用反转和转动线约束质子-电子质量比的变化
Constraining changes in the proton-electron mass ratio with inversion and rotational lines
摘要：
本文报道了从$z \sim 0.685$吸收体到B 0218 +357的$_3$ ~（1，1），CS 1-0和$_2$-CO~0 $_{\rm 00}$-1 $_{\rm 01}$谱线的深绿岸望远镜（GBT）光谱。反转（NH $_3$）和旋转（CS，H $_2$ CO）线频率对质子-电子质量比$μ$有不同的依赖关系，这意味着线红移之间的比较对$μ$的变化很敏感。一个联合的3-分量适合NH $_3$，CS，和H $_2$ CO线产生$[Δμ/μ] = (-3.5 \pm 1.2) \times 10^{-7}$，从$z \sim 0.685$到今天，其中的错误包括系统的影响，从不同的物种和可能的频率依赖源形态比较线。由于含氮和含碳物种之间的源形态和速度偏移的时间变化，系统误差的两个额外的来源仍然存在。我们没有发现$μ$变化的显著性（$\ge 3 σ$）证据，并获得了严格的$3σ$约束，$[Δμ/μ] < 3.6 \times 10^{-7}$，超过6.2 Gyrs;这是目前最好的限制，从任何技术，并为任何回顾时间，由一个因子$\gtrsim 5$的$μ$的时间变化。
英文摘要：
We report deep Green Bank Telescope (GBT) spectroscopy in the redshifted NH$_3$~(1,1), CS~1-0 and H$_2$CO~0$_{\rm 00}$-1$_{\rm 01}$ lines from the $z \sim 0.685$ absorber towards B0218+357. The inversion (NH$_3$) and rotational (CS, H$_2$CO) line frequencies have different dependences on the proton-electron mass ratio $μ$, implying that a comparison between the line redshifts is sensitive to changes in $μ$. A joint 3-component fit to the NH$_3$, CS, and H$_2$CO lines yields $[Δμ/μ] = (-3.5 \pm 1.2) \times 10^{-7}$, from $z \sim 0.685$ to today, where the error includes systematic effects from comparing lines from different species and possible frequency-dependent source morphology. Two additional sources of systematic error remain, due to time variability in the source morphology and velocity offsets between nitrogen-bearing and carbon-bearing species. We find no statistically-significant ($\ge 3 σ$) evidence for changes in $μ$, and obtain the stringent $3σ$ constraint, $[Δμ/μ] < 3.6 \times 10^{-7}$, over 6.2~Gyrs; this is the best present limit on temporal changes in $μ$ from any technique, and for any lookback time, by a factor $\gtrsim 5$.
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