High-precision neutron star radius measurements of quiescent low-mass X-ray binaries in globular clusters: Constraints to the ultra-dense matter equation of state

理解宇宙中密度最大的物质的行为是核物理学的圣杯。当物质被压缩到比原子核更大的密度时，没有人能测试它的行为，因为它不能在地球上的任何实验室复制。宇宙中唯一发现这种物质的地方是中子星的核心。一颗被称为超新星的濒临死亡的大质量恒星爆炸后，会留下一颗中子星，这是一颗质量与太阳相当的致密天体，被压缩成一个20公里长的球体。通过精确测量中子星的半径和质量，我们在理解超稠密物质的行为方面取得了很大进展。我们建议观测静止的低质量X射线双星，即已知拥有中子星的天体，并以大约5%的精度获得半径测量。拥有大量精确测量半径的观测中子星样本，将有助于揭示中子星内部的物质，并将解决众多提出的关于超稠密物质的理论之间的现有冲突。

Understanding the behavior of the densest matter of the Universe is a Holy Grail of nuclear physics. When matter is compressed to densities greater than that of an atomic nucleus, no one can test how it behaves because it cannot be reproduced in any laboratory on Earth. The only place in the Universe to find this type of matter is in the core of neutron stars. The explosion of a dying massive star, called supernova, leaves behind a neutron star, a compact object with the mass of our Sun, compressed into a 20-km sphere. We are making great progress toward understanding the behavior of ultra-dense matter by precisely measuring neutron star radii and masses. We propose to observe quiescent low-mass X-ray binaries, objects that are known to host a neutron star, and to obtain radius measurements with about 5% accuracy. Having a large sample of observed neutron stars with precisely measured radii will shed light on the matter inside neutron stars and will solve an existing conflict between the numerous proposed theories about ultra-dense matter.