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毫秒脉冲器PSR 1937+21:一个高度稳定的时钟
概括
脉冲星PSR 1937+21表现出显著的频率稳定性,与原子钟相美. 这项研究为宇宙引力辐射能量密度提供了新的上限.
科学领域:
- 天文学 天文学
- 天体物理学 天体物理学
- 脉冲星天文学 脉冲星天文学
背景情况:
- 脉冲星,就像PSR 1937+21一样,表现出稳定的旋转和尖的无线电脉冲.
- 这些特性使得脉冲星可以作为高度精确的宇宙时钟发挥作用.
- 原子钟代表了长期频率稳定的当前标准.
研究的目的:
- 为了评估脉冲星PSR 1937+21的长期频率稳定性.
- 将脉冲星的稳定性与最先进的原子钟进行比较.
- 为了确定一个宇宙背景引力辐射的能量密度的上限.
主要方法:
- 使用阿雷西博射电望远镜精确测量脉冲到达时间.
- 采用先进的测量技术,实现大约300纳秒的不确定性,相对于原子时间.
- 自1982年11月以来,每两周进行一次测量,以分析长期稳定趋势.
主要成果:
- 在超过4个月的平均时间内,PSR 1937+21的分数频率稳定性至少为6×10{-14).
- 测量精度似乎受到参考原子钟在长时间间隔上的稳定性所限制.
- 对于每年0.23个周期的重力辐射的能量密度,确定了7 x 10(-36) g/cm3的固定的上限.
结论:
- 脉冲星PSR 1937+21作为一个高度稳定的时钟,可能超过原子钟.
- 这项研究为宇宙引力辐射的密度提供了关键的限制.
- 引力辐射的导出极限大约是关闭宇宙所需的密度的4 x 10(-7).
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