A Candidate Binary Microlensing Event in the 2018 Gamma-Ray Flare of 3C 279
Abstract
The April 2018 gamma-ray flare of the flat-spectrum radio quasar 3C~279 exhibited sharp peaks within a broader outburst. Its rapid substructure was previously attributed to magnetic reconnection. Motivated by its distinctive temporal profile within our comparison sample of bright blazar flares and its resemblance to caustic-crossing features in optical microlensing events, we investigate a finite-source binary-microlensing interpretation. A jointly fitted model of binary-lens magnification, a smooth intrinsic flare, and Gaussian-process variability reproduces the principal double-peaked structure of the GeV light curve. The adopted local solution has a binary mass ratio of q≃0.098 and an Einstein timescale of tE≃0.327~d. The absolute lens mass and projected source radius depend on the lens distance and relative proper motion. The fitted geometry can correspond to a Galactic planetary-mass binary or an intervening stellar or substellar system, with different physical source sizes in each case. We present binary microlensing as a testable interpretation of this event, with the finite-source structure offering a potential probe of the compact GeV-emitting region.
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BibTeX
@misc{yang2026candidate,
title = {{A Candidate Binary Microlensing Event in the 2018 Gamma-Ray Flare of 3C 279}},
author = {Yihong Yang and Jianeng Zhou and Haibin Ren and Wei Zhu and Haiyun Zhang and Dahai Yan and Hongping Deng and Hengxiao Guo and Zhen Yan and Liang Chen and Minfeng Gu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.40255},
eprint = {2610.40255},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.40255},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - A Candidate Binary Microlensing Event in the 2018 Gamma-Ray Flare of 3C 279
AU - Yihong Yang
AU - Jianeng Zhou
AU - Haibin Ren
AU - Wei Zhu
AU - Haiyun Zhang
AU - Dahai Yan
AU - Hongping Deng
AU - Hengxiao Guo
AU - Zhen Yan
AU - Liang Chen
AU - Minfeng Gu
PY - 2026
DA - 2026/10/29
PB - arXiv
DO - 10.48550/arxiv.2610.40255
UR - https://arxiv.org/abs/2610.40255
AB - The April 2018 gamma-ray flare of the flat-spectrum radio quasar 3C~279 exhibited sharp peaks within a broader outburst. Its rapid substructure was previously attributed to magnetic reconnection. Motivated by its distinctive temporal profile within our comparison sample of bright blazar flares and its resemblance to caustic-crossing features in optical microlensing events, we investigate a finite-source binary-microlensing interpretation. A jointly fitted model of binary-lens magnification, a smooth intrinsic flare, and Gaussian-process variability reproduces the principal double-peaked structure of the GeV light curve. The adopted local solution has a binary mass ratio of q≃0.098 and an Einstein timescale of t_E≃0.327~d. The absolute lens mass and projected source radius depend on the lens distance and relative proper motion. The fitted geometry can correspond to a Galactic planetary-mass binary or an intervening stellar or substellar system, with different physical source sizes in each case. We present binary microlensing as a testable interpretation of this event, with the finite-source structure offering a potential probe of the compact GeV-emitting region.
ER -