Constraints on the presence of a 3.5 keV dark matter emission line from Chandra observations of the Galactic centre

Context. Recent findings of line emission at 3.5 keV in both individual and stacked X-ray spectra of galaxy clusters have been speculated to have dark matter origin.
Aims: If the origin is indeed dark matter, the emission line is expected to be detectable from the Milky Way dark matter halo.
Methods: We perform a line search in public Chandra X-ray observations of the region near Sgr A*. We derive upper limits on the line emission flux for the 2.0-9.0 keV energy interval and discuss their potential physical interpretations including various scenarios of decaying and annihilating dark matter.
Results: While we find no clear evidence for its presence, the upper flux limits are not inconsistent with the recent detections for conservative mass profiles of the Milky Way.
Conclusions: The results depend mildly on the spectral modelling, and strongly on the choice of dark matter profile.