  We study the impact of lensing magnification on the observed
three-dimensional galaxy clustering in redshift space. We used the RayGal suite
of N-body simulations, from which we extracted samples of dark matter particles
and haloes in the redshift regime of interest for future large redshift
surveys. Several magnitude-limited samples were built that reproduce various
levels of magnification bias ranging from s = 0 to s = 1.2, where s is the
logarithmic slope of the cumulative magnitude number counts, in three redshift
intervals within 1 < z < 1.95. We studied the two-point correlation function
multipole moments in the different cases in the same way as would be applied to
real data, and investigated how well the growth rate of structure parameter
could be recovered. In the analysis, we used an hybrid model that combines
non-linear redshift-space distortions and linear curved-sky lensing
magnification. We find that the growth rate is underestimated when
magnification bias is not accounted for in the modelling. This bias becomes
non-negligible for z > 1.3 and can reach 10% at z = 1.8, depending on the
properties of the target sample. In our data, adding the lensing linear
correction allowed us to recover an unbiased estimate of the growth rate in
most cases when the correction was small, even when the fiducial cosmology was
different from that of the data. For larger corrections (high redshifts, low
bias, and high s value), we find that the weak-lensing limit has to be treated
with caution as it may no longer be a good approximation . Our results also
show the importance of knowing s in advance instead of letting this parameter
free with flat priors because in this case, the error bars increase
significantly.
