First magnetic field detected “outside” of a galaxy

Posted: May 21, 2017 by oldbrew in Astronomy, Astrophysics, Gravity, research
Tags: ,

Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, the largest astronomical project in the world –
Magellanic Clouds near top of image [credit: NASA / Ames]

It’s unimaginably vast: astronomers say ‘this structure is a 75,000 light-year long filament of gas and dust’. Trying to separate out the effects of gravity and magnetism here should be an interesting challenge.

A magnetic field appears to span the space between the Large and Small Magellanic Clouds, the two dwarf galaxies being consumed by our Milky Way Galaxy, reports Sky & Telescope via

For stargazers in the Northern Hemisphere, it’s easy to forget that the Milky Way is actively consuming two dwarf galaxies. Those in the Southern Hemisphere have a front row seat to watch our galaxy wreak havoc on the Large and Small Magellanic Clouds (LMC and SMC).

But there’s more to the story — the dwarfs are not only gravitationally interacting with the Milky Way but with each other as well.

The gravitational effects evident from these interactions can tell us a lot about the history and evolution of these galaxies as well as the environments surrounding them, but gravity isn’t the only force at work here. Magnetic fields play a role as well, one astronomers are still trying to puzzle out.

Now, for the first time, researchers using the Australia Telescope Compact Array radio telescope in New South Wales, Australia, have detected a magnetic field in the space between the Magellanic Clouds.

Called the Magellanic Bridge, this structure is a 75,000 light-year long filament of gas and dust that stretches from the LMC to the SMC. These results are published in the Monthly Notices of the Royal Astronomical Society (full text available).

Detecting the Invisible

Magnetic fields can be found within and around planets and stars but also on the scales of galaxies. We’ve detected galactic magnetic fields in both our own galaxy and in several other disk galaxies, but an extragalactic magnetic field is something else.

This is the first magnetic field detected “outside” of a galaxy.

Continued here.

  1. oldbrew says:

    If 75,000 light years sounds big, there’s this: ‘A colossal ‘sausage’ of magnetism’…

    The largest objects in the universe may be these deep-space magnetic fields

    The researchers’ new radio-wave photos of the “Sausage” and other relics look more esoteric, but they’re perhaps the most detailed images ever taken of such objects.

    The images revealed that the three relics are highly organized, and that the motion of their particles is generating immense magnetic fields— much like a coil of wire in a motor.

    Here’s one of the new images of the “Sausage” relic — the photo shows the intensity of its radio wave emission (red is greater, blue is weaker):

  2. JB says:

    Too bad Halton Arp didn’t live long enough to be vindicated in the flesh.

  3. BoyfromTottenham says:

    Is this magnetic field related to the massive electric currents discovered a couple of years ago, or something else?

  4. JB says:

    @ Totterham

    The twain are inseparable.

  5. oldbrew says:

    Yes, no magnetism without electricity, as a rule. No bar magnets in space AFAIK, but even if there were, their magnetic properties would have to come from somewhere. Astrophysics is no exception to the rule.

  6. RoswellJohn says:

    I think the claim that this is the first magnetic field discovered outside of a galaxy is overrated. The technique of using Faraday Rotation to measure magnetic fields in space has existed for 30-40 years and I know I’ve read of measurements of inter-galactic fields before. They could be the first to measure those particular fields between the two sub-galaxies.

  7. oldbrew says:

    Extragalactic magnetic fields

    Observations are probably still too scarce to reveal the magnitude and distribution of extragalactic magnetic fields. Kronberg (1994) has extensively reviewed all available observations based on synchrotron radiation and its Faraday rotation…Kronberg has speculated about a ubiquitous magnetic field.
    – – –
    Are magnetic fields ignorable?

    At large radii, gravity decreases as R². In contrast, magnetic fields evolve locally due to gas motions. As in the case of the Sun, at large enough radii, magnetic fields may become more important than gravity, or even dominant.
    . . .
    It can be concluded that interpreting rotation curves, while ignoring the influence of magnetic fields may be completely unrealistic. It is therefore remarkable that a fact that may be so far-reaching concerning our cosmological beliefs has been object to such scarce attention.

    The magnetic hypothesis takes this fact into consideration and tries to determine whether magnetic fields alone, without requiring any dark matter, and without modifying our physical laws, are able to explain the observed flat and fast rotation curves. The existence of dark matter cannot be completely excluded, but here we explore the extreme case with no DM at all.
    [bold added]

    ‘magnetic fields evolve locally due to gas motions.’ – Really?

  8. RoswellJohn says:

    OB: ‘magnetic fields evolve locally due to gas motions.’ – Really?

    Astronomers say “gas” instead of plasma because they don’t want to encourage the Plasma Universe people. Outside of our solar system it seems to be illegal for an astronomer to say “plasma”. 🙂

  9. oldbrew says:

    John – sounds like science with the blinkers on :/

    Do meteorites really ‘burn up’ in the atmosphere?

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