charles 2009-3-23 10:44
重力透鏡與類星體
A Five Quasar Gravitational Lens
[img]http://i1.tinypic.com/2d7yo39.jpg[/img]
影像提供: K. Sharon (Tel Aviv U.) and E. Ofek (Caltech), ESA, NASA
[color=navy]Explanation:[/color]
What's happening near the center of this cluster of galaxies? At first glance, it appears that several strangely elongated galaxies and fully five bright quasars exist there. In reality, an entire cluster of galaxies is acting as a gigantic gravitational lens that distorts and multiply-images bright objects that occur far in the distance. The five bright white points near the cluster center are actually images of a single distant quasar. This Hubble Space Telescope image is so detailed that even the host galaxy surrounding the quasar is visible. Close inspection of the above image will reveal that the arced galaxies at 2 and 4 o'clock are actually gravitationally lensed images of the same galaxy. A third image of that galaxy can be found at about 10 o'clock from the cluster center. Serendipitously, numerous strange and distant galaxies dot the above image like colorful jewels. The cluster of galaxy that acts as the huge gravitational lens is cataloged as SDSS J1004+4112 and lies about 7 billion light years distant toward the constellation of Leo Minor.
[color=navy]說明:[/color]
這個星系團的中心到底發生了什麼事？乍看之下，那裡有數個被扯長的星系和五個完整的明亮類星體。實情是，整個星系團的行為就像是一個巨大的重力透鏡，把更遙遠明亮天體會聚成數個曲的影像。這五個位在星系團中心的類星體，其實是單一個遙遠類星體的影像。這幅哈伯太空望遠鏡極為清晰，連類星體的寄主星系都看得見。仔細檢視上面這幅影像，就會發現位在二、四點鐘方向的星系是同一個星系的重力透鏡影像，這個星的第三個影像出現在十點鐘的方向。上面影像中像多彩珠寶的眾多奇特遙遠星系，則是另一項意外的收穫。這個行為像巨大重力透鏡的星系團編號是SDSS J1004+4112，它位在北天的小獅座內，離我們約有七十億光年遠。
[size=2]資料來源: Scientific American
Department of Physics, NCKU[/size]