Chandra Observations of Extreme Mass Loss from the Progenitors of Luminous Type IIn SNe

To determine exposure times, we draw upon our extensive experience with Chandra observations of GRBs and SNe. The exposure times have been calculated to ensure that any non-detections constrain the background density to a factor of �5−10 below that predicted by an extension of the CSM profile measured from optical data at � few × 1015 cm. Such measurements require the exquisite sensitivity of Chandra, and the total time we request on Chandra ACIS-S for late-time observations of 10 luminous Type IIn SNe is 155 ks. As argued above, this moderate amount of time, will allow us to either detect all of the sources (if the CSM extends to � few × 1016 cm) or place strong constraints on the physical extent of the dense CSM and hence on the mass loss history of the progenitors. In the possible case of low signal to noise detections which preclude a measurement of the absorption from the data, we note that the Lx / �2 scaling will allow us to obtain a measurement of the CSM density to a factor of � 1.5 for CSM absorptions spanning 2 orders of magnitude. Upon detection of any X-ray emission from our Type IIn SNe, we plan to propose for additional observations in future Chandra cycles to trace the CSM to larger scales. Since the SNe are a few years old, observations with a gap of � year will be required. We also note that archival Chandra observations of our target fields taken before the SN exploded cannot be used for this proposal.