Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary System
: Valtonen, Mauri J.; Zola, Staszek; Gupta, Alok C.; Kishore, Shubham; Gopakumar, Achamveedu; Jorstad, Svetlana G.; Wiita, Paul J.; Gu, Minfeng; Nilsson, Kari; Marscher, Alan P.; Zhang, Zhongli; Hudec, Rene; Matsumoto, Katsura; Drozdz, Marek; Ogloza, Waldemar; Berdyugin, Andrei V.; Reichart, Daniel E.; Mugrauer, Markus; Dey, Lankeswar; Pursimo, Tapio; Lehto, Harry J.; Ciprini, Stefano; Nakaoka, T.; Uemura, M.; Imazawa, Ryo; Zejmo, Michal; Kouprianov, Vladimir V.; Davidson Jr, James W.; Sadun, Alberto; Strobl, Jan; Weaver, Z. R.; Jelinek, Martin
Publisher: Institute of Physics Publishing
: BRISTOL
: 2024
: Astrophysical Journal Letters
: ASTROPHYSICAL JOURNAL LETTERS
: ASTROPHYS J LETT
: L17
: 968
: 2
: 8
: 2041-8205
: 2041-8213
DOI: https://doi.org/10.3847/2041-8213/ad4d9b(external)
: https://iopscience.iop.org/article/10.3847/2041-8213/ad4d9b(external)
: https://research.utu.fi/converis/portal/detail/Publication/457085547(external)
We report the study of a huge optical intraday flare on 2021 November 12 at 2 a.m. UT in the blazar OJ 287. In the binary black hole model, it is associated with an impact of the secondary black hole on the accretion disk of the primary. Our multifrequency observing campaign was set up to search for such a signature of the impact based on a prediction made 8 yr earlier. The first I-band results of the flare have already been reported by Kishore et al. (2024). Here we combine these data with our monitoring in the R-band. There is a big change in the R-I spectral index by 1.0 +/- 0.1 between the normal background and the flare, suggesting a new component of radiation. The polarization variation during the rise of the flare suggests the same. The limits on the source size place it most reasonably in the jet of the secondary BH. We then ask why we have not seen this phenomenon before. We show that OJ 287 was never before observed with sufficient sensitivity on the night when the flare should have happened according to the binary model. We also study the probability that this flare is just an oversized example of intraday variability using the Krakow data set of intense monitoring between 2015 and 2023. We find that the occurrence of a flare of this size and rapidity is unlikely. In machine-readable Tables 1 and 2, we give the full orbit-linked historical light curve of OJ 287 as well as the dense monitoring sample of Krakow.
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The research at Boston University was supported in part by National Science Foundation grant AST-2108622 and a number of NASA Fermi Guest Investigator grants; the latest is 80NSSC23K1507. This work was partly funded by NCN grant No. 2018/29/B/ST9/01793 (S.Z.) and JSPS KAKENHI grant No. 19K03930 (K.M.). S.C. acknowledges support by ASI through contract ASI-INFN 2021-43-HH.0 for SSDC and the Instituto Nazionale di Fisica Nucleare (INFN). R.H. acknowledges the EU project H2020 AHEAD2020, grant agreement 871158, and internal CTU grant SGS21/120/OHK3/2T/13. A.C.G. is partially supported by the Chinese Academy of Sciences (CAS) President's International Fellowship Initiative (PIFI; grant No. 2016VMB073). M.F.G. is supported by the National Science Foundation of China (grant 11873073), the Shanghai Pilot Program for Basic Research-Chinese Academy of Science, Shanghai Branch (JCYJ-SHFY-2021-013), the National SKA Program of China (grant No. 2022SKA0120102), the science research grants from the China Manned Space Project with No. CMSCSST-2021-A06, and the Original Innovation Program of the Chinese Academy of Sciences (E085021002). Z.Z. is thankful for support from the National Natural Science Foundation of China (grant No. 12233005).
