NASA 美国宇航局的每日一图 3月份
发布: 2009-1-14 17:53 | 作者: webmaster | 来源: 本站原创 | 查看: 179次
2008 March 30 
影像提供: S. Colombi (IAP), CFHT Team
说明: 我们所看到的远处宇宙，和实际的景像完全一样吗？天文学家不希望是如此，否则戏就唱不下去了。 因为，介于遥远宇宙和我们之间不可见的暗物质，会让来自宇宙深处的影像变形，就像老旧的玻璃，会让源自另一边的影像变形一样。如果把远方的星系和邻近的星系做比较，看它们是否不寻常的平坦或和太相似，就可以推断出两者之间的差别，然后再反推什么样的暗物质分布，会产生这样的重力透镜变形。在分析二十万个加法夏望远镜 (CFHT)所量测的星系形状后，天文学家的确发现暗物质有呈网络状分布的倾向。而未来的观测，应该能进一步解析出暗物质的详细分布。 上面这幅计算机仿真所产生的影像，显示这种分布形态的暗物质(红色)如何扭曲来自遥远星系(蓝色)的光。
Explanation: Is the distant universe really what it appears to be? Astronomers hope not. Intervening dark matter, which is normally invisible, might show its presence by distorting images originating in the distant universe, much the way an old window distorts images originating on the other side. By noting the degree to which background galaxies appear unusually flat and unusually similar to neighbors, the dark matter distribution producing these weak gravitational lensing distortions can be estimated. Analysis of the shapes of 200,000 distant galaxies imaged with the Canada-France-Hawaii Telescope (CFHT) does indicate the presence of a massive network of distributed dark matter. Futureresults may even be able to discern details of the distribution. The above computer generated simulation image shows how dark matter, shown in red, distorts the light path from and apparent shape of distant galaxies, depicted in blue.
Explanation: Is the distant universe really what it appears to be? Astronomers hope not. Intervening dark matter, which is normally invisible, might show its presence by distorting images originating in the distant universe, much the way an old window distorts images originating on the other side. By noting the degree to which background galaxies appear unusually flat and unusually similar to neighbors, the dark matter distribution producing these weak gravitational lensing distortions can be estimated. Analysis of the shapes of 200,000 distant galaxies imaged with the Canada-France-Hawaii Telescope (CFHT) does indicate the presence of a massive network of distributed dark matter. Futureresults may even be able to discern details of the distribution. The above computer generated simulation image shows how dark matter, shown in red, distorts the light path from and apparent shape of distant galaxies, depicted in blue.
