Upper limits on the luminosity of the progenitor of Type Ia supernova SN 2014J

We analysed archival data of Chandra pre-explosion observations of the position of SN 2014J in M82. No X-ray source at this position was detected in the data, and we calculated upper limits on the luminosities of the progenitor. These upper limits allow us to firmly rule out an unobscured supersoft X-ray source progenitor with a photospheric radius comparable to the radius of white dwarf near the Chandrasekhar mass (similar to 1.38 M-circle dot) and mass accretion rate in the interval where stable nuclear burning can occur. However, due to a relatively large hydrogen column density implied by optical observations of the supernova, we cannot exclude a supersoft source with lower temperatures, kT less than or similar to 70 eV. We find that the supernova is located in the centre of a large structure of soft diffuse emission, about 200 pc across. The mass, similar to 3 x 10(4) M-circle dot and short cooling time of the gas, tau(cool) similar to 8 Myr, suggest that it is a supernova-inflated superbubble, associated with the region of recent star formation. If SN 2014J is indeed located inside the bubble, it likely belongs to the prompt population of Type Ia supernovae, with a delay time as short as similar to 50 Myr. Finally, we analysed the one existing post-supernova Chandra observation and placed upper limit of similar to(1-2) x 10(37) erg s(-1) on the X-ray luminosity of the supernova itself.