SIMBAD references

2007MNRAS.376..549M - Mon. Not. R. Astron. Soc., 376, 549-556 (2007/April-1)

Magnetic field limits and spectral variability in the Circinus galaxy H2O megamasers.

McCALLUM J.N., ELLINGSEN S.P. and LOVELL J.E.J.

Abstract (from CDS):

We have used the Australia Telescope Compact Array (ATCA) to search for polarized emission from the Circinus galaxy H2 O megamasers. No linear or circular polarized emission was detected with 3σ upper limits of 24 and 39 mJy, respectively, corresponding to fractional polarizations of 0.6 and 0.9 per cent for the strongest line. These results allow us to place upper limits on the strength of the nuclear magnetic field of ≤150 mG near the outer edge of the masing disc and ≤360 mG at the inner edge.

Rapid variability, thought to be due to interstellar scintillation, is a well-known feature of the Circinus H2 O megamasers. Our Stokes-I data show evidence for changes in the shape of the maser line spectral profiles, as well as their intensity. In addition to the rapid variations, the maser light curves also exhibit variations with a time-scale of the order of days (although our observations are too short to characterize this well). These behaviours support the hypothesis that the Circinus H2 O megamasers undergo diffractive interstellar scintillation, which has previously only been observed in pulsars and in one active galactic nucleus.


Abstract Copyright: 2007 The Authors. Journal compilation © 2007 RAS

Journal keyword(s): masers - polarization - scattering - galaxies: individual: Circinus

Simbad objects: 8

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