  We present an analysis of Chandra observations of the position of ten nearby
(< 25 Mpc) type Ia supernovae, taken before the explosions. No sources
corresponding to progenitors were found in any of the observations. We
calculated upper limits on the bolometric luminosities of the progenitors
assuming black-body X-ray spectra with temperatures of 30-150 eV. This is
inspired by the fact that luminous super-soft X-ray sources have been suggested
as the direct progenitors of type Ia supernovae. The upper limits of two
supernovae in our sample are comparable to the luminosities of the brightest
observed super-soft sources, ruling out such sources as the progenitors of
these supernovae. In contrast to Liu et al (2012) we find that for SN2011fe we
can rule out Eddington luminosity systems for black body temperatures as low as
40 eV. Our findings are consistent with statistical studies comparing the
observed type Ia supernova rate to the number of super-soft sources or the
integrated X-ray luminosity in external galaxies. This suggest that either the
progenitors of type Ia supernovae are not accreting, nuclear burning white
dwarfs, or that they do not look like the classical super-soft sources, e.g.
because they are obscured.
