  Mostly multiband photometric transit observations have been used so far to
retrieve broadband transmission spectra of transiting exoplanets in order to
study their atmosphere. An alternative method has been proposed and has only
been used once to recover transmission spectra using chromatic
Rossiter-McLaughlin observations. Stellar activity has been shown to
potentially imitate narrow and broadband features in the transmission spectra
retrieved from multiband photometric observations; however, there has been no
study regarding the influence of stellar activity on the retrieved transmission
spectra through chromatic Rossiter-McLaughlin. In this study with the modified
SOAP3.0 tool, we consider different types of stellar activity features (spots
and plages), and we generated a large number of realistic chromatic
Rossiter-McLaughlin curves for different types of planets and stars. We were
then able to retrieve their transmission spectra to evaluate the impact of
stellar activity on them. We find that chromatic Rossiter-McLaughlin
observations are also not immune to stellar activity, which can mimic broadband
features, such as Rayleigh scattering slope, in their retrieved transmission
spectra. We also find that the influence is independent of the planet radius,
orbital orientations, orbital period, and stellar rotation rate. However, more
general simulations demonstrate that the probability of mimicking strong
broadband features is lower than 25% and that can be mitigated by combining
several Rossiter-McLaughlin observations obtained during several transits.
