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arXiv · 2304.00893

Significant cocoon emission and photosphere duration stretching in GRB 211211A: a burst from a neutron star - black hole merger

Yan-Zhi Meng·Xiangyu Ivy Wang·Zi-Ke Liu
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Abstract

The radiation mechanism (thermal photosphere or magnetic synchrotron) and the progenitor of gamma-ray burst (GRB) are under hot debate. Recently discovered, the prompt long-duration ($\sim$ 10 s, normally from the collapse of massive stars) property of GRB 211211A strongly conflicts with its association with a kilonova (normally from the merger of two compact objects, NS-NS, NS-BH, or NS-WD, duration $\lesssim$ 2 s). In this paper, we find the probability photosphere model with a structured jet can satisfactorily explain this peculiar long duration, through the duration stretching effect ($\sim$ 3 times) on the intrinsic longer ($\sim$ 3 s) duration of NS-BH (neutron star and black hole) merger, the observed empirical 2SBPL spectrum (with soft low-energy index $\alpha$ of $\sim$ -1) and its evolution. Also, much evidence of the NS-BH merger origin is found, especially the well fit of the afterglow-subtracted optical-NIR light curves by the significant thermal cocoon emission and the sole thermal red kilonova component. Finally, a convincing new explanation for the X-ray afterglow plateau is revealed.

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Yan-Zhi Meng, Xiangyu Ivy Wang, Zi-Ke Liu. 2023-04-03. Significant cocoon emission and photosphere duration stretching in GRB 211211A: a burst from a neutron star - black hole merger. https://doi.org/10.21203/rs.3.rs-2876000%2Fv1

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