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10,326 results on '"Wang, Xi"'

2. Observation of spectral lines in the exceptional GRB 221009A

Author

Zhang, Yan-Qiu, Xiong, Shao-Lin, Mao, Ji-Rong, Zhang, Shuang-Nan, Xue, Wang-Chen, Zheng, Chao, Liu, Jia-Cong, Zhang, Zhen, Wang, Xi-Lu, Ge, Ming-Yu, Yi, Shu-Xu, Song, Li-Ming, An, Zheng-Hua, Cai, Ce, Li, Xin-Qiao, Peng, Wen-Xi, Tan, Wen-Jun, Wang, Chen-Wei, Wen, Xiang-Yang, Wang, Yue, Xiao, Shuo, Zhang, Fan, Zhang, Peng, and Zheng, Shi-Jie

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

As the brightest gamma-ray burst ever observed, GRB 221009A provided a precious opportunity to explore spectral line features. In this paper, we performed a comprehensive spectroscopy analysis of GRB 221009A jointly with GECAM-C and Fermi/GBM data to search for emission and absorption lines. For the first time we investigated the line feature throughout this GRB including the most bright part where many instruments suffered problems, and identified prominent emission lines in multiple time intervals. The central energy of the Gaussian emission line evolves from about 37 MeV to 6 MeV, with a nearly constant ratio (about 10\%) between the line width and central energy. Particularly, we find that both the central energy and the energy flux of the emission line evolve with time as a power law decay with power law index of -1 and -2 respectively. We suggest that the observed emission lines most likely originate from the blue-shifted electron positron pair annihilation 511 keV line. We find that a standard high latitude emission scenario cannot fully interpret the observation, thus we propose that the emission line comes from some dense clumps with electron positron pairs traveling together with the jet. In this scenario, we can use the emission line to directly, for the first time, measure the bulk Lorentz factor of the jet ($\Gamma$) and reveal its time evolution (i.e. $\Gamma \sim t^{-1}$) during the prompt emission. Interestingly, we find that the flux of the annihilation line in the co-moving frame keeps constant. These discoveries of the spectral line features shed new and important lights on the physics of GRB and relativistic jet., Comment: Accepted by SCIENCE CHINA Physics, Mechanics & Astronomy (SCPMA)

Published
2024
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21. Images of hairy Reissner-Nordstr\'{o}m black hole illuminated by static accretions

Author

Meng, Yuan, Kuang, Xiao-Mei, Wang, Xi-Jing, Wang, Bin, and Wu, Jian-Pin

Subjects
General Relativity and Quantum Cosmology
Abstract

We investigate the shadow and optical appearance of the hairy Reissner-Nordstr\"{o}m (RN) black hole illuminated by two toy models of static accretion. The hairy RN black hole was constructed in the gravitation decoupling approach to describe the deformation of a Schwarzschild black hole due to the inclusion of additional arbitrary source (scalar field, tensor field, fluidlike dark matter, etc). So it is characterized by the parameters: mass ($M$), deformation factor ($\alpha$), electric charge ($Q$) and the additional hairy charge ($l_o$), differentiating from the case in RN black hole. Though the specific background theory that results in this hairy RN black hole is still tricky, here we shall focus on the novel observable features introduced by the hair of this black hole. First, we find that for the hairy RN black hole, the event horizon, radius of photon sphere and critical impact parameter all increase as the increasings of $Q$ and $l_o$, but decrease as $\alpha$ grows. The three characterized parameters are found to have significant effects on the photon trajectories, shadows and images of hairy RN black hole surrounded by the static accretion disk and spherical accretion, respectively. Particularly, both $Q$ and $l_o$ have mutually reinforcing effects on the optical appearance and shadows of the hairy RN black hole, which implies that we may not distinguish the electric charge and hairy charge from the shadow and image of black hole in this scenario. Additionally, because of the competing effects of the charge parameters ($Q, l_o$) and the deviation parameter $\alpha$ on the observed intensities of brightness, the optical appearance between the hairy RN black hole and RN black hole could have degeneracies, indicating the indistinguishability. Our current results contribute more to the phenomenal aspects which could be helpful to build the background theory of hairy RN black hole., Comment: 15 pages, 6 figures

Published
2024
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26. Improving the SO2 tolerance of CO2 reduction electrocatalysts using a polymer/catalyst/ionomer heterojunction design

Author

Papangelakis, Panagiotis, Miao, Rui Kai, Lu, Ruihu, Liu, Hanqi, Wang, Xi, Ozden, Adnan, Liu, Shijie, Sun, Ning, O’Brien, Colin P., Hu, Yongfeng, Shakouri, Mohsen, Xiao, Qunfeng, Li, Mengsha, Khatir, Behrooz, Huang, Jianan Erick, Wang, Yakun, Xiao, Yurou Celine, Li, Feng, Zeraati, Ali Shayesteh, Zhang, Qiang, Liu, Pengyu, Golovin, Kevin, Howe, Jane Y., Liang, Hongyan, Wang, Ziyun, Li, Jun, Sargent, Edward H., and Sinton, David

Published
2024
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