By Andrea Ghez
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| Photo: Keck Astronomer Andrea Ghez (center
left) with Keck Senior Scientist Peter Wizinowich (center
right) after Andrea's recent Evening with Astronomers
lecture. Andrea presented current research findings confirming
the existence of a supermassive black hole at the center
of our Milky Way Galaxy. Photo courtesy of Sarah Anderson. |
It's hard to convey how important Adaptive Optics (AO) has been
to my research. But I've given it a stab below.
Initially, I think the astronomy community did not believe that
AO would work. Only a few of us were "believers," chomping at
the bit to try it out. AO has proved to be a tremendous success,
and now there is a ground swell of enthusiasm from astronomers
who never before ventured into the field of Adaptive Optics.
For me AO has been the single most exciting advance at the Keck
Observatory (or even more generally in the field of large ground-based
telescopes). It has been thrilling to be a member of the Keck
community, which was the first 10-meter class telescope to see
a Laser Guide Star (LGS) being used for Adaptive Optics. The
LGS was absolutely essential to the success of my program.
I've been working with techniques to get high angular resolution
images of the center of our Galaxy for more than a decade. My
objective has been to understand whether or not our Galaxy hosted
a supermassive black hole at its center and, if so, what are
its properties.
Before Adaptive Optics there was only a very limited amount
that could be done. I had to work with images at a single wavelength
that were not very sensitive to faint stars. While this got
me off to a good start on my basic questions, I can now obtain
images at many different wavelengths and of much fainter stars,
as well as spectroscopy of the stars. (Spectrographs spread
the light from celestial objects into their component colors.
By studying the spectra, or unique "fingerprint" of an object,
astronomers learn much more about the nature of that object
than from a simple image.)
AO is a much more powerful way to probe for the existence and
properties of a central black hole. I now have definitive evidence
of a supermassive black hole and have uncovered a number of
surprises about it. One of the most interesting surprises is
that the black hole is surrounded by very young stars, which
introduces what I call a "paradox of youth." A black hole creates
a very hostile environment to star birth, but yet these young
stars did manage to form. There is currently no adequate explanation
for how these stars could have formed - in spite of a large
variety of interesting suggestions. This discovery has generated
an active new field of research in the past few years.
Having access to the Keck Observatory was the single most important
reason that I accepted a faculty job at UCLA, and it is the
reason that I stay at UCLA. It is an honor and privilege to
use the world's largest telescope for my research. Working with
the laser guide star at Keck has been the most exciting thing
that I've done since I started at Keck in 1994.
To see some of Andrea's results, visit her results on UCLA's website.
Read "Adaptive Optics and the Keck Observatory", a June 2005
paper by Keck Scientist Peter Wizinowich. For a good technical
overview of the Keck LGS/AO system, visit here
and click on "Laser Guide Star AO." 
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