language: en

arXiv:0807.2262v1 [astro-ph] 14 Jul 2008

[Astronomy & Astrophysics manuscript no. paper]

[c ESO 2008]

July 14, 2008

Simulating polarized Galactic synchrotron emission at all frequencies the Hammurabi code

A. Waelkens 1 ,? , T. Jaffe 2 , M. Reinecke 1 , F. S. Kitaura 1 , T. A. Enßlin 1
1 Max Planck Institut für Astrophysik (MPA),
Karl-Schwarzschildstr. 1, 85741 Garching, Germany
e-mail: waelkens@mpa-garching.mpg.de
2 Jodrell Bank Centre for Astrophysics, University of Manchester,
Alan Turing Building, Oxford Road, Manchester, M13 9PL, UK

[Received Month ??, ????; accepted Month ??, ????]

ABSTRACT Context. Galactic synchrotron emission, rotation measure (RM) and the deflection of ultra-high-energy-cosmic-rays (UHECR) permit detailed studies of the Galactic magnetic field (GMF). The synchrotron emission has also to be measured in order to be separated from other astrophysicaly interesting signals like the CMB. Aims. We present a publicly available code called hammurabi for generating mock polarized observations of Galactic synchrotron emission for telescopes like LOFAR, SKA, Planck and WMAP, based on model inputs for the GMF, the cosmic-ray density distribution and the thermal electron density. We also present mock UHECR deflection measure (UDM) maps based on model inputs for the GMF. In future, when UHECR sources are identified, this will allow us to define UDM as a GMF probe in a similar way as polarized radio sources permit us to define rotation measures. Methods. To demonstrate the code's abilities mock observations are compared to real data as a means to constrain the input parameters of our simulations with a focus on large-scale magnetic field properties. Results. The Galactic magnetic field models in the literature seem to fail to reproduce any additional observational data which was not included in their design. Conclusions. As expected, attempts at trying to model the synchrotron, UHECR deflection and RM input parameters, show that any additional observational data set greatly increases the constraints on the models. The hammurabi code addresses this by allowing to perform simulations of several different data sets simultaneously, providing the means for a more reliable constraint of the magnetized inter-stellar-medium.

Key words. Radio continuum: ISM ? ISM: mangetic fields ? ISM: cosmic rays

1. Introduction