Quantitative comparisons of very-high-energy gamma-ray blazar flares with relativistic reconnection models
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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Date
2023-10-01
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en
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Astronomy and Astrophysics, Volume 678
Abstract
The origin of extremely fast variability is one of the long-standing questions in the gamma-ray astronomy of blazars. While many models explain the slower, lower energy variability, they cannot easily account for such fast flares reaching hour-to-minute timescales. Magnetic reconnection, a process where magnetic energy is converted to the acceleration of relativistic particles in the reconnection layer, is a candidate solution to this problem. In this work, we employ state-of-the-art particle-in-cell simulations in a statistical comparison with observations of a flaring episode of a well-known blazar, Mrk 421, at a very high energy (VHE, E>100 GeV). We tested the predictions of our model by generating simulated VHE light curves that we compared quantitatively with methods that we have developed for a precise evaluation of theoretical and observed data. With our analysis, we can constrain the parameter space of the model, such as the magnetic field strength of the unreconnected plasma, viewing angle and the reconnection layer orientation in the blazar jet. Our analysis favours parameter spaces with magnetic field strength 0.1 G, rather large viewing angles (6-8°), and misaligned layer angles, offering a strong candidate explanation for the Doppler crisis often observed in the jets of high synchrotron peaking blazars.Description
Funding Information: We thank the anonymous referee whose insightful comments helped us improve this manuscript. We thank Dr. Julian Sitarek for the helpful discussion on the determination of the sensitivity of MAGIC, and Dr. Cosimo Nigro for providing us with the script for the calculation of MAGIC sensitivity. We thank Dr. Axel Arbet-Engels for the helpful discussion on the SEDs of our observed dataset. This work has made use of the published light curves of Mrk 421 observed by MAGIC and VERITAS, and we thank Dr. Ana Babić for providing the data and additional help. J.J. was supported by the Academy of Finland projects 320085 and 345899. T.H. was supported by the Academy of Finland projects 317383, 320085, 322535, and 345899. E.L. was supported by the Academy of Finland projects 317636 and 320045. M.P. acknowledges support from the MERAC Foundation through the project THRILL and from the Hellenic Foundation for Research and Innovation (H.F.R.I.) under the ‘2nd call for H.F.R.I. Research Projects to support Faculty members and Researchers’ through the project UNTRAPHOB (Project ID 3013). I.M.C. and M.P. acknowledge support from the Fermi Guest Investigation grants 80NSSC18K1745 and 80NSSC20K0213. Publisher Copyright: © The Authors 2023.
Keywords
Galaxies: Active, Galaxies: Jets, Gamma rays: Galaxies, Magnetic reconnection, Methods: Miscellaneous, Radiation mechanisms: Non-thermal
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Citation
Jormanainen, J, Hovatta, T, Christie, I M, Lindfors, E, Petropoulou, M & Liodakis, I 2023, ' Quantitative comparisons of very-high-energy gamma-ray blazar flares with relativistic reconnection models ', Astronomy and Astrophysics, vol. 678, A140 . https://doi.org/10.1051/0004-6361/202346286