Frontiers of Astronomy lecture series at the Cleveland Museum of Natural History:Probing the Early Universe with Extremely Energetic Gamma-Ray Bursts
April 24, 2008, 8 pm
The Gamma-Ray Burst phenomenon was discovered in the late ’60s and announced in the early ’70s. After many decades of confusion about the nature of this transient phenomenon, NASA’s Compton Gamma Ray Observatory (1991-2000) advanced astronomers’ understanding to the point that their galactic origin became less and less viable. It was the keen X-ray eyes of the Italian-Dutch BeppoSAX satellite that in 1997 caught the first X-ray afterglow of a burst, which in turn also led to the discovery of optical emission following the brief flare in the gamma-band. This allowed astronomers to establish their distances, and to their amazement they turned out to be very distant, cosmological sources -- where one uses redshifts instead of light-years as a measure of their distance. Their large apparent brightness and the large distances imply enormous energies, which for a while challenged our theoreticians.
In the past years a better understanding of the GRB-phenomenon has emerged, linking these transients to the final, violent moments of exploding, massive stars and the merging of exotic binary systems of compact stars, such as two neutron stars or a neutron star and a black hole. The processes that take place when black holes form in these events provide a laboratory for the exploration of ultra-relativistic physics, and their afterglow emissions can be used to probe the processes of star formation and chemical evolution in the earliest proto-galactic structures that emerged from the Big Bang. When astronomers observe a gamma-ray burst at a very large distance, they may be looking at the death-cry of one of the first stars ever born in the Universe. With NASA’s Swift satellite (2004- ), dedicated to the study of this phenomenon, they are currently witnessing these bursts twice a week. With future missions on the drawing boards, astronomers may be able to follow up on one burst every day.
Hartmann describes the history of GRB studies and gives an outlook on how astronomers will use these explosive events to study the beginnings of galaxy formation in the early Universe.
More about Dr. Hartmann:
Dieter Hartmann was born in 1953 in the small town of Northeim in Northern Germany. After completing a degree in physics engineering, he studied astronomy at Gauss’ Observatory of Göttingen University. After completion of his M.S. degree, he continued his studies in astrophysics at UC Santa Cruz, where he worked with Prof. S. E. Woosley on supernovae and gamma-ray bursts. He received his Ph.D. in 1989, spent one year as a postdoctoral researcher at Lawrence Livermore National Laboratory, and began his current employment at Clemson University in 1991. His primary research interests are gamma-ray bursts, supernovae and astronomy with radioactivities, especially the study of nucleosynthesis through their gamma-ray line emission. He is serving the community as a science editor of The Astrophysical Journal and teaches graduate and undergraduate physics and astronomy courses at Clemson University.
Frontiers of Astronomy is a free lecture series that offers those with an interest in astronomy the chance to learn about some of the latest research in the field. Presentations are given in the Museum's Murch Auditorium. On clear evenings, the Ralph Mueller Observatory will be open afterward. Frontiers of Astronomy is sponsored by the Department of Astronomy at Case Western Reserve University through the support of the Arthur S. Holden, Sr. Endowment; The Cleveland Museum of Natural History; and The Cleveland Astronomical Society. No tickets or reservations are required.
