The Ralph B. Baldwin Professorship in Astronomy Inaugural Lecture

May 1, 2008 - 4:00 pm

"Extragalactic Superluminal Radio Jets" Given By Hugh Aller, Professor of Astronomy Will be held TOMORROW, Thursday, May 1, 2008 ~ 4:10 p.m. at the Alumni Center, Founders Room Professor Aller will discuss the emissions of extragalactic superluminal radio jets as observed through the eyes of the Peach Mountain Observatory telescope near Dexter. For more information please call 734-615-6653 Find the following related stories in the University Record, or printed for your convenience below: Featured event: Cosmic radio jets are the focus of inaugural lecture http://www.ur.umich.edu/0708/Apr28_08/23.php Michigan telescopes help give astronomers insights into blazars http://www.ur.umich.edu/0708/Apr28_08/24.php Featured event: Cosmic radio jets are the focus of inaugural lecture The emissions of extragalactic superluminal radio jets through the eyes of the telescope at the Peach Mountain Observatory near Dexter will be the topic of the Ralph Baldwin Professorship in Astronomy Inaugural Lecture. The talk will be given by Hugh Aller, professor of astronomy, at 4:10 p.m. May 1 in the Founders Room of the Alumni Center. Aller, who assumed leadership of the observatory in the Stinchfield Woods more than two decades ago, will discuss how the telescope has become a major player in the study of the radio jets and the cooperative work done on this phenomenon with other observatories around the world. Aller joined the faculty in 1968 and served as chair of the Department of Astronomy from 1990-2000. He is the first Ralph B. Baldwin Professor of Astronomy. The professorship was endowed by a $2 million gift from Baldwin and the Baldwin family. Baldwin received his bachelor's degree in astronomy from U-M in 1934 and his doctorate in 1937. He co-pioneered the theory that lunar craters were primarily the result of meteor impacts, instead of volcanic activity, a theory later confirmed by eyewitness accounts of the Apollo astronauts. In 1947 he returned to the family business, Oliver Machine Company in Grand Rapids, where he rose to chairman before retiring in 1987. Five generations of his family have attended U-M. "The University has been great to me," Baldwin says. "I wanted to give something back." The lecture and reception are open to the public. For information call 615-6653. Michigan telescopes help give astronomers insights into blazars By Nicole Casal Moore News Service For the first time astronomers have observed a blazar in action, substantiating a prevailing theory about how these luminous and energetic galactic cores work. In this illustration, a blazar emits a jet of high-energy plasma. A shock wave follows a spiral path as it moves away from the black hole and through a section of the jet where the magnetic field is wound in a coil. (Photo by Cosmovision For Boston University) A paper on the observations appears in the April 24 issue of Nature. Two U-M astronomers contributed to the research, which was led by Alan Marscher of the Institute for Astrophysical Research at Boston University. Blazars, among the most energetic objects in the universe, are fueled by supermassive black holes at the core of certain giant elliptical galaxies. Periodically, they emit jets of high-energy plasma at almost the speed of light. Competing theoretical models sought to explain how this phenomenon occurs. One model predicted that the jets were propelled by magnetic fields that were twisted by the gravity of the black hole and the materials falling into it. This is the behavior the astronomers detected. "What we've observed is the mechanism by which the acceleration of relativistic particles in the emanating jets occurs. Knowing that mechanism enhances our understanding of the physics that goes into the acceleration process," says Hugh Aller, a professor in the Department of Astronomy . Relativistic particles are particles traveling close to the speed of light. "Often, we'd observe blazars, but they didn't do anything. It's been difficult to catch these outbursts when they occur," he says. Scientists from across the globe aimed a variety of telescopes at the blazar BL Lacertae, about 950 million light-years away from Earth. Optical, X-ray and radio telescopes monitored the galaxy at different electromagnetic wavelengths periodically for several years. U-M recorded radio light curves at the Radio Astronomy Observatory at Peach Mountain in Dexter. "This is the first observational evidence that really fits with the picture that the theoreticians have had," says Margo Aller, a research scientist and lecturer in the Department of Astronomy. "The reason we have this evidence is a very fine sampling of a large number of instruments, including the Michigan radio telescopes." Scientists hope to get a closer look at blazar jets when NASA launches its Gamma-ray Large Area Space Telescope (GLAST) satellite observatory in May. The paper is called "The inner jet of an active galactic nucleus as revealed by a radio to gamma-ray outburst."