Full sky study of diffuse Galactic emission at decimeter wavelenghts*

A detailed knowledge of the Galactic radio continuum is of high interest for studies of the dynamics and structure of the Galaxy as well as for the problem of foreground removal in Cosmic Microwave Background measurements. In this work we present a full-sky study of the diffuse Galactic emission at frequencies of few GHz, where synchrotron radiation is by far the dominant component. We perform a detailed combined analysis of the extended surveys at 408, 1420 and 2326 MHz (by Haslam et al. 1982; Reich 1982; Reich & Reich 1986; Jonas et al. 1998, respectively). Using the technique applied by Schlegel et al. (1998) to the IRAS data, we produce destriped versions of the three maps. This allows us to construct a nearly-full-sky map of the spectral index and of the normalization factor with sub-degree angular resolution. The resulting distribution of the spectral indices has an average of $\bar\beta = 2.695$and dispersion $\sigma_{\beta} = 0.120$. This is representative for the Galactic diffuse synchrotron emission, with only minor effects from free-free emission and point sources. The maps produced in this work are available via ftp at cdsarc.u-strasbg.fr