论文标题
使用所有Chandra ACIS-S观测值对Cassiopeia a冷却中子星的中子星超流体的限制
Constraints on neutron star superfluidity from the cooling neutron star in Cassiopeia A using all Chandra ACIS-S observations
论文作者
论文摘要
分析Cassiopeia中心的Chandra观测值（NS）在ACIS探测器的子阵列（微弱）模式下采取的超新星残留物在ACIS探测器的子阵列（微弱）模式下揭示了在最新的（2020年5月）（2020年5月）的观察值之后，从2006年到2020年的源表面温度显着降低。 2000 $ - $ 2019在ACIS探测器的分级模式下获取的数据可能会受到仪器效应的强烈影响。我们使用所有ACI数据进行了关节光谱分析，以限制NS参数和冷却速率。我们将cassiopeia a ns的质量限制为$ m = 1.55 \ pm0.25〜m_ \ odot $，其半径为$ r = 13.5 \ pm 1.5 $ km。如果允许吸收氢柱密度变化，则表面温度冷却速率在10年内为$ 2.2 \ pm 0.3 $ 0.3 \ pm $ 1.6 \ pm 0.2 $ 0.2 $ 0.2 $ 0.2 $在10年内固定。观察到的冷却可以通过由于Cooper对形成（CPF）过程引起的超流体NS内部的中微子发射的增强来解释。基于对所有ACI数据的分析，我们限制了NS核心内三重态中子配对的最大临界温度，$（4-9.5）\ times 10^{8} $K。根据先前的研究，CPF中性粉发射所需的有效强度至少比现有的显微镜计算高2个。
Analysis of Chandra observations of the neutron star (NS) in the centre of the Cassiopeia A supernova remnant taken in the subarray (FAINT) mode of the ACIS detector performed by Posselt and collaborators revealed, after inclusion of the most recent (May 2020) observations, a significant decrease of the source surface temperature from 2006 to 2020. The obtained cooling rate is consistent with those obtained from analysis of the 2000$-$2019 data taken in the GRADED mode of the ACIS detector, which is potentially more strongly affected by instrumental effects. We performed a joint spectral analysis using all ACIS data to constrain the NS parameters and cooling rate. We constrain the mass of the Cassiopeia A NS at $M=1.55\pm0.25~M_\odot$, and its radius at $R=13.5\pm 1.5$ km. The surface temperature cooling rate is found to be $2.2\pm 0.3$ per cent in 10 years if the absorbing hydrogen column density is allowed to vary and $1.6\pm 0.2$ per cent in 10 years if it is fixed. The observed cooling can be explained by enhanced neutrino emission from the superfluid NS interior due to Cooper Pair Formation (CPF) process. Based on analysis of all ACIS data, we constrain the maximal critical temperature of triplet neutron pairing within the NS core at $(4-9.5)\times 10^{8}$ K. In accordance with previous studies, the required effective strength of the CPF neutrino emission is at least a factor of 2 higher than existing microscopic calculations suggest.
