Thread: Galactic Map of Magnetic Fields Charted

From Physorg



The sky map of the Faraday effect caused by the magnetic fields of the Milky Way. Red and blue colors indicate regions of the sky where the magnetic field points toward and away from the observer, respectively. The band of the Milky Way (the plane of the Galactic disk) extends horizontally in this panoramic view. The center of the Milky Way lies in the middle of the image. The North celestial pole is at the top left and the South Pole is at the bottom right.


Scientists at the Naval Research Laboratory (NRL) are part of an international team that has pooled their radio observations into a database, producing the highest precision map to date of the magnetic field within our own Milky Way galaxy.

The team, led by the Max Planck Institute for Astrophysics (MPA), used the database they created and were able to apply information theory techniques to produce the map, explains NRL's Dr. Tracy Clarke, a member of the research team. "The key to applying these new techniques is that this project brings together over 30 researchers with 26 different projects and more than 41,000 measurements across the sky. The resulting database is equivalent to peppering the entire sky with sources separated by an angular distance of two full moons." This incredible volume of data results in a new, unique all-sky map that gives scientists the ability to measure the magnetic field structure of the Milky Way in unparalleled detail.

The map shows scientists a quantity known as Faraday depth, a concept that depends on magnetic fields along a specific line of sight. The research team created the map by combining the more than 41,000 individual measurements using a unique image reconstruction technique. The researchers at MPA are specialists in the new discipline of information field theory. Dr. Tracy Clarke, working in NRL's Remote Sensing Division, is part of the team of international radio astronomers who provided the radio observations for the database. The new, high-precision map not only shows the Galactic magnetic field's structure on large scales, it also reveals small-scale features that help scientists better understand turbulence in the Galactic gas.

The Milky Way, along with all other galaxies, possesses magnetic fields. Until now, scientists have been puzzled over the origin of these galactic magnetic fields. The assumption was that the magnetic fields were created by processes where mechanical energy is converted into magnetic energy. These same kinds of processes occur in the interior of the Earth and the Sun. The map that the team has created will give scientists valuable knowledge about the structure of Galactic magnetic fields throughout the Milky Way.

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