Galactic nuclei offer some indication of axionlike particles
May 28, 2009 By Miranda Marquit(PhysOrg.com) -- “Axionlike particles are interesting because they come up regularly when scientists study string theory. By looking at their properties, you hope to learn about string theory, or some other unified theory of physics. From a cosmological point of view, axionlike particles are of interest because they could be connected to dark energy,” Clare Burrage tells PhysOrg.com. The main hiccup in this study of axionlike particles, however, is the fact that their existence - much like their cousins, axions - has yet to be proven.
Burrage is a scientist at Deutsches Elektonen-Synchrotron DESY in Hamburg, Germany. She believes that some cosmological evidence for axionlike particles might have been found. Along with Anne-Christine Davis at the Centre for Mathematical Sciences in Cambridge, U.K., and Douglas Shaw at Queen Mary University of London, Burrage has been studying luminosity relations in active galactic nuclei. The team believes that their results offer a good case for the existence of axionlike particles, which are thought to have low mass and weak interactions. Their work is available in Physical Review Letters: “Active Galactic Nuclei Shed Light on Axionlike Particles.”
“For a long time, it has been speculated that a magnetic field could be used to change photons into axionlike particles. It is possible to look for these particles in the laboratory, and it is also possible to look for them using astronomy. We are looking for axionlike particles in astronomy, first by comparing observations of active galactic nuclei to what we expect to be the effects of the presence of axionlike particles.”
Active galactic nuclei are compact regions at the centers of galaxies. These nuclei are characterized by higher than normal luminosity. Using galactic centers for reference has long been a practice when discovering distant objects and determining cosmic evolution. Burrage and her peers suggest that active galactic nuclei appear dimmer than they should, due to the presence of axionlike particles. “We have seen in the past that if photons pass through a magnetic field, like one might have near galactic nuclei, and they are converted to axionlike particles, you would lose a lot of light,” she explains. “You would see a much dimmer object than expected. That is what we are seeing when we look at the precision measurements we have studied.”
Burrage points out that, while the results of this data crunching are encouraging, they are not conclusive. “The problem with astronomy is that you can’t go out and poke the galaxy,” she says. “There’s a lot about the physics that we don’t understand. There could be another explanation that mimics the effects we are looking for. We need to see it in the lab as well, if we want to back up our assertion that we are dealing with axionlike particles.”
Right now, there are experiments going on in many laboratories, attempting to determine whether axionlike particles really do exist. One is happening at CERN, and that is the experiment Burrage is most interested in. “The experimenters are using what is called the CERN Axion Solar Telescope,” she says. “It has a cap on the end of a telescope pointed at the sun that would keep out photons. Axionlike particles, though, would pass through the cap. Then a magnetic field would be passed through the telescope, changing any axionlike particles into photons. If you could see light, even with the cap on, it would be a good indicator of the existence of these particles.” Other experiments are going on at Fermi Lab and at DESY, and involve a similar process that would result in the appearance of light “passing through” a thick barrier.
At the present time, though, Burrage and her colleagues are interested in looking at the dimming results of other astronomical objects. “We are interested in the lab results of the experiments with axionlike particles, but we are not involved. Instead, we are looking to see if other types of astronomical objects are affected as the way active galactic nuclei are. If these effects are seen in observations of other objects, the case for axionlike particles is strengthened.”
More information: Clare Burrage, Anne-Christine Davis, Douglas J. Shaw, “Active Galactic Nuclei Shed Light on Axionlike Particles,” Physical Review Letters (2009). Avialable online: http://link.aps.org/doi/10.1103/PhysRevLett.102.201101 .
Copyright 2009 PhysOrg.com.
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Mar 03, 2008 |
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could someone clarify this for me and my cousin daryl and my other cousin daryl
Or is there some hitch in that the magnetic fields required have to be so strong that nobody can make them yet?
