* Astronomy

Title: Infrared imaging and polarimetric observations of the pulsar wind nebula in G21.5-0.9
Authors: A. Zajczyk, Y.A. Gallant, P. Slane, S.P. Reynolds, R. Bandiera, C. Gouiffès, E. Le Floc'h, F. Comerón, L. Koch Miramond

We present infrared observations of G21.5-0.9 with the Very Large Telescope, the Canada-France-Hawaii Telescope and the Spitzer Space Telescope. Using the VLT/ISAAC camera equipped with a narrow band [Fe II] 1.64 \mu m filter the entire pulsar wind nebula in G21.5-0.9 was imaged. This led to detection of iron line-emitting material in the shape of a broken ring-like structure following the nebula's edge. The detected emission is limb-brightened. We also detect the compact nebula surrounding PSR J1833-1034, both through imaging with the CFHT/AOB-KIR instrument (K' band) and the IRAC camera (all bands) and also through polarimetric observations performed with VLT/ISAAC (Ks band). The emission from the compact nebula is highly polarised with an average value of the linear polarisation fraction P_{L}^{avg} \simeq 0.47, and the swing of the electric vector across the nebula can be observed. The infrared spectrum of the compact nebula can be described as a power law of index \alpha_{IR} = 0.72 ±0.11, and suggests that the spectrum flattens between the infrared and X-ray bands.

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Position (J2000):  RA 18h 33m 33.50s | Dec -10º 34' 06.70"