Black holes and galaxies: A closer link.A new study offers the first direct evidence direct evidence n. real, tangible, or clear evidence of a fact, happening, or thing that requires no thinking or consideration to prove its existence, as compared to circumstantial evidence. (See: circumstantial evidence, evidence) that supermassive black holes grow along with the galaxies they inhabit. Astronomers had suspected as much, but because most galaxies today are billions of years old, the notion was difficult to test. In their work, Michael R. Merrifield R(obert) Bruce Born 1921. American biochemist. He won a 1984 Nobel Prize for developing a method of synthesizing peptides and proteins from amino acids. To measure galactic age, the astronomers analyzed the color and intensity of starlight. Massive stars, for instance, live briefly and emit lots of blue light. If a galaxy isn't in the throes of starbirth yet is radiating strongly at the blue end of the spectrum, it's likely to be relatively young. Merrifield's team found that Andromeda Andromeda, in astronomyAndromeda, in astronomy, northern constellation located to the NE of Pegasus and to the S of Cassiopeia. Its brightest star, Alpheratz (Alpha Andromedae), marks the northeast corner of the Great Square in Pegasus. The constellation also contains the bright stars Mirach (Beta Andromedae) and Almach (Gamma Andromedae) and the famous Great Nebula, or Andromeda Galaxy, the only galaxy visible to the naked eye in the Northern and 22 other nearby galaxies believed to house central black holes range in age from 4 billion to 12 billion years. Moreover, the researchers determined that the lightest black holes reside in the youngest galaxies, and the heaviest ones in the oldest.Black holes apparently bulk up as they dine on stars and gas in their host galaxies. Mergers between galaxies in the young cosmos may have hastened that process by driving gas toward the core black holes, notes Abraham Loeb of Harvard University. Merrifield, Duncan A. Forbes of the University of Birmingham in England, and Alejandro I. Terlevich of Swinburne University in Hawthorn hawthorn /haw·thorn/ (haw´thorn) a shrub or tree of the genus Crataegus, or a preparation of the flowers, fruit, and leaves of certain of its species, having a mechanism of action similar to that of digitalis; used to decrease output in congestive heart failure; also used in traditional Chinese medicine, homeopathy, and folk medicine., Australia, report their study in the April 1 MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. "This new work is further evidence that the growth of the hole is related to the evolution of the galaxy," says Martin J. Rees of the University of Cambridge in England. |
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