论文标题

黑洞到Photosphere:3D GRMHD的折叠模拟揭示了摇摆和混合组成喷气机

Black hole to photosphere: 3D GRMHD simulations of collapsars reveal wobbling and hybrid composition jets

论文作者

Gottlieb, Ore, Liska, Matthew, Tchekhovskoy, Alexander, Bromberg, Omer, Lalakos, Aretaios, Giannios, Dimitrios, Mösta, Philipp

论文摘要

长期$γ$射线爆发(GRB)伴随着大型恒星的崩溃,并携带有关中央发动机的信息。但是,没有3D型号能够通过黑洞(BH)到Photosphere遵循这些喷气机。我们介绍了第一个这样的3D通用磁性流体动力模拟,该模拟范围超过6个数量级。崩溃的恒星包膜形成一个吸积盘,该磁盘向内拖动了在BH周围积累的磁通量,它在动态上很重要,并发射了双极喷气机。喷气机以$ \ sim10^{12} $ cm的开头$θ_j\ sim6^\ circ $和lorentz factor $γ_j\ lysesim 30 $,毫无限制的$ \ gtrsim90 \%$ $。我们发现(i)磁盘射流系统自发地相对于BH旋转轴而发生未对准。结果,射流具有角度$θ_T\ sim12^\ circ $,可以自然地解释GRB Lightcurves中的静态时间。检测$θ_j+θ_t$的有效开头表明,固有的GRB速率的数量级低于标准估计。这表明,成功的GRB可能比目前想象的要稀有,并且仅以$ \ sim 0.1 \%$ $ $ $ \%的超新星IB/c出现,这意味着喷气式飞机要么在大多数超级nova IB/c祖先中都没有启动或窒息。 (ii)射流中的磁能由于与恒星的混合而降低,导致喷气机在光球处与磁性和热成分的混合组成,其中$ \ sim 10 \%的气体维持磁化$σ\ gtrsim 0.1 $。这表明光电组件和重新连接都可能在及时发射中起作用。

Long-duration $γ$-ray bursts (GRBs) accompany the collapse of massive stars and carry information about the central engine. However, no 3D models have been able to follow these jets from their birth by a black-hole (BH) to the photosphere. We present the first such 3D general-relativity magnetohydrodynamic simulations, which span over 6 orders of magnitude in space and time. The collapsing stellar envelope forms an accretion disk, which drags inwardly the magnetic flux that accumulates around the BH, becomes dynamically important and launches bipolar jets. The jets reach the photosphere at $\sim10^{12}$ cm with an opening angle $θ_j\sim6^\circ$ and a Lorentz factor $Γ_j\lesssim 30$, unbinding $\gtrsim90\%$ of the star. We find that (i) the disk-jet system spontaneously develops misalignment relative to the BH rotational axis. As a result, the jet wobbles with an angle $θ_t\sim12^\circ$, which can naturally explain quiescent times in GRB lightcurves. The effective opening angle for detection $θ_j+θ_t$ suggests that the intrinsic GRB rate is lower by an order of magnitude than standard estimates. This suggests that successful GRBs may be rarer than currently thought and emerge in only $\sim 0.1\%$ of supernovae Ib/c, implying that jets are either not launched or choked inside most supernova Ib/c progenitors. (ii) The magnetic energy in the jet decreases due to mixing with the star, resulting in jets with a hybrid composition of magnetic and thermal components at the photosphere, where $\sim 10\%$ of the gas maintains magnetization $σ\gtrsim 0.1$. This indicates that both a photospheric component and reconnection may play a role in the prompt emission.

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