Andrew Yee
October 18th 05, 03:10 PM
ESO Education and Public Relations Dept.
--------------------------------------------------------------
Text with all links and the photos are available on the ESO
Website at URL:
http://www.eso.org/outreach/press-rel/pr-2005/phot-33-05.html
--------------------------------------------------------------
Contact:
Almudena Prieto
Max-Planck Institute for Astronomy, Heidelberg, Germany
Phone: +34 67 702 66 57
For immediate release: 17 October 2005
ESO Press Photo 33/05
Feeding the Monster
New VLT Images Reveal the Surroundings of a Super-massive Black
Hole
ESO PR Photo 33a/05
The Centre of the Active Galaxy NGC 1097
Caption: ESO PR Photo 33a/05 is a colour-composite image
of the central 5,500 light-years wide region of the spiral
galaxy NGC 1097, obtained with the NACO adaptive optics on
the VLT. More than 300 star forming regions -- white spots
in the image -- are distributed along a ring of dust and
gas in the image. At the centre of the ring there is a
bright central source where the active galactic nucleus and
its super-massive black hole are located. The image was
constructed by stacking J- (blue), H- (green), and Ks-band
(red) images. North is up and East is to the left. The
field of view is 24 x 29 arcsec2, i.e. less than 0.03%
the size of the full moon!
Near-infrared images of the active galaxy NGC 1097, obtained
with the NACO adaptive optics instrument on ESO's Very Large
Telescope, disclose with unprecedented detail a complex central
network of filamentary structure spiralling down to the centre
of the galaxy. These observations provide astronomers with new
insights on how super-massive black holes lurking inside
galaxies get fed.
"This is possibly the first time that a detailed view of the
channelling process of matter, from the main part of the
galaxy down to the very end in the nucleus is released," says
Almudena Prieto (Max-Planck Institute, Heidelberg, Germany),
lead author of the paper describing these results.
Located at a distance of about 45 million light-years in the
southern constellation Fornax (the Furnace), NGC 1097 is a
relatively bright, barred spiral galaxy seen face-on. At
magnitude 9.5, and thus just 25 times fainter than the
faintest object that can be seen with the unaided eye, it
appears in small telescopes as a bright, circular disc.
NGC 1097 is a very moderate example of an Active Galactic
Nucleus (AGN), whose emission is thought to arise from matter
(gas and stars) falling into oblivion in a central black
hole. However, NGC 1097 possesses a comparatively faint
nucleus only, and the black hole in its centre must be on a
very strict "diet": only a small amount of gas and stars is
apparently being swallowed by the black hole at any given
moment.
Astronomers have been trying to understand for a long time
how the matter is "gulped" down towards the black hole.
Watching directly the feeding process requires very high
spatial resolution at the centre of galaxies. This can be
achieved by means of interferometry as was done with the VLTI
MIDI instrument on the central parts of another AGN, NGC 1068
(see ESO PR 17/03), or with adaptive optics [1].
Thus, astronomers [2] obtained images of NGC 1097 with the
adaptive optics NACO instrument attached to Yepun, the fourth
Unit Telescope of ESO's VLT. These new images probe with
unprecedented detail the presence and extent of material in
the very proximity of the nucleus. The resolution achieved
with the images is about 0.15 arcsecond, corresponding to
about 30 light-years across. For comparison, this is only
8 times the distance between the Sun and its nearest star,
Proxima Centauri.
ESO PR Photo 33b/05
Filamentary Structures in NGC 1097
Caption: ESO PR Photo 33b/05: The left image shows the same
central region as imaged in PR Photo 33a/05 but this time
as seen in the J-Ks colour. It clearly shows the nucleus,
the central spiral arms extending up to 1,300 light-years
from the centre, and the star-forming ring. The right image
shows the same but after a masking process has been applied
to suppress the central stellar light of the galaxy. The
central spiral arms are now seen as dark channels, some
extending up to the star-forming ring. North is up and
East is to the left.
