C.D.S. - SIMBAD4 rel 1.7 - 2020.07.08CEST02:32:48

2013A&A...558A..45H - Astronomy and Astrophysics, volume 558A, 45-45 (2013/10-1)

Non-Zeeman circular polarization of CO rotational lines in SNR IC 443.


Abstract (from CDS):

We study interstellar magnetic fields by measuring the polarization in molecular spectral lines and thermal emission of dust. We report detection of non-Zeeman circular polarization and linear polarization levels of up to 1% in the 12CO spectral line emission in a shocked molecular clump around the supernova remnant (SNR) IC 443. We examine our polarization results to confirm that the circular polarization signal in CO lines is caused by a conversion of linear to circular polarization, consistent with anisotropic resonant scattering. In this process background, linearly polarized CO emission interacts with similar foreground molecules aligned with the ambient magnetic field and scatters at a transition frequency. The difference in phase shift between the orthogonally polarized components of this scattered emission can cause a transformation of linear to circular polarization. We compared linear polarization maps from the dust continuum, which were obtained with PolKa at APEX, and 12CO (J=2->1) and (J=1->0) from the IRAM 30-m telescope. We found no consistency between the two sets of polarization maps. We then reinserted the measured circular polarization signal in the CO lines across the source to the corresponding linear polarization signal to test whether the linear polarization vectors of the CO maps were aligned with those of the dust before this linear to circular polarization conversion. After the flux correction for the two transitions of the CO spectral lines, the new polarization vectors for both CO transitions aligned with the dust polarization vectors, establishing that the non-Zeeman CO circular polarization is due to a linear to circular polarization conversion.

Abstract Copyright:

Journal keyword(s): polarization - techniques: spectroscopic - ISM: magnetic fields - ISM: clouds - ISM: individual objects: IC 443

Simbad objects: 5

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Number of rows : 5

N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
1 M 1 SNR 05 34 31.94 +22 00 52.2           ~ 5594 4
2 NAME OMC-1 MoC 05 35 14 -05 22.4           ~ 1015 2
3 NAME Orion-KL SFR 05 35 14.16 -05 22 21.5           ~ 2001 1
4 Ass Gem OB 1 As* 06 09.8 +21 35           ~ 166 0
5 IC 443 SNR 06 18 02.7 +22 39 36           ~ 1100 1

    Equat.    Gal    SGal    Ecl

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