We predict the performance of the Planck satellite in determining the bulk flow
through kinetic Sunyaev-Zeldovich (kSZ) measurements. As velocity tracers, we
use ROSAT All-Sky Survey (RASS) clusters as well as expected cluster catalogs
from the upcoming missions Planck and eRosita (All-Sky Survey: EASS). We
implement a semi-analytical approach to simulate realistic Planck maps as well
as Planck and eRosita cluster catalogs. We adopt an unbiased kinetic SZ filter
(UF) and matched filter (MF) to maximize the cluster kSZ signal to noise ratio.
We find that the use of Planck CMB maps in conjunction with the currently
existing ROSAT cluster sample improves current upper limits on the bulk flow
determination by a factor ~5 (~ 10) when using the MF (UF). The accuracy of bulk
flow measurement increases with the depth and abundance of the cluster sample:
for an input bulk velocity of 500 km/s, the UF recovered velocity errors
decrease from 94 km/s for RASS, to 73 km/s for Planck and to 24 km/s for EASS;
while the systematic bias decreases from 44% for RASS, 5% for Planck, to 0% for
EASS. The 95% upper limit for the recovered bulk flow direction Delta {alpha}
ranges between 4 circ and 60 circ depending on cluster sample and adopted
filter. The kSZ dipole determination is mainly limited by the effects of thermal
SZ (tSZ) emission in all cases but the one of EASS clusters analyzed with the
unbiased filter. This fact makes the UF preferable to the MF when analyzing
Planck maps.
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