The Crab nebula is a supernova remnant exhibiting a highly polarized synchrotron radiation at radio and millimetre wavelengths .
It is the brightest source in the microwave sky with an extension of 7 by 5 arcminutes , and is commonly used as a standard candle for any experiment which aims to measure the polarization of the sky .
Though its spectral energy distribution has been well characterized in total intensity , polarization data are still lacking at millimetre wavelengths .
We report in this paper high resolution observations ( 18 ^ { \prime \prime } FWHM ) of the Crab nebula in total intensity and linear polarization at 150 GHz with the NIKA camera . NIKA , operated at the IRAM 30 m telescope from 2012 to 2015 , is a camera made of Lumped Element Kinetic Inductance Detectors ( LEKIDs ) observing the sky at 150 and 260 GHz .
From these observations we are able to reconstruct the spatial distribution of the polarization degree and angle of the Crab nebula , which is found to be compatible with previous observations at lower and higher frequencies .
Averaging across the source and using other existing data sets we find that the Crab nebula polarization angle is consistent with being constant over a wide range of frequencies with a value of -87.7 ^ { \circ } \pm 0.3 in Galactic coordinates .
We also present the first estimation of the Crab nebula spectral energy distribution polarized flux in a wide frequency range : 30–353 GHz .
Assuming a single power law emission model we find that the polarization spectral index \beta _ { pol } = – 0.347 \pm 0.026 is compatible with the intensity spectral index \beta = – 0.323 \pm 0.001 .