We demonstrate that future radius measurement of the NICER mission have the potential to reveal the existence of a strong phase transition in dense neutron star matter by confirming the existence of so called twin stars, compact star configurations with the same mass but different radii. The latest radius constraints from NICER for the pulsars J0740+6620 as well as J0030+0451 are discussed using relativistic mean field equations of state with varying stiffness, connected with a first order phase transition to quark matter. We show, that twin star solutions are compatible with the new radius constraint but are located at radii \emph{below} the present constraints from NICER serving as a smoking gun for a strong phase transition in neutron star matter. This scenario is realized if a strong phase transition takes place in neutron stars of the first branch with masses above $2\,M_\odot$.
Twin stars and the stiffness of the nuclear equation of state: ruling out strong phase transitions below $1.7n_0$ with the new NICER radius measurements
Bayesian Inference of Dense-Matter Equations of State from Small-Radius Compact Stars with Twin-Star Scenarios
School of Physics, Nankai University（南开大学物理学院）；Shenzhen Research Institute of Nankai University（南开大学深圳研究院）；Department of Physics, Faculty of Science, Tianjin University（天津大学理学院物理系）
本文通过贝叶斯方法研究致密物质方程 of state，探讨小半径致密星体是否能被双星情景所容纳，通过约束参数发现相变特征及对潮汐变形性的影响。
Rapid Orbital Decay in the Ultracompact Double-degenerate Binary eRASSU J060839.5$-$704014
Inter-University Centre for Astronomy and Astrophysics（天文与天体物理大学中心）；Max-Planck-Institut für extraterrestrische Physik（马普地外物理学研究所）；Massachusetts Institute of Technology（麻省理工学院）；School of Astronomy and Space Science, Nanjing University（南京大学天文与空间科学学院）；Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education（教育部现代天文与天体物理重点实验室（南京大学））；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；School of Science, Qingdao University of Technology（青岛理工大学理学院）；Department of Physics（物理系）
