A cannibalistic galaxy with a powerful heart

Apr 04, 2012
The peculiar galaxy Centaurus A as seen in longer infrared wavelengths and X-rays. Inner structural features seen in this image are helping scientists to understand the mechanisms and interactions within the galaxy, as are the jets seen extending over thousands of light years from the black hole believed to be at its heart. Newly discovered clouds co-aligned with the jets can also be seen in the infrared data, which are colored red and orange. The X-ray image data in this combined picture are shown in blue/cyan/purple and highlight the highly energetic jet region as well as structures that co-align with the infrared and X-ray jet (top left). Image credit: Far-infrared: ESA/Herschel/PACS/SPIRE/C.D. Wilson, MacMaster University, Canada; X-ray: ESA/XMM-Newton/EPIC

Observations by the two of the European Space Agency's space observatories have provided a multi-wavelength view of the mysterious galaxy Centaurus A. The new images, from the Herschel Space Observatory and the XMM-Newton x-ray satellite, are revealing further hints about its cannibalistic past and energetic processes going on in its core.

At a distance of around 12 million light years, Centaurus A is the closest large elliptical galaxy to our own . It has been marked as unusual since shortly after its in the due to a thick lane of dust across its centre – an unusual feature for an . But it wasn't until a century later that the galaxy's true nature was revealed.

Emanating from its core are two massive jets of material streaming from a massive black hole in the heart of Centaurus A. When observed by radio telescopes, the jets stretch for up to a million light years, though the Herschel and XMM-Newton results focus on the inner regions.

The twisted disk of material in the center is clearly visible, the remnants of a galaxy that was swallowed up long ago, and also two clumps of dust in the top left and bottom right corners. The two plumes are the glow from material spewing out from the black hole in the center of the galaxy. Credit: Far-infrared: ESA/Herschel/PACS/SPIRE/C.D. Wilson, MacMaster University, Canada; X-ray: ESA/XMM-Newton/EPIC

"Centaurus A is the closest example of a galaxy to us with massive jets from its central black hole," explained Prof Christine Wilson of McMaster University, Canada, who is leading the study of Centaurus A with Herschel. "Observations with Herschel, XMM-Newton and telescopes at many other wavelengths allow us to study their effects on the galaxy and its surroundings."

Strong radio emission is caused by electrons travelling at close to the speed of light through strong magnetic fields, and is so bright that the jets are even visible in the far-infrared images from the Herschel . As well as the jets, the images from this infrared observatory also show a twisted disc of dust near the galaxy's centre.

In visible light the galaxy appears as a ball of stars, with a thick lane of dust running across it. The far-infrared light shows the glow from jets of material emanating from near the black hole in the galaxy's core. Also visible is a twisted disc of dust, the remnants of a galaxy that was swallowed up in the galaxy's distant past, and two clumps of dust in the top-left and bottom-right corners. In X-rays the jets become visible, as well as the X-ray glow from the super-heated material that they are plowing in to. Credit: Far-infrared: ESA/Herschel/PACS/SPIRE/C.D. Wilson, MacMaster University, Canada; X-ray: ESA/XMM-Newton/EPIC; visible: ESO/MPG 2.2-m telescope on La Silla

This odd shape is strong evidence that Centaurus A underwent a cosmic collision with another galaxy in the distant past. The colliding galaxy was ripped apart to form the warped disc, and the formation of young stars heats the dust to cause the infrared glow seen by Herschel.

Such collisions often result in shells and rings of gas and dust, and Centaurus A is no exception. Herschel observations have now confirmed the presence of two clumps of dust that seem to be lined up with the two lobes of the jets.

"The apparent alignment of two clumps with the two jets now seems to be a cosmic coincidence, and it appears that the dust originated from one of the colliding galaxies." explained Dr Robbie Auld, of Cardiff University. "Unlike most dust Herschel sees, which is heated by nearby star formation, the dust in these clumps is being heated by old stars in Centaurus A itself, up to 50,000 light years away."

In visible light the galaxy appears as a ball of stars, with a thick lane of dust running across it. The far-infrared light shows a glow from jets of material emanating from near the black hole in the galaxy's core. Also visible is a twisted disc of dust, the remnants of a galaxy that was swallowed up in the galaxy's distant past, and also two clumps of dust in the top left and bottom right. In X-rays the jets become clearly visible, along with the X-ray glow from the super-heated material that they are plowing in to. Credit: Far-infrared: ESA/Herschel/PACS/SPIRE/C.D. Wilson, MacMaster University, Canada; X-ray: ESA/XMM-Newton/EPIC; visible: ESO/MPG 2.2-m telescope on La Silla.

