The effect of heavy ions on the dispersion properties of kinetic Alfvén waves in astrophysical plasmas

Context. Spacecraft measurements have shown Kinetic Alfv\'en Waves propagating in the terrestrial magnetosphere at lower wavenormal angles than predicted by linear Vlasov theory of electron-proton plasmas. To explain these observations, it has been suggested that abundant heavy ion populations this region may strong, non-trivial effects allow Alfv\'enic waves to acquire right-handed polarization with respect background magnetic field, as case typical plasma. Aims. We study dispersion properties plasmas stationary phase-space distribution functions different populations. Our extensive numerical analysis allowed us quantify role components on transition from left-hand polarized electromagnetic ion-cyclotron (EMIC) mode right-hand kinetic wave (KAW) mode. Methods. used Vlasov-Maxwell obtain relation for oblique waves. The was obtained numerically considering four oxygen concentrations ranging between 0.0 and 0.2 all propagation angles, a function both wavenumber plasma beta parameter. Results. inclusion O+ ions is found considerably reduce angle EMIC KAW number beta. With increasing concentrations, become more damped specific regions. However, weakly effectively propagate smaller wave-normal case, observations.