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  3. (1)Scientists say Chandra provides first evidence that two mysteries can coexist in one galaxy. (2)In a very bright galaxy 4

(1)Scientists say Chandra provides first evidence that two mysteries can coexist in one galaxy. (2)In a very bright galaxy 4

admin2021-08-05  62
问题     (1)Scientists say Chandra provides first evidence that two mysteries can coexist in one galaxy.
    (2)In a very bright galaxy 400 million light-years away, two black holes are drifting toward each other and in millions of years will merge with an eruption of energy and a burst of gravitational waves that could warp the very fabric of space, astronomers said Tuesday.
    (3)The Scientists said the Chandra X-ray Observatory has found the first evidence that two immense black holes can coexist in the same galaxy and mat they are moving toward each other for an eventual merger.
    (4)The double black holes were found in a bright, highly active galaxy known as NGC6240, about 400 million light-years from the Earth.
    (5)Astronomers studied NGC6240 because it produced unexplained bursts of X-rays that appeared to come from one of two nuclei at the galactic center. Images collected by radio, infrared and optical observations showed two bright spots, but did not pinpoint the origin of the X-rays.
    (6)When Chandra, with its sensitive X-ray detectors, focused on the nuclei, astronomers hoped it would tell them whether either of the two points of activity were black holes.
    (7)"Much to our surprise, we found that both were active black holes," Stefanie Komossa of the Max Planck Institute in Germany, said in a statement.
    (8)"Finding two black holes in one galaxy," said Komossa, "supports the idea that black holes can grow to enormous masses in the centers of galaxies by merging with other black holes."
    (9)An artist’s conception shows two black holes whirling around each other at the center of a galaxy.
    (10)Guenther Hasinger, also of Max Planck, said the Chandra images captured the unmistakable markings of two black holes—high-energy photons swirling around the dense black hole centers and X-rays spewing out from iron atoms being pulled into the center at a high rate of speed.
    (11)Komossa and Hasinger are co-authors of a study submitted for publication in the Astrophysical Journal Letters.
    (12)The two black holes in NGC6240 are now about 3,000 light-years apart and are expected to merge some time in the next few hundred million years, the researchers said. The merger will be accompanied by an eruption of radiation and a burst of gravitational waves that will spread throughout the universe, causing ripples in me fabric of space, the astronomers said.
    (13)The gravitational ripples could cause minute changes in the distance between any two points in the universe, they said.
    (14)In another study, French and Argentine astronomers said that observations by the Hubble Space Telescope and ground-based telescopes have detected a stellar black hole streaking across the Milky Way at about 250,000 miles an hour. A companion star is being dragged along and slowly devoured by the black hole, according to scientists at the French Atomic Energy Commission and me Institute for Astronomy and Space Physics in Argentina.
    (15)The astronomers said the stellar black hole may have been created by an exploding star in the inner disk of the Milky Way. The black hole is 6,000 to 9,000 light years away, me researchers said. A report on the observations appears Tuesday in me journal Astronomy and Astrophysics.
    (16)A black hole is a point in space that is so dense with matter mat its gravitational field will not let anything—not even light—escape. Stellar black holes, equal to 3.5 to about 15 solar masses, can be formed by the collapse of a single massive star. But galactic black holes, such as those in NGC6240, are much larger, equal perhaps to millions of solar masses, and are usually at the center of galaxies. The Milky Way, home galaxy of the sun and its planets, is thought to have a black hole at its center. With its immense gravitational pull, a black hole can suck in gas, dust and other matter from the surrounding space. Entire stars can be stripped and pulled into the bottomless maw. As it spirals in at near light speeds, matter captured by a black hole heats by millions of degrees and gives out intense radiation in several parts of me spectrum, including X-rays. The orbiting Chandra observatory is able to detect these X-rays and relay the data to Earth for study by astronomers.
Which of the following is NOT true, according to the passage?
选项 A、Nothing can escape the gravitational field of a black hole.
B、X-rays from black holes can be detected and studied.
C、Intense radiation is found to be coming out of black holes.
D、Black holes are usually found at the center of galaxies.
答案D
解析 最后一段提到，galactic black holes通常处于星系的中心，而D偷换概念，用black holes代替了galactic black holes，故D为答案。A与末段首句相符；B、C与末段最后两句相符，均应排除。
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