The Bose-Einstein condensate/scalar field dark matter model , considers that the dark matter is composed by spinless-ultra-light particles which can be described by a scalar field .
This model is an alternative model to the \Lambda -cold dark matter paradigm , and therefore should be studied at galactic and cosmological scales .
Dwarf spheroidal galaxies have been very useful when studying any dark matter theory , because the dark matter dominates their dynamics .
In this paper we study the Sextans dwarf spheroidal galaxy , embedded in a scalar field dark matter halo .
We explore how the dissolution time-scale of the stellar substructures in Sextans , constrain the mass , and the self-interacting parameter of the scalar field dark matter boson .
We find that for masses in the range ( 0.12 < m _ { \phi } < 8 ) \times 10 ^ { -22 } eV , scalar field dark halos without self-interaction would have cores large enough to explain the longevity of the stellar substructures in Sextans , and small enough mass to be compatible with dynamical limits .
If the self-interacting parameter is distinct to zero , then the mass of the boson could be as high as m _ { \phi } \approx 2 \times 10 ^ { -21 } eV , but it would correspond to an unrealistic low mass fot the Sextans dark matter halo .
Therefore , the Sextans dwarf galaxy could be embedded in a scalar field/BEC dark matter halo with a preferred self-interacting parameter equal to zero .