Power spectrum of HI intensity fluctuations in DDO 210
Power spectrum of HI intensity fluctuations in DDO 210
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DDO 210 中 HI 强度波动的功率谱
DOI：
10.1111/j.1745-3933.2006.00220.x
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发表时间：
2006
影响因子：
--
通讯作者：
Jay Bharadwaj
中科院分区：
文献类型：
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作者：
A. Begum;Jay Bharadwaj
我们使用一个非常适合于极低信噪比的基于概率的估计器测量了极暗（M B ~-10.9）矮星系DDO 210中H i强度起伏的功率谱。DDO 210的H i功率谱符合幂律P HI（U）=A U α，在80 pc到500 pc的长度尺度上α=−2.75 ± 0.45。我们还发现，功率谱不随速度通道宽度的增加而改变，这表明所测量的波动主要对应于密度波动。然而，Kolmogorov湍流（速度结构函数谱斜率为1/2）不能从目前的观测中排除。斜率α的值与在银河系中获得的值相似。与银河系相比，DDO 210的H i低三个数量级，没有旋臂，也没有可测量的持续星星形成。然而，这两个星系的功率谱斜率相似（也与LMC和SMC的测量值相似）的事实表明，存在一些普遍的，独立于恒星形成的现象，负责在气体中产生精细尺度结构。
We measure the power spectrum of H i intensity fluctuations in the extremely faint (M B ~−10.9) dwarf galaxy DDO 210 using a visibility-based estimator that is well suited to very low signal-to-noise ratio regimes. DDO 210's H i power spectrum is well fitted by a power law P HI (U) =A U α , with α=−2.75 ± 0.45 over the length-scales 80 pc to 500 pc. We also find that the power spectrum does not change with an increase in the velocity channel width, indicating that the measured fluctuations correspond mainly to density fluctuations. However, Kolmogorov turbulence (with a velocity structure function spectral slope of ⅔) cannot be ruled out from the present observations. The value of the slope α is similar to that obtained in the Milky Way. Compared with the Milky Way, DDO 210 has three orders of magnitude less H i, no spiral arms, and also no measurable ongoing star formation. The fact that the power spectrum slope is nonetheless similar in these two galaxies (and also similar to the values measured for the LMC and SMC) suggests that there is some universal, star-formation-independent phenomenon responsible for producing fine scale structure in the gas.