NRAO: Magnetic-Field Discovery; Clues to Galaxy-Formation

[bystander]

Magnetic-Field Discovery Gives Clues to Galaxy-Formation Process
National Radio Astronomy Observatory | 2015 Jun 18

[img3="Combined radio/optical image of galaxy IC 342, using data from both the VLA and the Effelsberg telescope. Lines indicate the orientation of magnetic fields in the galaxy.

Credit: R. Beck, MPIfR; NRAO/AUI/NSF; Graphics: U. Klein, AIfA;
Background image: T.A. Rector, University of Alaska Anchorage
and H. Schweiker, WIYN; NOAO/AURA/NSF."]https://public.nrao.edu/wp-content/uplo ... 2_nrao.jpg[/img3][hr][/hr]

Astronomers making a detailed, multi-telescope study of a nearby galaxy have discovered a magnetic field coiled around the galaxy's main spiral arm. The discovery, they said, helps explain how galactic spiral arms are formed. The same study also shows how gas can be funneled inward toward the galaxy's center, which possibly hosts a black hole.

"This study helps resolve some major questions about how galaxies form and evolve," said Rainer Beck, of the Max-Planck Institute for Radio Astronomy (MPIfR), in Bonn, Germany.

The scientists studied a galaxy called IC 342, some 10 million light-years from Earth, using the National Science Foundation's Karl G. Jansky Very Large Array (VLA), and the MPIfR's 100-meter Effelsberg radio telescope in Germany. Data from both radio telescopes were merged to reveal the magnetic structures of the galaxy.

The surprising result showed a huge, helically-twisted loop coiled around the galaxy's main spiral arm. Such a feature, never before seen in a galaxy, is strong enough to affect the flow of gas around the spiral arm.

"Spiral arms can hardly be formed by gravitational forces alone," Beck said. "This new IC 342 image indicates that magnetic fields also play an important role in forming spiral arms."

The new observations provided clues to another aspect of the galaxy, a bright central region that may host a black hole and also is prolifically producing new stars. To maintain the high rate of star production requires a steady inflow of gas from the galaxy's outer regions into its center. ...

Twisted magnetic loop in the Giraffe galaxy IC 342
Max Planck Institute for Radio Astronomy | 2015 Jun 18

Magnetic fields in the nearby spiral galaxy IC 342: A multi-frequency radio polarization study - Rainer Beck

• Astronomy & Astrophysics 578 A93 (June 2015) DOI: 10.1051/0004-6361/201425572
  arXiv.org > astro-ph > arXiv:1502.05439 > 18 Feb 2015 (v1), 28 May 2015 (v3)