As can be seen in last year's image (see ESO PR Photo 35d/04),
NGC 1097 has a very strong bar and a prominent star-forming
ring inside it. Interior to the ring, a secondary bar crosses
the nucleus almost perpendicular to the primary bar. The newly
released NACO near-infrared images show in addition more than
300 star-forming regions, a factor four larger than previously
known from Hubble Space Telescope images. These "HII regions"
can be seen as white spots in ESO PR Photo 33a/05. At the
centre of the ring, a moderate active nucleus is located.
Details from the nucleus and its immediate surroundings are
however outshone by the overwhelming stellar light of the
galaxy seen as the bright diffuse emission all over the
image.
The astronomers therefore applied a masking technique that
allowed them to suppress the stellar light (see ESO PR Photo
33b/05). This unveils a bright nucleus at the centre, but
mostly a complex central network of filamentary structures
spiralling down to the centre.
"Our analysis of the VLT/NACO images of NGC 1097 shows that
these filaments end up at the very centre of the galaxy",
says co-author Juha Reunanen from ESO.
"This network closely resembles those seen in computer models",
adds co-worker Witold Maciejewski from the University of
Oxford, UK. "The nuclear filaments revealed in the NACO images
are the tracers of cold dust and gas being channelled towards
the centre to eventually ignite the AGN."
The astronomers also note that the curling of the spiral
pattern in the innermost 300 light-years seem indeed to
confirm the presence of a super-massive black hole in the
centre of NGC 1097. Such a black hole in the centre of a
galaxy causes the nuclear spiral to wind up as it approaches
the centre, while in its absence the spiral would be
unwinding as it moves closer to the centre.
An image of NGC 1097 and its small companion, NGC 1097A, was
taken in December 2004, in the presence of Chilean President
Lagos with the VIMOS instrument on ESO's Very Large Telescope
(VLT). It is available as ESO PR Photo 35d/04.
More information
This ESO Press Photo is based on research published in the
October issue of Astronomical Journal, vol. 130, p. 1472
("Feeding the Monster: The Nucleus of NGC 1097 at Subarcsecond
Scales in the Infrared with the Very Large Telescope", by M.
Almudena Prieto, Witold Maciejewski, and Juha Reunanen).
Notes
[1]: "Adaptive Optics" is a modern technique by which ground-
based telescopes can overcome the undesirable blurring effect
of atmospheric turbulence. With adaptive optics, the images
of stars and galaxies captured by these instruments are at
the theoretical limit, i.e., almost as sharp as if the
telescopes were in space.
[2]: The astronomers are M. Almudena Prieto (Max-Planck
Institute for Astronomy, Heidelberg, Germany), Witold
Maciejewski (University of Oxford, UK), and Juha Reunanen
(ESO, Garching, Germany).
