Abstract
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 language | English |
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Pages (from-to) | 696-703 |
Number of pages | 8 |
Journal | Astrophysical Journal |
Volume | 564 |
Issue number | 2 I |
DOIs | |
State | Published - Jan 10 2002 |
Keywords
- Galaxies: active
- Galaxies: individual (NGC 5128)
- Galaxies: magnetic fields radio lines: galaxies
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science