We present our observations of SN 2010mb, a Type Ic SN lacking spectroscopic signatures of H and He. SN 2010mb has a slowly-declining light curve (∼600days) that cannot be powered by 56Ni/56Co radioactivity, the common energy source for Type Ic SNe. We detect signatures of interaction with hydrogen-free CSM including a blue quasi-continuum and, uniquely, narrow oxygen emission lines that require high densities (∼109cm−3). From the observed spectra and light curve we estimate that the amount of material involved in the interaction was ∼3M⊙. Our observations are in agreement with models of pulsational pair-instability SNe described in the literature.
@article{arxiv.1309.6496,
title = {Direct evidence for a supernova interacting with a large amount of hydrogen-free circumstellar material},
author = {Sagi Ben-Ami and Avishay Gal-Yam and Paolo A. Mazzali and Maryam Modjaz and Itay Rabinak and Mark Sullivan and Lars Bildsten and Dovi Poznanski and Ofer Yaron and Iair Arcavi and Joshua S. Bloom and Assaf Horesh and Mansi M. Kasliwal and Shrinivas R. Kulkarni and Peter E. Nugent and Eran O. Ofek and Daniel Perley and Robert Quimby and Dong Xu},
journal= {arXiv preprint arXiv:1309.6496},
year = {2015}
}