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Astrophysicist Reinhard Genzel wins million-dollar Shaw Prize
Few have spent more time pondering the nature of our galactic center

| 17 July 2008

Astrophysicist Reinhard Genzel, a professor of physics at Berkeley and director of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, has been awarded the 2008 Shaw Prize in Astronomy, the Shaw Prize Foundation in Hong Kong has announced.

The prize, one of three — the others are in mathematics and the life sciences — has been awarded annually since 2004; it is funded by Hong Kong businessman Run Run Shaw. The prize carries a monetary award of $1 million.

Genzel received the award “in recognition of his outstanding contribution in demonstrating that the Milky Way contains a supermassive black hole at its center,” according to the foundation’s website.

“Reinhard is doing very important work,” says Nobel laureate Charles Townes, a Berkeley professor emeritus of physics who collaborated with Genzel more than 25 years ago on early observations of the Milky Way’s core. “We’ve been working on it together for a long time, and I am glad he has gotten it nailed down now perfectly.”

Genzel joins two other Berkeley astrophysicists who have received the Shaw Prize in Astronomy. Saul Perlmutter, professor of physics and staff scientist at Lawrence Berkeley National Laboratory, shared the award in 2006; Geoffrey Marcy, professor of astronomy, shared the award in 2005. The late Shiing-Shen Chern, at the time a professor emeritus of mathematics at Berkeley, won the 2004 Shaw Prize in Mathematics.

A black hole at the center

In 1969, Donald Lynden-Bell and Martin Rees suggested that the Milky Way might contain a supermassive black hole at its center, but evidence was lacking because the galactic core is obscured by interstellar dust and could only be detected as a relatively faint radio source.

Genzel was a postdoctoral fellow at Berkeley working with Townes when they first presented observations hinting that the center of our galaxy harbored a massive black hole. The evidence was weak, however, and Genzel worked steadfastly over the ensuing decades to prove his case.

“He now has a remarkable technique by which he can measure very accurately and determine quite precisely the mass and behavior of stars circulating around the galactic center,” Townes says. Genzel and his collaborators developed this technique to use with telescopes of the European Southern Observatory, and for many years Genzel’s team carried out a program of observing the galactic center and its surrounding stars.

He and colleagues cemented their assertions in 2002, when they reported the orbit of a star around the galactic center and concluded that it circled an object with the mass of 3 million stars like our sun, all tightly packed into a region smaller than our solar system. Though other teams have confirmed this finding, Townes says, “Reinhard was first and has done the best work.”

According to theoretical astrophysicist Eliot Quataert, a Berkeley professor of astronomy and physics, Genzel’s group “has continued to make quite remarkable strides, both in observing the orbits of stars around the black hole, which has provided evidence beyond any reasonable doubt that there is a black hole at the center of the galaxy, and then also pushing forward in trying to get observations of the emission from the gas that is spiraling into the black hole.”

Quataert notes that Genzel’s group and a competing group at UCLA have now measured the orbits of about a dozen stars circling the black hole, confirming Genzel’s 2002 results and pinning down the mass of the central black hole to nearly 4 million times that of the sun.

The Shaw Prize is an international award to honor individuals who are currently active in their respective fields and who have achieved distinguished and significant advances, who have made outstanding contributions in culture and the arts, or who have achieved excellence in other domains.

Genzel and other winners of the 2008 Shaw Prizes will be presented with a medal at a ceremony in Hong Kong on Sept. 9.