Bibcode
Asensio Ramos, A.
Bibliographical reference
The Astrophysical Journal, Volume 701, Issue 2, pp. 1032-1043 (2009).
Advertised on:
8
2009
Journal
Citations
75
Refereed citations
59
Description
Some recent investigations of spectropolarimetric observations of the
Zeeman effect in the Fe I lines at 630 nm carried out with the Hinode
solar space telescope have concluded that the strength of the magnetic
field vector in the internetwork regions of the quiet Sun is in the hG
regime and that its inclination is predominantly horizontal. We
critically reconsider the analysis of such observations and carry out a
complete Bayesian analysis with the aim of extracting as much
information as possible from them, including error bars. We apply the
recently developed BAYES-ME code that carries out a complete Bayesian
inference for Milne-Eddington atmospheres. The sampling of the posterior
distribution function is obtained with a Markov Chain Monte Carlo scheme
and the marginal distributions are analyzed in detail. The
Kullback-Leibler divergence is used to study the extent to which the
observations introduce new information in the inference process
resulting in sufficiently constrained parameters. Our analysis clearly
shows that only upper limits to the magnetic field strength can be
inferred, with fields in the kG regime completely discarded.
Furthermore, the noise level present in the analyzed Hinode observations
induces a substantial loss of information for constraining the azimuth
of the magnetic field. Concerning the inclination of the field, we
demonstrate that some information is available to constrain it for those
pixels with the largest polarimetric signal. The results also point out
that the field in pixels with small polarimetric signals can be nicely
reproduced in terms of a quasi-isotropic distribution.
Related projects
Magnetism, Polarization and Radiative Transfer in Astrophysics
Magnetic fields pervade all astrophysical plasmas and govern most of the variability in the Universe at intermediate time scales. They are present in stars across the whole Hertzsprung-Russell diagram, in galaxies, and even perhaps in the intergalactic medium. Polarized light provides the most reliable source of information at our disposal for the
Tanausú del
Pino Alemán