VLA H I Zeeman observations of Centaurus A

A. P. Sarma, T. H. Troland, M. P. Rufen

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


We present H I absorption observations toward the nucleus and neighboring radio features of Centaurus A, with the aim of studying the magnetic field using the Zeeman effect. The H I profiles toward the nucleus reveal for the first time a broad absorption component that extends up to 635 km s -1 and is centered near 583 km s-1. This broad component may be a blend of absorption in several clouds located in the ∼100 pc radius circumnuclear ring of Cen A. We set upper limits on the line-of-sight magnetic field (Blos) in Cen A in the regions traced by the H I absorption components. The best value (fit ± 1 σ error) for B los in the dust lane is -3 ± 7 μG. For the redshifted narrow line width components observed toward the nucleus, Blos is ∼ 10 ± 20 μG. If we assume the spin temperature Ts ≤ 50 K in these redshifted clouds, our analysis shows that the magnetic fields will be energetically significant if Blos ≥ 5 μG for cloud sizes around a few parsecs or larger.

Original languageEnglish
Pages (from-to)696-703
Number of pages8
JournalAstrophysical Journal
Issue number2 I
StatePublished - Jan 10 2002


  • Galaxies: active
  • Galaxies: individual (NGC 5128)
  • Galaxies: magnetic fields radio lines: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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