In x-rays the effect of the two jets of material is clearly visible. Showing the presence of extremely hot gas, the images from the XMM-Newton x-ray clearly show the axis of the one of the jets. While the other jet itself is not seen in by XMM-Newton, the gas it is ploughing into is shocked and heated to very high temperatures, creating a bright x-ray glow.

"XMM-Newton is the observatory most suited to detecting extended weak X-ray emission, often allowing us to see halos around galaxies for the first time," notes Norbert Schartel, XMM-Newton Project Scientist.

In the centre of the galaxy, the massive black hole is also having an effect on its immediate surroundings. The material around it glows brightly in x-rays, but there has identified an apparent deficit of dust within a few thousand of the black hole.

"This could be due to intense x-rays destroying the tiny dust grains, or due to the way the warped ring of dust is affecting star formation" said Prof Wilson. "Either way, Centaurus A is the ideal place to study the extreme processes that occur near super-massive ".

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Tuxford
1 / 5 (3) Apr 05, 2012
'Cosmic coincidence' nonsense. Just rubbish. Astronomers are clearly stupid.

Yes, the dust deficit surrounding the AGN at the core is due to the massive outbursts of the core star, like we see in so many other examples. It's like a leaf blower in all directions. And the clumps are likely the depository of the jets, new daughter galaxies forming from the ejected new matter. No doubt stars are forming there too.
Tennex
1 / 5 (2) Apr 05, 2012
This odd shape is strong evidence that Centaurus A underwent a cosmic collision with another galaxy in the distant past
It's indeed possible, but my feeling is different in this particular case. IMO the black holes at the center of galaxies are just overgrown version of magnetars, which do radiate the matter in their poles. The trick is, the rotational axis of these stars is not equivalent to the direction, in which these stars emanate jets - after all, this is just why we can see them as a pulsars. IMO what we can see here is just galactic version of pulsar.

There is even more interesting question, whether the concurrency of rotational axis and polar jets is really accidental or if it's not a consequence of CP symmetry breaking at the galactic scale. As we know, many galaxies which had evaporate their matter exhibit only one jet in asymmetric way, in this sense they're behaving like the radioactive cobalt nuclei, which do emanate the particles in one direction preferentially.
Tennex
1 / 5 (2) Apr 05, 2012
My general view of galactic evolution is as follows: at the very beginning the large cluster of dark matter collapses with its gravity, until its density reaches the Schwarzschild criterion. Above this limit the cluster changes into white hole (it's called the gravastar, dark matter star in some theories), which cannot radiate all its energy freely into outside. The formation of this white hole is gradualistic process, though. At first the matter formed with baryogenesis inside of gravastar is kept at distance with intensive pressure of radiation. But as the matter is condensing, the pressure of photons is not sufficient to keep it at distance and the gravastar will change into large white hole with many jets. As its matter is condensing, the number of jets gradually decreases, until the odd number remains. And this is just the moment, when the black hole can get its twist. The resulting body with two jets will always rotate with concurrent axis of jets and axis of rotation.
Tennex
1 / 5 (2) Apr 05, 2012
The further evolution of galaxy is rather straightforward. The central white hole is losing its mass gradually, while shrinking itself and becoming more and more dense. At the certain moment it cannot emanate the jets anymore and it changes into cold black hole in the relativistic sense, which we can expect at the heart of Milky Way too. It will just emanate the neutrinos and axions through its poles an its axis of rotation will stabilize.

Note that Andromeda galaxy is substantially younger than the Milky Way and it still exhibits more pronounced activity of its central black holes. In accordance with it its galactic plane is not as flat and regular, as at the case of Milky Way - it's irregular history still manifest itself at the first sight. Please note this is only hypothesis in this moment, but we can met with too many galaxies with irregular jets on the sky.
Tennex
1 / 5 (1) Apr 05, 2012
For example the Centaurus A galaxy is a prototype of galaxy with tilted jets. It's galactic ring is pretty flat and regular, while its jets are asymmetric heavily. http://www.nustar...rusA.jpg

It would indicate, that the direction of jets is really the intrinsic property of central black hole itself - it's not a remnant of some collision. If such a galaxy would be a fresh remnant of the galactic merger, it's galactic plane would be a more irregular too. Such an interpretation would make the magnetars and galactic black holes even more similar at the conceptual level, than astronomers ever expected.
yyz
5 / 5 (1) Apr 06, 2012
"It's galactic ring is pretty flat and regular..."

