The observed radio/gamma-ray emission correlation for blazars with the Fermi-LAT and the RATAN-600 data

Муфахаров, Т. В.; Мингалиев, М. Г.; Sotnikova, Yu. V.; Naiden, Ya. V.; Erkenov, A. K.

doi:10.1093/mnras/stv772

Cited by 10 publications

(8 citation statements)

References 34 publications

(40 reference statements)

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“…In particular, Ackermann et al (2011) found that the correlation strength decreases when higher γ-ray energies are considered. A similar result is reported in a more recent work by Mufakharov et al (2015), in which the authors explore the correlation between radio at cm wavelengths and γ-ray emission at E > 100 MeV for 123 1FGL Fermi blazars. In that work, based on quasi-simultaneous observations, the authors find a positive and statistically significant correlation between the emission bands, that weakens when higher γ-ray energies are used.…”

Section: Introductionsupporting

confidence: 86%

“…, Kovalev et al 2009;Ghirlanda et al 2010;Nieppola et al 2011). However, the correlation strength seems to decrease when higher γ-ray energies are considered (see Ackermann et al 2011;Mufakharov et al 2015). In the present work we explore the possible existence of a correlation between radio and GeV-TeV γ-ray emission, by using the most complete and unbiased AGN samples available at present, extracted from the 1FHL and 2FHL catalogs.…”

Section: Discussionmentioning

confidence: 97%

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Exploring the connection between radio and GeV-TeV γ-ray emission in the 1FHL and 2FHL AGN samples

Lico

Giroletti

Orienti

et al. 2017

A&A

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Context. With the advent of the Fermi Large Area Telescope (LAT) it was revealed that blazars, representing the most extreme radioloud active galactic nuclei (AGN) population, dominate the census of the γ-ray sky, and a significant correlation was found between radio and γ-ray emission in the 0.1 -100 GeV energy range. However, the possible connection between radio and very high energy (VHE, E > 0.1 TeV) emission still remains elusive, owing to the lack of a homogeneous coverage of the VHE sky. Aims. The main goal of this work is to quantify and assess the significance of a possible connection between the radio emission on parsec scale measured by the very long baseline interferometry (VLBI) and GeV-TeV γ-ray emission in blazars, which is a central issue for understanding the blazar physics and the emission processes in these objects. Methods. We investigate the radio VLBI and high energy γ-ray emission by using two large and unbiased AGN samples extracted from the first and second Fermi-LAT catalogs of hard γ-ray sources detected above 10 GeV (1FHL) and 50 GeV (2FHL). For comparison, we perform the same correlation analysis by using the 0.1 -300 GeV γ-ray energy flux provided by the third Fermi-LAT source catalog (3FGL). We assess the correlation statistical significance by means of a method based on permutations of the luminosities, by taking into account the various observational biases, which may apparently enhance or spoil any intrinsic correlation. Results. We find that the correlation strength and significance depend on the γ-ray energy range with a different behavior among the blazar sub-classes. Overall, the radio and γ-ray emission above 10 GeV turns out to be uncorrelated for the full samples and for all of the blazar sub-classes with the exception of high synchrotron peaked (HSP) objects, which show a strong and significant correlation. On the contrary, when 0.1 -300 GeV γ-ray energies are considered, a strong and significant correlation is found for the full blazar sample as well as for all of the blazar sub-classes. Conclusions. We interpret and explain this correlation behavior within the framework of the blazar spectral energy distribution properties. In the most powerful blazars, in general of low synchrotron peaked type, the high energy emission component peaks at energies lower that those sampled by the LAT. On the contrary, in HSP blazars the part of the high energy spectrum affected by cooling effects is well beyond the energy range sampled by the LAT, showing a rising spectrum both in the 3FGL and 1FHL/2FHL energy ranges.

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Section: Introductionsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 97%

Exploring the connection between radio and GeV-TeV γ-ray emission in the 1FHL and 2FHL AGN samples

Lico

Giroletti

Orienti

et al. 2017

A&A

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“…Since the same population of jet electrons is responsible for these two peaks, we might expect the synchrotron and gamma-ray emission from individual blazars to be correlated, and this has proven to be the case. Many studies have found statistical correlations between the radio/sub-mm band and the > 0.1 GeV time-averaged fluxes measured by the Fermi LAT instrument (e.g., Kovalev et al 2009;Ackermann et al 2011;Lister et al 2011;Giommi et al 2012;Fuhrmann et al 2014;Mufakharov et al 2015). Mahony et al (2010) have also shown that the fraction of radio-loud AGN detected by Fermi steadily increases with increasing 20 GHz flux density.…”

Section: Introductionmentioning

confidence: 99%

WHY HAVE MANY OF THE BRIGHTEST RADIO-LOUD BLAZARS NOT BEEN DETECTED IN GAMMA-RAYS BY FERMI ?

