No X-Rays from the Very Nearby Type Ia SN 2014J: Constraints on Its Environment

Deep X-ray observations of the post-explosion environment around the very nearby Type Ia SN 2014J (d _L = 3.5 Mpc) reveal no X-ray emission down to a luminosity L_x < 7 × 10³⁶ erg s^-1 (0.3-10 keV) at δt ~ 20 days after the explosion. We interpret this limit in the context of inverse Compton emission from upscattered optical photons by the supernova shock and constrain the pre-explosion mass-loss rate of the stellar progenitor system to be \dot{M}<10^-9 {{M}_⊙ yr^-1} (for wind velocity v_w = 100 km s^-1). Alternatively, the SN shock might be expanding into a uniform medium with density n _CSM < 3 cm^-3. These results rule out single-degenerate (SD) systems with steady mass loss until the terminal explosion and constrain the fraction of transferred material lost at the outer Lagrangian point to be <=1%. The allowed progenitors are (1) white dwarf-white dwarf progenitors, (2) SD systems with unstable hydrogen burning experiencing recurrent nova eruptions with recurrence time t < 300 yr, and (3) stars where the mass loss ceases before the explosion.