"If such a galaxy would be a fresh remnant of the galactic merger, it's galactic plane would be a more irregular too."

I guess you're not familiar with infrared imagery of Cen A showing the disk of the cannabalized galaxy is warped into a parallelogram-shape:

http://en.wikiped...arIR.jpg

http://en.wikiped...usA3.jpg

You might want to look at some of the recent kinematic studies of Cen A that also point to a merger, like this 2008 study that found evidence of gas "sloshing" near the center of the galaxy: http://arxiv.org/...95v1.pdf

"Note that Andromeda galaxy is substantially younger than the Milky Way..."

Source?
Kinedryl
not rated yet Apr 06, 2012
Note that Andromeda galaxy is substantially younger than the Milky Way Source?
For example the Wikipedia, I'd guess..

The contemporary cosmology is centered around accretion model, because it's believed, the Big Bang produced the matter in finely divided state and this matter just condensed into larger bodies. The Hubble deep field pictures doesn't support this view, though. The same conceptual shift we can observe at the case of theories of forming the planets from protoplanetary disks with accretion of dust to planetesimals. Or even the evolution is modelled with strictly bottom to up approach by now: the organisms with smaller genomes always come first and they just evolved with mutations into larger ones.

IMO this view will be modified in near future, as the things may be formed with gradual condensation and evaporation of excessive matter from existing sparse objects too. http://phys.org/n...ion.html
yyz
5 / 5 (1) Apr 06, 2012
" Note that Andromeda galaxy is substantially younger than the Milky Way Source?

For example the Wikipedia, I'd guess.."

The wiki entry refers to a 2010 paper that, by means of a a computer simulation, proposed that a major merger between two galaxies occurred between 5 and 9 Gya to form what is now M 31: http://arxiv.org/...0679.pdf

Keep in mind that major (and minor) mergers are thought to have occurred in the formation of the Milky Way as well, much as outlined in the paper regarding M 31, and that the oldest globular clusters in both galaxies are about the same age, ~10 Gyr. I know of no astronomers arguing that M 31 is younger than the Milky Way Galaxy and I see you have no relevant refs to support that.

And no comment on the supposed "flat and regular" galactic ring in Cen A? There are, after all, several recent papers outlining observational evidence for a galactic merger scenario in Cen A. Are you familiar with any of them?
Lurker2358
not rated yet Apr 08, 2012
this is what happens in simulated galaxy collisions.

http://www.youtub...cBlvfjow

As you can see, the longer the model runs, the more the merged Quasar and galaxy continues to contract, pulling back in even the ejected plumes and tails to the core of the system, and collapsing more and more.

If this simulation kept running for 30 more seconds or so, almost the whole system will have collapsed to nothing.

The claim by mainstream that stars and such do not interact is BULLSHIT.

In fact, gravity alone would not do this, as the galaxies relative motion would go into a pogo orbit, conserving relative energy.

The fact that so much dust, planets, and stars are physically colliding with one another is what causes the galaxies to lose relative velocity and fall into one another's black holes.

The plumes ejected in the first and second pass are about as massive as an entire spiral arm of a galaxy...and then they eventually fall all the way back into the core.
Lurker2358
not rated yet Apr 08, 2012
I mean, first pass would likely produce so much radiation and tidal forces that it would destroy all life in either galaxy, nevermind the second and third pass.

The claims by certain supposedly phd level physicists that there are no collisions happening here is absolute ignorant and uneducated remark.

Even after the first pass, you see a gigantic outburst of gas and radiation from the galaxy on the right side, as probably stellar collisions and black holes are producing new stars, supernovas and mini-jets and other forces, exploding away what must be millions of star systems worth of matter.

I just laugh at Kaku and some of the other nut-jobs who claim you wouldn't even know it if two galaxies were colliding. That's just complete ignorance.

I'm not talking about a dwarf galaxy that's not much bigger than a Globular cluster, I mean two REAL galaxies.

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