2020 Fiscal Year Annual Research Report
Non-thermal Emission from Binary Neutron Star Mergers
| Project/Area Number |
20J12200
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| Research Institution | The University of Tokyo |
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Principal Investigator |
LIN Haoxiang 東京大学, 理学系研究科, 特別研究員(DC2)
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| Project Period (FY) |
2020-04-24 – 2022-03-31
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| Keywords | 連星中性子星合体 / 重力波 / 高速電波バースト / ガンマ線バースト |
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| Outline of Annual Research Achievements |
Fast radio bursts (FRBs) are high-energy transients recently discovered in radio with mysterious origin. Binary neutron star (BNS) mergers are one of the proposed origins of FRBs, which associates FRBs with potential counterparts of gravitational waves, short gamma-ray bursts, and radio afterglows from the merger ejecta. We have proposed that, if FRBs do come from BNS mergers, the current and future radio follow-up observation of FRBs can be used to constrain the properties of merger ejecta, and hence the BNS origin.
In this research, we have statistically simulated a large (>10^4) population of BNS afterglow radio light curves powered by the two components: a relativistic jet and a slower isotropic ejecta, and estimate their detection probabilities at the radio sensitivities in FRB follow-up observation. We found that the detection probabilities are between 1--10 per cent, and hence the current observations do not constitute a severe challenge to BNS origin. We estimated that about a few hundred follow-up observations (i.e. 10 times of current sample) will give a meaningful constraint or lead to a afterglow detection, which is achievable soon by the new-generation radio projects including CHIME, ASKAP and FAST.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The progress is proceeded as planned. as we have summarized our proposed idea "using follow-up observational results of FRBs to constrain their origin" into journal paper publication and international conference presentation, though the outbreak of COVID-19 pandemic had forced the cancellation of some on-site meetings, which created a substantial amount of carry-over.
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| Strategy for Future Research Activity |
Considering the huge amount of the released energy, both binary neutron star mergers and fast radio bursts may play a non-ignorable role in the production of (ultra-high-energy) cosmic rays. The recent and upcoming operation of new-generation gamma-ray telescopes (e.g. CTA) facilitates the observation of high-energy gamma-rays from nearby galaxies, which may provide hints to the origin of cosmic rays.
In our plan of the future work, we will explore the possibility of multi-messenger (gravitational waves, radio, gamma rays, cosmic rays) observations of binary neutron star mergers and fast radio bursts. We will focus on the formal construction of a statistical method in order to estimate detection rate and evaluate observational bias and distribution of detected events, and apply it to discuss future detectability in the context of current facilities. This research should expectedly serve as reference for future multi-messenger observational strategies involving CTA.
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