FRB 121102：无超新星类似抛射物或磁星能量源，暗示双白矮星并合
FRB 121102: No supernova-like ejecta or magnetar power, hinting at a binary WD merger
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中文总结 AI 辅助
本研究通过FRB 121102的观测数据约束其能量源，排除超新星抛射物与磁星能量源的可能，提出其起源为双白矮星并合的新假说。
中文摘要 AI 辅助
我们利用重复快速射电暴FRB 121102的时变色散测量，以及其关联持续射电源（PRS）的早期射电观测，对其潜在“引擎”施加严格约束。相对论性PRS等离子体的能量大于10^49.5 erg，年龄约60年，对应潜在源功率超过10^40 erg s^-1。若潜在源为中子星，这意味着其能量来源为旋转能而非磁能，符合约10毫秒、约10^12.5 G的中子星特征；吸积也可能是可行的能量来源。约束相对论性PRS等离子体的冷等离子体的速度与动能，与其为典型超新星抛射物的假设不一致（除非抛射物质量的很大一部分由约10^-2.5分数大小的高密度团块携带）——其膨胀速度被限制在数百km/s，这也意味着它是在相对论性PRS等离子体辐射开始前约10^3年从源中抛射出的。这些约束可由白矮星双星并合前身系统满足：并合期间及之后，约一个太阳质量的一部分以低速被抛射，且在并合遗迹约10^3年的热演化期后形成一颗快速旋转的中子星。
英文摘要
We use measurements of the time-dependent dispersion measure of the repeating FRB 121102, together with earlier radio observations of its associated persistent radio source (PRS), to derive stringent constraints on its underlying ``engine.'' The energy held by the relativistic PRS plasma is $>10^{49.5}$ erg, and its age is $\approx60$ yr, corresponding to an underlying source power exceeding $10^{40}$ erg s$^{-1}$. If the underlying source is a neutron star, this implies a rotational rather than a magnetic energy source, consistent with a $\sim10$ ms, $\sim10^{12.5}$ G neutron star. Alternatively, accretion may also be a viable energy source. The velocity and the kinetic energy of the cold plasma confining the relativistic PRS plasma are inconsistent with it being typical supernova ejecta (unless a significant fraction of the ejecta mass is carried by high-density clumps of $\approx10^{-2.5}$ fractional size)- its expansion speed is limited to a few hundred km/s, which also implies that it was ejected from the source more than $\approx 10^3$ yr preceding the onset of relativistic PRS plasma emission. These constraints may be satisfied by a white dwarf binary merger progenitor system, where a fraction of a solar mass was ejected at a slow speed during and after the merger, and a rapidly rotating neutron star was formed after $\sim10^3$ yr thermal evolution period of the merger remnant.
