have been searching the sky for millennia, hoping to decipher its
mysteries. With the advent of powerful telescopes and advanced
computer equipment, many new discoveries have been made. Now, Ben
Sulman ’06 has added
to these discoveries, identifying a pulsar deep within the center
of the Milky Way with the help of Oberlin’s new supercomputer.
discovered "his" pulsar
during a summer internship at the National Radio Astronomy Observatory
(NRAO) in Charlottesville, Virginia. There he worked with astronomer
Scott Ransom and NRAO's Green Bank Telescope, the largest fully
steerable radio telescope in the world. Sulman helped Ransom study
a star cluster known as Terzan 5, which holds a buzzing beehive
of rapidly spinning millisecond pulsars - all 28,000 light years
"I thought this would be a good
opportunity for Ben to get some hands-on experience in the field,"
says Professor of Physics and Astronomy Dan Stinebring, who helped
arrange the internship with Ransom. "Plus, he will be able to
continue his research at Oberlin, now that the summer is over,
with me as his mentor."
To help Ransom sort pulsars from "false" signals
like radio interference, Sulman used Oberlin’s new supercomputer.
After logging on to the supercomputer from his laptop in Virginia,
Sulman uploaded Ransom’s data and began running a software
program designed to search out pulsar candidates.
"A single observation on this star
cluster is seven hours long and generates 700 gigabytes of data," Ransom
says. "It would take a single desktop computer years to analyze
this much data. That's why we need to use Oberlin’s supercomputer
for a project like this."
The supercomputer searched through the data for a week before
generating several candidates for Ransom and Sulman to study further.
The duo then plotted each candidate’s frequency on a graph,
checking to see if the pulse repeated itself at frequent intervals
and appeared in more than one observation. In the case of Sulman's
pulsar, both tests proved positive.
"The pulsar I discovered had all
the typical characteristics," he says. "It repeated itself
in frequent intervals and turned up in 10 out of 15 data sets that
spanned a year of observation."
The information that Sulman collected
was entered into a public database that can be accessed by other
radio astronomers. The data can then be used to test theories
of gravity such as general relativity, or to search for black holes
within the star cluster.
"Scientists use the clock-like precision
of pulsars to test the theories of physics," says Ransom. "By
measuring the signal of a pulsar through the years, we can probe
the history of a star cluster or learn more about the objects that
directly surround the pulsar and affect its rotation."
Sulman's collaboration with Ransom
isn't over; he plans to continue using the supercomputer to run
Ransom’s data sets this semester. Sulman also plans to use
the data as part of a senior honors project.
who will supervise Sulman's use of the supercomputer, is confident
that Sulman will be able to make many more discoveries with Ransom's
"Very few undergraduate institutions
have a computer powerful enough to handle the demands of this project," he
says. "I’m pretty sure that this won’t be the
last pulsar Ben discovers with Oberlin’s supercomputer."