Probing the Energetics and Environments of Hydrogen-poor Core-Collapse SNe

Envelopestripped, corecollapse SNe (i.e. Type Ibc) have recently enjoyed asurge of interest thanks to their association with GammaRay Bursts (GRBs). Thepeculiar circumstances that enable a small fraction of SNe Ibc to launch arelativistic jet are not understood. Along the same line, the progenitors of SNeIbc and their relation to those of GRBs have yet to be observationallyidentified. Here we propose a continuation of our XMM program, as part of ourmultiwavelength effort, to enable progress. The primary goals are: (i)Constrain the preSN massloss history of the progenitor star by sampling theenvironment around Hstripped corecollapse SNe. (ii) Constrain the presence ofengines driving the explosion of the most energetic SNe Ibc that are NOT observationally associated with GRBs. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]