Zeeman Component Decomposition (ZCD) of polarized spectra: Application for the quiet Sun internetwork magnetic field

TL;DR

The paper introduces Zeeman Component Decomposition (ZCD), a novel method for analyzing polarized spectra in the quiet Sun, enabling improved magnetic field measurements by combining multiple lines and Stokes parameters with enhanced SNR.

Contribution

It extends the NDD technique to handle arbitrary Zeeman splitting and multiple lines, allowing more accurate magnetic field analysis in solar spectropolarimetry.

Findings

Enhanced SNR in spectropolarimetric data.

Ability to analyze multiple lines with arbitrary Zeeman splitting.

Improved determination of magnetic field strengths.

Abstract

Multiline techniques assuming similar line profiles have become a standard tool in stellar astronomy for increasing the signal-to-noise ratio (SNR) of spectropolarimetric measurements. However, due to the widely-used weak field approximation their benefits could not so far be used for solar observations, where a large variety of Stokes profiles emerge from local magnetic fields and measuring weak fields in the quiet Sun remains a challenge. The method presented here permits us to analyze many lines with arbitrary Zeeman splitting and to simultaneously deploy Stokes IQUV spectra to determine a common line profile with the SNR increased by orders of magnitude. The latter provides a valuable constraint for determining separately field strengths for each contributing absorber. This method represents an extension of our recently developed technique of Nonlinear Deconvolution with Deblending (NDD, Sennhauser et al. 2009), which accounts for the nonlinearity in blended profiles. Equipped with all those abilities, ZCD is the perfect tool to further increase the informative value of high-precision polarimetric observations.