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首页> 外文期刊>The Astrophysical journal >INTERSTELLAR SCINTILLATION OBSERVATIONS OF 146 EXTRAGALACTIC RADIO SOURCES
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INTERSTELLAR SCINTILLATION OBSERVATIONS OF 146 EXTRAGALACTIC RADIO SOURCES

机译：146个星系外无线电源的星际闪烁观测

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摘要

From 1979 to 1996 the Green Bank Interferometer was used by the Naval Research Laboratory to monitor the flux density from 146 compact radio sources at frequencies near 2 and 8 GHz. We filter the "light curves" to separate intrinsic variations on times of a year or more from more rapid interstellar scintillation (ISS) on times of 5-50 days. Whereas the intrinsic variation at 2 GHz is similar to that at 8 GHz (although diminished in amplitude), the ISS variation is much stronger at 2 than at 8 GHz. We characterize the ISS variation by an rms amplitude and a timescale and examine the statistics of these parameters for the 121 sources with significant ISS at 2 GHz. We model the scintillations using the NE2001 Galactic electron model assuming the sources are brightness-limited. We find the observed rms amplitude to be in general agreement with the model, provided that the compact components of the sources have about 50% of their flux density in a component with maximum brightness temperatures 10~(11)-10~(12) K. Thus, our results are consistent with centimeter-wavelength VLBI studies of compact active galactic nuclei, in that the maximum brightness temperatures found are consistent with the inverse synchrotron limit at 3 x 10~(11) K, boosted in jet configurations by Doppler factors up to about 20. The average of the observed 2 GHz ISS timescales is in reasonable agreement with the model at Galactic latitudes above about 10°. At lower latitudes the observed time-scales are too fast, suggesting that the transverse velocity increases beyond about 1 kpc, which may be due to differential Galactic rotation.
机译：从1979年到1996年，海军研究实验室使用Green Bank干涉仪监测146个紧凑型无线电源在2 GHz和8 GHz附近的通量密度。我们过滤“光曲线”以将一年或更长时间内的固有变化与5-50天时间内更快速的星际闪烁（ISS）分开。尽管2 GHz的固有变化与8 GHz的变化相似（尽管幅度减小了），但ISS的变化在2时要比8 GHz的强得多。我们用均方根幅度和时标来表征ISS的变化，并检查2 GHz下具有ISS的121个源的这些参数的统计数据。我们使用NE2001银河电子模型对闪烁进行建模，假设光源是亮度受限的。我们发现观测到的均方根振幅与模型基本一致，条件是光源的紧凑组件在最大亮度温度为10〜（11）-10〜（12）K的组件中具有其通量密度的约50％。因此，我们的结果与紧凑型活动银河核的厘米波长VLBI研究一致，因为发现的最大亮度温度与多普勒因子在射流结构中提高的逆同步加速器极限3 x 10〜（11）K一致。高达约20。在20.0以上的银河纬度上，观测到的2 GHz ISS时标的平均值与该模型合理吻合。在较低的纬度上，观测到的时间尺度太快，表明横向速度增加超过了大约1 kpc，这可能是由于银河旋转不同所致。

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