论文标题
来自银河磁铁SGR SGR 1935+2154的极明亮无线电爆发的流出特性的多波长约束
Multi-Wavelength Constraints on the Outflow Properties of the Extremely Bright Millisecond Radio Bursts from the Galactic Magnetar SGR 1935+2154
论文作者
论文摘要
非常明亮的连贯无线电爆发，持续毫秒的持续时间，让人联想到宇宙学快速无线电爆发（FRB），与银河系磁铁SGR SGR 1935 $+$ 2154的异常X射线爆发共同发现。我们研究了事件是由磁层内的磁能注入触发的，从而同时产生磁性捕获的火球（FB）和相对论流出的可能性。 X射线突发的热成分与被困的FB一致，平均温度为$ \ sim200 $ - $ 300 $ KEV，大小为$ \ sim10^5 $ cm。同时，X射线爆发的非热组件和相干无线电突发可能来自相对论流出。我们计算出流出的动态演变，并以$ 10^{39} $ - $ 10^{40} $ ERG与被困FB相当的能源预算推出，对于不同的初始BARYON负载$η$和磁性化$σ_0$。如果硬X射线和无线电爆发都是由于流出的能量耗散而产生的，则流出性能通过将光子逃逸的条件和固有的定时偏移$ \ lyssim10 $ MS组合在无线电和X射线脉冲上的尖峰中来限制。我们表明，必须以$ r _ {\ rm x} \ gtrsim10^{8} $ cm从磁铁中生成硬X射线突发，而与发射机制无关。此外，我们发现流出迅速加速至lorentz $ 10^2 \lysSimγ\ Lessim10^3 $，到达到磁层的边缘时，耗散的发生在$ 10^{12} $ cm $ cm $ \ \ simsim r _ lisesim r _ {\ rm rm ram ximsimsim，x}} \ \ sim10^^^^^^^^^14^mm10^^^MM 10^^^^MM 10^^^| {14.我们的结果意味着极其清洁（$η\ gtrsim10^4 $）或高度磁化（$σ_0\ gtrsim10^3 $）流出，这可能与现象的稀有性一致。
Extremely bright coherent radio bursts with millisecond duration, reminiscent of cosmological fast radio bursts (FRBs), were co-detected with anomalously-hard X-ray bursts from a Galactic magnetar SGR 1935$+$2154. We investigate the possibility that the event was triggered by the magnetic energy injection inside the magnetosphere, thereby producing magnetically-trapped fireball (FB) and relativistic outflows simultaneously. The thermal component of the X-ray burst is consistent with a trapped FB with an average temperature of $\sim200$-$300$ keV and size of $\sim10^5$ cm. Meanwhile, the non-thermal component of the X-ray burst and the coherent radio burst may arise from relativistic outflows. We calculate the dynamical evolution of the outflow, launched with an energy budget of $10^{39}$-$10^{40}$ erg comparable to that for the trapped FB, for different initial baryon load $η$ and magnetization $σ_0$. If hard X-ray and radio bursts are both produced by the energy dissipation of the outflow, the outflow properties are constrained by combining the conditions for photon escape and the intrinsic timing offset $\lesssim10$ ms among radio and X-ray burst spikes. We show that the hard X-ray burst must be generated at $r_{\rm X}\gtrsim10^{8}$ cm from the magnetar, irrespective of the emission mechanism. Moreover, we find that the outflow quickly accelerates up to a Lorentz factor of $10^2\lesssimΓ\lesssim10^3$ by the time it reaches the edge of the magnetosphere and the dissipation occurs at $10^{12}$ cm $\lesssim r_{\rm radio,X}\lesssim10^{14}$ cm. Our results imply either extremely-clean ($η\gtrsim10^4$) or highly-magnetized ($σ_0\gtrsim10^3$) outflows, which might be consistent with the rarity of the phenomenon.
