Gamma-ray flares from the jet of the blazar CTA 102 in 2016–2018

CTA 102 is a γ -ray bright blazar that exhibited multiple flares in observations by the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope during the period of 2016–2018. We present results from the analysis of multi-wavelength light curves with the aim of revealing the nature of γ -ray flares from the relativistic jet in the blazar. We analysed radio, optical, X-ray, and γ -ray data obtained in a period from 2012 September 29 to 2018 October 8. We identified six flares in the γ -ray light curve, showing a harder-when-brighter trend in the γ -ray spectra. We performed a cross-correlation analysis of the multi-wavelength light curves. We found nearly zero time lags between the γ -ray and optical and X-ray light curves, implying a common spatial origin for the emission in these bands. We found significant correlations between the γ -ray and radio light curves as well as negative or positive time lags with the γ -ray emission lagging or leading the radio during different flaring periods. The time lags between the γ -ray and radio emission propose the presence of multiple γ -ray emission sites in the source. As seen in 43 GHz images from the Very Long Baseline Array, two moving disturbances (or shocks) were newly ejected from the radio core. The γ -ray flares from 2016 to 2017 are temporally coincident with the interaction between a travelling shock and a quasi-stationary one at ∼0.1 mas from the core. The other shock was found to have emerged from the core nearly simultaneously with the γ -ray flare in 2018. Our results suggest that the γ -ray flares originated from shock-shock interactions.

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Publication Details

Journal
Astronomy and Astrophysics
Published
2025-02-01
DOI
https://doi.org/10.1051/0004-6361/202450003
Citations
1
Primary Topic
Astrophysics and Cosmic Phenomena
Type
article
Field-Weighted Citation Impact
1.87

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article

Gamma-ray flares from the jet of the blazar CTA 102 in 2016–2018

M. Tornikoski, Efthalia Traianou, J. Tammi, Juan Carlos Algaba et al.
1 citations
Astronomy and Astrophysics
Astrophysics and Cosmic Phenomena
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article

Gamma-ray flares from the jet of the blazar CTA 102 in 2016–2018

M. Tornikoski, Efthalia Traianou, J. Tammi, Juan Carlos Algaba, I. Myserlis, I. Agudo, Hyeon‐Woo Jeong, Antonio Fuentes, F. D’Ammando, Venkatessh Ramakrishnan, Whee Yeon Cheong, C. Casadio, Bindu Rani, A. Lähteenmäki, Sang-Hyun Kim, Jongho Park, Juan Escudero, Clemens Thum, Sang-Sung Lee
article en
1 citations

Abstract

CTA 102 is a γ -ray bright blazar that exhibited multiple flares in observations by the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope during the period of 2016–2018. We present results from the analysis of multi-wavelength light curves with the aim of revealing the nature of γ -ray flares from the relativistic jet in the blazar. We analysed radio, optical, X-ray, and γ -ray data obtained in a period from 2012 September 29 to 2018 October 8. We identified six flares in the γ -ray light curve, showing a harder-when-brighter trend in the γ -ray spectra. We performed a cross-correlation analysis of the multi-wavelength light curves. We found nearly zero time lags between the γ -ray and optical and X-ray light curves, implying a common spatial origin for the emission in these bands. We found significant correlations between the γ -ray and radio light curves as well as negative or positive time lags with the γ -ray emission lagging or leading the radio during different flaring periods. The time lags between the γ -ray and radio emission propose the presence of multiple γ -ray emission sites in the source. As seen in 43 GHz images from the Very Long Baseline Array, two moving disturbances (or shocks) were newly ejected from the radio core. The γ -ray flares from 2016 to 2017 are temporally coincident with the interaction between a travelling shock and a quasi-stationary one at ∼0.1 mas from the core. The other shock was found to have emerged from the core nearly simultaneously with the γ -ray flare in 2018. Our results suggest that the γ -ray flares originated from shock-shock interactions.

Astronomy and AstrophysicsVol. 694
Goddard Space Flight Center (US), Institute of Astronomy and Astrophysics, Academia Sinica (TW), University of Crete (GR), University of Turku (FI), American University (US), Korea Astronomy and Space Science Institute (KR), University of Malaya (MY), Kyung Hee University (KR), Istituto di Radioastronomia di Bologna (IT), Instituto de Radioastronomía Milimétrica (ES), Instituto de Astrofísica de Andalucía (ES), Korea University of Science and Technology (KR), Foundation for Research and Technology Hellas (GR), Aalto University (FI)
National Science Foundation, Smithsonian Institution, U.S. Department of Energy, National Aeronautics and Space Administration, California Institute of Technology, National Radio Astronomy Observatory, POSCO TJ Park Foundation, National Research Foundation, Ministry of Education, Culture, Sports, Science and Technology, Academia Sinica, Aalto-Yliopisto, Korea Astronomy and Space Science Institute, National Research Foundation of Korea, Agenzia Spaziale Italiana, Max-Planck-Gesellschaft, Vetenskapsrådet, Centre National de la Recherche Scientifique, Istituto Nazionale di Astrofisica, National Astronomical Observatory of Japan, High Energy Accelerator Research Organization, Istituto Nazionale di Fisica Nucleare, Ministry of Science and ICT, South Korea, Instituto de Astrofísica de Andalucía, Smithsonian Astrophysical Observatory, Japan Aerospace Exploration Agency, National Institutes of Natural Sciences, Agencia Estatal de Investigación, Institut National de Physique Nucléaire et de Physique des Particules
Openalex Percentile: Top 16%
Astrophysics and Cosmic Phenomena
1.87
DOIOpen Access PDFOpenAlex
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