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spacer spacer spacer January 12, 2006

Inside a black hole


Artist’s conception of the inner ring structure of galaxy NGC 1097, which is about 4,500 light-years in diameter. Kambiz Fathi studied the detailed motions of this gas and presented his results at a meeting of the American Astronomical Society.

Photo courtesy of Gemini Observatory by Jon Lomberg

How does matter spiral its way to the center of a galaxy and into the mouth of a supermassive black hole? A new study led by RIT scientist Kambiz Fathi provides the best glimpse yet at material descending into the core of a galaxy hosting a large black hole. The study predicts that, barring obstruction, the galactic debris will take about 200,000 years to make a one-way trip through the inner regions of the galaxy and into oblivion.

An international team of scientists led by Fathi, together with astronomers in Brazil, Italy and Chile, measured the internal motions of gas surrounding the nucleus of the active galaxy, NGC 1097. Using modern spectroscopic techniques with the Gemini South Telescope in Chile, the team measured the motion of matter streaming from the galaxy’s spiral arms—dense areas of stars and gas in a spiral configuration— to the heart of the galaxy. The observations zoomed in 10 times closer to the supermassive black hole than ever before, to see clouds of material within 10 light-years of the galactic core. Previous observations of this type of environment have detected gas clouds located between 100 and 1,000 light-years from the galaxy’s nucleus.

Fathi presented his results at the annual meeting of the American Astronomical Society on Jan. 9 in Washington, D.C.

“It is the first time anyone has been able to follow gas this close to the supermassive black hole in the center of a galaxy,” says Fathi, a postdoctoral scholar in the College of Science. “The work of our team confirms some aspects of the main theories that have never been observationally confirmed to this level. We have been able to show that it is possible to measure these velocities down to these scales.”

Modeling the galaxy’s spectra revealed the dynamic shifts in the gas and showed the spiral arms pulling gas from about a thousand light-years out from the center to the nucleus at 52 kilometers (31 miles) per second.

The team measured the streaming motions toward the black hole by using two-dimensional spectroscopy to capture spectral data at hundreds of points surrounding the nucleus of the galaxy.
These observations were captured with integral field spectroscopy, which takes light from hundreds of different parts of the telescope’s field simultaneously and splits it from each region into a rainbow or spectrum of light.

“This allows astronomers to do in 30 minutes what would have taken four nights a decade ago,” says Fathi.

NGC 1097 is located about 47 million light-years away in the southern constellation, Fornax.
This work used data from the Gemini Observatory’s Multi-Object Spectrograph integral field unit and the Hubble Space Telescope’s high resolution Advanced Camera for Surveys.

The results of this study will appear in an upcoming issue of The Astrophysical Journal Letters.

Susan Gawlowicz

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