Astronomers reveal a 'blue whale of space'
July 7, 2009
This is a composite image showing the size of the radio glow from the galaxy Centaurus A in comparison to the full Moon. The white dots in the sky represent not stars but background radio sources -- galaxies like Centaurus A in the distant universe. The foreground antennas are of CSIRO's Australia Telescope Compact Array, which gathered the data for the Centaurus A image. Credit: Image credit - Ilana Feain, Tim Cornwell & Ron Ekers (CSIRO/ATNF). ATCA northern middle lobe pointing courtesy R. Morganti (ASTRON), Parkes data courtesy N. Junkes (MPIfR). Photo of the ATCA and Moon: Shaun Amy, CSIRO.
CSIRO astronomers have revealed the hidden face of an enormous galaxy called Centaurus A, which emits a radio glow covering an area 200 times bigger than the full Moon.
The galaxy's radio waves have been painstakingly transformed into a highly detailed image, which is being unveiled to the public for the first time.
Centaurus A lies 14 million light-years away, in the southern constellation Centaurus, and houses a monster black hole 50 million times the mass of the Sun.
The galaxy's black hole generates jets of radio-emitting particles that billow millions of light years out into space.
The spectacular sight is invisible to the naked eye.
"If your eyes could see radio waves you would look up in the sky and see the radio glow from this galaxy covering an area 200 times bigger than the full Moon," said the lead scientist for the project, Dr Ilana Feain of CSIRO's Australia Telescope National Facility (ATNF).
"Only a small percentage of galaxies are of this kind. They're like the blue whales of space - huge and rare."
Particles emitting radio waves stream millions of light-years into space from the heart of the galaxy Centaurus A in this picture made by CSIRO. Data for the image was gathered with CSIRO's Australia Telescope Compact Array and Parkes radio telescope: the frequency of the radio waves was 1.4 GHz. The smallest structure visible in the image is 680 parsecs (210 light-years) across : the scale bar represents 50,000 parsecs (about 163,000 light-years). The white dots are not stars but background radio sources, each a huge galaxy like Centaurus A in the distant universe. Image credit - Ilana Feain, Tim Cornwell & Ron Ekers (CSIRO/ATNF). ATCA northern middle lobe pointing courtesy R. Morganti (ASTRON), Parkes data courtesy N. Junkes (MPIfR).
Seen at radio wavelengths, Centaurus A is so big and bright that no-one else has ever tried making such an image."This is the most detailed radio image ever made of Centaurus A, and indeed of any galaxy that produces radio jets," said Dr Lewis Ball, Acting Director of the ATNF.
"Few other groups in the world have the skills and the facilities to make such an image, and we were the first to try."
Dr Feain and her team used CSIRO's Australia Telescope Compact Array telescope near Narrabri, NSW, to observe the galaxy for more than 1200 hours, over several years.
This produced 406 individual images, which were 'mosaiced' together to make one large image.
Dr Feain combined the Compact Array data and data taken from CSIRO's Parkes radio telescope.
Processing the image - combining the data, taking out the effects of radio interference, and adjusting the dynamic range - took a further 10,000 hours.
Astronomers will use the image to help them understand how black holes and radio jets interact with a galaxy's stars and dust, and how the galaxy has evolved over time.
Centaurus A is the closest of the galaxies with a supermassive black hole producing radio jets, which makes it the easiest to study.
Astronomers are interested in studying more of these rare, massive galaxies to determine the role black holes play in galaxy formation and growth.
Dr Feain said the sample of galaxies we have today is just the tip of the iceberg, because current telescopes don't combine the sensitivity needed to detect these sources and the ability to survey large areas of sky.
Enter ASKAP, the Australian SKA Pathfinder telescope, a new telescope being developed by CSIRO and partners, located in Western Australia.
ASKAP will be a survey telescope, designed for projects such as hunting for galaxies like Centaurus A in the distant universe. It is a precursor facility for the planned Square Kilometre Array (SKA), the world's largest radio telescope.
"ASKAP will be incredibly fast," said Professor Brian Boyle, CSIRO SKA Director. "Gathering the Centaurus A data with the Compact Array took 1200 hours. With ASKAP, it would take five minutes."
ASKAP is on schedule for completion in 2012. In its first six hours of operation it will generate more information than all previous radio telescopes combined.
Centaurus A was one of the first cosmic radio sources known outside our own Galaxy and it has a special connection with Australia.
The (visible) galaxy was discovered and recorded at Parramatta Observatory near Sydney in 1826. It was later catalogued under the name NGC 5128.
As a radio source, Centaurus A was discovered from Dover Heights in Sydney by CSIRO scientists in 1947.
The CSIRO image of Centaurus A were presented on Friday July 3 at an international conference, The Many Faces of Centaurus A, at the Mint in Sydney.
Jan 28, 2009 |
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The two blobs of radio glow do indeed seem to confirm the presence of "jets of radio-emitting particles" coming from a compact object at the core of the Centaurus A galaxy.
However, neutron stars and even ordinary stars emit jets of material axially.
Our studies conclude that a neutron star is at the core of the Sun and other ordinary stars, emitting the hydrogen that fills interstellar space [Journal of Fusion Energy 25 (2006) 107-114; http://tinyurl.com/27mvlp ]
A massive neutron star is probably the object at the core of the Centaurus A galaxy.
With kind regards,
Oliver K. Manuel
http://myprofile....anuelo09
Of course, the classification of our star being a similar to a neutron star near its center makes more sense.... if that is what you really mean.
See: "The Sun's origin, composition and source of energy," 32nd Lunar & Planetary Science Conference, Houston, TX, March 12-16, 2001 http://arxiv.org/.../0411255
With kind regards,
Oliver K. Manuel
http://www.omatumr.com
Thanks, lomed, for your comment and the reference to Wikipedia.
Energy from neutron repulsion definitely "has not already been included in calculations."
In fact, ASTROPHYSICISTS HAVE RELIGIOUSLY AVOIDED ANY MENTION of the repulsive forces between neutrons that was reported in 2001, 2002, 2003, etc in nuclear rest mass data for the 3000 types of atoms that comprise the entire visible universe.
At the bottom of this page you can see for yourself how this repulsive force powers galactic and stellar centers and fills interstellar space with Hydrogen, a neutron-decay product: http://tinyurl.com/m8rxdb
With kind regards,
Oliver K. Manuel
http://www.omatumr.com
In order to accurately determine the size limit (maximum mass without gravitational collapse) of a neutron star, one would have to know the equation of state of neutron star matter in your model. Optimally, one would know the pressure as well as the mass-energy density each as a function of the density of neutrons.
The Pauli exclusion principle manifests itself in fermions as a repulsive force between any two fermions that are in the same quantum state. This force leads to neutrons confined to a nucleus having an energy at absolute zero of around 30 MeV (as given on the wikipedia page cited in my previous post.) Thus, even though it may not be qualitatively the same as in your papers, neutron repulsion is part of quantum physics and even produces an energy value of the same order of magnitude as your result.