Scientists Probe Black Hole's Inner Sanctum (Forwarded)

University News Services
Rochester Institute of Technology
Rochester, New York

For more information:

Kambiz Fathi, RIT Astrophysics Group
585-733-4334

Susan Gawlowicz, RIT University News Services
585-475-5061

Peter Michaud, Gemini Observatory
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Release Date: Jan. 09, 2006

Scientists Probe Black Hole's Inner Sanctum

How does matter spiral its way to the center of a galaxy and into the
mouth of a supermassive black hole? A new study provides the best glimpse
yet at the death spiral of material as it descends into the core of a
galaxy hosting a large black hole. The study predicts that, barring
obstructions, 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 Kambiz Fathi at Rochester
Institute of Technology, together with astronomers in Brazil, Italy, and
Chile, measured the internal motions of gas surrounding the nucleus of the
active galaxy NGC1097. Using sophisticated spectroscopic techniques with
the Gemini South Telescope in Chile, the team measured the spiral motions
of gas streaming inside the nuclear ring. Using sophisticated
spectroscopic techniques with the Gemini South Telescope in Chile, the
team measured the motion of matter streaming from the galaxy's spiral arms
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 the team's results at the 207th meeting of the American
Astronomical Society 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 another galaxy," says Fathi, a
postdoctoral scholar at RIT. "The work of our team confirms the main
theories that have never been observationally confirmed at 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.
Previous imaging by the Hubble Space Telescope and the European Southern
Observatory Very Large Telescope has shown structure inside the central
ring of NGC1097. The Gemini data complement this with a velocity map of
the gas inside the ring.

"When we extrapolate our last data points, about 30 light-years from the
black hole, this is where we find that it would take about 200,000 years
for the gas to travel the last leg of its one-way journey to the
supermassive black hole," says Fathi.

The team measured the streaming motions toward the black hole by using
two-dimensional spectroscopy to capture spectral data at several thousand
points surrounding the nucleus of the galaxy.

"The resolution of this data is unprecedented when you look at how we were
able to isolate so many different points around the nucleus of this galaxy
and acquire a spectrum for each point at once," says team member Thaisa
Storchi Bergmann of Instituto de Fisica in Brazil. "This paints an
incredibly detailed picture of the region around the black hole and gives
us a new glimpse at something we could only imagine before."

The technology that allows these types of observations is called integral
field spectroscopy. It takes light from many different parts of the
telescope's field simultaneously and splits the light 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.

NGC1097 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.

Project collaborators include Thaisa Storchi-Bergmann, UFRGS, Brazil;
David Axon and Andrew Robinson, RIT, USA; Alessandro Capetti, INAF-Turin,
Italy, Alessandro Marconi, INAF-Florence, Italy; Rogemar Riffel, UFRGS,
Brazil, and Claudia Winge, Gemini Observatory, Chile.

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

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Note to editors: Artwork is available at
http://www.gemini.edu/ngc1097