Upper Limit on the QCD Axion Mass from Isolated Neutron Star Cooling
Upper Limit on the QCD Axion Mass from Isolated Neutron Star Cooling
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DOI：
10.1103/physrevlett.128.091102
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发表时间：
2022-03-01
影响因子：
8.6
通讯作者：
Safdi, Benjamin R.
中科院分区：
文献类型：
--
作者：
Buschmann, Malte;Dessert, Christopher;Safdi, Benjamin R.
量子色动力学(QCD)轴子可以改变中子星(NSS)的冷却速率。轴子是在NS核内由核子韧致辐射产生的，当核子处于超流状态时，库珀对破裂和形成过程。我们表明，附近孤立的壮丽的七个NSS中的四个以及PSR J0659是轴子冷却研究的主要候选者，因为它们是同时代的，从运动学角度已知其年龄为数十万年，并且它们具有很好的测量表面亮度。我们将这些数据与包含轴子的专用NS冷却模拟进行比较，分析与状态方程、NS质量、表面组成和超流性相关的不确定性。我们对轴子和中微子发射率的计算包括高密度抑制因子，这些因子也影响SN1987A和以前的NS对轴子的冷却极限。我们在孤立的NS数据中没有发现轴子的证据，在Kim-Shifman-VainshteinZakharov QCD轴子模型的背景下，我们在95%的置信度水平下约束m(A)小于或类似于16 meV。对NS冷却和核子超流的进一步了解可能会进一步改善这些极限，或者导致在较弱耦合处发现轴子。
The quantum chromodynamics (QCD) axion may modify the cooling rates of neutron stars (NSs). The axions are produced within the NS cores from nucleon bremsstrahlung and, when the nucleons are in superfluid states, Cooper pair breaking and formation processes. We show that four of the nearby isolated magnificent seven NSs along with PSR J0659 are prime candidates for axion cooling studies because they are coeval, with ages of a few hundred thousand years known from kinematic considerations, and they have well-measured surface luminosities. We compare these data to dedicated NS cooling simulations incorporating axions, profiling over uncertainties related to the equation of state, NS masses, surface compositions, and superfluidity. Our calculations of the axion and neutrino emissivities include high density suppression factors that also affect SN 1987A and previous NS cooling limits on axions. We find no evidence for axions in the isolated NS data, and within the context of the Kim-Shifman-VainshteinZakharov QCD axion model, we constrain m(a) less than or similar to 16 meV at 95% confidence level. An improved understanding of NS cooling and nucleon superfluidity could further improve these limits or lead to the discovery of the axion at weaker couplings.