We investigate the gravitational constraints imposed to dark matter halos in the context of finite temperature scalar field dark matter. We find constraints to produce multiple images by dark matter only, we show that there are differences with respect to the full Bose Einstein condensate halo when the temperature of the scalar field in dark matter halos is taken into account. The non zero temperature allows the scalar field to be in excited states and recently, their existence has proved to be necessary to fit rotation curves of dark matter dominated galaxies of all sizes, it also explained the non universality of the halo density profiles. Therefore, we expect that combining observations of rotation curves and strong lensing systems can give us a clue to the nature of dark matter. Finally, we propose a method to identify the excited state of a strong lens halo, knowing various halo excited states can provide information of the scalar field dark matter halo evolution which can be tested using numerical simulations.

4 pages, 2 figures