[论文解读] Supernova-like explosion of massive rotating stars from disks surrounding a black hole

Sho Fujibayashi, Alan Tsz-Lok Lam+2 more|arXiv (Cornell University)|Sep 5, 2023

Gamma-ray bursts and supernovaePhysics and Astronomy被引用 3

一句话总结

本研究通过广义相对论黏性-辐射流体动力学模拟表明，质量大、快速旋转的恒星（20–45 M⊙）在坍缩成黑洞时，其周围环状盘中的黏性加热可驱动类似超新星的爆发。这些爆发的能量可达约10⁵² erg，喷射质量约为5 M⊙，⁵⁶Ni质量超过0.15 M⊙，与高能超新星（如宽线型Ic型）相匹配。

ABSTRACT

We perform a new general-relativistic viscous-radiation hydrodynamics simulation for supernova-like explosion associated with stellar core collapse of rotating massive stars to a system of a black hole and a massive torus paying particular attention to large-mass progenitor stars with the zero-age main-sequence mass of $M_\mathrm{ZAMS}=$20, 35, and 45$M_\odot$ of Ref.~\cite{Aguilera-Dena2020oct}. Assuming that a black hole is formed in a short timescale after the onset of the stellar collapse, the new simulations are started from initial data of a spinning black hole and infalling matter that self-consistently satisfy the constraint equations of general relativity. It is found that with a reasonable size of the viscous parameter, the supernova-like explosion is driven by the viscous heating effect in the torus around the black hole irrespective of the progenitor mass. The typical explosion energy and ejecta mass for the large-mass cases ($M_\mathrm{ZAMS}=35$ and $45M_\odot$) are $\sim 10^{52}$ erg and $\sim 5M_\odot$, respectively, with $^{56}$Ni mass larger than $0.15M_\odot$. These are consistent with the observational data of stripped-envelope and high-energy supernovae such as broad-lined type Ic supernovae. This indicates that rotating stellar collapses of massive stars to a black hole surrounded by a massive torus can be a central engine for high-energy supernovae. By artificially varying the angular velocity of the initial data, we explore the dependence of the explosion energy and ejecta mass on the initial angular momentum and find that the large explosion energy $\sim 10^{52}$ erg and large $^{56}$Ni mass $\geq 0.15M_\odot$ are possible only when a large-mass compact torus with mass $\gtrsim 1M_\odot$ is formed.

研究动机与目标

• 通过广义相对论模拟研究高能超新星（如宽线型Ic型超新星）的机制。
• 确定黑洞周围不同旋转速度的环状盘中黏性加热是否可在大质量旋转恒星坍缩中驱动类似超新星的爆发。
• 评估黑洞-环状盘系统中爆炸能量与喷射物质量对初始角动量和环状盘质量的依赖关系。
• 通过测试网格分辨率对黑洞质量与自旋演化的影响，验证数值精度。
• 探讨黏性加热机制作为大质量恒星核心坍缩中高能超新星中心引擎的可行性。

提出的方法

• 执行满足约束方程的自洽初始数据的广义相对论黏性-辐射流体动力学模拟。
• 采用α-黏性模型（ν = αν cs H）来模拟环状盘中的角动量输运与黏性加热。
• 初始数据由自旋黑洞和来自零龄主序星（20、35和45 M⊙）的吸积物质组成。
• 使用自适应网格加密与高分辨率网格，确保黑洞质量与自旋演化的数值收敛性。
• 通过在三维流体动力学代码中使用中微子输运近似，对时间积分质量与能量通量，计算爆炸能量与喷射物质量。
• 通过比较低分辨率与高分辨率模拟（如AD35-15与AD35-15-hi）进行收敛性测试。

Figure 1: Specific angular momentum, $j$ , as a function of the enclosed mass, $m$ , for the models of $M_{\mathrm{ZAMS}}=9$ , 20, 35, and $45M_{\odot}$ in Ref. [ 1 ] (solid curves). We also plot $j_{\mathrm{ISCO}}$ for a given black hole of mass $m$ and corresponding angular momentum $J(m)$ by the

实验结果

研究问题

• RQ1 黑洞周围大质量、不同旋转速度的环状盘中的黏性加热是否可在大质量旋转恒星坍缩中驱动类似超新星的爆发？
• RQ2 在大质量恒星坍缩中，爆炸能量与喷射物质量对初始角动量与环状盘质量的依赖关系如何？
• RQ3 模拟的爆发特性（能量、⁵⁶Ni质量）是否与宽线型Ic型超新星等高能超新星的观测数据一致？
• RQ4 数值分辨率如何影响黑洞质量与自旋演化及最终爆炸能量学的准确性？
• RQ5 黏性加热机制是否足以驱动能量约为10⁵² erg、⁵⁶Ni质量超过0.15 M⊙的爆发，且适用于大质量前体星？

主要发现

• 无论前体星质量如何（20–45 M⊙），由环状盘中黏性加热驱动的类似超新星的爆发能量可达约10⁵² erg。
• 对于35 M⊙与45 M⊙的前体星，喷射物质量可达约5 M⊙，⁵⁶Ni质量超过0.15 M⊙，与宽线型Ic型超新星一致。
• 仅当初始形成质量大于1 M⊙的环状盘时，才会产生能量约为10⁵² erg且⁵⁶Ni质量≥0.15 M⊙的爆发。
• 更高网格分辨率导致黑洞质量略低、喷射物质量略高，这是由于黏性加热更高效且吸积减少。
• 高分辨率模拟中爆炸能量略大，证实黏性加热是环状盘中一种稳健的能量来源。
• 数值收敛性测试显示黑洞质量与自旋的收敛阶数为四阶，当Δx ≤ 0.016 M_BH时，误差小于1.6%，Δχ ≈ 0.004（t = 80,000 M_BH时）。

Figure 2: Snapshots of the profiles for several quantities at selected time slices for model AD35-15 . At each time, the rest-mass density (top-left), entropy per baryon (top-right), temperature (bottom-left), and electron fraction (bottom-right) are displayed. The poloidal velocity field is depicte