The Galactic Center Excess (GCE) is an extended gamma-ray source in the central region of the Galaxy found in Fermi Large Area Telescope (Fermi-LAT) data. One of the leading explanations for the GCE is an unresolved population of millisecond pulsars (MSPs) in the Galactic bulge. Due to differing star formation histories it is expected that the MSPs in the Galactic bulge are older and therefore dimmer than those in the Galactic disk. Additionally, correlations between the spectral parameters of the MSPs and the spin-down rate of the corresponding neutron stars have been observed. This implies that the bulge MSPs may be spectrally different from the disk MSPs. We perform detailed modelling of the MSPs from formation until observation. Although we confirm the correlations, we do not find they are sufficiently large to significantly differentiate the spectra of the bulge MSPs and disk MSPs when the uncertainties are accounted for. Our results demonstrate that the population of MSPs that can explain the gamma-ray signal from the resolved MSPs in the Galactic disk and the unresolved MSPs in the boxy bulge and nuclear bulge can consistently be described as arising from a common evolutionary trajectory for some subset of astrophysical sources common to all these different environments. We do not require that there is anything unusual about inner Galaxy MSPs to explain the GCE. Additionally, we use a more accurate geometry for the distribution of bulge MSPs and incorporate dispersion measure estimates of the MSPs' distances. We find that the elongated boxy bulge morphology means that some the bulge MSPs are closer to us and so easier to resolve. We identify three resolved MSPs that have significant probabilities of belonging to the bulge population.

中文翻译：

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比较星系隆起和星系盘毫秒脉冲星

银河中心过剩 (GCE) 是费米大面积望远镜 (Fermi-LAT) 数据中发现的银河中心区域的扩展伽马射线源。对 GCE 的主要解释之一是银河隆起中未解决的毫秒脉冲星 (MSP) 群。由于不同的恒星形成历史，预计银河凸起中的 MSP 比银河盘中的 MSP 更老，因此更暗。此外，还观察到 MSP 的光谱参数与相应中子星的自旋下降率之间的相关性。这意味着凸起的 MSP 可能与磁盘 MSP 在光谱上不同。我们对 MSP 从形成到观察进行详细建模。虽然我们确认了相关性，当考虑到不确定性时，我们没有发现它们足够大以显着区分凸起 MSP 和磁盘 MSP 的光谱。我们的结果表明，可以解释来自银盘中已解析 MSP 和未解析 MSP 中的伽马射线信号的 MSP 群体可以一致地描述为来自某些子集的共同进化轨迹。所有这些不同环境共有的天体物理来源。我们不要求内部星系 MSP 有任何异常来解释 GCE。此外，我们使用更精确的几何形状来计算凸出 MSP 的分布，并结合对 MSP 距离的离散度量估计。我们发现拉长的四四方方的凸起形态意味着一些凸起的 MSP 离我们更近，因此更容易解析。我们确定了三个已解决的 MSP，它们很有可能属于膨胀种群。