fiducial model parameters. We use the diffusive reacceleration scheme in Galprop with Alfvén speed of 36 km/s. These diffusion coefficient values are consistent with those used in the literature to fit cosmic ray data [@Ptuskin:2005ax]. The energy loss coefficient $B(E,\vec{x})$ is calculated in GALPROP. It is dominated by inverse Compton scattering and synchrotron radiation for electrons and positrons in the energy range of interest. The energy loss due to inverse Compton scattering is calculated using the Klein-Nishina cross section with an interstellar radiation field that comes with the GALPROP package, discussed in [@Porter:2005qx; @Strong:1998fr].

Energy loss due to synchrotron radiation is calculated using an exponential form of the galactic magnetic field, B(r,z) = B\_0 f\_C(R)+ (1-f\_C(R) )B\_e\^[-(r-r\_)/r\_b-|z|/z\_b]{} \[eq:B-field\], where $R^2=r^2+z^2$, $B_0$ is the magnetic field at the center of the galaxy and $B_\odot=5\mu {\rm G}$ is the local magnetic field. We choose a characteristic scale $r_b=10$ kpc and $z_b=2$ kpc to be consistent with earlier studies aiming to explain the Haslam data and cosmic ray data [@Strong:1998fr; @Broadbent:1990]. The value $B_0$ and the function $f_C(R)$ encode our ignorance about the magnetic field at the center of the galaxy. Neither the detailed structure nor the value of the magnetic field in 