Lister

Aller

et al. 2015

ApJ

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We use the complete MOJAVE 1.5 Jy sample of active galactic nuclei (AGN) to examine the gammaray detection statistics of the brightest radio-loud blazars in the northern sky. We find that 23% of these AGN were not detected above 0.1 GeV by the Fermi LAT during the 4-year 3FGL catalog period partly because of an instrumental selection effect, and partly due to their lower Doppler boosting factors. Blazars with synchrotron peaks in their spectral energy distributions located below 10 13.4 Hz also tend to have high-energy peaks that lie below the 0.1 GeV threshold of the LAT, and are thus less likely to be detected by Fermi. The non-detected AGN in the 1.5 Jy sample also have significantly lower 15 GHz radio modulation indices and apparent jet speeds, indicating that they have lower than average Doppler factors. Since the effective amount of relativistic Doppler boosting is enhanced in gamma-rays (particularly in the case of external inverse-Compton scattering), this makes them less likely to appear in the 3FGL catalog. Based on their observed properties, we have identified several bright radio-selected blazars that are strong candidates for future detection by Fermi.

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“…Whereas the fraction of sources in the MOJAVE-1 sample with a counterpart in the 4FGL catalog is 83%, the fraction in the beamed AGN sub-sample of the BAT 105-month catalog is only 65%. A significant correlation between radio flux densities and gamma-ray flux measured by Fermi/LAT has been found since its operation (e.g., Ackermann et al 2011;Mufakharov et al 2015). The relation of the detection statistic in the LAT survey of X-ray-bright blazars is discussed further in Sect.…”

Section: Comparison With Other Catalogsmentioning

confidence: 95%

Hard X-ray properties of radio-selected blazars

Langejahn

Kadler

Wilms

et al. 2020

A&A

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Context. Hard X-ray properties of beamed AGN have been published in the 105-month Swift/BAT catalog, but there have not been any studies carried out so far on a well-defined, radio-selected sample of low-peaked blazars in the hard X-ray band. Aims. Using the statistically complete MOJAVE-1 sample, we aim to determine the hard X-ray properties of radio-selected blazars, including the enigmatic group of gamma-ray-faint blazars. Additionally, we aim to determine the contribution of radio-selected lowpeaked blazars to the diffuse CXB. Methods. We determined photon indices, fluxes, and luminosities in the range of 20 keV -100 keV of the X-ray spectra of blazars and other extragalactic jets from the MOJAVE-1 sample, derived from the 105-month Swift/BAT survey. We calculated log N-log S distributions and determined the luminosity functions.Results. The majority of the MOJAVE-1 blazars are found to be hard X-ray emitters albeit many at low count rates. The log Nlog S distribution for the hard X-ray emission of radio-selected blazars is clearly non-Euclidean, in contrast to the radio flux density distribution. Approximately 0.2% of the CXB in the 20 keV -100 keV band can be resolved into MOJAVE-1 blazars. Conclusions. The peculiar log N-log S distribution disparity might be attributed to different evolutionary paths in the X-ray and radio bands, as tested by luminosity-function modeling. X-ray variability can be ruled out as the dominant contributor. Low-peaked blazars constitute an intrinsically different source population in terms of CXB contribution compared to similar studies of X-ray-selected blazars. The hard X-ray flux and spectral index can serve as a good proxy for the gamma-ray detection probability of individual sources. Future observations combining deep X-ray survey, for example, with eROSITA, and targeted gamma-ray observations with CTA can benefit strongly from the tight connection between these high-energy bands for the different blazar sub-classes. 1 arXiv:2004.00477v1 [astro-ph.HE] 1 Apr 2020 M. Langejahn et al.: Hard X-ray properties of radio-selected blazars quasars (FSRQ), out of 1632 sources, including 114 unclassified AGN and an additional 129 unidentified sources. The recent 4FGL catalog of the gamma-ray all-sky survey from Fermi/LAT (The Fermi-LAT collaboration 2019) alone contains 1102 BL Lac type and 681 FSRQ type blazars out of a total of 2940 associated blazars and blazar candidates.In this work, we perform a detailed analysis of X-ray data from the most recent Swift/BAT survey maps for the radioselected MOJAVE-1 (Monitoring Of Jets in Active galactic nuclei with VLBA Experiments) beamed AGN sample. We report the hard X-ray characteristics in the 20 keV -100 keV band of this statistically complete extragalactic jet sample, which is mostly composed of blazars.This paper is structured as follows: Sect. 2 gives a short introduction to the MOJAVE program as well as the Swift mission and describes the object samples and data basis we used. The analysis, including the applied methods and assumptions...

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The observed radio/gamma-ray emission correlation for blazars with the Fermi-LAT and the RATAN-600 data

Cited by 10 publications

References 34 publications

Exploring the connection between radio and GeV-TeV γ-ray emission in the 1FHL and 2FHL AGN samples

Exploring the connection between radio and GeV-TeV γ-ray emission in the 1FHL and 2FHL AGN samples

WHY HAVE MANY OF THE BRIGHTEST RADIO-LOUD BLAZARS NOT BEEN DETECTED IN GAMMA-RAYS BY FERMI ?

Hard X-ray properties of radio-selected blazars

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