We propose a new analogue model of gravity - the evolving quark gluon plasma (QGP) produced in relativistic heavy ion collisions. This quark gluon plasma is the “most inviscid” fluid known. Such low kinematic viscosity is believed to reflect strongly correlated nature for QGP in these experiments. Hence, it may provide a good example of a quantum fluid naturally suited to studies of acoustic Hawking radiation. Due to rapid longitudinal expansion, presence of a sonic horizon is also naturally guaranteed here, though, in general, this horizon is not static. Using Ultra relativistic quantum molecular dynamics (UrQMD) simulations, we show that, under certain conditions, the longitudinal velocity of the plasma, near the sonic horizon, can become time independent for a short span during the evolution of the system. During this period, we can have a conformally static acoustic metric with a (conformal) Killing horizon coinciding with the apparent horizon. An asymptotic observer will then see a thermal flux of phonons, constituting the Hawking radiation, coming from the horizon. For the relatively low energy collision considered here, where the resulting QCD system is governed by non-relativistic hydrodynamics, we estimate the Hawking temperature to be about 4-5 MeV (with the temperature of the QCD fluid being about 135 MeV). We discuss the experimental signatures of this Hawking radiation in terms of a thermal component in the rapidity dependence of the transverse momentum distribution of detected particles. We also discuss extension to ultra-relativistic case which should lead to a higher Hawking temperature, along with the effects of dynamical horizon leading to blue/red shift of the temperature.

我们提出了一种新的引力模拟模型-在相对论重离子碰撞中产生的不断演化的夸克胶子等离子体（QGP）。夸克胶子等离子体是已知的“最不粘稠”的流体。据信，在这些实验中，如此低的运动粘度反映了QGP的强烈相关性。因此，它可以提供一个自然适合于声学霍金辐射研究的量子流体的很好的例子。由于纵向的快速膨胀，在这里自然也可以保证存在声波层位，尽管通常来说，该层位不是静态的。使用超相对论量子分子动力学（UrQMD）仿真表明，在某些条件下，靠近声波层的等离子体纵向速度在系统演化过程中可能会在短时间内变得与时间无关。在此期间，我们可以得到一个共形静态声学度量，其（共形）Killing地平线与视在地平线一致。然后，一个渐近观察者将看到来自地平线的声子热通量，该声子构成了霍金辐射。对于此处考虑的相对较低的能量碰撞，在最终的QCD系统受非相对论流体动力学控制的情况下，我们估计霍金温度约为4-5 MeV（QCD流体的温度约为135 MeV）。我们从热学的角度讨论了这种霍金辐射的实验特征分量与检测颗粒的横向动量分布的速度相关性。我们还将讨论扩展到超相对论情形，这将导致更高的霍金温度，以及动态视界的影响导致温度的蓝/红偏移。