15 GHz Monitoring of Gamma-ray Blazars with the OVRO 40 Meter Telescope in Support of Fermi

TL;DR

This study monitors 1158 gamma-ray blazars at 15 GHz over two years, revealing a significant correlation between radio and gamma-ray emissions, and introduces a new variability analysis method.

Contribution

The paper presents a novel likelihood-based method for quantifying intrinsic variability in radio light curves of blazars.

Findings

Significant correlation between radio flux density and gamma-ray photon flux.

Introduction of a new variability amplitude statistic with error estimates.

First two-year results from a high-cadence blazar monitoring program.

Abstract

We present results from the first two years of our fast-cadence 15 GHz gamma-ray blazar monitoring program, part of the F-GAMMA radio monitoring project. Our sample includes the 1158 blazars north of -20 degrees declination from the Candidate Gamma-Ray Blazar Survey (CGRaBS), which encompasses a significant fraction of the extragalactic sources detected by the Fermi Gamma-ray Space Telescope. We introduce a novel likelihood analysis for computing a time series variability amplitude statistic that separates intrinsic variability from measurement noise and produces a quantitative error estimate. We use this method to characterize our radio light curves. We also present results indicating a statistically significant correlation between simultaneous average 15 GHz radio flux density and gamma-ray photon flux.