Using an idealized set-up , we investigate the dynamical role of cosmic rays ( CRs ) in the early stages of galactic outflows for galaxies of halo masses 10 ^ { 8 } , 10 ^ { 11 } and 10 ^ { 12 } M _ { \odot } .
The outflow is launched from a central region in the galactic disk where we consider three different constant star formation rates ( 0.1 , 1 , and 10 M _ { \odot } yr ^ { -1 } ) over a dynamical timescale of 50 Myr .
We determine the temperature distribution of the gas and find that CRs can reduce the temperature of the shocked gas , which is consistent with previous results .
However , we show that CRs do not have any noticeable effect on the mass loading by the outflow .
We find that CRs can reduce the size of the outflow , which contradicts previous claims of efficient dynamical impact of CRs ; however , it is consistent with earlier theoretical models of cosmic ray driven blastwave as well as stellar wind .
We discuss the dependence of our results on CR injection prescriptions and compare them with earlier studies .
We conclude that in the early stages of galactic outflows the dynamical role of CRs is not important .