A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä
Gamma-ray flares from the jet of the blazar CTA 102 in 2016–2018
Tekijät: Kim, Sanghyun; Lee, Sang-Sung; Algaba, Juan Carlos; Rani, Bindu; Park, Jongho; Jeong, Hyeon-Woo; Cheong, Whee Yeon; D'Ammando, Filippo; Lahteenmaki, Anne; Tornikoski, Merja; Tammi, Joni; Ramakrishnan, Venkatessh; Agudo, Ivan; Casadio, Carolina; Escudero, Juan; Fuentes, Antonio; Traianou, Efthalia; Myserlis, Ioannis; Thum, Clemens
Kustantaja: EDP Sciences
Kustannuspaikka: LES ULIS CEDEX A
Julkaisuvuosi: 2025
Journal: Astronomy and Astrophysics
Tietokannassa oleva lehden nimi: Astronomy & Astrophysics
Lehden akronyymi: ASTRON ASTROPHYS
Artikkelin numero: A291
Vuosikerta: 694
Sivujen määrä: 14
ISSN: 0004-6361
eISSN: 1432-0746
DOI: https://doi.org/10.1051/0004-6361/202450003
Verkko-osoite: https://doi.org/10.1051/0004-6361/202450003
Rinnakkaistallenteen osoite: https://research.utu.fi/converis/portal/detail/Publication/491322035
CTA 102 is a gamma-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 gamma-ray flares from the relativistic jet in the blazar. We analysed radio, optical, X-ray, and gamma-ray data obtained in a period from 2012 September 29 to 2018 October 8. We identified six flares in the gamma-ray light curve, showing a harder-when-brighter trend in the gamma-ray spectra. We performed a cross-correlation analysis of the multi-wavelength light curves. We found nearly zero time lags between the gamma-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 gamma-ray and radio light curves as well as negative or positive time lags with the gamma-ray emission lagging or leading the radio during different flaring periods. The time lags between the gamma-ray and radio emission propose the presence of multiple gamma-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 gamma-ray flares from 2016 to 2017 are temporally coincident with the interaction between a travelling shock and a quasi-stationary one at similar to 0.1 mas from the core. The other shock was found to have emerged from the core nearly simultaneously with the gamma-ray flare in 2018. Our results suggest that the gamma-ray flares originated from shock-shock interactions.
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This research has made use of data from the OVRO 40-m monitoring program (Richards et al. 2011), supported by private funding from the California Institute of Technology and the Max Planck Institute for Radio Astronomy, and by NASA grants NNX08AW31G, NNX11A043G, and NNX14AQ89G and NSF grants AST-0808050 and AST- 1109911. This publication makes use of data obtained at the Metsähovi Radio Observatory, operated by Aalto University in Finland. The IAA-CSIC group acknowledges financial support from the grant CEX2021-001131-S funded by MCIN/AEI/10.13039/501100011033 to the “Instituto de Astrofísica de Andalucía-CSIC”. Acquisition and reduction of the POLAMI data was supported in part by MICIN through grants PID2019-107847RB-C44 abd PID2022-139117NB-C44. The POLAMI observations were carried out at the IRAM 30 m Telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). CC acknowledges support by the European Research Council (ERC) under the HORIZON ERC Grants 2021 programme under grant agreement No. 101040021. The Submillimeter Array is a joint project between the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics and is funded by the Smithsonian Institution and the Academia Sinica. We recognize that Maunakea is a culturally important site for the indigenous Hawaiian people; we are privileged to study the cosmos from its summit. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2011.0.00001.CAL. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. This study makes use of VLBA data from the VLBA-BU Blazar Monitoring Program (BEAM-ME and VLBA-BU-BLAZAR; http://www.bu.edu/blazars/BEAM-ME.html), funded by NASA through the Fermi Guest Investigator Program. The VLBA is an instrument of the National Radio Astronomy Observatory. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated by Associated Universities, Inc. Data from the Steward Observatory spectropolarimetric monitoring project were used. This program is supported by Fermi Guest Investigator grants NNX08AW56G, NNX09AU10G, NNX12AO93G, and NNX15AU81G. The Fermi LAT Collaboration acknowledges generous ongoing support from a number of agencies and institutes that have supported both the development and the operation of the LAT as well as scientific data analysis. These include the National Aeronautics and Space Administration and the Department of Energy in the United States, the Commissariat à l’Energie Atomique and the Centre National de la Recherche Scientifique / Institut National de Physique Nucléaire et de Physique des Particules in France, the Agenzia Spaziale Italiana and the Istituto Nazionale di Fisica Nucleare in Italy, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), High Energy Accelerator Research Organization (KEK) and Japan Aerospace Exploration Agency (JAXA) in Japan, and the K. A. Wallenberg Foundation, the Swedish Research Council and the Swedish National Space Board in Sweden. Additional support for science analysis during the operations phase is gratefully acknowledged from the Istituto Nazionale di Astrofisica in Italy and the Centre National d’Études Spatiales in France. This work performed in part under DOE Contract DE-AC02-76SF00515. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MIST) (2020R1A2C2009003). This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT; RS-2024-00449206). This research has been supported by the POSCO Science Fellowship of POSCO TJ Park Foundation.
