Article
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The First VHE Activity of OJ 287 and the Extragalactic Background Light
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Version 1
: Received: 15 July 2024 / Approved: 15 July 2024 / Online: 16 July 2024 (04:40:00 CEST)
How to cite: Yadav, S.; Kushwaha, P. The First VHE Activity of OJ 287 and the Extragalactic Background Light. Preprints 2024, 2024071256. https://doi.org/10.20944/preprints202407.1256.v1 Yadav, S.; Kushwaha, P. The First VHE Activity of OJ 287 and the Extragalactic Background Light. Preprints 2024, 2024071256. https://doi.org/10.20944/preprints202407.1256.v1
Abstract
The BL Lacertae (BL Lac) object OJ 287 underwent an intense X-ray activity phase, exhibiting its brightest recorded X-ray flare in 2016-2017, characterized by much softer X-ray spectra and, concurrently, its first-ever recorded very-high-energy (VHE) emission (100--560 GeV), reported by the VERITAS observatory. Broadband spectral energy distribution reveals a new jet emission component similar to high-synchrotron-peaked BL Lac objects, thereby implying the soft X-ray spectrum for the synchrotron emission. Using the advantage of simultaneous X-ray and VHE spectral information, as well as the source being a low-synchrotron-peaked BL Lac object, we systematically explored the extragalactic background light (EBL) spectrum by demanding that the VHE spectrum cannot be harder than the X-ray spectrum. We used three different phenomenological forms of the EBL spectral shape (power-law, parabola, and polynomial) motivated by current constraints on the EBL with the Bayesian Monte Carlo approach to infer the credible EBL range. Our study favors an almost flat power-law spectral shape and is consistent with previous studies. The other spectral forms capable of capturing curvature though result in a better statistics value; the improvement is statistically insignificant given the additional parameters.
Keywords
OJ 287; EBL; BL Lacertae objects; Bayesian statistics; VHE gamma-rays
Subject
Physical Sciences, Astronomy and Astrophysics
Copyright: This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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