A simplified view of blazars: the gamma-ray case

TL;DR

This paper extends a simplified blazar classification model to gamma-ray observations, successfully matching Fermi-LAT survey data and predicting the nature of unassociated sources and the properties of BL Lacs and FSRQs.

Contribution

It introduces a gamma-ray band extension of a simplified blazar model, validated by Monte Carlo simulations against Fermi-LAT data, and predicts the nature of unclassified gamma-ray sources.

Findings

Simulations match observed BL Lac and FSRQ distributions.

Reproduces the gamma-ray -- radio flux correlation.

Predicts many unclassified sources are FSRQs with hidden emission lines.

Abstract

We have recently proposed a new simplified scenario where blazars are classified as flat-spectrum radio quasars (FSRQs) or BL Lacs according to the prescriptions of unified schemes, and to a varying combination of Doppler boosted radiation from the jet, emission from the accretion disk, the broad line region, and light from the host galaxy. Here we extend our approach, previously applied to radio and X-ray surveys, to the gamma-ray band and, through detailed Monte Carlo simulations, compare our predictions to Fermi-LAT survey data. Our simulations are in remarkable agreement with the overall observational results, including the percentages of BL Lacs and FSRQs, the fraction of redshift-less objects, and the redshift, synchrotron peak, and gamma-ray spectral index distributions. The strength and large scatter of the oft-debated observed Gamma-ray -- radio flux density correlation is also reproduced. In addition, we predict that almost 3/4 of Fermi-LAT BL Lacs, and basically all of those without redshift determination, are actually FSRQs with their emission lines swamped by the non-thermal continuum and as such should be considered. Finally, several of the currently unassociated high Galactic latitude Fermi sources are expected to be radio-faint blazars displaying a pure elliptical galaxy optical spectrum.