Issue |
A&A
Volume 695, March 2025
|
|
---|---|---|
Article Number | A100 | |
Number of page(s) | 8 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361/202452834 | |
Published online | 11 March 2025 |
Repeating fast radio bursts from synchrotron maser radiation in localized plasma blobs: Application to FRB 20121102A
1
Guangxi Key Laboratory for Relativistic Astrophysics, School of Physical Science and Technology, Guangxi University, Nanning 530004, China
2
Institute of Astronomy and Astrophysics, School of Mathematics and Physics, Anqing Normal University, Anqing 246133, People’s Republic of China
⋆ Corresponding authors; lyufen@aqnu.edu.cn; lew@gxu.edu.cn
Received:
31
October
2024
Accepted:
8
February
2025
The radiation physics of repeating fast radio bursts (FRBs) remains enigmatic. Motivated by the observed narrow-banded emission spectrum and ambiguous fringe pattern of the spectral peak frequency (νpk) distribution of some repeating FRBs, such as FRB 20121102A, we propose that the bursts from repeating FRBs arise from synchrotron maser radiation in localized blobs within weakly magnetized plasma that relativistically moves toward observers. Assuming the plasma moves toward the observers with a bulk Lorentz factor of Γ = 100 and the electron distribution in an individual blob is monoenergetic (γe ∼ 300), our analysis shows that bright and narrow-banded radio bursts with peak flux density ∼1 Jy at peak frequency (νpk) ∼3.85 GHz can be produced by the synchrotron maser emission if the plasma blob has a magnetization factor of σ ∼ 10−5 and a frequency of νP ∼ 4.5 MHz. The spectrum of bursts with lower νpk tends to be narrower. Applying our model to the bursts of FRB 20121102A, the distributions of both the observed νpk and isotropic energy Eiso detected by the Arecibo telescope at the L band and the Green Bank Telescope at the C band are successfully reproduced. We find that the νP distribution exhibits several peaks, similar to those observed in the νpk distribution of FRB 20121102A. This implies that the synchrotron maser emission in FRB 20121102A is triggered in different plasma blobs with varying νP, likely due to the inhomogeneity of relativistic electron number density.
Key words: masers / plasmas / radiation mechanisms: non-thermal
© The Authors 2025
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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