论文标题
关于“超大”中子星的形成以及向自发标量的动态过渡
On the formation of "supermassive" neutron stars and dynamical transition to spontaneous scalarization
论文作者
论文摘要
众所周知，中子星可以在特定类别的标量张量理论（STT）下进行相变，其中新的顺序参数{\ it标量电荷}出现在恒星中。这是Damour和Esposito-Farèse于1993年发现的自发标量（SC）的众所周知的现象。在这种机制下，对于给定状态的总体相对论（GR）的最大质量（GR）可以负担得起，而对于给定的状态方程式，而无需考虑额外的观察性约束（例如，Binary Systems）。这打开了可能形成中子恒星的可能性，而无需刚需要刚性或更外国的状态方程来形成质量，而$ \ sim 2 m_ \ odot $。因此，STT至SC可能会解释紧凑的物体，最近在天空中观察到的大量物体以脉冲星的形式（PSR J0348+0432，$ M = 2.01 M = 2.01 M = PM 0.04 \ PM 0.04 \ odot $ \ odot $ \ odot $在2013年，PSR J1614-2230，$ M = 1.97 \ pm 0.04 m _ $ $ \ osot in+mm = 1.04 m = 1.04 m = 66或odot。 2.14^{+0.10} _ { - 0.09} m_ \ odot $在2019年观察到）。但是，我们认为，即使这是可能的，STT内的最大质量模型也不能仅仅是由初始“隔离”未量化的中子星的动态过渡形成的，其质量不能超过GR中的最大质量。这是因为SC作为一种充满活力的构型，会产生一个最终的静态恒星，其质量低于具有固定baryon质量的初始恒星。初始配置和最终配置之间的质量差异以标量场的形式辐射出来。因此，如果存在于自然界中，则标量中子星的最大质量模型必须由不同的过程，也许是宇宙学起源或随后的额外标量电荷和质量形成。
It is well known that neutron stars can undergo a phase transition under a certain class of Scalar Tensor Theories of gravity (STT's) where a new order parameter, the {\it scalar charge}, appears within the star. This is the well known phenomenon of spontaneous scalarization (SC) discovered by Damour and Esposito-Farèse in 1993. Under such mechanism neutron stars can afford in principle a maximum mass larger than in general relativity (GR) for a given equation of state without taking into account additional observational constraints (e.g. binary systems). This opens the possibility that neutron stars might be formed with masses as large as $\sim 2 M_\odot$ without the need of stiff, or more exotic, equations of state for the nuclear matter. Thus, STT's through SC may account for compact objects with large masses observed recently in the sky in the form of pulsars (PSR J0348+0432 with $M= 2.01 M_\pm 0.04\odot$ observed in 2013, PSR J1614-2230 with $M= 1.97\pm 0.04 M_\odot$ observed in 2010 or J0740+6620 $M= 2.14^{+0.10}_{-0.09} M_\odot$ observed in 2019). However, we argue that even if that was possible such maximum mass models within STT cannot be formed solely from the dynamic transition of an initial "isolated" unscalarized neutron star whose mass cannot exceed the maximum mass in GR. This is because SC, being an energetic-preferred configuration, produces a final static star with a mass lower that the initial one with a fixed baryon mass. The mass difference between the initial and final configurations is radiated away in the form of a scalar-field. Thus, maximum mass models of scalarized neutron stars, if present in nature, must have formed by a different process, perhaps of cosmological origin or by the subsequent accretion of additional scalar charge and mass.
