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Milky Way Magnetic Fields Charted

Soulskill posted more than 2 years ago | from the apparently-we-can-do-that dept.

Space 14

eldavojohn writes "Using radio telescope data, scientists from around the world have plotted the Milky Way Galaxy's magnetic field in the form of Faraday Depth. From the article, 'For 150 years, scientists have measured cosmic magnetic field by observing the Faraday effect. They know that when polarized light passes though a magnetized medium, the plane of polarization turns. This concept is called Faraday rotation. The strength and direction of the magnetic field governs the amount of rotation that occurs. So scientists observe the rotation to investigate the magnetic fields' properties. Radio astronomers study the polarized light from distant radio source, passing through the Milky Way on the way to Earth, in order to measure our Galaxy's magnetic field. By measuring the polarization of the light sources at different frequencies, researchers can determine the amount of Faraday rotation.' In the future, radio telescope technologies like LOFAR, eVLA, ASKAP, MeerKAT and the SKA hope to provide enhanced Faraday rotation data so scientists can better understand turbulence in galactic gas and these galactic magnetic field structures."

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It's a dupe (5, Informative)

Janek Kozicki (722688) | more than 2 years ago | (#38928657)

And it doesn't mention the most important part: that they have improved a lot in the field of information processing & information theory, just to filter out the information from very noisy measurements. They developed a information Hamiltonian and information field theory, interesting stuff http://arxiv.org/pdf/0806.3474v3 [arxiv.org]

dupe's here:
http://science.slashdot.org/story/11/12/07/1811216/new-all-sky-map-shows-the-magnetic-fields-of-the-milky-way [slashdot.org]

Re:It's a dupe (1)

poly_pusher (1004145) | more than 2 years ago | (#38928809)

Hmm, I missed the original. Thanks for the Dup! Fascinating.

Re:It's a dupe (1)

EdIII (1114411) | more than 2 years ago | (#38928959)

Not technically a dupe on Slashdot's part alone.

2/3/2012 10:30 EST - NRL News Release 7-12r
Contact: Donna McKinney, (202) 767-2541

Seems the source is a dupe as well.

Re:It's a dupe (1)

marcosdumay (620877) | more than 2 years ago | (#38930581)

Thanks, I wouldn't have even downloaded the paper without that information.

Re:It's a dupe (1)

hairyfeet (841228) | more than 2 years ago | (#38931797)

For those of us who are not physicists could someone please explain this in English? Because trying to follow this while hitting the Wiki quickly convinced me I'd need about two weeks worth of studying magneto optical effects just to even have half a clue here. No need for car analogies, simple layman's terms would be good.

Why is important? (4, Interesting)

EdIII (1114411) | more than 2 years ago | (#38928931)

I have never heard of measuring the magnetic field of a galaxy or celestial object.

Can an astrophysicist enlighten us on what you can learn with this information?

Re:Why is important? (0)

Anonymous Coward | more than 2 years ago | (#38929341)

So when we send spacecrafts with magnetic HDD's in them we know where it could get erased. Probably.

Re:Why is important? (5, Informative)

jo_ham (604554) | more than 2 years ago | (#38929379)

It helps to understand the chemistry of interstellar space, and much of the information we don't actually know about, and post-big-bang conditions.

For example, the presence of the H3+ ion in diffuse clouds, where it has been detected so clearly exists there, but its formation processes as we understand them currently would suggest it would not form there (only in dense clouds), thus there's clearly a jigsaw piece missing. The current suggestion is that the diffuse clouds can have a "clumpy" consistency, with areas of much higher density. Things like galactic magnetic fields and other effects that can act on material in the clouds can help to explain things like this. (It may not answer the H3+ molecule question, but others like it).

Re:Why is important? (1)

datavirtue (1104259) | more than 2 years ago | (#38933071)

I was talking with someone not to long ago about whether or not magnetic fields can be disturbed if passed through light. This came up in a convo about eavesdropping on network lines, as they mentioned fiber was immune I wondered if you could pass a magnetic field through a fiber line and note a disturbance on some scale allowing you to decode the data. It seems that if light polarization can be changed by a magnetic field that an inverse of this can somehow be possible. Is the polarization change only possible in a vacuum?

Re:Why is important? (5, Informative)

rusty0101 (565565) | more than 2 years ago | (#38929647)

I'm not an astrophysicist, but I am aware of a few things that being able to map out a galactic magnetic field (or collection of fields) can be useful for.

We know that our knowledge of the makeup of galaxies is not complete, and knowing what the magnetic structure looks like can help point us at things that we may have missed. For example Magnatars are a variation of neutron stars that are very powerful magnetic objects. We know where some are based on observations of gamma ray emissions when their magnetic fields untwist (you will need an astrophysicist to explain why the twisting happens) but just their existence and movement within the galaxy should have an observable effect on the galactic magnetic field that may point us towards a better understanding of where and how many there are.

Additionally magnetic fields have an effect on, and are affected by the distribution of matter. So a better understanding of the structure of the galactic magnetic field should give us a more complete understanding of the structure of the galaxy to begin with. They may also help us to understand phenomena that we can see better. For example the arms or spirals of a galaxy are not 'static' relative to the stars in the arm. They are more of an effect of stars circling the galaxy clumping up or building into a wave, (for the bright portions of the arms) or moving apart (for the dim or spaces between the arms.) Having a good picture of the magnetic structure may give us pointers to what is causing these bunching and moving apart effects.

Finally we know that the magnetic field of Earth protects us from various radiation effects from the sun, which has it's own magnetic field that very well is affecting interstellar radiation. What sorts of affects on galactic and intergalactic radiation does the galactic magnetic field (and similar fields in other galaxies) have.

In time we may also be able to determine things like the age of a galaxy based on more than it's composition of stars. The structure of it's magnetic field where we can detect that, may tell us things about the age of it's stars. Do these fields grow with the absolute mass of a galaxy, is it greater or smaller based on the size of the galactic black hole for a galaxy. How do magnetic fields differ based on the structure of the galaxy that generates them.

OT Question: Assburglar syndrome. (-1)

Anonymous Coward | more than 2 years ago | (#38929079)

My roomie has asked me to help him practise the symptoms of Asperger Syndrome, because his employee psych-evaluation is coming up and he's convinced that demonstrating the traits of an aspie will improve his chances of promotion.

Because, as he puts it, "Everyone knows all real genius geeks are aspies".

So I'm thinking about ways to "improve" on his performance, maybe by subtly giving him pointers which will make him look like a closet child-molester or something.

Ideas and/or suggestions?

Re:OT Question: Assburglar syndrome. (-1)

Anonymous Coward | more than 2 years ago | (#38929703)

Act like a spastic pedant. Complain about shit not being a prime number. Or complain that shit is an odd number. Ask women if they have a penis.

its electricity (3, Interesting)

grantspassalan (2531078) | more than 2 years ago | (#38929641)

It's not "gas", but "plasma" carrying electric currents. There is no known way, at least here on earth, to make a magnetic field, except by moving electric charges. In permanent magnets, moving charges are aligned orbiting electrons. Neutral gas can never in all eternity, no matter how dense, make a magnetic field. There are enormous electric currents in the galaxy that give rise to the magnetic fields.

a minor issue (0)

Anonymous Coward | more than 2 years ago | (#38929747)

its 'EVLA', not 'eVLA'

It's not like the array is online or computerized or any more electronic than it already was. The only thing that's different is the computers have been upgraded and the antennas can handle more data. That's about it.

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