We quantify the effect of supernova Type Ia peculiar velocities on the derivation of cosmological parameters .
The published distant and local Ia SNe used for the Supernova Legacy Survey first-year cosmology report form the sample for this study .
While previous work has assumed that the local SNe are at rest in the CMB frame ( the No Flow assumption ) , we test this assumption by applying peculiar velocity corrections to the local SNe using three different flow models .
The models are based on the IRAS PSCz galaxy redshift survey , have varying \beta = \Omega _ { m } ^ { 0.6 } / b , and reproduce the Local Group motion in the CMB frame .
These datasets are then fit for w , \Omega _ { m } , and \Omega _ { \Lambda } using flatness or \Lambda CDM and a BAO prior .
The \chi ^ { 2 } statistic is used to examine the effect of the velocity corrections on the quality of the fits .
The most favored model is the \beta = 0.5 model , which produces a fit significantly better than the No Flow assumption , consistent with previous peculiar velocity studies .
By comparing the No Flow assumption with the favored models we derive the largest potential systematic error in w caused by ignoring peculiar velocities to be \Delta w = +0.04 .
For \Omega _ { \Lambda } , the potential error is \Delta \Omega _ { \Lambda } = -0.04 and for \Omega _ { m } , the potential error is \Delta \Omega _ { m } < +0.01 .
The favored flow model ( \beta = 0.5 ) produces the following cosmological parameters : w = -1.08 ^ { +0.09 } _ { -0.08 } , \Omega _ { m } = 0.27 ^ { +0.02 } _ { -0.02 } assuming a flat cosmology , and \Omega _ { \Lambda } = 0.80 ^ { +0.08 } _ { -0.07 } and \Omega _ { m } = 0.27 ^ { +0.02 } _ { -0.02 } for a w = -1 ( \Lambda CDM ) cosmology .