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Simultaneous Multiband Photometry of the Early Optical Afterglow of GRB 240825A with Mephisto by Cheng, Yehao; Pan, Yu; Yang, Yuan-Pei; Zhang, Jinghua; Du, Guowang; Fang, Yuan; Kumar, Brajesh; Guo, Helong; Er, Xinzhong; Chen, Xinlei; Liu, Chenxu; Wang, Tao; Qin, Zhenfei; Jin, Yicheng; Zou, Xingzhu; Han, Xuhui; Zhang, Pinpin; Xin, Liping; Wu, Chao; Lian, Jianhui; Liu, Xiangkun; Liu, Xiaowei is a scholarly article available to read on EtoBox.

What is Simultaneous Multiband Photometry of the Early Optical Afterglow of GRB 240825A with Mephisto about?

Gamma-ray bursts (GRBs) are the most luminous transients in the universe. The interaction of the relativistic jet with the circumburst medium produces an afterglow and generates multiwavelength emission. In this work, we present simultaneous multiband photometry of GRB~240825A with the Multi-channel Photometric Survey Telescope (Mephisto) and analyze its temporal and spectral properties. The measurement began 128 seconds after the GRB trigger and continued until the fourth day when the afterglow essentially diminished and the measured brightness was close to that of the host galaxy. Based on the multiband light curves in the $uvgriz$ bands, we find that the optical flux density satisfies $F_{\nu,{\rm obs}}\propto t^{-1.34}\nu^{-2.48}$ with a spectral index of $2.48$ much larger than those of most other GRBs. To reconcile the measured much softer spectral energy distribution (SED) with that predicted by the standard afterglow model, an extra host-galaxy extinction of $E_{B-V}\sim(0.37-0.57)$ mag is required. We interpreted this excess as arising from a dense circumburst medium. We further find that the SED of the optical afterglow hardened as the afterglow decayed and the color exce

Author

Cheng, Yehao; Pan, Yu; Yang, Yuan-Pei; Zhang, Jinghua; Du, Guowang; Fang, Yuan; Kumar, Brajesh; Guo, Helong; Er, Xinzhong; Chen, Xinlei; Liu, Chenxu; Wang, Tao; Qin, Zhenfei; Jin, Yicheng; Zou, Xingzhu; Han, Xuhui; Zhang, Pinpin; Xin, Liping; Wu, Chao; Lian, Jianhui; Liu, Xiangkun; Liu, Xiaowei

Published

2024

Language

EN