论文标题
GRB 140423a：在余辉中向星际介质过渡的恒星风的情况
GRB 140423A: A Case of Stellar Wind to Interstellar Medium Transition in the Afterglow
论文作者
论文摘要
我们介绍了GRB〜140423A的非常早期的基于地面的光学后续观测，该观察是由\ emph {swift}/bat和{\ it fermi}/gbm发现的。它的宽带余辉由{\ it swift}/xrt和基于地面的光学望远镜从$ t_0+$ 70.96〜s到4.8〜d，{\ it swift}/bat Trigger之后。这是迅速光学排放观察的另一种情况。 GRB 140423A的多波长光曲线的时间和光谱关节拟合表明，出色的行为与外部冲击模型一致，包括从恒星风到星际介质（ISM）和能量注射的过渡。就光学曲线而言，早期的余辉中有一个发病颠簸，指数上升$α_ {\ rm o，i} = -0.59 \ pm 0.04 $（达到$ t _ {\ rm peak} -t_0 \ t_0 \ oft 206 $ 〜s）。然后，它以陡峭的索引$α_ {\ rm o，ii} = 1.78 \ pm 0.03 $腐烂，并显示出更陡峭的“过渡”，$α_ {\ rm o，iii} = 1.13 \ 1.13 \ pm 0.03 $ 0.03 $ t_0 + 5000 $ 〜s。观察到的X射线余辉以及光光曲线也反映了出色的行为。 X射线和光学余辉之间的光谱能分布没有明显的演变，其平均值为光子指数$γ\约1.95 $。这种“过渡”与外部冲击模型一致，它通过引入持久的能量注入，并用弹射器的Lorentz因子分层引入持久的能量注入，从而使Circumburst培养基从风向ISM过渡。来自蒙特卡洛马尔可夫链拟合中的最佳参数是$ e _ {\ rm k，iso} \约2.14 \ times10^{55} $ erg，$γ_0\ of 162 $，$ε_e\ $ε_e\ \ 0.02 $，约0.02 $，$ε_b\ε_b\ε_b\最1.7 \ times10^$ __ $ _______________________________________________________ $ __ $ 1.0^$ a} $ r_T \大约4.1 \ times10^{17} $ cm，$ n \ of 11.0 \ rm \ cm \ cm^{ - 3} $，$ l_0 \ of 3.1 \ times10^{52} \ rm \ rm \ rm \ erg \ erg \ s^s^{ - 1}} rad。
We present very early ground-based optical follow-up observations of GRB~140423A, which was discovered by \emph{Swift}/BAT and by {\it Fermi}/GBM. Its broadband afterglow was monitored by {\it Swift}/XRT and ground-based optical telescopes from $T_0+$70.96~s to 4.8~d after the {\it Swift}/BAT trigger. This is one more case of prompt optical emission observation. The temporal and spectral joint fit of the multiwavelength light curves of GRB 140423A reveals that achromatic behavior is consistent with the external shock model including a transition from a stellar wind to the interstellar medium (ISM) and energy injection. In terms of the optical light curves, there is an onset bump in the early afterglow with a rising index $α_{\rm O,I} = -0.59 \pm 0.04$ (peaking at $t_{\rm peak}-T_0 \approx 206$~s). It then decays with a steep index $α_{\rm O,II} = 1.78 \pm 0.03$, and shows a steeper to flatter "transition" with $α_{\rm O,III} = 1.13 \pm 0.03$ at around $T_0 + 5000$~s. The observed X-ray afterglow reflects an achromatic behavior, as does the optical light curve. There is no obvious evolution of the spectral energy distribution between the X-ray and optical afterglow, with an average value of the photon index $Γ\approx 1.95$. This "transition" is consistent with an external shock model having the circumburst medium transition from a wind to the ISM, by introducing a long-lasting energy injection with a Lorentz factor stratification of the ejecta. The best parameters from Monte Carlo Markov Chain fitting are $E_{\rm K,iso} \approx 2.14\times10^{55}$ erg, $Γ_0 \approx 162$, $ε_e \approx 0.02$, $ε_B \approx 1.7\times10^{-6}$, $A_\ast \approx 1.0$, $R_t \approx 4.1\times10^{17}$ cm, $n \approx 11.0 \rm\ cm^{-3}$, $L_0 \approx 3.1\times10^{52} \rm\ erg\ s^{-1}$, $k \approx 1.98$, $s \approx 1.54$, and $θ_j > 0.3$ rad.