National contacts for the media:
Belgium: Dr. Rodrigo Alvarez, +32-2-474 70 50
Finland: Ms. Terhi Loukiainen, +358 9 7748 8385
Denmark: Dr. Michael Linden-Vørnle, +45-33-18 19 97
France: Dr. Daniel Kunth, +33-1-44 32 80 85
Germany: Dr. Jakob Staude, +49-6221-528229
Italy: Prof. Massimo Capaccioli, +39-081-55 75 511
The Netherlands: Ms. Marieke Baan, +31-20-525 74 80
Portugal: Prof. Teresa Lago, +351-22-089 833
Sweden: Dr. Jesper Sollerman, +46-8-55 37 85 54
Switzerland: Dr. Martin Steinacher, +41-31-324 23 82
United Kingdom: Mr. Peter Barratt, +44-1793-44 20 25
--------------------------------------------------------------
ESO Press Information is available on the WWW at
http://www.eso.org/outreach/press-rel/
--------------------------------------------------------------
(c) ESO Education & Public Relations Department
Karl-Schwarzschild-Strasse 2, D-85748 Garching, Germany
--------------------------------------------------------------
--------------------------------------------------------------
Text with all links and the photos are available on the ESO
Website at URL:
http://www.eso.org/outreach/press-rel/pr-2005/phot-33-05.html
--------------------------------------------------------------
Contact:
Almudena Prieto
Max-Planck Institute for Astronomy, Heidelberg, Germany
Phone: +34 67 702 66 57
For immediate release: 17 October 2005
ESO Press Photo 33/05
Feeding the Monster
New VLT Images Reveal the Surroundings of a Super-massive Black
Hole
ESO PR Photo 33a/05
The Centre of the Active Galaxy NGC 1097
Caption: ESO PR Photo 33a/05 is a colour-composite image
of the central 5,500 light-years wide region of the spiral
galaxy NGC 1097, obtained with the NACO adaptive optics on
the VLT. More than 300 star forming regions -- white spots
in the image -- are distributed along a ring of dust and
gas in the image. At the centre of the ring there is a
bright central source where the active galactic nucleus and
its super-massive black hole are located. The image was
constructed by stacking J- (blue), H- (green), and Ks-band
(red) images. North is up and East is to the left. The
field of view is 24 x 29 arcsec2, i.e. less than 0.03%
the size of the full moon!
Near-infrared images of the active galaxy NGC 1097, obtained
with the NACO adaptive optics instrument on ESO's Very Large
Telescope, disclose with unprecedented detail a complex central
network of filamentary structure spiralling down to the centre
of the galaxy. These observations provide astronomers with new
insights on how super-massive black holes lurking inside
galaxies get fed.
"This is possibly the first time that a detailed view of the
channelling process of matter, from the main part of the
galaxy down to the very end in the nucleus is released," says
Almudena Prieto (Max-Planck Institute, Heidelberg, Germany),
lead author of the paper describing these results.
Located at a distance of about 45 million light-years in the
southern constellation Fornax (the Furnace), NGC 1097 is a
relatively bright, barred spiral galaxy seen face-on. At
magnitude 9.5, and thus just 25 times fainter than the
faintest object that can be seen with the unaided eye, it
appears in small telescopes as a bright, circular disc.
NGC 1097 is a very moderate example of an Active Galactic
Nucleus (AGN), whose emission is thought to arise from matter
(gas and stars) falling into oblivion in a central black
hole. However, NGC 1097 possesses a comparatively faint
nucleus only, and the black hole in its centre must be on a
very strict "diet": only a small amount of gas and stars is
apparently being swallowed by the black hole at any given
moment.
Astronomers have been trying to understand for a long time
how the matter is "gulped" down towards the black hole.
Watching directly the feeding process requires very high
spatial resolution at the centre of galaxies. This can be
achieved by means of interferometry as was done with the VLTI
MIDI instrument on the central parts of another AGN, NGC 1068
(see ESO PR 17/03), or with adaptive optics [1].
Thus, astronomers [2] obtained images of NGC 1097 with the
adaptive optics NACO instrument attached to Yepun, the fourth
Unit Telescope of ESO's VLT. These new images probe with
unprecedented detail the presence and extent of material in
the very proximity of the nucleus. The resolution achieved
with the images is about 0.15 arcsecond, corresponding to
about 30 light-years across. For comparison, this is only
8 times the distance between the Sun and its nearest star,
Proxima Centauri.
ESO PR Photo 33b/05
Filamentary Structures in NGC 1097
Caption: ESO PR Photo 33b/05: The left image shows the same
central region as imaged in PR Photo 33a/05 but this time
as seen in the J-Ks colour. It clearly shows the nucleus,
the central spiral arms extending up to 1,300 light-years
from the centre, and the star-forming ring. The right image
shows the same but after a masking process has been applied
to suppress the central stellar light of the galaxy. The
central spiral arms are now seen as dark channels, some
extending up to the star-forming ring. North is up and
East is to the left.
