标题： 利用SKA脉冲星测时阵列揭示首批超大质量黑洞的形成 显示英文标题

标题： Unravelling the formation of the first supermassive black holes with the SKA pulsar timing array

摘要： 高红移的星系合并会激发其中央超大质量黑洞的活动，最终导致它们的并合——这可能是低频引力波的潜在来源，可被平方公里阵列（SKA）脉冲星测时阵列（PTA）探测到。 与黑洞供能相关的两个关键参数是类星体吸积的爱丁顿比 $\eta_{\rm Edd}$，以及吸积过程的辐射效率 $\epsilon$（它影响所谓的类星体活跃期 $t_{\rm QSO}$）。 我们预测了通过SKA PTA探测引力波事件的范围，发现相关的双星系统具有以周到年为量级的轨道周期，可以通过相对论性多普勒速度增强和/或光变曲线的光学变化来观测。 结合SKA的探测范围和最新的高红移黑洞质量和亮度函数观测限制，以及基于暗物质晕并合率的理论预测，我们预测了作为主黑洞质量函数在 $z \gtrsim 6$处预期的SKA PTA事件的活动对应体的数量。 我们发现，最 massive 黑洞的类星体对应体将在 $z \gtrsim 6$的SKA PTA误差椭圆内 ${uniquely \ localizable}$。 我们还预测了作为类星体爱丁顿比和活跃期函数的预期对应体数量。 我们的结果显示，SKA PTA探测可以对第一代超大质量黑洞的播种和增长机制施加严格的约束。 显示英文摘要

摘要： Galaxy mergers at high redshifts trigger the activity of their central supermassive black holes, eventually also leading to their coalescence -- and a potential source of low-frequency gravitational waves detectable by the SKA Pulsar Timing Array (PTA). Two key parameters related to the fuelling of black holes are the Eddington ratio of quasar accretion $\eta_{\rm Edd}$, and the radiative efficiency of the accretion process, $\epsilon$ (which affects the so-called active lifetime of the quasar, $t_{\rm QSO}$). We forecast the regime of detectability of gravitational wave events with SKA PTA, finding the associated binaries to have orbital periods on the order of weeks to years, observable through relativistic Doppler velocity boosting and/or optical variability of their light curves. Combining the SKA regime of detectability with the latest observational constraints on high-redshift black hole mass and luminosity functions, and theoretically motivated prescriptions for the merger rates of dark matter haloes, we forecast the number of active counterparts of SKA PTA events expected as a function of primary black hole mass at $z \gtrsim 6$. We find that the quasar counterpart of the most massive black holes will be ${uniquely \ localizable}$ within the SKA PTA error ellipse at $z \gtrsim 6$. We also forecast the number of expected counterparts as a function of the quasars' Eddington ratio and active lifetime. Our results show that SKA PTA detections can place robust constraints on the seeding and growth mechanisms of the first supermassive black holes.