Galaxy NGC 3147
Stefano Bianchi
Dipartimento di Matematica e Fisica, Universita` degli Studi Roma Tre
Rome, Italy
Email: bianchi@fis.uniroma3.it
Videos
Artist’s Impression of NGC3147 black hole disc
Astronomers using the NASA/ESA Hubble
Space Telescope have observed an unexpected thin disc of material
encircling a supermassive black hole at the heart of the spiral galaxy
NGC 3147, located 130 million light-years away.
The
presence of the black hole disc in such a low-luminosity active galaxy
has astronomers surprised. Black holes in certain types of galaxies such
as NGC 3147 are considered to be starving as there is insufficient
gravitationally captured material to feed them regularly. It is
therefore puzzling that there is a thin disc encircling a starving black
hole that mimics the much larger discs found in extremely active
galaxies.
Of particular interest, this disc of material circling the black hole offers a unique opportunity to test Albert Einstein’s theories of relativity.
The disc is so deeply embedded in the black hole’s intense
gravitational field that the light from the gas disc is altered,
according to these theories, giving astronomers a unique peek at the
dynamic processes close to a black hole.
“We’ve never seen the effects of both general and special relativity in visible light with this much clarity,” said team member Marco Chiaberge of AURA for ESA, STScI and Johns Hopkins Univeristy.
The disc’s material was measured by Hubble to be whirling
around the black hole at more than 10% of the speed of light. At such
extreme velocities, the gas appears to brighten as it travels toward
Earth on one side, and dims as it speeds away from our planet on the
other. This effect is known as relativistic beaming.
Hubble’s observations also show that the gas is embedded so deep in a
gravitational well that light is struggling to escape, and therefore
appears stretched to redder wavelengths. The black hole’s mass is around
250 million times that of the Sun.
“This is an intriguing peek at a disc very close to a
black hole, so close that the velocities and the intensity of the
gravitational pull are affecting how we see the photons of light,” explained the study’s first author, Stefano Bianchi, of Università degli Studi Roma Tre in Italy.
In order to study the matter swirling deep inside this
disc, the researchers used the Hubble Space Telescope Imaging
Spectrograph (STIS)
instrument. This diagnostic tool divides the light from an object into
its many individual wavelengths to determine the object's speed,
temperature, and other characteristics at very high precision. STIS was
integral to effectively observing the low-luminosity region around the
black hole, blocking out the galaxy’s brilliant light.
The astronomers initially selected this galaxy to validate
accepted models about lower-luminosity active galaxies: those with
malnourished black holes. These models predict that discs of material
should form when ample amounts of gas are trapped by a black hole’s
strong gravitational pull, subsequently emitting lots of light and
producing a brilliant beacon called a quasar.
“The type of disc we see is a scaled-down quasar that we did not expect to exist,” Bianchi explained. “It’s
the same type of disc we see in objects that are 1000 or even 100 000
times more luminous. The predictions of current models for very faint
active galaxies clearly failed.”
The team hopes to use Hubble to hunt for other very compact discs around low-luminosity black holes in similar active galaxies.
More Information
The Hubble Space Telescope is a project of international cooperation between ESA and NASA.
The international team of astronomers in this study
consists of Stefano Bianchi (Universita` degli Studi Roma Tre, Italy),
Robert Antonucci (University of California, Santa Barbara, USA),
Alessandro Capetti (INAF - Osservatorio Astrofisico di Torino, Italy),
Marco Chiaberge (Space Telescope Science Institute and Johns Hopkins
University, Baltimore, USA), Ari Laor (Israel Institute of Technology,
Israel), Loredana Bassani (INAF/IASF Bologna, Italy), Francisco J.
Carrera (CSIC-Universidad de Cantabria, Spain), Fabio La Franca
(Universita` degli Studi Roma Tre, Italy), Andrea Marinucci (Universita`
degli Studi Roma Tre, Italy), Giorgio Matt1 (Universita` degli Studi
Roma Tre, Italy), Riccardo Middei (Universita` degli Studi Roma Tre,
Italy), Francesca Panessa (INAF Istituto di Astrofisica e Planetologia
Spaziali, Italy).
Image credit: ESA/Hubble, M. Kornmesser
Links
Contacts
Stefano Bianchi
Dipartimento di Matematica e Fisica, Universita` degli Studi Roma Tre
Rome, Italy
Email: bianchi@fis.uniroma3.it
Bethany Downer
ESA/Hubble, Public Information Officer
Garching, Germany
Email: bethany.downer@partner.eso.org
ESA/Hubble, Public Information Officer
Garching, Germany
Email: bethany.downer@partner.eso.org
Source: ESA/Hubble/News
