GRB 211211A: The Case for an Engine Powered over r-Process Powered Blue Kilonova
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| Format: | Preprint |
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2024
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| _version_ | 1866911980051234816 |
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| author | Hamidani, Hamid Tanaka, Masaomi Kimura, Shigeo S. Lamb, Gavin P. Kawaguchi, Kyohei |
| author_facet | Hamidani, Hamid Tanaka, Masaomi Kimura, Shigeo S. Lamb, Gavin P. Kawaguchi, Kyohei |
| contents | The recent Gamma-Ray Burst (GRB) GRB 211211A provides the earliest ($\sim 5$ h) data of a kilonova (KN) event, displaying bright ($\sim10^{42}$ erg s$^{-1}$) and blue early emission. Previously, this KN has been explained using simplistic multi-component fitting methods. Here, in order to understand the physical origin of the KN emission in GRB 211211A, we employ an analytic multi-zone model for r-process powered KN. We find that r-process powered KN models alone cannot explain the fast temporal evolution and the spectral energy distribution (SED) of the observed emission. Specifically, i) r-process models require high ejecta mass to match early luminosity, which overpredicts late-time emission, while ii) red KN models that reproduce late emission underpredict early luminosity. We propose an alternative scenario involving early contributions from the GRB central engine via a late low-power jet, consistent with plateau emission in short GRBs and GeV emission detected by Fermi-LAT at $\sim10^4$ s after GRB 211211A. Such late central engine activity, with an energy budget of $\sim \text{a few }\%$ of that of the prompt jet, combined with a single red-KN ejecta component, can naturally explain the light curve and SED of the observed emission; with the late-jet -- ejecta interaction reproducing the early blue emission and r-process heating reproducing the late red emission. This supports claims that late low-power engine activity after prompt emission may be common. We encourage very early follow-up observations of future nearby GRBs, and compact binary merger events, to reveal more about the central engine of GRBs and r-process events. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2406_14366 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | GRB 211211A: The Case for an Engine Powered over r-Process Powered Blue Kilonova Hamidani, Hamid Tanaka, Masaomi Kimura, Shigeo S. Lamb, Gavin P. Kawaguchi, Kyohei High Energy Astrophysical Phenomena The recent Gamma-Ray Burst (GRB) GRB 211211A provides the earliest ($\sim 5$ h) data of a kilonova (KN) event, displaying bright ($\sim10^{42}$ erg s$^{-1}$) and blue early emission. Previously, this KN has been explained using simplistic multi-component fitting methods. Here, in order to understand the physical origin of the KN emission in GRB 211211A, we employ an analytic multi-zone model for r-process powered KN. We find that r-process powered KN models alone cannot explain the fast temporal evolution and the spectral energy distribution (SED) of the observed emission. Specifically, i) r-process models require high ejecta mass to match early luminosity, which overpredicts late-time emission, while ii) red KN models that reproduce late emission underpredict early luminosity. We propose an alternative scenario involving early contributions from the GRB central engine via a late low-power jet, consistent with plateau emission in short GRBs and GeV emission detected by Fermi-LAT at $\sim10^4$ s after GRB 211211A. Such late central engine activity, with an energy budget of $\sim \text{a few }\%$ of that of the prompt jet, combined with a single red-KN ejecta component, can naturally explain the light curve and SED of the observed emission; with the late-jet -- ejecta interaction reproducing the early blue emission and r-process heating reproducing the late red emission. This supports claims that late low-power engine activity after prompt emission may be common. We encourage very early follow-up observations of future nearby GRBs, and compact binary merger events, to reveal more about the central engine of GRBs and r-process events. |
| title | GRB 211211A: The Case for an Engine Powered over r-Process Powered Blue Kilonova |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2406.14366 |