Jan 8 2002
From The Space Library
Using images from NASA’s Chandra X-ray Observatory, scientists found evidence that an ancient eruption had burst through a cluster of galaxies, which could explain why those galaxies act like massive magnetic fields. Scientists believed that the universe’s largest known structures bounded by gravity~called galaxy clusters~might be the source of highly energetic and recurring explosions, which cause the clusters to behave like huge cosmic magnets. Chandra’s images of the galaxy cluster Abell 2597 had revealed a cloud of hot gas with two dark circular cavities called ghost cavities, containing little x-ray or radio emissions. The images suggested that powerful explosions around a black hole in the cluster’s center might have occurred when these ghost cavities expelled material from the black hole’s vicinity, creating gaps in the cluster’s hot gas. Scientists believed that these cavities might eventually move to the edge of the cluster, similar to the movement of air bubbles to the surface of water, thereby transporting magnetic fields to the cluster gas. The images suggested that these explosions are recurring. If the recurring explosions continue to create more cavities, this could explain the strong magnetic field of the extremely hot gas throughout the cluster. (NASA, “Chandra Finds Ghosts of Eruption in Galaxy Cluster,” news release 02-02, 8 January 2002.)
Using the most sensitive images ever taken by the HST, scientists found new evidence of star creation, challenging the findings of much of the existing research on the origin of the universe. Although the HST had captured images of portions of the skies that appear empty to the naked eye, the images revealed nearly 5,000 galaxies. Led by Kenneth M. Lanzetta of the State University of New York at Stony Brook, a team of scientists had examined approximately 150 of those galaxies spectroscopically, inferring from color variations their actual distance from Earth, as well as the properties of less visible light from even fainter and more distant galaxies. The scientists had also conducted spectroscopic analysis of remote quasars to measure the early universe’s gas density, because high gas density implies high creation rates of stars, which are the building blocks of galaxies and the birthplaces of solar systems. The new images indicated that countless stars had begun forming at a period closer to the birth of the universe than previous research had suggested. Although the HST had captured the images in 1995 and 1998, using the most advanced available technology, the findings suggested that the peak of star creation had occurred earlier than Hubble’s ability to detect it. However, the scientists believed that they could date the peak of star creation to within a few hundred million years after the Big Bang. (NASA, “Hubble Suggests First Stars Opened in a Blaze of Glory,” news release 02-01, 8 January 2002; William Harwood, “Stars May Have Brightened Infant Universe,” Washington Post, 9 January 2002.)
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