High-resolution imaging of the M87 core

Abstract

The nature of the centre of the elliptical galaxy M87 is still a matter of controversy. To obtain improved spatial resolution we have recorded alternately a number of short-exposure images of the M87 core and several comparison stars with an ISIT camera at the AMOS 1.6-m telescope at Haleakala, Maui. An analysis of selected images (0.54–0.60 arc s FWHM (full width at half maximum)) indicates that there is no significant difference between the apparent widths of the M87 core and the stars. The true core width appears to be definitely <0.3 arc s and probably <0.20 arc s. Thus, we do not observe a hypothetical stellar cusp created by the potential of a massive black hole.