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The connection between the 15 GHz radio and gamma-ray emission in blazars

Published online by Cambridge University Press:  24 March 2015

W. Max-Moerbeck ,
J. L. Richards ,
T. Hovatta ,
V. Pavlidou ,
T. J. Pearson ,
A. C. S. Readhead ,
O. G. King  and
R. Reeves
W. Max-Moerbeck
Affiliation:
National Radio Astronomy Observatory (NRAO), P.O. Box 0, Socorro, NM 87801, USA email: wmax@nrao.edu
J. L. Richards
Affiliation:
Department of Physics, Purdue University, West Lafayette, IN 47907, USA
T. Hovatta
Affiliation:
Aalto University Metsähovi Radio Observatory, Metsähovintie 114, 02540 Kylmälä, Finland
V. Pavlidou
Affiliation:
Department of Physics, University of Crete / Foundation for Research and Technology - Hellas, Heraklion 71003, Greece
T. J. Pearson
Affiliation:
Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125, USA
A. C. S. Readhead
Affiliation:
Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125, USA
O. G. King
Affiliation:
Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125, USA
R. Reeves
Affiliation:
Departamento de Astronomía, Universidad de Concepción, Casilla 160-C, Concepción, Chile
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Abstract

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Since mid-2007 we have carried out a dedicated long-term monitoring programme at 15 GHz using the Owens Valley Radio Observatory 40 meter telescope (OVRO 40m). One of the main goals of this programme is to study the relation between the radio and gamma-ray emission in blazars and to use it as a tool to locate the site of high energy emission. Using this large sample of objects we are able to characterize the radio variability, and study the significance of correlations between the radio and gamma-ray bands. We find that the radio variability of many sources can be described using a simple power law power spectral density, and that when taking into account the red-noise characteristics of the light curves, cases with significant correlation are rare. We note that while significant correlations are found in few individual objects, radio variations are most often delayed with respect to the gamma-ray variations. This suggests that the gamma-ray emission originates upstream of the radio emission. Because strong flares in most known gamma-ray-loud blazars are infrequent, longer light curves are required to settle the issue of the strength of radio-gamma cross-correlations and establish confidently possible delays between the two. For this reason continuous multiwavelength monitoring over a longer time period is essential for statistical tests of jet emission models.

Keywords

galaxies: activeradio continuum: galaxiesgamma rays: galaxiesquasars: generalBL Lacertae objects: generalmethods: data analysismethods: statisticaltechniques: miscellaneous
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 10 , Issue S313: Extragalactic jets from every angle , September 2014 , pp. 17 - 20
Copyright
Copyright © International Astronomical Union 2015 

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