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界的圣杯。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，因为它无法在地球上的任何实验室中复制。宇宙中唯一能找到这种物质的地方是中子星的核心。一颗垂死的大质量恒星的爆炸，被称为超新星，留下了一颗中子星，一颗与太阳质量相当的致密天体，被压缩成一个20公里的球体。通过精确测量中子星的半径和质量，我们在理解超致密物质的行为方面取得了巨大进展。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，并以约5%的精度获得半径测量值。拥有大量精确测量半径的中子星观测样本，将有助于了解中子星内部的物质，并将解决目前关于超致密物质的众多理论之间的冲突。

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.