Magnetar as the Central Engine of AT2018cow: Optical, Soft X-Ray, and Hard X-Ray Emission
| Autor: | Long Li, Shu-Qing Zhong, Di Xiao, Zi-Gao Dai, Shi-Feng Huang, Zhen-Feng Sheng |
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| Jazyk: | angličtina |
| Rok vydání: | 2024 |
| Předmět: | |
| Zdroj: | The Astrophysical Journal Letters, Vol 963, Iss 1, p L13 (2024) |
| Druh dokumentu: | article |
| ISSN: | 2041-8213 2041-8205 46439889 |
| DOI: | 10.3847/2041-8213/ad2611 |
| Popis: | AT2018cow is the most extensively observed and widely studied fast blue optical transient to date; its unique observational properties challenge all existing standard models. In this paper, we model the luminosity evolution of the optical, soft X-ray, and hard X-ray emission, as well as the X-ray spectrum of AT2018cow with a magnetar-centered engine model. We consider a two-zone model with a striped magnetar wind in the interior and an expanding ejecta outside. The soft and hard X-ray emission of AT2018cow can be explained by the leakage of high-energy photons produced by internal gradual magnetic dissipation in the striped magnetar wind, while the luminous thermal UV/optical emission results from the thermalization of the ejecta by the captured photons. The two-component energy spectrum yielded by our model with a quasi-thermal component from the optically thick region of the wind superimposed on an optically thin synchrotron component well reproduces the X-ray spectral shape of AT2018cow. The Markov Chain Monte Carlo fitting results suggest that in order to explain the very short rise time to peak of the thermal optical emission, a low ejecta mass M _ej ≈ 0.1 M _⊙ and high ejecta velocity ${v}_{\mathrm{SN}}\approx 0.17c$ are required. A millisecond magnetar with P _0 ≈ 3.7 ms and B _p ≈ 2.4 × 10 ^14 G is needed to serve as the central engine of AT2018cow. |
| Databáze: | Directory of Open Access Journals |
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