局部虚空的远界在扩张吗？
Is the far border of the Local Void expanding?
摘要：
根据等级结构形成情景中的演化模型，星系的空洞预计会扩大。局部空洞（LV）是最近的大空洞，它提供了一个独特的机会来测试观测这样的膨胀。已经发现，在LV边界上的本星系群正在以约260 km/s的速度远离空洞中心。在这项研究中，我们调查的运动的星系在远侧边界的LV检查存在一个可能的膨胀。我们选取了径向速度在3000 ~ 5000 km/s的晚型、边向旋涡星系，进行了HI 21 cm线和H波段成像观测。近红外Tully-Fisher关系是用大量星系样本校准的，并仔细校正了Malmquist偏差。它被用来计算LV样本星系的距离和奇异速度。为了避免Malmquist偏差的影响，在36个具有高质量HI线宽测量的样品LV星系中，只选择了15个星系测量它们的距离和特有速度。这15个星系的平均奇特速度为-419+208-251 km/s，与零相差不大。由于Tully-Fisher关系固有的大散射，我们不能断定是否有一个系统的运动对LV中心的星系在远侧边界的空隙。然而，我们的结果是一致的假设，这些星系在远侧边界有一个平均速度约260公里/秒相当于什么是在本星系群的位置。
英文摘要：
According to models of evolution in the hierarchical structure formation scenarios, voids of galaxies are expected to expand. The Local Void (LV) is the closest large void, and it provides a unique opportunity to test observationally such an expansion. It has been found that the Local Group, which is on the border of the LV, is running away from the void center at ~260 km/s. In this study we investigate the motion of the galaxies at the far-side border of the LV to examine the presence of a possible expansion. We selected late-type, edge-on spiral galaxies with radial velocities between 3000 km/s and 5000 km/s, and carried out HI 21 cm line and H-band imaging observations. The near-infrared Tully-Fisher relation was calibrated with a large sample of galaxies and carefully corrected for Malmquist bias. It was used to compute the distances and the peculiar velocities of the LV sample galaxies. Among the 36 sample LV galaxies with good quality HI line width measurements, only 15 galaxies were selected for measuring their distances and peculiar velocities, in order to avoid the effect of Malmquist bias. The average peculiar velocity of these 15 galaxies is found to be -419+208-251 km/s, which is not significantly different from zero. Due to the intrinsically large scatter of Tully-Fisher relation, we cannot conclude whether there is a systematic motion against the center of the LV for the galaxies at the far-side boundary of the void. However, our result is consistent with the hypothesis that those galaxies at the far-side boundary have an average velocity of ~260 km/s equivalent to what is found at the position of the Local Group.
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