空间功率谱分析是研究星际介质湍动特性的常用方法。以此方法利用GALFA HI巡天数据分析Geminga附近一块中性氢云的湍动特性，其21cm谱线积分亮温度图的空间功率谱符合幂律分布，谱指数为-4.0±0.1。与银河系内本地星际介质的功率谱(谱指数大于-3.0)相比，该云的功率谱较陡。分析陡谱的成因，排除了中性氢云在视线方向所取的速度宽度不足、云周围存在垂直于视线方向的有序磁场、能量传递过程中有损失等因素的影响。这个结果暗示Geminga周围可能存在一个区域，其内部湍动特性与银河系其他区域的湍动特性不同，进而导致了Geminga TeV晕中较低的扩散系数。
程皓麟
,
朱辉
,
陈天禄
,
田文武
,
崔晓红
,
吴丹
,
高启
. Geminga TeV晕周围星际介质的湍动特性[J]. 中国科学院大学学报, 2024
, 41(3)
: 306
-311
.
DOI: 10.7523/j.ucas.2022.076
Space power spectrum analysis is a common method to study the turbulence property of interstellar medium. In this paper, we applied this method to analyze a neutral hydrogen cloud near Geminga with data from the GALFA (galactic Arecibo L-band feed array) HI survey. The spatial power spectrum of the cloud can be well described by a power-law with an index of -4.0±0.1 which is steeper than the turbulent power spectrum of local galactic interstellar medium (the spectral index is larger than -3.0). We considered several physical conditions that may lead to the steeper spectrum and found none of the thin HI slice along the line of sight direction, highly ordered magnetic field perpendicular to line of sight direction or energy loss during the energy cascade be responsible for the steeper spectrum. This indicates that the turbulence property around Geminga is very different to the local galactic interstellar medium which may account for the abnormally low diffusion coefficient in Gemninga TeV halo.
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