Bow shock sources close to the Galactic centre
  We provide an up-to-date summary of the current observational and theoretical
studies of stellar bow-shock sources close to the Galactic centre. The symmetry
axis of a bow shock provides the information on the relative motion of the star
with respect to the ambient medium, while the photometry and spectroscopy in
NIR domain give information about the 3D motion of the star. Hence, it is
possible from this data to obtain an estimate on the motion of the ambient
medium. In combination with the estimate of the bow-shock size, it is possible
to infer the valuable information on the density of the hot accretion flow
close to the Galactic centre. In particular, we outline a statistical method to
determine the ambient density slope based on either multiple bow-shock
detections for one star along its orbit or multiple bow-shock detections for
several sources at different distances from Sgr A*.
