The Galactic center radio source shines below the Compton limit
The Galactic center radio source shines below the Compton limit
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银河中心射电源的亮度低于康普顿极限
DOI：
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发表时间：
1991
期刊：
影响因子：
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通讯作者：
L. Ozernoy
中科院分区：
文献类型：
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作者：
C. Gwinn;R. M. Danen;T. K. Tran;J. Middleditch;L. Ozernoy
银河中心射电源 Sgr A* 在 1.3 和 0.8 毫米波长处不存在折射闪烁，导致该源的亮温观测极限低于 0.5 {乘} 10{sup 12} K。这低于非相干同步加速器发射等离子体的最大亮度 10 exp 12 K，称为康普顿极限。赵等人观察到了预期的折射闪烁，这是由于星际等离子体对源的强烈展宽所致。在分米波长。事实证明，在 1.3 和 0.8 毫米波长下在 0.1 秒到 24 小时之间的时间跨度内观察它们是不可能的。这种闪烁会被源尺寸大于约 0.1 AU 的猝灭，或者等效地，对于 Sgr A{星号}，在 0.8 mm 波长处小于 0.5 {乘} 10 {sup 12} K。闪烁还需要散射等离子体中尺度尺寸为 0.1 AU 的波动，以高于约 100 km/s 的速度穿过视线。散射 Sgr A{星号} 的等离子体满足后两个条件，并且由于源的尺寸而没有闪烁。这一观测结果加强了人马座A{星号}作为静止星系核的认定。 35 参考文献
Absence of refractive scintillation of Sgr A*, the Galactic center radio source, at 1.3 and 0.8 mm wavelengths places an observational limit of brightness temperature of below 0.5 {times} 10{sup 12} K on the source. This is less than the maximum brightness of an incoherently synchrotron-emitting plasma, 10 exp 12 K, known as the Compton limit. The refractive scintillations expected, due to strong broadening of the source by the interstellar plasma, are observed by Zhao et al. at decimeter wavelengths. It has proven to be impossible to observe them at 1.3 and 0.8 mm wavelengths over time spans between 0.1 s and 24 hr. Such scintillations are quenched by source size greater than about 0.1 AU, or, equivalently, less than 0.5 {times} 10{sup 12} K for Sgr A{asterisk}, at 0.8 mm wavelength. The scintilations would also require fluctuations with scale sizes of 0.1 AU in the scattering plasma, moving across the line of sight at velocities above about 100 km/s. The plasma that scatters Sgr A{asterisk} satisfies the latter two conditions, and the absence of scintillations is due to the size of the source. This observation strengthens the identification of Sgr A{asterisk} as a quiescent galactic nucleus. 35 refs.