As can be seen in last year's image (see ESO PR Photo 35d/04),
NGC 1097 has a very strong bar and a prominent star-forming
ring inside it. Interior to the ring, a secondary bar crosses
the nucleus almost perpendicular to the primary bar. The newly
released NACO near-infrared images show in addition more than
300 star-forming regions, a factor four larger than previously
known from Hubble Space Telescope images. These "HII regions"
can be seen as white spots in ESO PR Photo 33a/05. At the
centre of the ring, a moderate active nucleus is located.
Details from the nucleus and its immediate surroundings are
however outshone by the overwhelming stellar light of the
galaxy seen as the bright diffuse emission all over the
image.
The astronomers therefore applied a masking technique that
allowed them to suppress the stellar light (see ESO PR Photo
33b/05). This unveils a bright nucleus at the centre, but
mostly a complex central network of filamentary structures
spiralling down to the centre.
"Our analysis of the VLT/NACO images of NGC 1097 shows that
these filaments end up at the very centre of the galaxy",
says co-author Juha Reunanen from ESO.
"This network closely resembles those seen in computer models",
adds co-worker Witold Maciejewski from the University of
Oxford, UK. "The nuclear filaments revealed in the NACO images
are the tracers of cold dust and gas being channelled towards
the centre to eventually ignite the AGN."
The astronomers also note that the curling of the spiral
pattern in the innermost 300 light-years seem indeed to
confirm the presence of a super-massive black hole in the
centre of NGC 1097. Such a black hole in the centre of a
galaxy causes the nuclear spiral to wind up as it approaches
the centre, while in its absence the spiral would be
unwinding as it moves closer to the centre.
An image of NGC 1097 and its small companion, NGC 1097A, was
taken in December 2004, in the presence of Chilean President
Lagos with the VIMOS instrument on ESO's Very Large Telescope
(VLT). It is available as ESO PR Photo 35d/04.
More information
This ESO Press Photo is based on research published in the
October issue of Astronomical Journal, vol. 130, p. 1472
("Feeding the Monster: The Nucleus of NGC 1097 at Subarcsecond
Scales in the Infrared with the Very Large Telescope", by M.
Almudena Prieto, Witold Maciejewski, and Juha Reunanen).
Notes
[1]: "Adaptive Optics" is a modern technique by which ground-
based telescopes can overcome the undesirable blurring effect
of atmospheric turbulence. With adaptive optics, the images
of stars and galaxies captured by these instruments are at
the theoretical limit, i.e., almost as sharp as if the
telescopes were in space.
[2]: The astronomers are M. Almudena Prieto (Max-Planck
Institute for Astronomy, Heidelberg, Germany), Witold
Maciejewski (University of Oxford, UK), and Juha Reunanen
(ESO, Garching, Germany).
National contacts for the media:
Belgium: Dr. Rodrigo Alvarez, +32-2-474 70 50
Finland: Ms. Terhi Loukiainen, +358 9 7748 8385
Denmark: Dr. Michael Linden-Vørnle, +45-33-18 19 97
France: Dr. Daniel Kunth, +33-1-44 32 80 85
Germany: Dr. Jakob Staude, +49-6221-528229
Italy: Prof. Massimo Capaccioli, +39-081-55 75 511
The Netherlands: Ms. Marieke Baan, +31-20-525 74 80
Portugal: Prof. Teresa Lago, +351-22-089 833
Sweden: Dr. Jesper Sollerman, +46-8-55 37 85 54
Switzerland: Dr. Martin Steinacher, +41-31-324 23 82
United Kingdom: Mr. Peter Barratt, +44-1793-44 20 25
--------------------------------------------------------------
ESO Press Information is available on the WWW at
http://www.eso.org/outreach/press-rel/
--------------------------------------------------------------
(c) ESO Education & Public Relations Department
Karl-Schwarzschild-Strasse 2, D-85748 Garching, Germany
--------------------------------------------------------------