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Title: Time correlation between the radio and gamma-ray activity in blazars and the production site of the gamma-ray emission

Journal Article · · Monthly Notices of the Royal Astronomical Society
 [1];  [2];  [3];  [4];  [4];  [4];  [5];  [4];  [4];  [6];  [6];  [7];  [8];  [9];  [6]
  1. California Inst. of Technology (CalTech), Pasadena, CA (United States); National Radio Astronomy Observatory (NRAO), Socorro, NM
  2. California Inst. of Technology (CalTech), Pasadena, CA (United States); Aalto Univ., Kylmala (Finland). Metsahovi Radio Observatory
  3. Purdue Univ., West Lafayette, IN (United States)
  4. California Inst. of Technology (CalTech), Pasadena, CA (United States)
  5. California Inst. of Technology (CalTech), Pasadena, CA (United States); Univ. of Concepcion (Chile)
  6. Max Planck Inst. for Radioastronomy, Bonn (Germany)
  7. Univ. of Manchester (United Kingdom)
  8. Max Planck Inst. for Radioastronomy, Bonn (Germany); California Inst. of Technology (CalTech), Pasadena, CA (United States); Univ. of Crete (Greece)
  9. SLAC National Accelerator Lab., Menlo Park, CA (United States)
+ Show Author Affiliations

In order to determine the location of the gamma-ray emission site in blazars, we investigate the time-domain relationship between their radio and gamma-ray emission. Light-curves for the brightest detected blazars from the first 3 years of the mission of the Fermi Gamma-ray Space Telescope are cross-correlated with 4 years of 15GHz observations from the OVRO 40-m monitoring program. The large sample and long light-curve duration enable us to carry out a statistically robust analysis of the significance of the cross-correlations, which is investigated using Monte Carlo simulations including the uneven sampling and noise properties of the light-curves. Modeling the light-curves as red noise processes with power-law power spectral densities, we find that only one of 41 sources with high quality data in both bands shows correlations with significance larger than 3σ (AO0235+164), with only two more larger than even 2.25σ (PKS 1502+106 and B2 2308+34). Additionally, we find correlated variability in Mrk 421 when including a strong flare that occurred in July-September 2012. These results demonstrate very clearly the difficulty of measuring statistically robust multiwavelength correlations and the care needed when comparing light-curves even when many years of data are used. This should be a caution. In all four sources the radio variations lag the gamma-ray variations, suggesting that the gamma-ray emission originates upstream of the radio emission. Continuous simultaneous monitoring over a longer time period is required to obtain high significance levels in cross-correlations between gamma-ray and radio variability in most blazars.

Research Organization:
SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
Sponsoring Organization:
USDOE
Grant/Contract Number:
AC02-76SF00515
OSTI ID:
1356451
Journal Information:
Monthly Notices of the Royal Astronomical Society, Vol. 445, Issue 1; ISSN 0035-8711
Publisher:
Royal Astronomical SocietyCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 99 works
Citation information provided by
Web of Science

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Cited By (41)

Magnetoluminescence book January 2017
Active galactic nuclei: what’s in a name? journal August 2017
Magnetoluminescence journal June 2017
Long-term multi-wavelength variability and correlation study of Markarian 421 from 2007 to 2009 journal September 2016
Long-term optical monitoring of TeV emitting blazars: I. Data analysis⋆ journal December 2018
Constraining the Physical Conditions in the jets of γ-Ray Flaring Blazars Using Centimeter-Band Polarimetry and Radiative Transfer Simulations. ii. Exploring Parameter Space and Implications journal January 2015
Resolving the High-Energy Universe with Strong Gravitational Lensing: the case of pks 1830–211 journal August 2015
Long-term Multiband Study of High-redshift Blazar S5 0836+71 journal December 2018
A flat-spectrum flare in S4 0444+63 revealed by a new implementation of multiwavelength single-dish observations journal January 2020
Gamma-ray observations of low-luminosity active galactic nuclei journal January 2020
Radio follow-up of the γ-ray flaring gravitational lens JVAS B0218+357 journal February 2016
Exploring the nature of the 2016 γ-ray emission in the blazar 1749+096 journal July 2018
Multiwavelength cross-correlations and flaring activity in bright blazars journal August 2018
A revised lens time delay for JVAS B0218+357 from a reanalysis of VLA monitoring data journal March 2018
The presence of interstellar scintillation in the 15 GHz interday variability of 1158 OVRO-monitored blazars journal September 2019
Correlation between γ-ray and radio emissions in Fermi blazars journal December 2014
On the Connection of Radio and γ-Ray Emission in Blazars journal December 2018
3C 84: Observational Evidence for Precession and a Possible Relation to TeV Emission journal August 2019
4.5 Years of Multi-Wavelength Observations of mrk 421 During the Argo-Ybj and Fermi Common Operation time journal January 2016
DISCOVERY OF γ -RAY EMISSION FROM THE RADIO-INTERMEDIATE QUASAR III ZW 2: VIOLENT JET ACTIVITY WITH INTRADAY γ -RAY VARIABILITY journal October 2016
Kinematics of Parsec-scale Jets of Gamma-Ray Blazars at 43 GHz within the VLBA-BU-BLAZAR Program journal September 2017
Signatures of the Disk–Jet Coupling in the Broad-line Radio Quasar 4C+74.26 journal October 2018
Temporal Variability and Estimation of Jet Parameters for Ton 599 journal October 2018
Characterizing the Gamma-Ray Variability of the Brightest Flat Spectrum Radio Quasars Observed with the Fermi LAT journal May 2019
Exploring the Origin of Multiwavelength Activities of High-redshift Flat-spectrum Radio Quasar PKS 1502+106 during 2014–2018 journal August 2019
Curvature-induced Polarization and Spectral Index Behavior for PKS 1502+106 journal October 2019
Long-term multi-wavelength variability and correlation study of Markarian 421 from 2007 to 2009 text January 2016
Constraining the Physical Conditions in the Jets of Gamma-ray Flaring Blazars using Centimeter-Band Polarimetry and Radiative Transfer Simulations. II. Exploring Parameter Space and Implications text January 2014
Resolving the High Energy Universe with Strong Gravitational Lensing: The Case of PKS 1830-211 text January 2015
Radio follow-up of the gamma-ray flaring gravitational lens JVAS B0218+357 text January 2016
Long-term multi-wavelength variability and correlation study of Markarian 421 from 2007 to 2009 text January 2016
Active Galactic Nuclei: what's in a name? text January 2017
A revised lens time delay for JVAS B0218+357 from a reanalysis of VLA monitoring data text January 2018
Signatures of the disk-jet coupling in the Broad-line Radio Quasar 4C+74.26 text January 2018
Multiwavelength Cross-Correlations and Flaring Activity in Bright Blazars text January 2018
The presence of interstellar scintillation in the 15 GHz interday variability of 1158 OVRO-monitored blazars text January 2019
Curvature induced polarization and spectral index behavior for PKS 1502+106 text January 2020
Gamma-ray observations of low-luminosity active galactic nuclei text January 2020
The radio/gamma-ray connection from 120 MHz to 230 GHz journal July 2016
Relativistic Jets of Blazars preprint January 2020
GeV-radio correlation in Markarian 421 text January 2021

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