> tried before now... magnetic fields required have to > be so strong
Good question, one does indeed need strong magnetic fields (~ few teslas over a range of few metres) but I believe that the Cern Solar Axion Telescope has been running since about 2002. Its already placed some of the tightest constraints on axionlike particles, but the axionlike particles suggested by this astrophysical signal are too weakly interacting for previous runs of CAST to have seen. I think they're improving the experiment now, and with a bit of luck the improved version should be able to see or rule out this putative axion signal.
"In the Italian PVLAS experiment polarized light propagates through the magnetic field of a 5 Telsa dipole magnet"
%u201CThe problem with astronomy is that you can%u2019t go out and poke the galaxy,%u201D she says. %u201CThere%u2019s a lot about the physics that we don%u2019t understand. There could be another explanation that mimics the effects we are looking for."
Now there is a real scientist. I would that others would show this degree of skepticism and humility before charging out the door and insisting that nobody should dare to disagree with their predictions. cough AGW Climatologists cough
Now there is a real propagandist. A particle physics article being used as a springboard for more GWD propaganda.
Would you guys mind taking your propaganda back to the metereology articles. I already bagged one troll this week in a discussion about micro-paleontology. You have enough places to write your propaganda. Keep it there please.
Ethelred
Burrage's quote merits the compliment I paid her. And these comment sections are intended to allow discussion and contrast of the content presented.
Science benefits from disagreement freely expressed, not demands for conformity.
I said nothing about the compliment. Though I will now. It was a bit over the top considering Burrage was simply making a joke about the difficulty of getting real data in some areas of science.
If that was you did I wouldn't have commented. You used it as a springboard for off-topic AGD propaganda. Emphasis on OFF-TOPIC.
Disagreement rationally and intelligently expressed with data to back it up. You are missing the data and the point which is that global warming was not involved here till YOU brought it up.
Its getting to be really annoying the way the deniers can't make single post without propagandizing the whole site. If you posted that on a thread where it was relevant I might have disagreed with it but I wouldn't have suggested that you shouldn't have made the comment.
It didn't belong here. Its that simple.
Ethelred
What happening inside nucleus of atoms? All a time?
There is only energy. How this energy keeping this energy in same density? What is that force and how is working?
Why we dont have a theory of everything yet?
Are we have a wrong model an atom?
Maybe space dont expanding?
Maybe energy expanding/exploding all a time in space who dont changes at all?
Red shift mide proof, also photons expanding and emit energy. With that energy, photons pushing themselfs same way what phtons expanding. When light is old, photons start pushing themselfs faster what old phtons expanding?
You cant proof, space expanding. You cant make any test with space!
Photons do not experience time so they can't age.
Wrong. Next you will be claiming that men have never been to the Moon.
Ethelred
Sorry Dude(Ethelred), you can only infer that space is expanding. There is no proof.
I bet you believe in redshift as a distance indicator even though objects of disparate redshifts have been found together, as well as a high redshift object in front of a low redshift object.
By that standard you can't prove anything except a math problem.
It IS an indicator. Not a guaranteed measurement. Based on the assumption that things work the same farther out than we can measure. You won't get far assuming that everything we can't test behaves according to different laws. Using more than one kind of candle improves the odds of the assumption being correct.
Care to post a link? I bet the claims are turn out to be open to question or in some cases already shown to wrong, such as apparent superluminal jets. Still I could be wrong on that so post a link please. Preferably to something reliable and not one of the crank sites that are so popular with some around here.
Ethelred
You cant told for me, how space expanding.
i can feel, see, hear. taste and smell energy.
You cant see, hear, taste, smell or feel space.
I can make test with energy.
You cant make a test with space.
"Science" people jus about BELIEVE, sapce expanding.
Big bang theory = Monster of spaghetti
Extra dimensions, expanding and curving space, dark matter and dark energy.
it is time to wake up, dudes!
changes of pressure.
http://onesimplep....com/296
Agree. http://www.venganza.org/
The plasma people can back up your statement with a lot of cold (but above 0degK), hard facts.
And a lot of utter nonsense. The Sun is powered by fusion. All claims to the contrary have included large portions of hand waving, at best.
Nice link. Fun site. Nevertheless the Big Bang has Big Evidence supporting it. It is no Giant Orbiting Aardark.
Ethelred