominance.

Findings

Black hole masses average at log M_BH ≈ 8.60.

Bi-modality in accretion rates with higher rates in broad line objects.

Positive correlation between Compton dominance and accretion rate.

Abstract

We present a catalog of central engine properties, i.e., black hole mass (mbh) and accretion luminosity (ld), for a sample of 1077 blazars detected with the Fermi~Large Area Telescope. This includes broad emission line systems and blazars whose optical spectra lack emission lines but dominated by the absorption features arising from the host galaxy. The average mbh for the sample is $\langle \log~M_{{\rm BH,all}~msun} \rangle=8.60$ and there are evidences suggesting the association of more massive black holes with absorption line systems. Our results indicate a bi-modality of ld~in Eddington units (ld/ledd) with broad line objects tend to have a higher accretion rate (ld/ledd$>$0.01). We have found that ld/ledd and Compton dominance (CD, the ratio of the inverse Compton to synchrotron peak luminosities) are positively correlated at $>$5$\sigma$ confidence level, suggesting that the latter can be used to reveal the state of accretion in blazars. Based on this result, we propose a CD based classification scheme. Sources with CD$>$1 can be classified as High-Compton Dominated or HCD blazars, whereas, that with CD$\lesssim$1 are Low-Compton Dominated (LCD) objects. This scheme is analogous to that based on the mass accretion rate proposed in the literature, however, it overcomes the limitation imposed by the difficulty in measuring ld and mbh for objects with quasi-featureless spectra. We conclude that the overall physical properties of Fermi blazars are likely to be controlled by the accretion rate in Eddington units. The catalog is made public at http://www.ucm.es/blazars/engines and Zenodo.